JPH11211611A - Eccentricity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure eccentricity of a micro aspherical lens and a spherical lens being employed in an endoscope efficiently with high accuracy. SOLUTION: While projecting a luminous flux from a projecting means 3 including a light source to the vicinity of the aspherical axis 8 of an aspherical lens 4 to be inspected, the lens 4 is turned about a rotary shaft 5 through a rotary means equipped with a spindle motor and the intensity distribution of the reflected image of the lens 4 is detected by a detection means 6 comprising a CCD. The reflected image is detected in at least three different directions of the lens 4 and delivered to an operating means 7. The operating means 7 calculates the coordinate at the center of gravity of each reflected image from the intensity distribution of the reflected image of the lens 4 and calculates the size of the track of the reflected image from the coordinate at the center of gravity. The operating means 7 corrects the calculated size with the magnification of the projecting means 3 and the detection means 6 thus determining eccentricity of the center of paraxial curvature of the lens 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the eccentricity and inclination of an aspherical lens, an inhomogeneous medium lens, and the like, and a measuring device or a processing machine for performing the measuring method.

[0002]

2. Description of the Related Art In optical equipment such as a camera, a microscope, and an endoscope, when a lens used is decentered with respect to an optical axis, an imaging performance is deteriorated. Therefore, in order to prevent such an obstacle, the eccentricity of the lens is measured in a device assembling process, a lens processing process and the like. In particular, in recent years, an aspheric lens is often used in order to realize a higher-performance and lower-cost optical device. Since the eccentricity of the aspherical lens is affected by the shift of the aspherical axis and the tilt of the aspherical axis, an apparatus for measuring the eccentricity of the aspherical lens is required to be able to measure the two.

Conventional eccentricity measuring means for an aspherical surface is disclosed in JP-A-4-268433 and JP-A-5-268433.
A method disclosed in 196540 and a method developed from these methods have been proposed. However, in these methods, it is necessary to put a marking for aspherical eccentricity measurement on the lens, or it is necessary to bring a measurement probe into contact with the lens. It was not suitable for measuring the eccentricity of a spherical lens.

[0004] In order to solve such a problem, Japanese Patent Application Laid-Open Nos. 8-159915 and 9-145537 disclose no marking for aspherical surface eccentricity measurement and a complete non-contact measurement is possible. A method has been proposed.
In these methods, the aspherical axis is measured from the eccentricity of the center of curvature near the aspherical axis of the aspherical surface and the center of curvature in the spherical surface around the aspherical surface. However, in the aspherical lens used for the endoscope, the center of curvature near the aspherical axis of the aspherical surface and the center of curvature in the spherical surface near the aspherical surface are often very close. It has been difficult to accurately measure the aspherical axis eccentricity of an aspherical lens for an endoscope.

Further, in an aspherical lens and a spherical lens for an endoscope, there is no need for a marking for measuring aspherical eccentricity and a method capable of complete non-contact measurement is disclosed in Japanese Patent Laid-Open No. 7-1.
20218 and JP-A-9-222380. These methods certainly allow highly accurate measurements. However, when optically measuring the eccentricity around the aspherical surface, a large error occurs due to astigmatism generated in the lens to be inspected, so that the performance inherent in the measuring device cannot be exhibited. In addition, it is not possible to correct the effects of mounting errors that occur when the lens is mounted on the measuring device, and it is not possible to measure a lens whose center thickness is larger than its outer diameter (hereinafter referred to as a rod lens). As described above, the methods disclosed in each of the above publications are insufficient for performing highly accurate eccentricity measurement in practical use.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a very accurate measurement of the eccentricity of a minute aspherical lens and a spherical lens used in an endoscope or the like. It is an object of the present invention to provide a measuring method and a measuring device that can be performed efficiently.

[0007]

To achieve the above object, an eccentricity measuring apparatus according to the present invention provides a luminous flux incident on two or more points including a portion other than at least one aspherical axis of a lens to be inspected including an aspherical surface. And the eccentricity of the aspherical surface is obtained from the trajectory of the reflected image obtained by rotating the test lens.

Further, the eccentricity measuring apparatus of the present invention comprises: means for causing a light beam to enter a test lens; means for rotating a test lens; means for detecting a reflected image from the test lens; A means for determining the eccentricity of the lens to be measured from the locus of the reflected image obtained by rotating the lens, a means for measuring the shake of the outer circumference of the lens to be measured, and a holding member for holding the outer circumference of the lens to be inspected; The tilt of the outer periphery of the test lens is obtained from the above-described shake of the outer periphery of the test lens.

Further, the eccentricity measuring apparatus according to the present invention obtains the eccentricity of the center of local curvature from the locus of a reflected image obtained by rotating a lens to be inspected by irradiating a light beam to a portion other than the aspherical axis. The eccentricity of the local center of curvature is obtained by obtaining the reflection image locus from the direction component coordinates in which the reflection images of the reflection image coordinates in at least three or more different test lens directions are shorter. I do.

[0010]

FIG. 1 is a diagram showing a cross section of an aspherical lens 1. FIG. As shown here, the eccentricity of the aspherical axis 2 is
It is represented by tilt (ε) and shift (δ) with respect to the reference axis. Here, the aspherical axis means the aspherical surface top (V).
And the axis passing through the paraxial center of curvature of the aspherical lens 1. The center of curvature of the aspherical lens 1 includes a paraxial center of curvature (C ₀ ) and a center of curvature corresponding to a peripheral portion other than the aspherical axis 2 of the aspherical lens 1 (L: hereinafter referred to as a local center of curvature). ). The local centers of curvature exist indefinitely.
For example, the eccentricity of the aspherical axis 2 can be measured by measuring at least two eccentricities of the paraxial center of curvature (C ₀ ) and the eccentricity of the local center of curvature (L) which are independent of each other.

The eccentricity measuring device of the present invention measures the eccentricity of the paraxial center of curvature as follows. First, as shown in FIG. 2A, a light beam is made to enter the vicinity of the aspherical axis 8 of the aspherical test lens 4 by the light projecting means 3 including a light source (hereinafter, FIG. 2A). The measurement performed in the arrangement as shown is referred to as vertical incidence measurement), the lens 4 to be measured is rotated about a rotation axis 5 by a rotating means (not shown), and the lens 4 is detected by a detecting means 6 having a CCD or the like. Is detected. At this time, reflected images are detected in at least three or more different directions of the lens 4 to be inspected, and are output to the arithmetic operation unit 7. The calculating means 7 calculates the barycentric coordinates of each reflected image from the intensity distribution of the reflected image of the test lens 4 and calculates the locus of the reflected image from the barycentric coordinates of each reflected image. Further, the result of correcting the magnitude of the locus of the reflected image by the calculating means 7 with the light projection magnification of the light projecting means 3 and the detection magnification of the detection means 6 becomes the eccentricity of the paraxial curvature center of the lens 4 to be measured.

