CN1090796C - Method for measuring actual space length by camera, optical system correction method and reference standard - Google Patents

Abstract

The present invention provides a method for precisely measuring the average actual space length of a pixel, and also provides an optical system correction method for measuring or adjusting an image pickup range, measuring image distortion and correcting the image distortion according to the result. This is divided by the number of pixels in that direction to give the average actual spatial length of a pixel in the grid image. The image pickup range can be calculated and adjusted, and the distortion distribution of the obtained image can be calculated and corrected by using the distortion distribution, so that the optical system can be corrected and the precision measurement can be performed.

Description

Method for measuring actual space length by camera, optical system correction method and reference standard

The present invention relates to the correction of the optical system of the image processing system, in particular to the measurement method of the actual space length, the correction method of the optical system and the reference gauge based on the image of the reference gauge captured by the camera through the optical system.

In recent years, the use of image processing systems for measurement and inspection at development sites and manufacturing sites has increased due to the advancement in speed and price reduction of image processing devices. Fig. 18 is a configuration diagram of a general processing system.

In the figure, the position of the sample (not shown) set in the position adjusting device 27 can be adjusted by the device 27 . The imaging device 24 is specifically a CCD camera, a line sensor, etc., and images a sample as an image. The optical system 23 images the sample on the imaging plane of the imaging device. The image memory 25 stores the obtained images. The arithmetic unit 26 performs predetermined processing on the obtained image.

With such a configuration, an image of a sample is captured, the obtained image is processed, and measurements are performed.

As a correction method for the optical system 23 of such a system, there is, for example, a method of imaging a line graph or a scale whose length is known, and calculating a magnification based on the length of the image. However, due to image distortion caused by the optical system 23 used for imaging, if the obtained image is measured as it is, the measurement result will contain errors. Therefore it is necessary to correct the distortion. In the technique described in Japanese Patent Application Laid-Open No. Sho 63-222247, a method for correcting distortion of a captured image of a radiographic imaging device is disclosed. In this method, a distortion measuring member having a radiation absorption coefficient is captured with the resulting image in a dot pattern. Compare the image point position of the obtained image with the real image point position that should have been imaged, and use the method of interpolation to make a distortion correction table to correct the image.

In recent years, however, audio-visual devices have been miniaturized, as is the trend shown in portable tape playback devices and movies. On the other hand, video recording devices such as movies and stationary VTRs are required to record for a long time. An important technology to satisfy such a request is high-density audio-visual recording. In order to maintain compatibility between recording and playback devices in various specifications such as VTR and DAT, and to realize high-density recording, how to perform high-linear track recording is an important technology. Therefore, a method of checking the linearity of the track is important. The existing technology of the magnetic recording track inspection device described in Japanese Patent Laying-Open No. 3-222102 is to regard the recording track as a grating, regard the curvature of the track as the deformation of the grating, and adopt the method of diffraction fringe-grating image analysis Method for making track linearity measurements. The basic configuration of the conventional magnetic recording track inspection device is substantially the same as the configuration example of the image processing system shown in FIG. 18 .

In the correction operation of such a conventional magnetic recording track inspection device, the actual spatial length corresponding to one pixel can be obtained from the set magnification of the optical system 23 . The actual spatial length referred to here means the actual length of the subject in an image obtained by an image processing system such as a magnetic recording track inspection device. On the other hand, in the magnetic recording track inspection device, it is necessary to make the imaging range correspond to the effective range of the track stripes of the magnetic tape (not shown). The adjustment operation of the imaging range is to perform a general adjustment while looking at the imaging range of the image captured by the imaging device 24 .

In addition, the confirmation method of the measurement accuracy of the magnetic recording track inspection device obtained as a result of such a calibration operation is as follows.

First, the displacement distribution of the track stripes on the actual tape in the tape width direction is measured with a magnetic recording track inspection device. Next, the displacement distributions of the same tapes at the same measurements were determined using microscopy methods. Microscopic Inspection Method The track edge position in the tape width direction was visually measured using a microscope. This result is compared with the ideal track edge position to find the displacement distribution of the track stripes. These two measurement results are compared to confirm the measurement accuracy.

However, the set magnification of the optical system 23 in FIG. 18 does not exactly match the magnification of the actually obtained image. For this reason, for example, in the measurement of the order of 1 micron or less, such as the linear measurement of the track stripes, it is not possible to obtain a magnification with sufficient accuracy or an average actual space length of one pixel. On the other hand, in the magnification measurement by the imaging of the line graph and the scale, only data on one line can be obtained.

Also, in the conventional imaging range adjustment method, the imaging range can only be roughly adjusted.

Also, regarding the correction of image distortion, in the measurement of image distortion using a dot pattern as described in Japanese Patent Application Laid-Open No. 63-222247, the number of data acquisitions in the measurement area is limited, since only these points can be increased. Interpolation points, the precision is not good.

In addition, there is no description regarding the correction method in the technology described in Japanese Patent Laid-Open No. 3-222102. Use magnetic tape as the measurement target for accuracy verification. Since the displacement distribution of the tape stripes on the tape is not known, it must be determined in advance using a microscope. However, the measurement accuracy of the inspection method using a microscope depends on the movement accuracy of the stage on which the magnetic tape is placed. Therefore, the measurement accuracy is only about ±0.3 microns at most, and inspections higher than this cannot be performed. Also, since the magnetic tape is very thin, it will deform if an excessive load is applied during handling. Therefore, there are problems such as changes in the displacement distribution, and the displacement distribution cannot be said to be known. Therefore, the correct measurement accuracy of the magnetic recording track inspection device cannot be confirmed.

The object of the present invention is to, in view of the above existing problems, provide a method for precisely measuring the average actual space length of a pixel, provide the measurement or adjustment of the imaging range, and the measurement of image distortion and the correction of image distortion with the feedback of the result. System calibration method.

The object of the present invention is also to provide, for the measurement or adjustment of the average actual space length and imaging range of a pixel, and the measurement of image distortion and the feedback of the result to realize the magnetic recording track inspection without the influence of image distortion. A calibration method and reference gauge for a recording track inspection device.

It is also an object of the present invention to provide a method for realizing these optical system correction methods and magnetic recording track inspection device correction methods with high precision.

Another object of the present invention is to provide a high-precision measurement accuracy confirmation method and a reference gauge used in the measurement accuracy confirmation.

The method for measuring the actual space length using an imaging device of the present invention takes the direction parallel to the grid line and/or the direction perpendicular to the grid line as the horizontal scanning direction, and uses the image formed by the optical system for the grating pattern containing the specified grid line. Take an image with an imaging device to obtain a raster image. In any area within the inspection area of the grid image, calculate the number of grid lines corresponding to one pixel column of the imaging device in the direction perpendicular to the grid lines for each pixel column, and then average them to calculate the grid line number The average value of the number. Calculate the actual space length of any area in the direction perpendicular to the grid lines by multiplying the grid spacing by the average number of grid lines. Divide the actual space length by the number of pixels in the same direction to calculate the average actual space length of one pixel in the direction perpendicular to the grid lines in the grid image. The optical system can be corrected on the basis of the thus obtained average actual spatial length of a pixel.

Also, as the track pattern of the magnetic recording track on the magnetic tape recorded and visualized by the magnetic recording and reproducing device, the reference gauge for the magnetic recording track inspection device for imaging and checking with the imaging device has on its surface, as the reference gauge. A line drawing of the datum of the coordinate system, and a raster drawing drawn at equal intervals at a specified angle with respect to the datum direction of the line drawing. The reference gauge used, the patterns have a thickness such that their surface is substantially equal to the height position of the magnetic tape when it is set on the magnetic recording track inspection device. This makes it possible to check the measurement accuracy with high precision.

FIG. 1 is a configuration diagram of a correction system of an optical system in an embodiment of the present invention.

FIG. 2 shows an example of a raster pattern of an embodiment of the present invention.

FIG. 3 is a block diagram showing the functions of the optical system calibration method according to the embodiment of the present invention.

Figure 4 is an illustration of a raster image of an embodiment of the present invention.

FIG. 5 is an explanatory diagram of line thinning processing according to the embodiment of the present invention.

Fig. 6 is an example of a raster pattern showing an embodiment of the present invention

Fig. 7 is an example of a raster pattern showing an embodiment of the present invention.

FIG. 8 is an explanatory diagram of an image correction method according to an embodiment of the present invention.

Fig. 9 is a block diagram of a magnetic recording track inspection device according to an embodiment of the present invention.

Fig. 10 shows the pattern on the datum gauge of the embodiment of the present invention.

11 is a functional block diagram of an optical system calibration method of the magnetic recording track inspection device according to the embodiment of the present invention.

Fig. 12 shows an example of a track stripe image of a magnetic tape according to an embodiment of the present invention.

Fig. 13 shows an example of the luminance distribution of a certain line in the grid image according to the embodiment of the present invention.

Fig. 14 shows an example of a power spectrum obtained by performing Fourier transform on the luminance distribution of a certain line in the raster image according to the embodiment of the present invention.

Fig. 15 is an explanatory diagram of a method of correcting a track stripe displacement distribution according to an embodiment of the present invention.

Fig. 16 shows a reference gauge used to confirm measurement accuracy in an example of the present invention.

Fig. 17 is an example of a pattern on a datum gauge according to an embodiment of the present invention.

Fig. 18 is a configuration diagram of a general image processing system.

The method for measuring the actual space length using an imaging device of the present invention includes the first step: taking the direction parallel to the grid line and/or the direction perpendicular to the grid line as the horizontal scanning direction, and using the known value The image formed by the optical system of the grating lines arranged at equal intervals is photographed by the imaging device to obtain the grating image. The second step: in any area within the inspection area of the grating image, calculate for each pixel column The number of grid lines corresponding to one pixel row of the imaging device in the direction perpendicular to the grid lines, the third step: averaging the number of grid lines for each pixel row obtained in the second step, Calculate the average value of the grid line number, the 4th step: multiply the grid line number average value by the grid spacing, calculate the actual space length of the arbitrary area in the direction perpendicular to the grid line, the 5th step: put The actual space length is divided by the number of pixels in the vertical direction of the grid line in the arbitrary area to calculate the average actual space length of one pixel in the direction perpendicular to the grid line in the grid image.

The second step may also include, in the inspection area, performing Fourier transform in the vertical direction of the grid lines in the grating diagram, extracting the fundamental frequency component from the obtained frequency spectrum, and inverting the extracted fundamental frequency component. Fourier transform, a step of calculating the phase value distribution of said grating pattern from the ratio of the real part to the imaginary part of the result thereof, and using said phase distribution, calculating the phase value perpendicular to said grating in any area of said examination area The step of the number of raster lines for each pixel column of the line.