In the eccentricity measuring apparatus of the present invention, in order to measure the eccentricity of the local center of curvature, as shown in FIG. (Hereinafter, the measurement performed in the arrangement as shown in FIG. 2B is referred to as oblique incidence measurement). The subsequent measuring method is the same as the method of measuring the eccentricity of the paraxial center of curvature described above.

In the eccentricity measuring device of the present invention, the calculating means 7
Calculates the eccentricity of the aspherical axis 8 from the eccentricity of the paraxial curvature center, the eccentricity of the local curvature center, and the geometric relationship between the paraxial curvature center and the local curvature center determined by the aspherical shape. In the eccentricity measuring apparatus according to the present invention, the incident position of the light beam on the test lens 4 can be arbitrarily selected for the peripheral portion other than the vicinity of the aspherical axis, but does not deviate from the effective diameter of the test lens 4. The eccentricity of the aspherical axis 8 can be measured with higher accuracy by making the light incident on a portion as far as possible from the aspherical axis 8 within the range. This is because the difference between the paraxial radius of curvature and the local radius of curvature is larger when the incident position of the light beam is set as far away from the aspherical axis 8 as possible. In the eccentricity measuring device of the present invention, it is also possible to measure the eccentricity of the aspherical axis 8 by measuring the eccentricity of two or more local curvature centers in the peripheral portion of the aspherical surface.

As described above, according to the eccentricity measuring device of the present invention, the eccentricity of the aspherical axis can be measured with high accuracy without any marking for aspherical eccentricity measurement at the same time as non-contact and aspherical processing. Is possible. Therefore, it can be said that the method is suitable for performing the eccentricity measurement of a micro aspherical lens used for an endoscope.

The local radius of curvature of the aspherical lens is different between the meridional direction and the sphere missing direction. Accordingly, astigmatism occurs at the time of oblique incidence measurement, and the reflected image of the aspheric lens may not be substantially circular but may be a linear reflected image 9 as shown in FIG. Since the width of the light intensity distribution 10 is narrow in the short direction of the reflection image 9, the center of gravity detection accuracy is good. On the other hand, in the long direction of the reflection image 9, the light intensity distribution 11 greatly expands, so that the detection accuracy of the barycentric coordinates becomes very poor. Therefore, if the trajectory 12 of the reflection image 9 is calculated from the barycentric coordinates of the reflection image 9 in the short and long directions and the eccentricity of the local curvature center is calculated, the eccentricity measurement accuracy deteriorates.

Therefore, in the eccentricity measuring apparatus of the present invention, in order to avoid the above-mentioned problem, the locus of the reflected image is obtained from the barycentric coordinates of the reflected image of the lens to be measured in the short direction and the azimuth of the corresponding lens. The eccentricity of the local curvature center is calculated. Accordingly, highly accurate eccentricity measurement of the aspherical axis can be performed without being affected by astigmatism.

Next, a method of calculating the eccentricity of the aspherical axis in the eccentricity measuring apparatus of the present invention will be described with reference to FIG.

FIG. 4 shows a non-eccentric aspherical surface 13 (shown by a solid line in the figure) and its aspherical axis 14 and an eccentricity aspherical surface 15 (shown by a dotted line in the figure) and its aspherical surface. The relationship between the aspherical axes 16 is shown. The aspheric axis 14 is
The rotation axis coincides with the rotation axis of the lens rotating means to be inspected. Also, FIG.
Have the following meanings.

V: Top of the aspherical surface 13 in the non-eccentric state R: Paraxial radius of curvature of the aspherical surface L _T : Center of local curvature in a meridional plane around the aspherical surface 13 in the non-eccentric state L _S : Non-eccentricity The local center of curvature in the spherical surface around the aspherical surface 13 in the state C: the paraxial center of curvature of the aspherical surface 13 in the non-eccentric state Q: the luminous flux in the peripheral part of the aspherical surface 13 in the non-eccentric state at the time of oblique incidence measurement incident point _{φ: ∠CVL T θ: ∠L T} L S V ε ASP: tilt [delta] _ASP with respect to the rotation axis of the aspherical shaft 16: shift VL _T with respect to the rotational axis of the aspherical surface axis 16: the point V and the point L _T Distance VL _S : Distance between point V and point L _S

Hereinafter, the barycentric coordinates are indicated by a coordinate system set in the detecting means. In the coordinate system of the aspherical surface 13 in the non-eccentric state, the XZ section is a meridional plane, and the YZ section is a spherical surface. In the coordinate system of the aspherical surface 13 in the non-eccentric state, the direction of the reference mark attached to the test lens (hereinafter, referred to as the direction of the test lens) is positive in the counterclockwise direction from the x-axis. In addition, the oblique incidence measurement is performed such that the light beam is perpendicularly incident on the non-eccentric aspheric surface 13.

As shown in FIG. 5A, the shorter direction of the oblique incidence reflection image 18 of the lens to be inspected in the reflection image trajectory 17 at the time of oblique incidence measurement is defined as the x-axis direction. Then, the coordinates of the center of gravity of the oblique incidence reflection image 18 when the x-coordinate of the center of gravity of the oblique incidence reflection image 18 is maximum are ( _{と す る Lx1} , △ _Ly1 ) (1). The direction of the lens to be inspected at this time is assumed to be A _L. Furthermore, the barycentric coordinates of the normal incidence reflection image 19 corresponding to the formula (1) and A _L at oblique incidence measurements ([delta] _Cx1, [delta] _Cy1) and ... (2). At this time, the relationship between the expressions (1) and (2) and the tilt shift of the aspherical axis is as follows. Here, β _C indicates the product of the light projection magnification and the detection magnification in the vertical incidence measurement, and β _L indicates the product of the light projection magnification and the detection magnification in the oblique incidence measurement.

As shown in FIG. 5B, the oblique incidence reflection image 18 is rotated by an arbitrary amount from the state of the expression (1) (corresponding to the rotation of the lens to be inspected). _{Let the} coordinates of the center of gravity of the reflection image 20 be (△ _Lx1 ′, △ _Ly1 ′) (4). The direction of the test lens at that time is assumed to be A _M. Further, the normal incident reflection image 21 corresponding to the expression (4) and A _M
The coordinates _{(δ Cx1 ', δ Cy1'} ) and ... (5). At this time, the relationship between Expressions (4) and (5) and the tilt shift of the aspherical axis is as follows.

Here, the tilt shift of the aspherical axis represented by the equation (6) is expressed by the tilt shift of the aspherical axis represented by the equation (5).
Since the shift can be regarded as being rotated by A _M -A _L, it can be expressed as follows. However, A = A _M -A _L.

Also, the following is obtained by substituting equation (7) into equation (6). In this equation (8), the unknowns are ε _ASP-y1 , ε _ASP-x1 , δ
_Since there are four _ASP-y1 and _δASP-x1 , in order to obtain a solution, the four components may be selected from equations (3) and (8).
Therefore, using the first, second, and fourth rows of equation (3) and the fourth row of equation (8), Becomes

In particular, when A = A _M -A _L = π / 2, it can be expressed as follows.

Similarly, in the reflected image trajectory at the time of oblique incidence measurement, the short direction of the reflected image is the y-axis direction and A = A _M -A _L = π
In the case of / 2, the equivalent to the equation (10) is as follows.

Further, if the formula (9), (10) or (11) is used, the tilt shift of the aspherical axis is obtained by using only the coordinates in the short direction of the reflected image among the coordinates of the obliquely incident reflected image. Can be calculated. In the trajectory of the oblique incidence reflection image, the maximum barycentric coordinates in the short direction of the reflection image and the direction of the test lens at this time are different from the directions of three or more test lenses and the short directions of the oblique incidence reflection image in these directions. Can be obtained by fitting a sine function to the measurement data of the barycentric coordinates of.

The tilt shift of the aspherical axis determined by the equation (9), (10) or (11) is based on the direction of the test lens at which the x-coordinate or the y-coordinate of the locus of the obliquely incident reflection image becomes maximum. The magnitude and direction of the tilt shift. When it is desired to measure the eccentricity based on the reference mark attached to the test lens, the test lens is set so that the reference mark is aligned with the reference of the azimuth of the measuring machine (x axis in FIG. 3), and the measurement is performed. (9)
The result obtained by the equation, the equation (10) or the equation (11) may be rotationally converted by an amount corresponding to the direction of the test lens at which the x-coordinate or the y-coordinate of the locus of the oblique incident reflection image is maximized.

With this configuration, it is not necessary to use the center coordinates of the reflection image in the direction in which the reflection image becomes longer due to astigmatism, so that the eccentricity of the local curvature center can be accurately obtained. As a result, the eccentricity of the aspherical lens can be obtained with high accuracy.

For an aspherical surface having a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface, as described above, a method of determining the eccentricity of the aspherical axis from the eccentricity of the paraxial center of curvature and the local center of curvature. May not be used. When performing normal incidence measurement, for an aspherical surface with a large paraxial radius of curvature,
Increasing the measurement sensitivity to eccentricity tends to increase the diameter of the light beam incident on the aspherical surface. On the other hand, for an aspherical surface having a large amount of change in the amount of aspherical surface, the range in which the radius of curvature can be approximated by the paraxial radius of curvature is very narrow. That is, when perpendicular incidence measurement is performed on an aspherical surface having a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface, a large difference occurs in the radius of curvature of the aspherical surface between the central portion and the peripheral portion of the incident light beam. Therefore,
A large spherical aberration occurs in the reflection image, and the image often blurs so that the coordinates of the center of gravity of the reflection image cannot be calculated. The same can occur in oblique incidence measurement. In such a case, the eccentricity of the aspherical axis cannot be measured, or even if it can be measured, the measurement accuracy is extremely poor.

However, according to the eccentricity measuring device of the present invention,
Even if an aspherical surface has a large paraxial curvature semicircle and a large amount of change in the amount of aspherical surface, large spherical aberration occurs in the reflected image only when the radius of curvature becomes smaller toward the periphery. And the eccentricity of the aspherical axis can be measured with high accuracy. Specifically, the eccentricity of two or more local centers of curvature is measured at the peripheral portion of the aspherical surface, and the eccentricity of each local center of curvature and the geometric relationship of the two or more local centers of curvature determined by the aspherical shape are determined. By calculating the eccentricity of the spherical axis, the above-mentioned problem can be solved.

Incidentally, there are mainly two methods for measuring the eccentricity of two or more local curvature centers in the peripheral portion of the aspherical surface. One is a method for measuring the eccentricity of the local center of curvature in the meridional plane or the spherically-deficient plane in at least two or more peripheral parts other than the vicinity of the aspherical axis. This is a method of measuring the eccentricity of the local center of curvature in the meridional plane and the spherical plane at least at one or more peripheral portions. Either method enables high-precision measurement, but higher measurement accuracy can be obtained by using different methods according to the aspherical shape.

When measuring an aspherical surface having a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface, the eccentricity measuring device of the present invention can be used to measure at least one peripheral portion other than the vicinity of the aspherical axis. By measuring the eccentricity of the local center of curvature in the meridional plane and the spherical plane, the eccentricity of the aspherical surface can be measured. At this time, it is possible to select an arbitrary peripheral part of the aspherical surface, but selecting a part further away from the aspherical axis within a range that does not deviate from the effective diameter enables more accurate eccentricity of the aspherical axis. This is convenient because it can be measured in a short time. This is because the difference between the local curvature semi-meridian in the meridional plane and the local curvature center in the spherical missing plane becomes larger.

The method of calculating the eccentricity of the aspherical axis described here is the same as the method performed using the above-mentioned equation (9), (10) or (11). It is necessary to use the following equation (12) instead of the equations (10) and (11). The meanings of the symbols in the expression (12) are the same as those shown in FIG.

According to the method described here, the eccentricity of the aspherical surface can be obtained without measuring the eccentricity of the paraxial center of curvature. Therefore, in an aspherical surface having a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface, blurring of the reflected image is extremely large due to the influence of spherical aberration at the time of normal incidence measurement, and the eccentricity of the paraxial curvature center cannot be measured. Even in this case, the eccentricity measurement of the aspherical surface can be performed with high accuracy. In particular, it is effective for measurement in the case where the difference between the local radius of curvature in the meridional plane and the local radius of curvature in the spherical surface is large in the periphery of the aspherical surface.

Further, when measuring an aspherical surface having a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface, according to the eccentricity measuring apparatus of the present invention, at least two aspherical surfaces other than those near the aspherical axis are measured.
By measuring the eccentricity in the meridional plane at the peripheral portion at or above the point, the eccentricity of the aspherical surface can be measured. In this case, it is possible to select two arbitrary peripheral portions of the aspherical surface (the two optional peripheral portions are distinguished from the first peripheral portion and the second peripheral portion). ) The eccentricity of the aspherical axis can be measured with higher accuracy by selecting two places as far apart as possible without departing from the effective diameter of the aspherical surface. This is because the difference between the local radii of curvature becomes larger.

The method for calculating the eccentricity of the aspherical axis is the same as the method using the above-mentioned equation (9), (10) or (11). ) And (11), the following expression (13) must be used. The meanings of the symbols in the equation (13) are the same as those shown in FIG. _{However, △ LxT, β L, VL} T,
Subscripts 1 and 2 attached to θ and φ correspond to a first peripheral portion and a second peripheral portion, respectively.

According to the method shown here, the eccentricity of the aspherical surface can be obtained without measuring the eccentricity of the paraxial center of curvature. Therefore, in the case of an aspherical surface having a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface, the reflected image is extremely blurred due to the influence of spherical aberration in vertical incidence measurement, and the eccentricity of the paraxial center of curvature cannot be measured. However, the eccentricity measurement of the aspherical surface can be performed with high accuracy. In particular, the first aspherical surface
This is effective when an eccentricity measurement of an aspheric surface having a large difference between the local radius of curvature in the meridional plane in the peripheral portion of the above and the local radius of curvature in the meridional surface in the second peripheral portion of the aspheric surface is performed.