The method for measuring the actual space length on the magnetic recording track using the imaging device of the present invention is to record the magnetic recording and reproducing device and carry out the magnetic track pattern of the magnetic recording track on the magnetic tape that has been visualized, and the optical system when the imaging device is used for imaging by the optical system. The calibration method of the system has the first step: the grating pattern containing the grating lines arranged at equal intervals with a known value of the grating pitch and parallel to the horizontal scanning direction of the imaging device and/or perpendicular to the direction is set in the substantial At the same position as the imaging position of the magnetic tape, the second step: taking an image of the grid image with the imaging device to obtain a grid image, the third step: the magnetic recording in the grid image In any area in the inspection area of the magnetic track inspection device, calculate the number of grid lines corresponding to one pixel column of the imaging device in the direction perpendicular to the grid line for each pixel column, the 4th step: The average number of the grid lines of each pixel row calculated in the 3rd step is calculated as the average value of the grid line number. The actual spatial length of the arbitrary area in the direction perpendicular to the line, the 6th step: divide the actual spatial length by the number of pixels in the vertical direction of the grid line in the arbitrary area, calculate the grid image, The average actual spatial length of a pixel in the direction perpendicular to the gate line.

The third step may also include, in the inspection area, performing Fourier transform in the vertical direction of the grid lines in the grating diagram, extracting the fundamental frequency component from the obtained frequency spectrum, and inverting the extracted fundamental frequency component. Fourier transform, a step of calculating the phase value distribution of said grating image from the ratio of the real part to the imaginary part of the result thereof, and using said phase distribution, calculating a phase value perpendicular to said grating in any area of said examination area The step of the number of grid lines for each pixel column in the direction of the line.

The method for measuring the actual space length using an imaging device of the present invention includes the first step: taking the direction parallel to the grid line and/or the direction perpendicular to the grid line as the horizontal scanning direction, and using the known value The image formed by the optical system of the grating lines arranged at equal intervals is photographed by the imaging device to obtain the grating image. The second step: in any area within the inspection area of the grating image, calculate for each pixel column The number of grid lines corresponding to one pixel column of the imaging device in the direction perpendicular to the grid lines, the third step: adding the number of grid lines obtained in the second step to each pixel column Average, calculate the average value of the number of grid lines, the fourth step: multiply the average number of grid lines by the grid pitch, calculate the actual space length of the arbitrary region in the direction perpendicular to the grid lines, the 4th step: Step 5: divide the actual space length by the number of pixels in the vertical direction of the grid line in the arbitrary area, and calculate the average actual value of a pixel in the direction perpendicular to the grid line in the grid image. Spatial length, the sixth step: multiply the actual spatial length by the number of pixels in the direction perpendicular to the grid lines in the inspection area to calculate the imaging range in the inspection area.

The second step may include: performing Fourier transform in the vertical direction of the grid lines in the grid pattern in the inspection area, extracting the fundamental frequency component from the obtained spectrum, and inverting the extracted fundamental frequency component. Fourier transform, a step of calculating the phase distribution of said grating image based on the ratio of the real part and imaginary part of the result thereof, and using said phase distribution, calculating the phase distribution of said grating line in any area of said examination area. The step of the number of grid lines for each pixel column in the vertical direction.

The sixth step may include multiplying the actual spatial length of the one pixel by the number of pixels in the inspection area in a direction perpendicular to the grid line to calculate the imaging range of the imaging device in the inspection area , a step of adjusting the magnification of the optical system to make the imaging range a predetermined value.

It may also be that the second step includes: performing Fourier transform in the direction perpendicular to the grating lines in the grating pattern in the inspection region, extracting the fundamental frequency component from the obtained spectrum, and extracting the fundamental frequency component from the obtained frequency spectrum. performing an inverse Fourier transform, calculating the phase distribution of the grating image based on the ratio of the real part and the imaginary part of the result, and using the phase distribution to calculate the phase distribution of the grating line in any region within the inspection region The step of the number of grid lines of each pixel column in the vertical direction, the sixth step includes multiplying the actual spatial length of the one pixel by the pixels in the direction perpendicular to the grid lines of the inspection area calculating the imaging range of the imaging device in the inspection region, and adjusting the magnification of the optical system to make the imaging range a predetermined value.

The method for measuring the actual space length on the magnetic recording track using the imaging device of the present invention is to record the magnetic recording and reproducing device and carry out the magnetic track pattern of the magnetic recording track on the magnetic tape that has been visualized, and the optical system when the imaging device is used for imaging by the optical system. The calibration method of the system has the first step: the grating pattern containing the grating lines arranged at equal intervals with a known value of the grating pitch and parallel to the horizontal scanning direction of the imaging device and/or perpendicular to the direction is set in the substantial At the same position as the imaging position of the magnetic tape, the second step: taking an image of the grid image with the imaging device to obtain a grid image, the third step: the magnetic recording in the grid image In any area in the inspection area of the magnetic track inspection device, calculate the number of grid lines corresponding to one pixel column of the imaging device in the direction perpendicular to the grid line for each pixel column, the 4th step: Describe the grid line number average of each pixel column obtained in the 3rd step, calculate the average value of the grid line number, the 5th step: multiply the grid line number average value by the grid spacing, calculate the grid line number and the grid line number average The actual spatial length of the arbitrary area in the vertical direction, the 6th step: divide the actual spatial length by the number of pixels in the vertical direction of the grid line in the arbitrary area, and calculate the vertical length in the grid image. The average actual spatial length of one pixel in the direction of the gate line, step 7: multiply the average actual spatial length of one pixel by the number of pixels in the inspection area in a direction perpendicular to the grid line , to calculate the imaging range of the inspection area.

The third step may also include: in the inspection area, perform Fourier transform in the vertical direction of the grid lines in the grid pattern, extract the fundamental frequency component from the obtained spectrum, and perform inverse Fourier transform on the extracted fundamental frequency component , a step of calculating the phase value distribution of the grating image according to the ratio of the real part to the imaginary part of the result, and using the phase value distribution to calculate the phase value perpendicular to the grid line in any region of the inspection region The step of the number of grid lines for each pixel column in the direction.

The seventh step may also include multiplying the average actual spatial length of one pixel by the number of pixels in the inspection area in a direction perpendicular to the grid lines to calculate the The imaging range is a step of adjusting the magnification of the optical system so that the imaging range is a predetermined value.

It may also be that the third step includes: performing Fourier transform in the vertical direction of the grating lines in the grid pattern in the inspection area, extracting the fundamental frequency component from the obtained spectrum, and performing inverse Fourier transform on the extracted fundamental frequency component. Transformation, the step of calculating the phase value distribution of the grid image according to the ratio of the real part to the imaginary part of the result, and using the phase value distribution, calculating the phase value perpendicular to the grid line in any area of the inspection area The step of the number of grid lines of each pixel column in the direction of , the seventh step includes multiplying the average actual spatial length of the one pixel by the number of pixels in the direction perpendicular to the grid lines of the inspection area, A step of calculating an imaging range of the imaging device in the inspection region, and adjusting a magnification of the optical system so that the imaging range becomes a predetermined value.

The optical system correction method of the present invention has, the first step: take the direction parallel to the grid line and/or the direction perpendicular to the grid line as the horizontal scanning direction, for the arrays that are arranged at equal intervals with known values The image formed by the optical system of the grid pattern of the grid line is photographed by the imaging device to obtain the grid image. The second step: in any area within the inspection area of the grid image, calculate for each pixel row the The number of grid lines corresponding to one pixel row of the imaging device in the direction perpendicular to the grid lines, the third step: averaging the number of grid lines obtained in the second step to each pixel row, and calculating the number of grid lines The average value, the 4th step: multiply the average value of the number of grid lines by the grid spacing, calculate the actual space length of the arbitrary area in the direction perpendicular to the grid line, the 5th step: put the actual The space length is divided by the number of pixels in the vertical direction of the grid line in the arbitrary area to calculate the average actual space length of a pixel in the grid image in a direction perpendicular to the grid line, and the 6th step: Using the actual spatial length, the displacement distribution in the vertical direction of the grid lines in the inspection area in the grid image is obtained, so as to obtain the distortion distribution in this direction in the entire inspection area.

It may also be that the second step includes: performing Fourier transform in the direction perpendicular to the grating lines in the grating pattern in the inspection region, extracting the fundamental frequency component from the obtained spectrum, and extracting the fundamental frequency component from the obtained frequency spectrum. performing an inverse Fourier transform, and calculating the phase distribution of the grating image according to the ratio of the real part and the imaginary part of the result, and using the phase distribution, calculating the phase distribution in any region in the inspection region, which is related to the The step of the number of grid lines of each pixel column in the direction perpendicular to the grid lines, the sixth step includes: using the phase value distribution to calculate the number of grid lines in the direction perpendicular to the grid lines in the inspection area Displacement distribution steps.

The optical system correction method for magnetic recording track imaging of the present invention is a magnetic recording track inspection of the magnetic recording track recorded by the magnetic recording and reproducing device and the track pattern of the magnetic recording track on the magnetic tape that has been visualized, and the optical system uses an imaging device to check the magnetic recording track. The calibration method of the optical system in the device has a first step: taking the grating pattern containing the grating lines arranged at equal intervals with known values as the grid pitch and parallel to the horizontal scanning direction of the imaging device and/or perpendicular to the direction, installed at substantially the same position as the imaging position of the magnetic tape, the second step: imaging the grid image with the imaging device to obtain a grid image, the third step: the In any area in the inspection area of the magnetic recording track inspection device, calculate the number of grid lines corresponding to one pixel column of the imaging device in a direction perpendicular to the grid lines for each pixel column, the fourth Step: average the number of grid lines obtained in the 3rd step for each pixel row, calculate the average value of the number of grid lines, the 5th step: multiply the average number of grid lines by the grid spacing, calculate the The actual spatial length of the arbitrary area in the direction perpendicular to the grid line, step 6: divide the actual spatial length by the number of pixels in the vertical direction of the grid line in the arbitrary area to calculate the grid The average actual spatial length of a pixel in the direction perpendicular to the grid line in the image, the 7th step: use the actual spatial length to obtain the distance between the grid line in the inspection area in the grid image Displacement distribution in the vertical direction, so as to obtain the distortion distribution of the optical system of the magnetic recording track inspection device in the entire inspection area.

It may also be that the third step includes: performing Fourier transform in the vertical direction of the grating lines in the grid pattern in the inspection area, extracting the fundamental frequency component from the obtained spectrum, and performing inverse Fourier transform on the extracted fundamental frequency component. Transformation, the step of calculating the phase value distribution of the grid image according to the ratio of the real part to the imaginary part of the result, and using the phase value distribution, calculating the phase value perpendicular to the grid line in any area of the inspection area The step of the number of grid lines of each pixel column in the direction of , the seventh step includes: using the phase value distribution to calculate the number of grid lines in the vertical direction of the grid lines in the inspection area in the grid image Displacement distribution steps.