In the case of an aspherical surface having a large paraxial radius of curvature and a large variation in the amount of aspherical surface, the eccentricity of the aspherical axis cannot be obtained from the eccentricities of the paraxial center of curvature and the local center of curvature as described above. In some cases. However, even in this case, when the eccentricity measurement of the center of curvature of the spherical surface closest to the aspherical shape in the range of the incident light beam diameter is performed by the normal incidence measurement using the eccentricity measurement device of the present invention, the result of the normal incidence measurement is obtained. The eccentricity of the aspherical axis can be obtained from the result of the oblique incidence measurement. Hereinafter, an eccentricity measuring method using this method will be described.

First, the position of the light projecting system or the detecting system is set so that the blur of the image is reduced to a level at which the barycentric coordinates of the reflected image can be sufficiently detected, and vertical incidence measurement is performed. Next, the oblique incidence measurement is performed by the method described with reference to FIGS. It should be noted here that in normal incidence measurement, even if the image blur is reduced to a level where the barycentric coordinates of the reflected image are sufficiently detectable, the incident light beam diameter is still large with respect to the variation of the aspherical amount, and the radius of curvature is large. Cannot be approximated by the paraxial radius of curvature. Because the eccentricity of the paraxial center of curvature is not measured, the eccentricity of the center of curvature of the spherical surface closest to the aspherical shape in the range where the aspherical surface and the light beam intersect (hereinafter referred to as the approximate center of curvature) is measured. This is because it is equivalent to measuring. However, since the approximate center of curvature may be regarded as existing on the aspherical axis, it is possible to calculate the eccentricity of the aspherical axis from the eccentricity of the approximate center of curvature and the eccentricity of the local center of curvature. That is, the following equation in which R in the following equation (10) is replaced by the approximate radius of curvature R _ap may be used.

[0041] Here, δ _Clap is the eccentricity of the approximate curvature center, and β _Cap is the product of the light projection magnification and the detection magnification when measuring the eccentricity of the approximate curvature center.

According to this method, an aspherical surface having a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface. In normal incidence measurement, blurring of the reflected image is extremely large due to the influence of spherical aberration, and the center of the paraxial radius of curvature is measured. Even when eccentricity cannot be measured, eccentricity measurement of the aspherical surface can be performed with high accuracy. In particular, in the peripheral portion of the aspherical surface, the difference between the local radius of curvature in the meridional plane and the local radius of curvature in the spherical missing surface is small, and the local radius of curvature in the meridional plane and the aspherical surface in the first peripheral portion of the aspherical surface. This is effective when performing eccentricity measurement of an aspherical surface having a small difference from the local radius of curvature in the meridional plane in the second peripheral portion.

Further, in the eccentricity measuring apparatus of the present invention, a hand projection for causing a light beam to enter the test lens, a hand projection for rotating the test lens, a means for detecting a reflected image from the test lens, The apparatus includes means for determining the eccentricity of the lens to be inspected from the locus of the reflected image obtained by rotating the lens, manual projection for measuring the shake of the outer periphery of the lens to be inspected, and a holding member for holding the outer peripheral portion of the lens to be inspected. Thus, eccentricity measurement can be performed based on the outer circumference of the lens to be measured.

There are various types of lens holding members. As shown in FIGS. 6A and 6B, the outer peripheral portion 24 of the lens 23 (here, a rod lens is used) is held by the holding member 25. A lens holder 2 of the sandwiching (chucking) type
2 is often used. The tilt of the lens holder 22 can be adjusted by a tilt adjusting mechanism 27 that makes the tilt of the lens holder 22 coincide with the rotation axis 26 of the means for rotating the lens 23. Further, the shift can be adjusted by a shift adjusting mechanism 28 for aligning the spherical center of the lens 23, the outer peripheral center of the lens 23, or the center of the holding member 25 with the rotation axis 26 of the means for rotating the lens 23. .

Incidentally, the tilt adjustment of the lens holder 22 is insufficient as shown in FIG. 6A, or the lens 23 is tilted and chucked as shown in FIG. Tilt)). What is directly obtained by the eccentricity measurement method described here is
This is the amount of eccentricity with respect to the rotation axis of the lens rotating means to be measured. Since the rod lens 23 has a long lens outer peripheral portion 24,
In the state shown in FIGS. 6A and 6B, δ (Lens-spin) = δ (Lens-outer axis) and ε (Lens-spin) = ε (Lens-outer axis) (15) does not. That is, the lens eccentricity measurement cannot be performed based on the lens outer circumference. Note that δ (Len
(s-spin) is the shift of the lens optical axis with respect to the rotation axis of the lens rotating means to be measured, δ (Lens-outer circumference axis) is the shift of the lens optical axis with respect to the center axis of the test lens outer circumference, and ε (Lens-spin) is the test piece Tilt of the lens optical axis with respect to the rotation axis of the lens rotation means,
ε (Lens-outer circumference axis) indicates the tilt of the lens optical axis with respect to the outer circumference center axis of the lens to be measured.

Even in such a case, according to the eccentricity measuring apparatus of the present invention, the tilt of the lens outer peripheral axis can be obtained by measuring the shake of the lens outer periphery at at least two different positions on the lens outer peripheral portion 24. Therefore, the lens holder 22
Even if there is a tilt of the lens itself or a chuck tilt when the lens 23 is chucked, the influence can be corrected, so that the tilt (ε) and shift (δ) of the lens optical axis with respect to the lens outer peripheral axis can be obtained. . That is, lens eccentricity measurement based on the lens outer peripheral axis becomes possible.

Further, in the eccentricity measuring apparatus of the present invention, the tilt adjustment of the lens holder 22 can be roughly performed or the eccentricity measurement of the rod lens can be performed with sufficiently high accuracy even if it is omitted. Is easy. Further, it is possible to omit the tilt adjusting mechanism 27 for adjusting the tilt of the lens holder 22 to the rotation axis 26 of the means for rotating the lens to be inspected, thereby simplifying the measuring device and reducing the cost. it can.

Further, in the eccentricity measuring apparatus of the present invention, means for causing a light beam to enter the lens to be inspected, means for rotating the lens to be inspected, means for detecting a reflected image from the lens to be inspected, and By providing a means for determining the eccentricity of the test lens from the trajectory of the reflected image obtained by rotating, a means for measuring the shake of the test lens outer periphery, and a holding member for holding the outer peripheral portion of the test lens, The tilt of the test lens outer peripheral portion can be obtained from the centering adjustment of the test lens holding portion using the reference jig and the measurement of the deflection of the test lens outer peripheral portion at one or more locations.

Hereinafter, the eccentricity measurement of the rod lens using the eccentricity measuring apparatus will be described with reference to FIGS. 6 (a) and 6 (b). First, the tilt adjustment mechanism 27 adjusts the tilt of the lens holder 22. Next, shift adjustment of the lens holder 22 is performed by the shift adjustment mechanism 28 so that the center of the lens outer periphery 24 near the holding member 25 of the lens holder 22 coincides with the rotation axis 26 of the lens rotation unit to be inspected. A reference jig (for example, a ball lens or the like) is used for the shift adjustment. After performing the above adjustment, the rod lens 23 is mounted on the lens holder 22, and the eccentricity is measured.

In the eccentricity measuring apparatus of the present invention, the shift of the lens holder 22 by the reference jig is performed, so that the outer periphery of the lens at the lower end of the lens (the chucked portion) with respect to the rotating shaft 26 of the lens rotating means to be inspected. The shift of the central axis may be regarded as almost zero. At this time, the tilt of the lens outer peripheral center axis with respect to the rotation axis 26 of the lens rotating means to be inspected is expressed by the following equation. ε (peripheral axis-spin) = δ (outer S1-spin) / d (16) Here, ε (peripheral axis-spin) is the center axis of the lens to be measured with respect to the rotation axis of the lens rotating means to be measured. Tilt, δ (outside S1-s
(pin / d) denotes the center of the outer periphery of the first surface of the test lens with respect to the rotation axis of the test lens rotating means, and d denotes the distance between the lower end of the test lens and the outer peripheral surface of the first surface.

If the tilt of the center axis of the lens outer periphery is obtained in this way, even if there is a tilt of the lens holder 22 itself or a chuck tilt when the rod lens 23 is chucked, the influence thereof can be corrected. The tilt shift of the lens optical axis with respect to the axis can be obtained. That is, lens eccentricity measurement based on the lens outer peripheral axis becomes possible. In the eccentricity measuring device shown here, two means for measuring the shake of the lens outer periphery are provided, or the measurement position is made variable so that the shake of the lens outer periphery can be measured at two different positions on the side surface of the lens. There is no need to provide a mechanism, so that the measurement device can be simplified and the cost can be reduced.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

First Embodiment FIG. 7 is a view showing the entire configuration of an eccentricity measuring apparatus according to a first embodiment. The eccentricity measuring device of the present embodiment measures the eccentricity of the lens surface eccentricity measurement unit 29 equipped with a member for observing the eccentricity of the lens surface to be inspected by vertical incidence measurement or oblique incidence measurement, and the eccentricity of the outer periphery of the lens to be inspected. A lens outer eccentricity measurement unit 30, a rotation angle encoder and a spindle motor are mounted, a lens holder unit 32 holding a test lens 31, and a control / calculation unit 33.

FIG. 8 is a detailed structural view of the inside of the lens surface eccentricity measuring unit 29. This figure shows a state viewed in the direction of arrow A shown in FIG. In the lens surface eccentricity measurement unit 29, light from a light source 34 which collimates the light of the semiconductor laser into parallel light by a built-in optical system (not shown) and emits the light is condensed by a microscope objective lens 35 to a point light source 36.
Is formed. After the image of the point light source 36 is reflected by the half prism 37, the image is projected on the lens 31 to be inspected in FIG. 7 through a light-projecting / imaging lens 38 and a rotating mirror 39 which are telecentric. Next, the light beam reflected by the test lens 31 is re-rotated by the rotating mirror 39 and the light projecting / imaging lens 3.
8. The light is guided to the observation optical system 40 via the half prism 37, but is formed by the light projecting / imaging lens 38 in the vicinity of the re-half prism 37. This image is obtained by the observation optical system 40.
And the amount of eccentricity of the lens surface of the test lens 31 is obtained. The observation optical system 40 includes a microscope objective lens 41, a triangular prism 42, a zoom lens 43, and a CCD camera 44. The rotating mirror 39 is for changing the angle of the light beam incident on the test lens 31 guided from the light projecting / imaging lens 38. In order to set the rotating mirror 39 to a desired angle, the rotating mirror 39 is provided with a stepping motor 45 controlled by the control / calculation unit 33.

Further, the position of the point light source 36 in the microscope objective lens 35 forming the point light source 36 is adjusted by a stepping motor 46 with a ball screw and a guide rail 47 which are controlled by the control / calculation unit 33 in FIG. It can be set almost arbitrarily in the direction of arrow K. Thereby, the incident position of the image of the point light source 36 projected on the surface of the test lens 31 can be changed, and the reflection magnification on the surface of the test lens 31 to be described later can be set to almost any value. . The observation optical system 40 can be set at a desired position in the direction of the arrow J by a stepping motor 48 with a ball screw and a guide rail 49 which are controlled by the control / calculation unit 33. Therefore, the focus position can be adjusted to the image reflected by the light projecting / imaging lens 38 from the surface of the test lens 31. The zooming of the zoom lens 43 is also controlled by the control / calculation unit 33.

As shown in FIG. 7, the lens surface eccentricity measuring unit 29 includes an XY stage 5 with a micrometer.
0 and a guide stage 51 with a stepping motor. For this reason, after the lens surface eccentricity measurement unit 29 is moved in the direction of arrow B by the guide stage 51, the XY stage 50
Fine movement adjustment is possible in the directions of arrows B and G so that the lens surface eccentricity measurement unit 29 is located at an appropriate position with respect to the test lens 31.

The lens outer circumference eccentricity measuring unit 30 is shown in FIG.
As shown in FIG. 5, a stage 54 with a micrometer and a guide stage 55 with a stepping motor
And is fixed to the base 52 via. The lens outer peripheral eccentricity measuring unit 30 can be moved in the direction of arrow B in the figure by the guide stage 55, and can be finely adjusted in the direction of arrow B by the stage 54.

The positional relationship between the lens surface eccentricity measuring unit 29 and the lens outer eccentricity measuring unit 30
In the measurement of 1, when the lens outer peripheral eccentricity is measured by a command from the control / arithmetic unit 33, the lens surface eccentricity measuring unit 29 is fully retracted to the left in FIG.
Instead, the lens outer circumference eccentricity measurement unit 30 automatically moves to a position where the outer circumference of the test lens 31 can be seen. Here, the image of the outer periphery of the test lens 31 is obtained by the CCD camera 5 provided in the outer periphery eccentricity measurement unit 30.
6 and sent to the control / arithmetic unit 33. Switching to the image from the lens surface eccentricity measurement unit 29 is performed by a measurer using a selector in the control / arithmetic unit 33.

The illumination of the lens 31 to be inspected is performed by oblique illumination dark field illumination in which the boundary between the lens surface of the lens 31 and the lens edge is easy to observe, and by epi-illumination bright field illumination in which a concave edge is easy to observe. And can be set freely by the measurer. The focus adjustment is manual in the apparatus of the present embodiment, but can be automated by adding appropriate equipment.