The optical system correction method of the present invention has, the first step: take the direction parallel to the grid line and/or the direction perpendicular to the grid line as the horizontal scanning direction, for the arrays that are arranged at equal intervals with known values The image formed by the optical system of the grid pattern of the grid line is photographed by the imaging device to obtain the grid image. The second step: in any area in the inspection area of the grid image, calculate the correlation between each pixel row and the grid image. The number of grid lines corresponding to one pixel row of the imaging device in the direction perpendicular to the line, the 3rd step: average the number of grid lines for each pixel row obtained in the second step, and calculate the ratio of the number of grid lines Average value, the 4th step: multiply the average value of the number of grid lines by the grid spacing, calculate the actual space length of the arbitrary area in the direction perpendicular to the grid line, the 5th step: divide the actual space length Divided by the number of pixels in the vertical direction of the grid line in the arbitrary area, calculate the average actual space length of a pixel in the direction perpendicular to the grid line of the grid image, the 6th step: use the According to the actual space length, the displacement distribution in the grating image in the vertical direction of the grid line in the inspection area is obtained, so as to obtain the distortion distribution of the optical system in this direction in the entire inspection area, the first Step 7: Using the distortion distribution to correct the image formed by the optical system.

It may also be that the second step includes: performing Fourier transform in the vertical direction of the grating lines in the grid pattern in the inspection area, extracting the fundamental frequency component from the obtained spectrum, and performing inverse Fourier transform on the extracted fundamental frequency component. Transformation, the step of calculating the phase value distribution of the grid image according to the ratio of the real part to the imaginary part of the result, and using the phase value distribution, calculating the phase value perpendicular to the grid line in any area of the inspection area The step of the number of grid lines of each pixel column in the direction, the sixth step includes: using the phase value distribution to calculate the displacement distribution in the direction perpendicular to the grid line in the inspection area .

The optical system calibration method for magnetic recording track imaging of the present invention is to check the magnetic recording track by using an imaging device for the optical system to check the track pattern of the magnetic recording track on the magnetic tape recorded by the magnetic recording and playback device and visualized. The calibration method of the optical system in the device has a first step: taking the grating pattern containing the grating lines arranged at equal intervals with known values as the grid pitch and parallel to the horizontal scanning direction of the imaging device and/or perpendicular to the direction, installed at substantially the same position as the imaging position of the magnetic tape, the second step: imaging the grid image with the imaging device to obtain a grid image, the third step: the In any area in the inspection area of the magnetic recording track inspection device, calculate the number of grid lines corresponding to one pixel column of the imaging device in a direction perpendicular to the grid lines for each pixel column, the fourth Step: average the number of grid lines obtained in the 3rd step to each pixel row, calculate the average value of the number of grid lines, the 5th step: multiply the average value of the number of grid lines by the grid spacing, calculate the The actual spatial length of the arbitrary area in the direction perpendicular to the grid line, step 6: divide the actual spatial length by the number of pixels in the vertical direction of the grid line in the arbitrary area to calculate the grid In the image, the average actual space length of a pixel in the direction perpendicular to the grid line, step 7: use the actual space length to obtain the grid line in the inspection area in the grid image Displacement distribution in the vertical direction, so that the distortion distribution of the optical system of the magnetic recording track inspection device in this direction is obtained in the entire inspection area. Step 8: use the imaging device to record the track pattern on the magnetic tape An image is taken, and the displacement distribution of the track pattern corrected by the distortion distribution is calculated.

It may also be that the third step includes: performing Fourier transform in the vertical direction of the grating lines in the grid pattern in the inspection area, extracting the fundamental frequency component from the obtained spectrum, and performing inverse Fourier transform on the extracted fundamental frequency component. Transformation, the step of calculating the phase value distribution of the grid image according to the ratio of the real part to the imaginary part of the result, and using the phase value distribution, calculating the phase value perpendicular to the grid line in any area of the inspection area The step of the number of grid stripes of each pixel column in the direction of the direction, the seventh step includes: using the phase value distribution to calculate the vertical direction of the grid line in the inspection area in the grid image The steps of the displacement distribution of .

The reference gauge of the present invention is to record and carry out the magnetic track pattern of the magnetic recording track on the magnetic tape that the magnetic recording and playback device has been visualized, and use the reference gauge for the magnetic recording track inspection device for imaging and checking with the imaging device. A line drawing as a reference of the coordinate system of the reference gauge and a grating pattern drawn at equal intervals to have a prescribed angle with respect to the reference direction of the line graph, the line graph and the grating pattern have such a thickness that Their surfaces when installed on the magnetic recording track inspection device are substantially equal to the height position of the magnetic tape when the magnetic tape is installed on the magnetic recording track inspection device.

The pitch of the grid pattern may also be substantially equal to the pitch of the track pattern on the magnetic tape.

The reference gauge of the present invention is to record and carry out the magnetic track pattern of the magnetic recording track on the magnetic tape that the magnetic recording and playback device has been visualized, and use the reference gauge for the magnetic recording track inspection device for imaging and checking with the imaging device. As the reference line diagram of the coordinate system of the reference gauge, it is substantially the same as in the ideal track pattern recorded on the magnetic tape by more than two magnetic heads with prescribed azimuth angles in the magnetic recording and playback device, so as to have a The track pattern recorded by the magnetic head of the azimuth angle is the bright part, and the track pattern obtained when the track pattern recorded by the magnetic head with another azimuth angle is the dark part is the same simulated track pattern, along at least one of the simulated track patterns on the simulated track pattern The displacement distribution of the simulated track pattern to the ideal track pattern of the displacement measurement line is known.

The line pattern and the simulated track pattern have such a thickness that their surfaces are at the height position of the upper surface of the magnetic tape when it is set on the magnetic recording track inspection device. substantially equal.

The optical system correction method for magnetic recording track imaging of the present invention is to record the magnetic recording and reproducing device and carry out the track pattern of the magnetic recording track on the magnetic tape that has been visualized, and use an imaging device for the optical system to perform imaging and inspection of magnetic recording. A correction method for an optical system of a magnetic track inspection device, wherein a line diagram as a reference of a coordinate system is set, and is substantially the same as that recorded on a magnetic tape by two or more magnetic heads with prescribed azimuth angles in said magnetic recording and reproducing device. In the ideal track pattern, the track pattern recorded by the magnetic head with an azimuth angle is the bright part, and the track pattern obtained when the track pattern recorded by the magnetic head with another azimuth angle is the dark part is substantially the same, and along at least one or more The displacement distribution of the displacement measurement line relative to the ideal track pattern is a known simulated track pattern, so that the surface of the two patterns is the same as the height of the upper surface of the magnetic tape when the magnetic tape is set on the magnetic recording track inspection device. The positions are substantially the same, the displacement distribution of the simulated track pattern to the ideal track pattern is measured by the magnetic recording track inspection device, the displacement distribution is compared with the displacement distribution measurement results, and the magnetic recording track inspection device is tested measurement accuracy.

The measurement of the displacement distribution can be carried out in the image of the simulated track pattern in the direction of the measurement of the displacement distribution by Fourier transform, take out the fundamental frequency component from the obtained frequency spectrum, and perform inverse Fourier transformation on it, according to the real part of the result and The ratio of the imaginary part calculates a phase value distribution of the image of the simulated track pattern, and using the phase value distribution, calculates a displacement distribution of the image of the simulated track pattern.

Again, the reference gauge of the present invention is recorded by the magnetic recording and reproducing device and has carried out the track pattern of the magnetic recording track on the magnetic tape that has been visualized, through the optical system, the reference gauge for the magnetic recording track inspection device that performs imaging and inspection with the imaging device , having, on its upper surface, a line drawing as the reference of the coordinate system of the reference gauge, and a grating pattern drawn at equal intervals to have a prescribed angle with respect to the line drawing, and in the magnetic recording and playback device, In the ideal track pattern recorded on the magnetic tape by two or more magnetic heads each having a specified azimuth angle, the track pattern recorded by the magnetic head with one azimuth angle is the bright part, and the track recorded by the magnetic head with the other azimuth angle A simulated track with the same track pattern obtained when the pattern is a dark part; the displacement distribution of the simulated track pattern to the ideal track pattern along at least one displacement measurement line on the simulated track pattern is known, The line pattern, the grid pattern, and the simulated track pattern have such thicknesses that their surfaces are different when set on the magnetic recording track inspection device than when the magnetic tape is set on the magnetic recording track inspection device. It is substantially equal to the position of the upper surface of the magnetic tape.

Example 1

Next, a first embodiment will be described with reference to FIGS. 1 to 8. FIG.

FIG. 1 is a block diagram of a correction system of an optical system. On the surface of the reference gauge 1 in the figure, a predetermined grid pattern 7 described below is drawn. The imaging device CCD camera 3 is configured to have a common optical axis with the optical system 2 constituted by a single lens or a lens group, and captures an image formed by the optical system 2 . The image memory 4 stores images from the CCD camera 3 , and the computing device 5 processes the images stored in the image memory 4 . The position adjustment device 6 of the reference gauge 1 is, for example, an XYθ stage.

FIG. 2 shows details of the grid pattern 7 described above. As shown in FIG. 2, a plurality of gate lines 7a are formed at equal intervals, which are known values.

The procedure of the correction method of the optical system 2 in the correction system of the optical system 2 having the above-mentioned structure will be described below according to the functional block diagram of FIG. 3 .

First, imaging of a grid image (step 101) will be described. First, adjust the position of the reference gauge 1 with the XYθ stage 6 so that the grid line 7a ( FIG. 2 ) of the reference gauge 1 shown in FIG. 1 is parallel to the horizontal scanning direction of the CCD camera. Then, the reference gauge 1 is photographed by the CCD camera 3 . FIG. 4 is a diagram showing the grid image 8 . The grid image 8 is captured by the CCD camera 3 on the grid image 7 on the reference gauge 1 and stored in the image memory 4 . As shown in FIG. 4 , in the grid image 8 , the horizontal scanning direction corresponding to the CCD camera 3 in FIG. 1 is defined as the X direction, and the direction corresponding to the vertical scanning direction is defined as the Y direction. In the calculation of the actual spatial length of a pixel, the imaging range and the distortion distribution, the number of grid lines in the inspection area 9 is related to the resolution, and the greater the number of grid lines, the higher the accuracy. Therefore, when taking pictures of the reference gauge 1 , it is preferable to capture as many grid lines 7 a as possible within the resolution of the CCD camera 3 . For example, when the number of pixels in the direction perpendicular to the grid lines 7a of the grid image 8 (Y direction in FIG. 4 ) is 512, the number of grid lines is preferably about 128.

The calculation of the number of grid lines (step 102) in FIG. 3 will be described below. First, an inspection area 9 , which is an area to be a reference object, is determined on the grid image 8 in FIG. 4 . The average actual spatial length of one pixel in the inspection area, the imaging range, the distortion distribution, and the like are all objects of correction. Therefore, the inspection region 9 may be set in the main use region in the image formed by the optical system in FIG. 1 . For example, if it is an optical system incorporated in a measuring device, it is only necessary to measure an area for photographing the measurement object. Also, an arbitrary area 10 is set within the inspection area 9 . Computes the average real spatial length of one pixel in the area. The greater the number of grid lines, the higher the calculation accuracy of the average actual space length of one pixel. Therefore, it is preferable that the number of grid lines 7a included in any region 10 is as large as possible when each grid line 7a falls within the resolution of the CCD camera. The inspection area 9 and the arbitrary area 10 may be the same area.

In any region 10 within the inspection region 9 of the raster image 8 stored in the image memory 4 , the number of raster lines included in each pixel column in the Y direction is calculated by the computing device 5 . The arithmetic unit 5 calculates the number of raster lines by, for example, the method described below.

First, binarization processing is performed on an image of an arbitrary region 10 . The binarization process is performed as follows. First, the threshold value of the luminance distribution is determined in an arbitrary region 10 . The threshold value may be an average value of luminance distribution in an arbitrary area 10 . Pixels above the threshold are regarded as bright parts, and pixels below the threshold are regarded as dark parts. The image of the arbitrary region 10 is converted into a binary image of bright and dark parts by the above processing. The image obtained by photographing the reference gauge 1 usually has good contrast and low noise, so once it is binarized, its luminance distribution becomes a complete rectangular wave. The number of grid lines can be calculated from the number of the rectangular waves.

Also, when calculating the number of raster lines in units of an integer number, it is preferable to set the arbitrary region 10 so that the number of raster lines included in the region becomes an integer as much as possible.

The calculation of the average value of the number of raster lines in FIG. 3 (step 103) will be described below. In the arithmetic unit 5 of FIG. 1, the average value of the obtained number of grid lines of each pixel column is calculated, and the average number of grid lines is calculated based on this.

Due to the influence of image distortion, the number of raster lines varies from place to place. In the calculation of the average number of raster lines in step 103, the average number of raster lines in the two-dimensional area 10 in FIG. 4 is calculated. Compared with the method of measuring on a line, such as using a line graph and a scale to obtain a magnification, such a measurement method is more important for the calculation of the average actual space length (step 105) and the calculation of the imaging range (step 106) of a pixel in Fig. 3 . The calculated average actual spatial length and imaging range of one pixel can be used to obtain representative values that more accurately express the grid image 8 .

The actual space length calculation (step 104) of FIG. 3 will be described below. In the calculation device 5 of FIG. 1, the product of the average number of grid lines and the known pitch length of the grid pattern 7 on the reference gauge is calculated, and the actual space length in the Y direction of the arbitrary area 10 in FIG. 4 is calculated accordingly.

The calculation of the average actual space length of one pixel in FIG. 3 (step 105) will be described below. In the calculation device 5 of Fig. 1, divide the actual space length on the Y direction of the arbitrary region 10 of Fig. 4 just obtained by the number of pixels in the Y direction of the arbitrary region 10, and calculate the average actual space length of one pixel accordingly. space length.

Next, the calculation of the imaging range in FIG. 3 (step 106) will be described. In the computing device 5 of FIG. 1, the average actual space length of one pixel is multiplied by the number of pixels in the Y direction of the inspection area 9 of FIG. 4, so the actual space length in the Y direction of the inspection area 9 can be calculated, That is, the camera range of the inspection area.

In addition, when the magnification of the optical system 2 in FIG. 1 can be continuously changed like a stereo microscope, it is also possible to adjust the magnification according to the calculated imaging range. When the desired imaging range is set in advance, the magnification is calculated from the actual spatial length of the imaging range and the actual spatial length of the imaging element of the CCD camera 3 . The imaging range is calculated after setting the optical system to the magnification. Due to the influence of image distortion and the like, the calculation result of the imaging range is usually inconsistent with the desired imaging range. Repeatedly calculating the magnification and imaging range of the optical system 2 to adjust the imaging range can make them consistent.

The calculation of the distortion distribution (step 107) in Fig. 3 will be described below. In the computing device 5 of FIG. 1, the displacement distribution in the inspection region 9 of the grating image 8 of FIG. , that is, the distortion distribution of the image caused by the optical system 2 in FIG. 1 . As a calculation method of the displacement distribution, for example, binarization is performed on the image of the inspection region 9 . In addition, the line thinning process as shown in FIG. 5 is performed, and the center position of the grid line 7a is calculated in units of pixels. In the image of FIG. 5 , the two lines in the upper part of the grid pattern have some bends, which are caused by the distortion of the optical system 2 . In this embodiment, as detailed below, the distortion distribution is used to correct the image formed by the optical system 2, so that the image distortion caused by the optical system when the CCD camera 3 takes pictures through the optical system 2 can be corrected. By multiplying the obtained position distribution by the average actual spatial length of one pixel, the position distribution of the grid lines 7a in units of actual spatial length can be obtained. Based on the comparison of the obtained position distribution with the real position distribution calculated from the pitch of the grid pattern 7 in FIG. 2 , the displacement distribution in the Y direction of the grid image 8 shown in FIG. 4 is calculated. The displacement data obtained in the above processing is only the data of the center position of the grid line 7 a in the inspection area 9 . In order to obtain the displacement distribution between the grid lines 7a, interpolation processing such as spline interpolation is performed.

In the measurement of such a pixel unit, the measurement accuracy of the displacement distribution depends on the grid pitch of the reference gauge 1 and the average actual spatial length of one pixel. The narrower the grid pitch, the higher the resolution of the displacement, the shorter the average actual space length of one pixel, and the higher the resolution of the position of the grid line 7a. On the other hand, the grating pitch can only be narrowed to the extent that the individual grating lines 7a can be identified in the optical system, or the limit of the manufacturing accuracy of the reference gauge 1 . And in conjunction with this, it is necessary to secure the number of pixels of the CCD camera 3 . Consider these together to determine the grid pitch of the reference gauge 1 and the number of pixels of the imaging device such as the CCD camera 3 . For example, assume that the resolution of the optical system 2 used is 8 micrometers. In this case, the grid pitch of the reference gauge 1 must be at least 16 microns or more. For example, if the grid pitch is 32 microns, and the number of pixels of the CCD camera 3 used is distributed to 512 pixels in the horizontal and vertical directions, then the number of the captured grid lines is preferably about 128. Therefore, the imaging range is approximately 4 mm square area.

The above descriptions are all about the processing in the Y direction of the inspection area in FIG. 4 . Use the XYθ table 6 to adjust the position of the reference gauge 1 so that the grid line 7a of the reference gauge 1 in Figure 1 is parallel to the vertical scanning direction of the CCD camera 3. After the reference gauge 1 is photographed by the CCD camera 3, repeat the same process as above. The program can calculate the actual spatial length, imaging range and distortion distribution of a pixel in the X direction. In addition, the grid patterns perpendicular to each other shown in FIG. 6 may be drawn on the reference gauge 1 in advance. It is also possible to make the raster image into a raster in two directions as shown in Figure 7, and process the captured raster images in the two directions at the same time in the X and Y directions.

The capturing of the image in Fig. 3 (step 108) will be described below. In image capturing, an image of the object to be measured is captured by the optical system 2 and the CCD camera 3 shown in FIG. 1 .

Next, the correction of the image in Fig. 3 (step 109) will be described. In the computing device 5 in FIG. 1 , image correction is performed using the obtained distortion distribution in the X and Y directions. The image to be corrected is an arbitrary image captured in the image capturing step (step 108).

Fig. 8 is a schematic diagram for explaining a method of correcting the luminance value of a certain pixel point. P(0,0), P(1,0), P(0,1), and P(1,1) are pixels. Next, the case where the luminance of the pixel P(0,0) is used as the correction object will be described. The position vector of each pixel follows the label of the pixel, and is taken as P(0,0), P(1,0), P(0,1), and P(1,1). And D(0,0), D(1,0), D(0,1) and D(1,1) are represented in each pixel P(0,0), P(1,0), P( 0, 1) and a vector of distortions of P(1, 1). At this time, the luminance distributions at P(0,0), P(1,0), P(0,1) and P(1,1) are denoted as B(0,0), B(1,0), B(0,1) and B(1,1), and the luminance at P(0,0) after correction is denoted as Bt(0,0). The corresponding positions of each pixel P(0,0), P(1,0), P(0,1) and P(1,1) after distortion correction are respectively denoted as Pt(0,0), Pt(1,0 ), Pt(0,1) and Pt(1,1). Also, the respective position vectors Pt(0, 0), Pt(1, 0), Pt(0, 1) and Pt(1, 1) are obtained by the following equations, respectively.

Pt(0,0)=P(0,0)-D(0,0)

Pt(1,0)=P(1,0)-D(1,0)

Pt(0,1)=P(0,1)-D(0,1)

Pt(1,1)=P(1,1)-D(1,1)

Here, the distances from Pt(0,0), Pt(1,0), Pt(0,1) and Pt(1,1) to P(0,0) are denoted as d(0,0), d( 1, 0), d(0, 1) and d(1, 1), then,

d(0,0)=|P(0,0)-Pt(0,0)|

d(1,0)=|P(0,0)-Pt(1,0)|

d(0,1)=|P(0,0)-Pt(0,1)|

d(1,1)=|P(0,0)-Pt(1,1)|

Also, K, L, M and N are defined by the following formulae.

K=(1/d(0,0))/(1/d(0,0)+1/d(1,0)+1/d(0,1)+1/d(1,1))

L=(1/d(1,0))/(1/d(0,0)+1/d(1,0)+1/d(0,1)+1/d(1,1))

M=(1/d(0,1))/(1/d(0,0)+1/d(1,0)+1/d(0,1)+1/d(1,1))

N=(1/d(1,1))/(1/d(0,0)+1/d(1,0)+1/d(0,1)+1/d(1,1))

In this case, Bt(0,0) is obtained by the following equation.

Bt(0,0)=K×B(0,0)+L×B(1,0)+M×B(0,1)+N×B(1,1)

As described above, in each pixel of the inspection region 9 , image correction can be performed by performing luminance calculation on four points next to the image pixel using the corrected pixels calculated from the distortion distribution.

Thus, according to the first embodiment, the average actual spatial length of one pixel when the CCD camera 3 captures the image formed by the optical system 2 can be precisely calculated. By multiplying the average actual spatial length of one pixel by the number of pixels in the vertical direction of the grid line 7a of the inspection area 9, the imaging range of the part corresponding to the inspection area 9 when the CCD camera 3 captures the image formed by the optical system 2 can be calculated.

Again, the average actual space length of one pixel is multiplied by the number of pixels in the vertical direction of the grid line 7a of the inspection area 9 to calculate the imaging range of the CCD camera 3 in the inspection area 9, and adjust the magnification of the optical system 2 to make the imaging range If the specified value is met, the imaging range of the part corresponding to the inspection area 9 can be adjusted when the CCD camera 3 captures the image formed by the optical system 2 .

Also, by using the average actual space length of one pixel, the displacement distribution in the orthogonal direction of the grid line 7a in the inspection area 9 is obtained, and the distortion distribution in the orthogonal direction of the grid line 7a in the optical system 2 is obtained in the entire inspection area 9, and it can be calculated When the CCD camera 3 captures the image formed by the optical system 2, the distortion distribution of the part corresponding to the inspection area 9 is displayed.