The lens holder unit 32 is fixed to the base 52. This lens holder unit 32
As shown in FIG. 9, a lens holding member 57 for detachably fixing the test lens 31, a rotation unit 58 having a spindle motor for rotating the fixed test lens 31, and a spindle rotation shaft 59. In contrast, the test lens 31
XY stage 60 for adjusting the shift of the position in the directions of arrows E and F in the figure, a tilt adjusting mechanism 61 for adjusting the inclination angle of the test lens 31 with respect to the spindle rotation shaft 59, and a rotation angle encoder. And a mechanism (not shown) for detecting how much the test lens 31 has rotated from the reference position. The lens holding member 57 has an opening / closing mechanism in the arrow direction D in the figure, and can sandwich and fix the lens 31 to be inspected by spring pressure.
The lens holding member 57 is replaceable so that the lens holding member 57 having an optimum shape for the lens 31 to be inspected can be used.

Further, the lens holder unit 32
Can control the rotation of the spindle motor in accordance with a command from a spindle rotation control unit in the control / arithmetic unit 33. The rotation angle of the test lens 31 from the reference position detected by the rotation angle encoder Is transmitted to the control / arithmetic unit 33.

The control / arithmetic unit 33 includes the lens 3 to be inspected.
(1) input of optical data (radius of curvature, surface interval, refractive index) and measurement conditions, capture of measured image data from the CCD camera 56 of the lens surface eccentricity measuring unit 29 and the outer peripheral eccentricity measuring unit 30, and the lens surface eccentricity measuring unit 29, outer eccentricity measuring unit 30 and lens holder unit 3
2 controls the respective movable members, and performs calculation processing and display of measurement data.

As shown in FIG. 7, the control / arithmetic unit 33 has a personal computer 63 connected to a monitor 62 and capable of running dedicated program software. The personal computer 63 on which the dedicated program software has been started,
The input of the data of the lens to be inspected 31 and the measurement conditions is accepted,
Based on the input data, the lens surface eccentricity measurement unit 29 is controlled via the lens surface eccentricity measurement unit control unit 64,
Further, the lens outer peripheral eccentricity measuring unit 30 is automatically controlled via the lens outer peripheral eccentricity measuring unit control unit 65. The control of the spindle motor of the lens holder unit 32 and the reading of the rotation angle encoder are performed via the spindle rotation control unit 66. The manual controller 67 is for fine adjustment of each unit.

Hereinafter, actual measurements performed using the eccentricity measuring apparatus of this embodiment will be described step by step.

First, data of the lens 31 to be tested and measurement conditions are input. Here, as shown in FIG.
Lens whose first surface is aspherical and has a long center thickness (rod lens)
Is the measurement target. The spherical surface data of the first surface of the test lens 31 is as shown below (unit is millimeter).

Aspherical surface data of the first surface C = 0.125, K = 0.4, E = −0.5 × 10 ⁻³ , F = −0.6 × 10 ⁻⁵ Lens center thickness 40 Second surface radius of curvature 2 Refractive index 1.5
The outer diameter φ 6 and the aspherical shape are given by the following equation (17). As shown in FIG. 10B, Z indicates a direction along the optical axis, and H indicates a direction perpendicular to the optical axis. Z = CH2 / (1+ (1 - (K +1) (CH) 2) 1/2) + EH 4 + FH 6 ... (17)

Here, one of the measurement conditions relates to the order of measurement. For example, the eccentric amount of the outer periphery of the test lens 31 is determined by the XY of the lens holder unit 32 shown in FIG.
When it is desired to adjust to zero by adjusting the stage 60, it is necessary to perform the measurement from the eccentricity of the outer circumference of the lens 31 to be measured. Further, when it is desired to suppress the eccentricity of the first surface to zero by adjustment, it is necessary to start from the measurement of the eccentricity of the surface. It is to set the order of such measurement.

Further, in the eccentricity measuring apparatus of the present embodiment, a light beam is made incident on the lens surface to be measured, and the eccentricity of the lens surface is obtained from the reflected image. Therefore, another factor to be specified in the measurement conditions is the reflection magnification on the surface of the lens to be measured. For example, as shown in FIG. 11 (a), when measuring the surface eccentricity of the first surface 69 of the lens 68, the reflection ratio is the incident point I ₁ of the incident light beam depends on the radius of curvature of the first surface 69, First
Position of the reflected image R ₁ in terms 69 is determined by the setting of the reflection ratio. In this embodiment, as described above, the reflection magnification can be set arbitrarily. Thereby, for example, FIG.
The spherical center C ₁ of the first surface 69 and the second surface 70 as shown in FIG.
In a lens close to the spherical center C ₂ , when a light beam is incident near the spherical center C ₁ of the first surface 69 during measurement of the first surface 69 (the reflection magnification is −1), the reflection at the second surface 70 Since the position of the image R ₂ ′ is close to the position of the reflection image R ₁ ′ on the first surface 69, the measurement becomes difficult.

However, taking advantage of the advantage that the eccentricity measuring apparatus of the present embodiment can set the reflection magnification of the lens surface to be examined arbitrarily, for example, as shown in FIG. setting the incident light beam, the position of the reflected image R ₂ of the second surface 70 moreover can blur the image away from the position of the reflected image R ₁ of the first surface 69, second surface during measurement of the first surface 69 It is possible to eliminate or weaken the influence of the reflected image of 70, and the measurement is facilitated.

Further, as shown in FIG.
Is small and has a strong curvature like an endoscope optical system, the optical path of the reflected light from the lens 31 to be measured is largely shifted from the incident optical path due to the eccentricity of the lens surface of the lens 31 to be measured. As a result, the reflected light path does not enter the light projecting / imaging lens 38, so that a situation arises in which measurement is impossible. However, in this case, by setting the absolute value of the reflection magnification small, it is possible to appropriately guide the reflected light to the projection / imaging lens 38.

Incidentally, in the eccentricity measuring apparatus of the present embodiment, oblique incidence measurement is used as a measuring method, but as described above, in the present invention, when measuring the amount of eccentricity of the aspherical surface, it is necessary to select several types of measurement forms. It is possible. For example, a combination of vertical incidence measurement and oblique incidence measurement, a combination of oblique incidence measurement at two different points, or a combination of the same point but with a meridian local curvature center and a spherical missing direction local curvature direction, etc. is there. However, in the oblique incidence measurement, it is necessary to set in advance the angle of incidence of the obliquely incident light beam on the lens surface to be measured, and whether the measurement is to be performed with the local curvature in the meridional direction or the missing-ball direction of the lens to be measured. For this reason, it is necessary to predefine conditions for oblique incidence measurement.

The measurement conditions when the eccentricity measuring apparatus of this embodiment is used are as follows. The inclination of the lens holder unit 32 is adjusted by the parallel flat plate. The shift adjustment of the lens holder unit 32 by the ball lens is performed. The first-surface aspherical surface measurement is based on a combination of the normal incidence measurement and the oblique incidence measurement. The grazing incidence measurement is a measurement of the meridional local center of curvature.
The incident angle is 20.36 °. The local radius of curvature in the meridian direction at this time is 6.06. Each eccentricity amount with respect to the lens outer peripheral axis is calculated based on the eccentricity measurement of the lens outer periphery and the reference position of the lens holder. The reflection magnification is -1 at normal incidence on the first surface, -1 at oblique incidence measurement, and -0.5 at normal incidence on the second surface.