Furthermore, by correcting the image formed by the optical system 2 using the distortion distribution, an image obtained when the image formed by the optical system 2 is captured by the CCD camera 3 can be corrected.

In any area within the inspection area of the grid image, calculate the average grid line number of each pixel column of the imaging device, multiply the grid pitch to calculate the actual spatial length of the arbitrary area in the specified direction, and divide it by the The number of pixels in the direction, from which the average actual space length of a pixel of the grid image can be obtained. With this, the imaging range can be calculated, the imaging range can be adjusted, the distortion distribution of the calculated image can be calculated, and the image can be corrected using the distortion distribution. Therefore, the optical system can be calibrated and the measurement object can be precisely measured. And all of these can start from the imaging of the raster image and perform a series of processing.

Example 2

Next, a second embodiment will be described with reference to Figs. 13 and 14 . In the present embodiment, phase analysis using Fourier transform is used in the correction of the optical system 2 .

The device used in the second embodiment is the same as the correction system of the optical system 2 used in the first embodiment. Also, the procedure of the calibration method of the optical system 2 is the same as the procedure of the calibration method of the optical system 2 of the first embodiment. However, in the second embodiment, phase information processing using Fourier transform is used in the calculation of the number of raster lines (step 102) in FIG. 3 . This is explained below.

First, in any area 10 in the inspection area 9 in the grid image 8 ( FIG. 4 ) stored in the image memory 4 of FIG. 1 , the calculation device 5 calculates the number of grid lines contained in each pixel column in the Y direction. The arithmetic unit 5 uses the phase information processing technique of the grating image 8 using Fourier transform as described below.

FIG. 13 is an example of the luminance distribution waveform diagram of a line in the inspection area 9 in the grid image 8 in the direction perpendicular to the grid line 7 a in the X direction or the Y direction. Perform Fourier transform on this to obtain the frequency spectrum.

FIG. 14 is a schematic diagram of the real part and imaginary part sum-of-squares power spectrum of the spectrum obtained when the luminance distribution in FIG. 13 is Fourier transformed. Only extract the fundamental frequency component (equivalent to the oblique line in Figure 14) representing the first harmonic component of the original waveform from the spectrum, and perform inverse Fourier transform, then a smooth waveform can be obtained in the real part to replace the original waveform, and in the imaginary The real part of the waveform can be shifted to a half-wavelength waveform. The arc tangent of the number obtained by dividing the imaginary part by the real part is obtained to obtain the phase value of the 1st harmonic of the original waveform on each pixel. In the phase value distribution of the inspection region 9 of the grating image 8 thus obtained, the amount of change in phase value in an arbitrary region 10 is calculated. A phase value variation of 2π is equivalent to one raster line. Therefore, dividing the phase value variation by 2π can calculate the number of raster lines contained in any region 10 with a precision below the decimal point. Therefore, it is possible to obtain a numerical value with higher precision than by a method such as binarization.

Next, in the distortion distribution calculation step (step 107 ) in FIG. 3 , phase information processing performed by Fourier transform is used. This is explained below.

In the calculation device 5, in the step of calculating the average actual spatial length of one pixel (step 105), the displacement distribution of the inspection region 9 of the grating image 8 is calculated by using the obtained average actual spatial length of a pixel, that is, the displacement distribution caused by the optical system 2 The image distortion distribution. When calculating the number of grid lines (step 102), if the phase in the examination region 9 of the grid image 8 has been calculated, this calculation result is used. If the phase has not been calculated, it is used in the calculation of the number of grating lines (step 102) to calculate the phase using the procedure described when performing Fourier transform phase information processing, and calculate the phase distribution in the inspection region 9 of the grid image 8. Take the difference between the position distribution of each pixel calculated from the average actual space length of a pixel, and the value obtained by dividing the obtained phase distribution by 2π at each pixel and multiplying the value obtained by the grid pitch to calculate the grid of the grid image 8. Displacement distribution in the orthogonal direction of line 7a. In the arithmetic processing using the above-mentioned Fourier transform, displacement data can be obtained from all pixels in the inspection area 9, and interpolation processing is not necessary. Furthermore, since the positional distribution can be calculated with an accuracy of less than a pixel unit, even when the distortion is smaller than one pixel, the distortion can be calculated with good accuracy. For example, even when an image is captured under the condition that the actual spatial length of each pixel is 5 microns, the amount of distortion of 5 microns or less can be calculated.

Adopting the second embodiment in this way, the grating pattern is used as the reference rule, and the phase information processing method of Fourier transform can be used, so that the calculation of the number of grating lines and the displacement distribution can reach the precision below the decimal point. Therefore, the calculation of the average actual spatial length of one pixel and the imaging range, the adjustment of the imaging range, the calculation of the distortion distribution of the obtained image, and the correction using the distortion distribution can have higher accuracy.

Example 3

Next, a third embodiment will be described with reference to FIGS. 9 to 12 and FIGS. 15 to 17. FIG.

FIG. 9 is a configuration diagram showing a magnetic recording track inspection device 20 . Predetermined patterns 41 to 43 are drawn on the surface of the reference gauge 21 . Said pattern 41～43 of this regulation, as shown in Figure 10, is the line diagram 41 as the reference of pattern, grid pitch is equal, and is known, preferably this grating pitch is equal to the magnetic track of the same azimuth angle of magnetic tape A raster pattern 42 parallel to the line pattern 41, and a raster pattern 43 perpendicular to the line pattern 41, such as a pitch (for example, 20 micrometers for DVC format).

A reference gauge 21 and a magnetic tape (not shown) are set on the sample setting table 22 . The thickness and flatness of the reference gauge 21 are such that when the reference gauge 22 is installed on the sample setting table 22, its height is the same as when the magnetic tape is installed. In this way, the optical system 2 of the magnetic recording track inspection device 20 can be calibrated with the reference gauge 21 . The CCD camera 3 as an imaging device is arranged on a common optical axis with the optical system 2 composed of a single lens or a lens group, and captures an image formed by the optical system 2 . Images obtained from the CCD camera are stored in the image memory 4 , and the computing device 5 processes the images stored in the image memory 4 . The position of the reference gauge 21 is adjusted by the position adjustment device 6 . This position adjustment device is, for example, an XYθ stage.

The procedure of the calibration method of the optical system 2 having the magnetic recording track inspection apparatus constructed as described above will be described with reference to the functional block diagram of FIG. 11 .

First, the setting of the reference gauge in Fig. 11 (step 201) will be described. The reference gauge 21 of FIG. 9 is set on the sample setting table 22 . In order to make the height and flatness of the reference gauge 21 and the magnetic tape (not shown) equal, the reference gauge 21 may be made to have the same thickness and flatness as the magnetic tape. However, in fact, the thickness of the magnetic tape is very thin, only several micrometers to tens of micrometers, so it is difficult to make the reference gauge 21 so thin. Therefore, the reference gauge 21 is made thicker than the magnetic tape by a certain thickness. In order to offset this height difference with the sample setting stand 22, a plate having a thickness equal to the height difference between the magnetic tape and the reference gauge 21 is assembled on the sample setting stand 22, and the plate is placed under the magnetic tape when the magnetic tape is set. Alternatively, a mechanism (not shown) that moves up and down in the direction of the optical axis of the optical system 2 is provided for the sample setting table 22 .

Next, the imaging procedure (step 202) of the grid image in Fig. 11 will be described. First, adjust the position of the reference gauge 21 with the XYθ stage, make the line diagram 41 (Fig. 10) of the reference gauge 21 of Fig. 9 parallel to the horizontal scanning direction of the CCD camera 3, then, use the CCD camera 3 to photograph respectively on the reference gauge 21 Raster Figures 42 and 43. For example, the raster image 42 is captured by the CCD camera 3 and the image stored in the image memory is the raster image 8 as shown in FIG. 4 . At this time, the reference gauge 21 is set at the same position as the magnetic tape. Also, the grid pitch of the reference gauge 21 is the same as the track pitch of the magnetic tape. In this way, the luminance distribution of the obtained raster image 8 is close to the luminance distribution when imaging a magnetic tape. Therefore, it is ideal as a correction method that can perform correction under conditions close to actual measurement.

Next, the processing of the raster image 8 obtained when the raster image 42 is photographed will be described, so that the processing such as calculation of the number of raster lines is performed in the Y direction. When photographing the pattern 43, just change the processing direction to the X direction.

The calculation of the number of grid lines (step 203) in FIG. 11 will be described below. The grid image 8 in FIG. 4 defines an area to be corrected, that is, an inspection area 9 . The actual spatial length, imaging range, and distortion distribution of the inspection area are all objects of correction. In the magnetic recording track inspection device 20 , the inspection area 9 is set so as to substantially coincide with the effective area of the magnetic tape to be measured, that is, the area where the track pattern is drawn. For example, the DVC format is 5.24mm. If the grid pitch is 20 microns, the number of grid lines 7a included in the inspection area 9 is 262. Therefore, the number of pixels in the inspection area 9 is preferably 1000 or more. Next, an arbitrary area 10 is set within the inspection area 9 . The average actual spatial length of one pixel is calculated in this arbitrary area 10 . The arbitrary area 10 may be set to be the same as the inspection area 9 .

In any region 10 within the inspection region 9 in the raster image 8 stored in the image memory 4, the number of raster lines contained in each pixel column in the Y direction is calculated using the computing device in FIG. 9 . The arithmetic unit 5 calculates the number of raster lines by the method described in the calculation of the number of raster lines (step 102) in the first embodiment.

The calculation of the average number of raster lines (step 204) in FIG. 11 will be described below. Similar to the calculation of the average number of raster lines (step 103 ) in the first embodiment, the computing device in FIG. 9 calculates the average number of raster lines in each pixel row to calculate the average number of raster lines.

The actual space length calculation (step 205) in FIG. 11 will be described below. The same as the processing of the actual space length calculation (step 104) of embodiment 1, in the arithmetic device of Fig. 9, the average number of grid lines is multiplied by the known spacing of the grid pattern 42 on the reference gauge 21 to calculate The actual spatial length of any area 10 in the Y direction.

The calculation (step 206) of the average actual space length of one pixel in Fig. 11 will be described below. Same as the processing of the calculation (step 105) of the average actual space length of one pixel in embodiment 1, in the computing device 5 of Fig. 9, at first the actual space length on the Y direction of the arbitrary region 10 obtained is divided by any The number of pixels in the Y direction of the area 10 is used to calculate the average actual spatial length of a pixel.

Next, the calculation of the imaging range (step 207) in Fig. 11 will be described. Same as the processing of the calculation (step 106) of the imaging range of embodiment 1, in the arithmetic device 5 of Fig. 9, the average actual space length of one pixel obtained by the calculation (step 206) of the average actual space length of one pixel is By multiplying by the number of pixels in the Y direction of the inspection area 9 , the actual spatial length of the inspection area 9 in the Y direction can be calculated, that is, the imaging range of the inspection area.

Also, as in the first embodiment, the magnification of the variable magnification optical system 2 can be adjusted based on the calculated imaging range so that the imaging range coincides with the effective area of the magnetic tape.

Next, the calculation of the distortion distribution (step 208) in FIG. 11 will be described. Same as the processing of the calculation of the distortion distribution (step 107) of embodiment 1, in the computing device 5 of Fig. 9, the average actual space length of one pixel obtained by the calculation of the average actual space length of one pixel (step 206) , calculate the displacement distribution of the grating image 8 in FIG. 4 in the inspection area 9 , that is, the distortion distribution of the image caused by the optical system 2 .

It is also possible to replace the grid patterns 42 and 43 ( FIG. 10 ) on the reference gauge 21 with grids in two directions as shown in FIG. 7 , and simultaneously process the grid image obtained by photographing the grid in the X direction and the Y direction.

Next, the capturing of the track pattern image (step 209) in Fig. 11 will be described. First, a magnetic tape is set on the sample setting stand 22 shown in FIG. 9 . At this time, the magnetic tape is at the same position as the reference gauge 21 . The tapes are pre-visualized. The position is adjusted with the XYθ stage 6 so that the edge of the magnetic tape is parallel to the horizontal scanning direction of the CCD camera 3 . Tracks recorded on the magnetic tape by two types of heads having different azimuth angles, that is, head gap angles, are recorded in parallel. When lighting is performed, the track with one azimuth angle is the bright portion, and the track with the other azimuth angle is the dark portion. Therefore, it just becomes a light and dark pattern like a raster pattern. This pattern is captured by the CCD camera 3 . The tracks are recorded with a slight inclination with respect to the length direction of the magnetic tape, so that an image 28 of the resulting track pattern is shown in FIG. 12 . As shown in FIG. 12, the length direction of the magnetic tape is X, and the width direction of the magnetic tape is Y. An image 28 of the tape pattern is stored in the memory 4 .

The calculation (step 210) of the track pattern displacement distribution excluding the influence of image distortion in FIG. 11 will be described below. First, the track pattern image 28 obtained in the track pattern imaging (step 209 ) is used, and the displacement distribution of the track pattern in the Y direction is calculated according to the displacement distribution calculation of the magnetic recording track inspection device 20 . The displacement distribution obtained at this time also includes the influence of image distortion.

FIG. 15 is an explanatory diagram of a method of correcting the displacement distribution of the track pattern. The vectors S _EX and S _EY respectively represent the X component and the Y component of the image distortion in a certain pixel P of the image 28 of the track pattern. These are the displacements of the Euler coordinate system, indicating where the pixel P is displaced from. The vectors S _LX and S _LY represent the displacement of the image distortion in the pixel P in the Lagrangian coordinate system, that is, where the point that should exist in the pixel P is displaced. It is assumed here that the differential value of the distortion distribution is very small, and the vectors S _LX and S _LY are approximated by the vectors S _EX and S _EY respectively.

By using such a method, the influence of the Y-direction component of the image distortion included in the vector D (not shown) representing the displacement of the track pattern in the Y-direction in the pixel P is _SEY itself. Since the differential value of the distortion distribution is assumed to be very small, the influence of the X-direction component of the image distortion included in the vector D is approximately represented by the vector S _EXY in FIG. 15 . θ in Fig. 15 is the inclination angle of the track. Therefore, the vector Dt representing the Y-direction displacement of the corrected track pattern is expressed by the following equation.

Dt＝DS _EY +S _EX ×Tanθ

In the arithmetic unit 5, this calculation is performed on the displacement distribution including the influence of the image distortion on the entire pixel to calculate the displacement distribution of the track pattern excluding the influence of the image distortion.

In addition, as another method of calculating the track pattern displacement distribution (step 210 ) excluding the influence of image distortion, the following processing may be performed by the arithmetic unit 5 .

That is, the track pattern image 28 obtained by capturing the track pattern image (step 209 ) is corrected using the distortion distribution in the X and Y directions by the method described in the image correction (step 109 ) of the first embodiment. Binary processing and line thinning processing are performed on the obtained corrected track pattern image 28, and the center position of the raster line is calculated in pixel units. The obtained position distribution is multiplied by the average actual space length of one pixel to obtain the position distribution of the track pattern in units of the actual space length. Based on the comparison of the obtained position distribution of the track pattern with that of the ideal track pattern, the displacement distribution of the track pattern image 28 is calculated. In order to obtain the displacement distribution between the grid lines, interpolation processing such as spline interpolation is performed.

Next, a method for confirming measurement accuracy of a magnetic recording track inspection device obtained by correcting the results of calculation of the average actual space length of one pixel, adjustment of imaging range, and calculation of distortion distribution will be described.

First, the reference gauge 44 for checking the measurement accuracy shown in FIG. The reference gauge 44 that measurement accuracy confirms is also the same as the situation of the reference gauge 21, and the thickness is the same as the thickness of the magnetic tape, or thicker than the certain thickness of the magnetic tape. The position of the pattern drawing screen of the reference gauge 44 for confirmation of measurement accuracy is the same.

The pattern shown in FIG. 16 is drawn on the reference gauge 44 for checking the measurement accuracy. The pattern includes a line pattern 41 and a simulated track pattern 45 . The pitch of the dummy track pattern 45 is drawn to be equal to the ideal pitch of tracks of the same azimuth angle as the track pattern recorded on the magnetic tape by the magnetic recording and reproducing apparatus. The angle (θ in FIG. 16) of the dummy track pattern 45 with respect to the graph 41 is selected to be equal to the ideal track angle of the track pattern recorded on the magnetic tape by the magnetic recording and reproducing apparatus. If it is a DVC format, the pitch is 20 microns and the track angle is 9.166809°. The graph 41 is used as a reference when adjusting the position when imaging the pseudo-track pattern 45 .

Next, the image of the reference gauge 44 for checking the measurement accuracy is captured by the magnetic recording track inspection device 20 , and the displacement distribution of the pseudo track pattern 45 excluding the influence of image distortion is calculated. When the image of the reference gauge 44 for checking the measurement accuracy is captured, a pseudo track pattern image (not shown) similar to the track pattern image 28 is obtained. Carry out the same processing as the calculation (step 210) of the displacement distribution of the magnetic track pattern that excludes the influence of image distortion in Figure 11 on the simulated track pattern image, to calculate the displacement distribution of the simulated track pattern 45 that excludes the influence of image distortion to the ideal track pattern (displacement distribution in the Y direction of FIG. 16).

The calculation of the displacement distribution of the pseudo track pattern 45 can also be performed by phase information processing using Fourier transform as described in the description of the distortion distribution calculation (step 107) of the second embodiment.

Furthermore, the displacement distribution of the simulated track pattern 45 with respect to the ideal track pattern is measured in advance by other measuring means. The data obtained by this measuring means becomes the basic data for checking the accuracy. Therefore, the measurement means must be a device with higher measurement accuracy than the magnetic recording track inspection device. The reference gauge 44 for confirming the measurement accuracy is produced in the same process as that of the mask used in the semiconductor field. At this time, the dark portion of the dummy track pattern 45 is formed by chrome film formed on the glass substrate. And no processing is done on the bright part of the analog track pattern 45 . The glass substrate can thus be seen. The measuring instrument used to measure the position of such lines drawn on the glass substrate with high precision is a light-wave interferometric coordinate measuring machine. In this way, the edge position of the mask pattern can be measured repeatedly, and the measurement can be performed with an accuracy of less than 0.01 micron. Using this measuring instrument, the position distribution of the grid lines of the dummy track pattern 45 of the reference gauge 44 for accuracy confirmation was measured, and the displacement distribution with respect to the ideal measurement pattern was calculated. The displacement distribution obtained above is hereinafter referred to as a reference displacement distribution. The reference displacement distribution has sufficient measurement accuracy to evaluate the measurement accuracy of the magnetic recording track inspection device in ultramicron. The reference gauge 44 for confirming the measurement accuracy is fabricated on a glass substrate so that the displacement distribution of the dummy track pattern 45 can be maintained. Thus, the basic displacement distribution is obtained as described above, making the displacement distribution of the simulated track pattern 45 known.

Next, data corresponding to the reference displacement distribution, that is, data on the same measurement line, is extracted from the displacement distribution obtained by the magnetic recording track inspection device. This is called the sample displacement distribution. By comparing the sample displacement distribution with the reference displacement distribution, the measurement accuracy of the magnetic recording track inspection device can be confirmed with an accuracy of submicron or less.

Furthermore, as shown in FIG. 17, the line pattern 41, the grid pattern 42 in the Y direction, the grid pattern 43 in the X direction, and the dummy track pattern 45 may be drawn on one reference gauge. Using such a reference gauge makes it possible to calculate the actual spatial length of one pixel average, calculate and adjust the imaging range, calculate distortion distribution, and confirm measurement accuracy without exchanging the reference gauge.

Thus, according to the third embodiment, the average actual spatial length of one pixel of the image obtained by the magnetic recording track inspection device 20 can be calculated.

Again, the average actual space length of one pixel is multiplied by the number of pixels in the direction perpendicular to the grating lines in the inspection area 9, the imaging range in the inspection area 9 can be calculated, and the relationship with the image obtained by the magnetic recording track inspection device 20 can be calculated. The imaging range of the portion corresponding to the inspection area 9 is checked.

Again, the average actual space length of one pixel is multiplied by the number of pixels in the orthogonal direction of the grid line of the inspection area 9 to calculate the imaging range in the inspection area 9 of the CCD camera 3, and the magnification of the optical system 2 is adjusted to make the imaging range as In this way, the imaging range of the part corresponding to the inspection area 9 of the image obtained by the magnetic recording track inspection device 20 can be adjusted.

With the average actual space length of one pixel, seek the displacement distribution of the grid line in the inspection area 9 of the grid image 8 in the orthogonal direction, and draw the optical system 2 of the magnetic recording track inspection device 20 in the entire inspection area 9. The distortion distribution in the intersecting direction can be used to calculate the distortion distribution of the part corresponding to the inspection area 9 of the image obtained by the magnetic recording track inspection device 20 .

In addition, the track pattern recorded on the magnetic tape is imaged by the CCD camera 3, and the displacement distribution of the corrected track pattern is calculated using the distortion distribution, so that the inspection result excluding the influence of image distortion can be obtained in the magnetic recording track inspection device 20.

Furthermore, the magnetic recording track inspection device can be calibrated with a prescribed reference gauge.

And because the pitch of the grating pattern on the reference gauge is equal to the pitch of the magnetic track with the same azimuth angle on the magnetic tape, the luminance distribution of the obtained grating image is close to the luminance distribution of the image of the track pattern. Therefore, correction can be performed under conditions close to actual measurement.

In addition, by using a predetermined reference gauge for checking the measurement accuracy, it is possible to perform the measurement accuracy confirmation after the calibration operation with higher accuracy.

Also, by presetting a variety of patterns including simulated track patterns on one reference gauge, it is possible to calculate the average actual space length of one pixel, calculate and adjust the imaging range, calculate the distortion distribution, and confirm the measurement accuracy. A series of processing.