Next, the dedicated program is started on the personal computer 63, the lens data and the measurement conditions are input, and the measurement is started. First, the tilt adjustment of the lens holder unit 32 is necessary. When a predetermined parallel plane plate is attached to the lens holder unit 32, the control / operation unit 3
In response to a command from 3, the lens outer peripheral eccentricity measuring unit 30 is automatically retracted, the lens surface eccentricity measuring unit 29 moves to the upper part of the lens holder unit 32, and the incident light beam is perpendicularly incident on the parallel plane plate. The rotating mirror 39 rotates as described above. Subsequently, the point light source 36 and the observation optical system 40 in the lens surface eccentricity measurement unit 29 automatically move to a position where a reflection image from the parallel plane plate can be measured. Further, the zoom lens 43 automatically becomes the minimum magnification in order to easily find the reflection image. Then, a reflection image from the parallel plane plate can be confirmed. By operating the manual controller 67, the lens holder unit 32 is rotated, and the locus of the rotation of the reflected image is recorded on the personal computer 63.
The zoom lens 43 is zoomed on the monitor 62 to a desired size. Further, by operating the manual controller 67, the light amount of the reflection image of the parallel plane plate is adjusted, and detailed focusing of the reflection image is performed.

Next, a measurement start command is sent from the personal computer 63 to obtain a circular locus of the reflected image. This is because the reflected images at three or more points having different spindle rotation angles can be controlled by the personal computer 6 via the image data interface of the control / calculation unit 33.
3 and obtained from the position of the center of gravity of the reflection image by the least square method or the like. FIG. 13 is a diagram showing a state of the monitor screen immediately after the measurement. W _C indicates a reflection image immediately after the measurement. Since the image data interface of the control / arithmetic unit 33 has a superimpose function, the reflected image W _C
Is the image currently being observed. Further, in the figure, the dotted line circular locus determined by calculation, O ₁ denotes the center of the circular trajectory. These are displayed by the processing of the personal computer 63. Next, the tilt of the lens holder unit 32 is adjusted by the tilt adjusting mechanism 61 of the lens holder unit 32 while watching the monitor 62 so that the reflected image W _C overlaps the center O ₁ . Thereby, the lens holder unit 3
The axis of the second lens holding member 57 and the spindle rotation axis 59 are substantially parallel.

When the next command is transmitted from the personal computer 63, the shift of the lens holder unit 32 by the ball lens 71 as shown in FIG. 14 is started. When the ball lens 71 is attached to the lens holder unit 32, the point light source 36 in the lens surface eccentricity measurement unit 29 is so arranged that the reflection image of the ball lens 71 can be measured at a predetermined reflection magnification by a command from the control / calculation unit 33. And the observation optical system 40 automatically moves. Thereafter, a target point of the adjustment is obtained by the same operation and measurement as the above-described tilt adjustment, and the XY stage 60 of the lens holder unit 32 performs the reshift adjustment.

With the above operation, the ball center position 72 of the ball lens 71 fixed to the lens holder unit 32 can be set as the reference point. Then, by performing the calculation together with the data of the lens outer peripheral eccentricity measurement acquired thereafter, it is possible to obtain the respective eccentric amounts of the lens to be inspected on the basis of the sum of the outer peripherals in the rod lens having a long center thickness. .

Next, the test lens 31 is mounted on the lens holder unit 32. Then, the first lens 31
Following the normal incidence measurement of the surface aspherical surface, the normal incidence measurement of the second spherical surface is performed. At this time, similarly to the above-described tilt adjustment and shift adjustment, an appropriate command is issued from the control / arithmetic unit 33, and measurement can be automatically performed under appropriate conditions. This condition is, for example, that the reflection magnification is set to −1 when measuring the first surface, and that it is set to −0.5 when measuring the second surface.

Here, a description will be given of the occurrence of an error in the observation magnification due to the focus adjustment of the reflected image. When the exit pupil position is closer to the half prism 37 as compared with the light projecting / imaging lens 38 shown in FIG. 8, as in the light projecting / imaging lens 38 'shown in FIG. The focus position of the image is at the position indicated by the image plane 73. Therefore, the test lens 3
1 due to an error in the radius of curvature or the center thickness of the observation optical system 4
The automatically set focus position of 0 may be shifted to the image plane 74, for example, and the reflected image may be blurred. Since the measurement is performed by observing the image plane 73 after performing the focus adjustment, it is clear that the size differs between d and e in the figure, which are the diameters of the locus of the reflected image. However, since the set observation magnification is calculated based on the data on the image plane 74, an error occurs in the measurement data.
However, in this embodiment, since the telecentric optical system is used for the light projecting / imaging lens 38, the trajectory and light flux of the reflected image are as shown in FIG. That is, the diameters of d 'and e', which are the trajectories of the reflected images, are clearly the same on the image plane 73 and the image plane 74, and no error occurs due to focus adjustment. As described above, in the eccentricity measuring device of the present embodiment,
The eccentricity δ of the paraxial spherical center of the first surface aspherical surface by the normal incidence measurement
_{Cx1, δ Cy1} is obtained. Also, the amount of eccentricity of the spherical center of the second spherical surface can be determined.

Next, the oblique incidence measurement of the first surface aspherical surface is started.
Here, the point light source 36 and the observation optical system 40 are moved so that the angle of incidence of the light beam on the test lens is 20.36 ° and the reflection magnification is −1 according to the measurement conditions in the oblique incidence measurement. Further, the rotating mirror 39 rotates, and the positions of the point light source 36 and the observation optical system 40 automatically move, and the zoom lens 4
3 is the lowest magnification. In this case, as shown in FIG.
Vertical reflective image W _L is observed. Then, as in the case of the vertical incidence measurement, the user operates the manual controller 67 to rotate the lens holder unit 32 and zoom the zoom lens 43 so that the locus of rotation of the reflected image becomes sufficiently large on the display 62. I do. The measurement data necessary for this case, a short image are the position and rotation angle of the reflected image W _L when (M direction in the figure) appears, in the long direction of the image of the reflected image W _L is rotated It is not necessary that all of the image be protruded from the screen of the monitor 62 and be observed.

Further, the light amount of the reflected image is adjusted to focus. After that, a command to start measurement is transmitted from the personal computer 63, and reflected images of three or more points having different rotation angles are transmitted to the personal computer 6.
Take in 3. Then, the rotational angle and position of the M direction of the reflected image W _L by fitting a sinusoidal function, and eccentricity △ _Lx1 △
_Lx1 '. A dotted line shown in FIG. 16 is that the locus of the center of gravity position of the reflected image W _L by the rotation.

[0081] Thereafter, using the data (10) of [delta] _Cx1 obtained at normal incidence measurements at the first surface as described above, [delta] _Cy1 and obtained by oblique incidence measurement △ _Lx1 and △ _Lx1 ', Eccentricity of aspheric axis (ε _ASP-x1 , ε _ASP-y1 , δ _ASP-x1 , δ _ASP-y1 )
And are calculated by a dedicated program. Here, R is 8, φ is 3.68 °, θ is 20.6 °, V
L _T is 6.11.