Next, a fourth embodiment will be described with reference to Fig. 13 and Fig. 14 . A case will be described in which phase analysis using Fourier transform is used for calibration of the optical system of the magnetic recording track inspection device.

The device used in the fourth embodiment is the same as the magnetic recording track inspection device 20 used in the third embodiment. The procedure of the correction method of the optical system of the magnetic recording track inspection device is also the same as the procedure of the correction method of the optical system of the magnetic recording track inspection device of the third embodiment. In this embodiment, phase information processing using Fourier transform is used in the calculation of the number of raster lines (step 203) in FIG. 11 . This will be explained.

In any region 10 within the inspection region 9 of the raster image 8 stored in the image memory 4 of FIG. 9 , the number of raster lines contained in each pixel in the Y direction is calculated by the computing device 5 . The arithmetic unit 5 uses a method of processing phase information of the grating image 8 by Fourier transform described below. FIG. 13 is an example of the waveform of the luminance distribution of each line in the direction perpendicular to the grid lines in the X direction or Y direction in the inspection region 9 of the grid image 8 . Perform Fourier transform on this to get the frequency spectrum.

FIG. 14 is a schematic diagram showing the power spectrum of the sum of squares of the real part and the imaginary part of the spectrum obtained when the luminance distribution in FIG. 13 is Fourier transformed. From this spectrum, only the fundamental frequency component representing the 1st harmonic component of the original waveform (equivalent to the oblique line in Figure 14) is taken out, and after inverse Fourier transform, a smooth waveform can be obtained in the real part to replace the original waveform, and in the imaginary part, it can be obtained A waveform that shifts the real part of the waveform by half a wavelength. The arc tangent of the number obtained by dividing the imaginary part by the real part is obtained to obtain the phase value of the 1st harmonic of the original waveform in each pixel. In the phase value distribution of the inspection region 9 of the grating image 8 thus obtained, the amount of change in the phase value in an arbitrary region 10 is calculated. A phase value variation of 2π is equivalent to one raster line. Therefore, dividing the phase value variation by 2π can calculate the number of raster lines contained in any region 10 with a precision below the decimal point. Therefore, it is possible to obtain a numerical value with higher precision than by a method such as binarization.

Next, a case will be described in which phase information processing using Fourier transform is used in the distortion distribution calculation step (step 208 ) in FIG. 11 . In the calculation device 5, in the step of calculating the average actual spatial length of a pixel (step 206), the calculated average actual spatial length of a pixel is used to calculate the displacement distribution of the inspection area 9 of the grating image 8, that is, the displacement distribution caused by the optical system 2 Distortion distribution of the image. When calculating the number of raster lines (step 203 ), if a phase calculation has already been performed in the inspection region 9 of the grid image 8 , this calculation result is used. If the phase has not been calculated, it is used in the calculation of the number of grid lines (step 203), and the phase calculation is performed by using the procedure described when performing Fourier transform phase information processing, and the phase distribution in the inspection region 9 of the grid image 8 is calculated. Take the difference between the position distribution of each pixel calculated from the average actual space length of one pixel, and the value obtained by dividing the obtained phase distribution by 2π at each pixel and multiplying the value obtained by the grid pitch to calculate the grid image 8 Displacement distribution in the orthogonal direction of the grid lines. In the above arithmetic processing using Fourier transform, displacement data can be obtained from all pixels in the inspection area 9, and interpolation processing is not necessary. Since the positional distribution can be calculated with an accuracy of less than a pixel unit, even when the distortion is less than one pixel, the distortion can be calculated with good accuracy. Furthermore, it is effective in cases where the number of grid lines has already been determined and the measurement accuracy cannot be improved by increasing the number of grid lines, as in a magnetic recording track inspection device.

In this way, according to the fourth embodiment, when calculating the number of raster lines, the phase information processing using Fourier transform is used, so that the number of raster lines can be obtained with high precision reaching decimal units. Therefore, the average actual spatial length of one pixel Measurement, calculation and adjustment of camera range can have higher precision.

In addition, phase information processing using Fourier transform is used to calculate the distortion distribution, so that the displacement distribution can be calculated in smaller pixel units, and the distortion distribution can be calculated with higher accuracy and the displacement distribution can be corrected using the distortion distribution.

Claims (22)

1. the real space length determination method with camera head is characterized in that having

The 1st step: the direction that is parallel to described grid line and/or perpendicular to the direction of this grid line as horizontal scan direction, make a video recording with camera head with the optical system imaging to containing with the grid figure of given value as the grid line of the equidistant configuration of grid spacing, obtain the grid picture

The 2nd step: in the arbitrary region in the inspection area of described grid picture, to each pixel column calculate with the vertical direction of described grid line on the bar number of the corresponding grid line of a pixel column of described camera head,

The 3rd step: with described the 2nd step try to achieve in addition average for the bar number of the grid line of each pixel column, calculate the mean value of the bar number of grid line,

The 4th step: described grid number of lines mean value be multiply by the grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line, and

The 5th step:, calculate in the described grid picture at average real space length perpendicular to a pixel on the direction of described grid line the number of pixels of described real space length divided by the orthogonal directions of the described grid line of described arbitrary region.

2. the real space length determination method with camera head according to claim 1 is characterized in that described step 2 comprises:

In described inspection area, in grid figure, carry out Fourier Tranform on the vertical direction of grid line, the step of taking out fundamental component from the frequency spectrum that obtains,

The fundamental component that takes out is carried out anti-Fourier Tranform, calculate the step of the phase value distribution of described grid picture from its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, calculate arbitrary region in described inspection area, perpendicular to the step of the grid number of lines of each pixel column of the direction of described grid line.

3. one kind with real space length determination method on the magnetic recording track of camera head, it is a kind of track patterns that magnetic recording/reproducing device is write down and carried out magnetic recording track on the tape of visualization processing, the bearing calibration of the optical system when making a video recording with camera head by optical system, it is characterized in that having

The 1st step: containing with the given value is that the grid spacing equidistantly disposes and is parallel to the horizontal scan direction of described camera head and/or perpendicular to the grid figure of the grid line of this direction, is arranged on identical with the camera position of the described tape in fact position,

The 2nd step: described grid figure is made a video recording obtaining the grid picture with described camera head,

The 3rd step: in the arbitrary region in the inspection area in described grid picture, to each pixel column calculate with the vertical direction of described grid line on the bar number of the corresponding grid line of a pixel column of described camera head,

The 4th step: with described the 3rd step try to achieve in addition average for the bar number of the grid line of each pixel column, calculate the mean value of the bar number of grid line,

The 5th step: the bar of described grid line is counted mean value multiply by described grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line,

The 6th step:, calculate in the described grid picture at average real space length perpendicular to a pixel on the direction of described grid line the number of pixels of described real space length divided by the vertical direction of the described grid line of described arbitrary region.

4. the real space length determination method with camera head according to claim 3 is characterized in that described the 3rd step comprises,

In described inspection area, in grid figure, carry out Fourier Tranform on the vertical direction of grid line, the step of taking out fundamental component from the frequency spectrum that obtains,

The fundamental component that takes out is carried out anti-Fourier Tranform, calculate the step of the phase value distribution of described grid picture from its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, calculate arbitrary region in described inspection area, perpendicular to the step of the grid number of lines of each pixel column on the direction of described grid line.

5. the real space length assay method with camera head is characterized in that, comprises

The 1st step: the direction that is parallel to described grid line and/or perpendicular to the direction of described grid line as horizontal scan direction, to contain with the given value be the grid spacing equidistantly the grid figure of the grid line of configuration make a video recording with camera head with the optical system imaging, obtain the grid picture

The 2nd step: in the arbitrary region in the inspection area of this grid picture, on the direction that each pixel column calculates and described grid line is vertical with the bar number of the corresponding grid line of a pixel column of described camera head,

The 3rd step: with described the 2nd step try to achieve in addition average for the bar number of the grid line of each pixel column, calculate the mean value of the bar number of grid line,

The 4th step: grid line is counted mean value multiply by described grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line,

The 5th step: described real space length divided by the described grid line of the described arbitrary region number of pixels in vertical direction, is calculated in the described grid picture at the average real space length perpendicular to a pixel on the direction of described grid line,

The 6th step: described real space length be multiply by number of pixels on described inspection area and the vertical direction described grid line, calculate the image pickup scope in described inspection area.

6. the real space length determination method with camera head according to claim 5 is characterized in that described the 2nd step comprises:

In described inspection area, on the direction vertical, carry out Fourier Tranform with grid line among the described grid figure, extract the step of fundamental component from the frequency spectrum that obtains,

The fundamental component that extracts is carried out anti-Fourier Tranform,, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described PHASE DISTRIBUTION, calculate in the arbitrary region of described inspection area, the step of the bar number of the grid line of each pixel column on the direction vertical with described grid line.

7. the real space length determination method with camera head according to claim 5 is characterized in that described the 6th step comprises:

A described average real space length of pixel be multiply by the number of pixels on the direction vertical of described inspection area with described grid line, calculate the image pickup scope of described camera head in described inspection area, adjust the multiplying power of optical system, making this image pickup scope is the step of setting.

8. the real space length determination method with camera head according to claim 5 is characterized in that described the 2nd step comprises:

In described inspection area, on the direction vertical, carry out Fourier Tranform with grid line among the described grid figure, extract the step of fundamental component from the frequency spectrum that obtains,

The fundamental component that extracts is carried out anti-Fourier Tranform,, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, the step of the bar number of the grid line of each pixel column on the direction in the arbitrary region of calculating in described inspection area, vertical with described grid line, described the 6th step comprises:

The average real space length of a described pixel be multiply by the number of pixels on the direction vertical of described inspection area with described grid line, calculate the image pickup scope of described camera head in described inspection area, adjust the multiplying power of optical system, making this image pickup scope is the step of predetermined value.

9. one kind with real space length determination method on the magnetic recording track of camera head, it is the track patterns that magnetic recording/reproducing device is write down and carried out the magnetic recording track on the tape of visualization processing, the bearing calibration of the optical system when making a video recording with camera head by optical system, it is characterized in that having

The 1st step: containing with the given value is that the grid spacing equidistantly disposes and is parallel to the horizontal scan direction of described camera head and/or perpendicular to the grid figure of the grid line of this direction, is arranged on identical with the camera position of the described tape in fact position,

The 2nd step: described grid figure is made a video recording obtaining the grid picture with described camera head,

The 3rd step: in the arbitrary region in the described inspection area in described grid picture, on the direction that each pixel column calculates and described grid line is vertical with the bar number of the corresponding grid line of a pixel column of described camera head,

The 4th step: with described the 3rd step try to achieve in addition average for the bar number of the grid line of each pixel column, calculate the mean value of the bar number of grid line,

The 5th step: described grid number of lines mean value be multiply by described grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line,

The 6th step: the number of pixels of described real space length, calculate in the described grid picture at average real space length perpendicular to a pixel on the direction of described grid line divided by the vertical direction of the described grid line of described arbitrary region, and

The 7th step: the average real space length of a described pixel be multiply by the number of pixels on the direction vertical of described inspection area, calculate the image pickup scope of described inspection area with described grid line.

10. the real space length determination method with camera head according to claim 9 is characterized in that described the 3rd step comprises:

In described inspection area, in grid figure, carry out Fourier Tranform on the vertical direction of grid line, the step of taking out fundamental component from the frequency spectrum that obtains,

The fundamental component that takes out is carried out anti-Fourier Tranform, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, calculate in the arbitrary region of described inspection area, perpendicular to the step of the bar number of the grid line of each pixel column on the direction of described grid line.

11. the real space length determination method with camera head according to claim 9 is characterized in that described the 7th step comprises:

The average real space length of a described pixel be multiply by the number of pixels on the direction vertical of described inspection area with described grid line, calculate the image pickup scope of described camera head in described inspection area, adjust the multiplying power of optical system, making this image pickup scope is the step of setting.

12. the real space length determination method with camera head according to claim 9 is characterized in that described the 3rd step comprises:

In described inspection area, on the vertical direction of the grid line of grid figure, carry out Fourier Tranform, the step of taking out fundamental component from the frequency spectrum that obtains,

The fundamental component that takes out is carried out anti-Fourier Tranform, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, calculate in the arbitrary region of described inspection area, perpendicular to the step of the bar number of the grid line of each pixel column on the direction of described grid line,

Described the 7th step comprises

The average real space length of a described pixel be multiply by the number of pixels on the direction vertical of described inspection area with described grid line, calculate the image pickup scope of described camera head in described inspection area, adjust the multiplying power of optical system, making this image pickup scope is the step of setting.

13. an optical system correction method is characterized in that having,

The 1st step: the direction that is parallel to described grid line and/or perpendicular to the direction of described grid line as horizontal scan direction, to contain with the given value be spacing equidistantly the grid figure of the grid line of configuration make a video recording with camera head with the optical system imaging, obtain the grid picture

The 2nd step: in the arbitrary region in the inspection area of described grid picture, to each pixel column calculate with the vertical direction of described grid line on the bar number of the corresponding grid line of a pixel column of described camera head,

The 3rd step: with described the 2nd step try to achieve in addition average to the number of lines of the grid line of each pixel column, calculate the mean value of the bar number of grid line,

The 4th step: grid line is counted mean value multiply by described grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line,

The 5th step: the number of pixels of described real space length, calculate in the described grid picture at average real space length perpendicular to a pixel on the direction of described grid line divided by the vertical direction of the described grid line of described arbitrary region, and

The 6th step: use described real space length, obtain in the described grid picture Displacements Distribution on the vertical direction of the described grid line of described inspection area, thereby the distortion that obtains this direction in whole described inspection area distributes.

14. optical system correction method according to claim 13 is characterized in that, described the 2nd step comprises:

In described inspection area, on the direction vertical, carry out Fourier Tranform with grid line among the grid figure, extract the step of fundamental component from the frequency spectrum that obtains,

The fundamental component that extracts is carried out anti-Fourier Tranform,, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described PHASE DISTRIBUTION, calculate the step of bar number of the grid line of each pixel column on the direction in the arbitrary region in the described inspection area, vertical with described grid line,

The 6th step comprises: use described phase value distribution, calculate the step of the Displacements Distribution on described inspection area, vertical with described grid line direction.

15. the optical system correction method of a magnetic recording track shooting usefulness, it is the track patterns that magnetic recording/reproducing device is write down and carried out the magnetic recording track on the tape of visualization processing, the bearing calibration of the optical system of the magnetic recording track check apparatus of making a video recording, checking with camera head by optical system, it is characterized in that having

The 1st step: equidistantly dispose as the grid spacing and be parallel to the horizontal scan direction of described camera head and/or, be arranged on identical with the camera position of the described tape in fact position containing perpendicular to the grid figure of the grid line of this direction with given value,

The 2nd step: described grid figure is made a video recording obtaining the grid picture with described camera head,

The 3rd step: in the arbitrary region in the inspection area in described grid picture, described magnetic recording track check apparatus, to each pixel column calculate with the vertical direction of described grid line on the bar number of the corresponding grid line of a pixel column of described camera head,

The 4th step: with described the 3rd step try to achieve in addition average to the bar number of the grid line of each pixel column, calculate the mean value of grid number of lines,

The 5th step: described grid number of lines mean value be multiply by described grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line,

The 6th step: the number of pixels of described real space length, calculate in the described grid picture at average real space length perpendicular to a pixel on the direction of described grid line divided by the vertical direction of the described grid line of described arbitrary region,

The 7th step: use described real space length, obtain in the described grid picture Displacements Distribution on the vertical direction of the described grid line of described inspection area, thereby the optical system that obtains described magnetic recording track check apparatus in whole described inspection area distributes in the distortion of this direction.

16. optical system correction method according to claim 15 is characterized in that, described the 3rd step comprises:

In described inspection area, in grid figure, carry out Fourier Tranform on the vertical direction of grid line, the step of taking out fundamental component from the frequency spectrum that obtains,

The fundamental component that takes out is carried out anti-Fourier Tranform, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, calculate the arbitrary region of described inspection area, perpendicular to the step of the bar number of the grid line of each pixel column on the direction of described grid line,

Described the 7th step comprises: use described phase value distribution, calculate in the described grid picture step of the Displacements Distribution on the vertical direction of the described grid line of described inspection area.

17. an optical system correction method is characterized in that having

The 1st step: the direction that is parallel to described grid line and/or perpendicular to the direction of described grid line as horizontal scan direction, to contain with the given value be spacing equidistantly the grid figure of the grid line of configuration make a video recording with camera head with the optical system imaging, obtain the grid picture

The 2nd step: in the arbitrary region in the inspection area of described grid picture, to each pixel column calculate with the vertical direction of described grid line on the bar number of the corresponding grid line of a pixel column of described camera head,

The 3rd step: the bar number to the grid line of each pixel column that described the 2nd step is tried to achieve is average, calculate the mean value of the bar number of grid line,

The 4th step: grid number of lines mean value be multiply by described grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line,

The 5th step: the number of pixels of described real space length, calculate in the described grid picture at average real space length perpendicular to a pixel on the direction of described grid line divided by the vertical direction of the described grid line of described arbitrary region,

The 6th step: use described real space length, obtain in the described grid picture Displacements Distribution on the vertical direction of the described grid line of described inspection area, distribute in the distortion of this direction thereby obtain described optical system in whole described inspection area,

The 7th step: revise described optical system imaging with described distortion distribution.

18. optical system correction method according to claim 17 is characterized in that, described the 2nd step comprises:

In described inspection area, on the vertical direction of the grid line of grid figure, carry out Fourier Tranform, the step of taking out fundamental component from the frequency spectrum that obtains,

The fundamental component that takes out is carried out anti-Fourier Tranform, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, calculate the arbitrary region of described inspection area, perpendicular to the step of the bar number of the grid line of each pixel column on the direction of described grid line,

Described the 6th step comprises: use described phase value distribution, calculate the step of the Displacements Distribution on described inspection area, vertical with described grid line direction.

19. the optical system correction method of a magnetic recording track shooting usefulness, it is the track patterns that magnetic recording/reproducing device is write down and carried out the magnetic recording track on the tape of visualization processing, by optical system with the make a video recording bearing calibration of optical system of the magnetic recording track check apparatus checked of camera head, it is characterized in that having

The 1st step: equidistantly dispose as the grid spacing and be parallel to the horizontal scan direction of described camera head and/or, be arranged on identical with the camera position of the described tape in fact position containing perpendicular to the grid figure of the grid line of this direction with given value,

The 2nd step: described grid figure is made a video recording obtaining the grid picture with described camera head,

The 3rd step: in the arbitrary region in the inspection area in described grid picture, described magnetic recording track check apparatus, to each pixel column calculate with the vertical direction of described grid line on the bar number of the corresponding grid line of a pixel column of described camera head,

The 4th step: with described the 3rd step try to achieve in addition average for the bar number of the grid line of each pixel column, calculate the mean value of grid number of lines,

The 5th step: described grid number of lines mean value be multiply by described grid spacing, calculate the real space length of the described arbitrary region on the direction vertical with described grid line,

The 6th step: the number of pixels of described real space length, calculate in the described grid picture at average real space length perpendicular to a pixel on the direction of described grid line divided by the vertical direction of the described grid line of described arbitrary region,

The 7th step: use described real space length, obtain in the described grid picture Displacements Distribution on the vertical direction of the described grid line of described inspection area, thereby the optical system that obtains described magnetic recording track check apparatus in whole described inspection area distributes in the distortion of this direction

The 8th step: with described camera head the track patterns that writes down on the tape is made a video recording, calculate the Displacements Distribution of the described track patterns of revising with described distortion distribution.

20. optical system correction method according to claim 19 is characterized in that, described the 3rd step comprises:

In described inspection area, on the vertical direction of the grid line of grid figure, carry out Fourier Tranform, the step of taking out fundamental component from the frequency spectrum that obtains,

The fundamental component that takes out is carried out anti-Fourier Tranform, calculate the step of the phase value distribution of described grid picture according to its result's the real part and the ratio of imaginary part, and

Use described phase value distribution, calculate the arbitrary region of described inspection area, perpendicular to the step of the bar number of the grid line of each pixel column on the direction of described grid line,

Described the 7th step comprises: use described phase value distribution, calculate in the described grid picture step of the Displacements Distribution on the vertical direction of the described grid line of described inspection area.

21. the optical system correction method of a magnetic recording track shooting usefulness, it is the track patterns of the magnetic recording track on the tape that magnetic recording/reproducing device is write down, carried out visualization processing, optical system correction method when making a video recording with camera head by optical system is characterized in that

Be provided as the line chart of the benchmark of coordinate system, with with in described magnetic recording/reproducing device respectively by in the plural ideal track pattern of azimuthal head records on tape with regulation, with the track patterns with an azimuthal head records is bright portion, the track patterns that obtains when being dark portion with the track patterns with another azimuthal head records is practically identical, and along the determining displacement line more than at least one, Displacements Distribution with respect to described ideal track pattern is known simulation track patterns, make that the height and position of the surface of described line chart and described simulation track patterns upper surface of described tape when on described magnetic recording track check apparatus described tape being set is practically identical

Measure the Displacements Distribution of described simulation track patterns with described magnetic recording track check apparatus to described ideal track pattern,

Described Displacements Distribution and described Displacements Distribution measurement result are compared, detected the mensuration precision of described magnetic recording track check apparatus.

22. optical system correction method according to claim 21 is characterized in that,

Described Displacements Distribution is measured, and in the image of described simulation track patterns, carries out Fourier Tranform on displacement measure of spread direction, takes out fundamental component from the frequency spectrum that obtains,

The fundamental component that is taken out is carried out anti-Fourier Tranform, calculates the phase value distribution of the image of described simulation track patterns according to its result's the real part and the ratio of imaginary part,

Use described phase value distribution, calculate the Displacements Distribution of the image of described simulation track patterns.

Images