When the above measurement is completed, the lens surface eccentricity measuring unit 29 retreats to the left in FIG. 7 and then the lens outer eccentricity measuring unit 30 moves to the left to measure the outer eccentricity of the lens 31 to be measured. enter. Here, the selector in the control / arithmetic unit 33 is switched, and focusing is manually performed so that the outer periphery of the lens 31 to be inspected is in focus. Also, as shown in FIG. 17, the position of the lens outer peripheral eccentricity measuring unit 30 is adjusted by the stage 54 with a micrometer so that the outer periphery of the lens 31 to be inspected is symmetrical with respect to the straight line N.

FIG. 17 shows a monitor screen at that time. When the test lens 31 is rotated, if there is eccentricity of the lens outer circumference, the outer circumference of the test lens 31 oscillates between the outer peripheral portion S and the outer peripheral portion T in the direction of the arrow in FIG. And measure the runout direction. The shake width is automatically detected by image processing at the intersection of the straight line N and the lens edge,
The angles at three or more rotation angles and the position of the lens edge are measured, and the positions are determined by optimizing them to a sine function.

With the above, the measurement is completed. Since the amounts actually measured are all based on the spindle rotation axis, the amount of eccentricity with respect to the desired reference axis can be obtained by a dedicated program. For example, the amount of eccentricity of the aspherical axis is determined with reference to an axis connecting the paraxial spherical center of the first surface and the spherical center of the second surface.

As described above, the eccentricity measuring apparatus of this embodiment is
Is the eccentricity of the paraxial center of curvature measured by normal incidence and the
By oblique incidence measurement at one point other than the aspherical axis of the lens
In combination with the eccentricity of the local center of curvature in the noon direction,
Eccentricity of the spherical axis (δ_ASP-x1, Δ _ASP-y1, Ε_ASP-x1, Ε
_ASP-y1) Was obtained, and in addition, (A) to
Similar results can be obtained by performing measurement in combination with (D).
You.

[0086] (A) [delta] due to the vertical incidence measurements _Cx1, [delta] _Cy1
And the eccentricity _{LS LSy1} of the local curvature in the spherical _missing direction at a certain point off the axis of the lens to be measured by oblique incidence measurement, and from the result, the eccentricity of the aspherical surface (δ _ASP-x1 , δ _ASP-y1 , ε _{ASP- x1} ,
ε _ASP-y1 ). In this case, the equation (11) is used.
The measurement conditions in the oblique incidence measurement at this time are, for example, when θ = 20.36 °, φ = 0.27 °, VL
_S = 7.16, and the local radius of curvature in the ball missing direction is 7.19.

(B) The meridional local curvature and the spherical missing direction local curvature are measured at one point off the axis of the lens to be measured by oblique incidence measurement without performing normal incidence measurement on the first aspheric surface. △ _LxT , △ _LxS is _calculated . In this case, the eccentricity of the aspherical surface _{(δ ASP-x1, δ ASP-} y1, ε ASP-x1, ε ASP-y1)
Is obtained by using the above equation (12). The measurement conditions in the oblique incidence measurement at this time are, for example, θ = 20.36
°, φ = 0.27 °, VL _T = 6.12, VL
_S = 7.16, local radius of curvature in the meridian direction is 6.06,
The local radius of curvature in the ball missing direction is 7.19.

(C) Measurement of vertical incidence on the first aspherical surface
In other words, the meridional direction off the axis of the lens under test is measured by oblique incidence measurement.
Different local curvature (or local curvature in missing direction)
Two points △_LxT1, △_LxT2Ask for. In this case, the aspherical surface
Heart (δ_ASP-x1, Δ_ASP-y1, Ε _ASP-x1, Ε_ASP-y1)
Equation (13) is used for this. Also, oblique incidence measurement at this time
Is, for example, θ₁= 20.36 °, θ
_Two= 7.32 °, φ₁= 0.27 °, φ_Two=
3.68 °, VL_T1= 6.12, VL_T2= 7.57, b
The local radii of curvature are 6.06 and 7.57, respectively.

(D) In the vertical incidence measurement, instead of measuring the eccentricity of the paraxial center of curvature, the eccentricity of the approximate center of curvature in the first surface aspherical portion covered by the incident light beam is obtained. In this case, the above equation (14) is used. Also, the approximate radius of curvature R
_ap is 8.43. It is assumed that dedicated program software for automatically calculating the approximate radius of curvature R _ap is provided.

Second Embodiment FIG. 18 is a view showing the entire configuration of an eccentricity measuring apparatus according to this embodiment. The same members as those in the first embodiment are denoted by the same reference numerals. The differences from the apparatus of the first embodiment are as follows.

The lens outer eccentricity measuring unit 30 is omitted, and the observation optics 40 in the lens surface eccentricity measuring unit 29 is used for measuring the outer eccentricity of the lens 31 to be measured.
However, when measuring the eccentricity of the outer circumference of the test lens 31, the ring illumination unit 75 is manually set at an appropriate position, and
The outer peripheral portion of 1 is made sufficiently bright. Projection / imaging lens 3 of lens surface eccentricity measurement unit 29
8 is not telecentric but has a finite exit pupil position. The error caused by the focus adjustment as described above is dealt with by correcting the data taken into the control / arithmetic unit 33 by a dedicated program based on the following equation (18). e = P / (PU) × d (18) where P is the distance between the focus position of the observation optical system 40 and the exit pupil position of the light projecting / imaging lens 38, and U is the observation optical system. The distance between the focal position 40 and the focused position of the reflected image, d is the observation optical system 4
E represents the size of the diameter of the locus of the reflected image at the focal position of 0, and e represents the size of the diameter of the locus of the reflected image at the in-focus position of the reflected image.

Third Embodiment FIG. 19 is a view showing the overall configuration of an eccentricity measuring apparatus according to the third embodiment . The difference from the apparatus of the first embodiment is that the lens outer peripheral eccentricity measuring unit is not based on observation of an image of the lens outer peripheral portion with a microscope, but using a distance meter (laser outer diameter measuring devices 76 and 77) using a laser. It is a point. Therefore, the measurement data of the outer peripheral eccentricity of the test lens 31 is taken into the personal computer 63 via the lens outer peripheral eccentricity measurement unit control unit 65. FIG. 20 is a diagram showing a schematic configuration of the lens holder unit 32 and the laser outer diameter measuring machines 76 and 77 provided in the eccentricity measuring apparatus of the present embodiment.

In FIG. 20, a rod lens 78 is held and fixed by a lens holding portion 80 of a lens holder 79 so that a lens outer peripheral portion 81 is sandwiched therebetween. Adjustment of tilt and shift of the lens holder 79 with respect to the spindle shaft 82 is performed by a tilt adjustment mechanism 83 and a shift adjustment mechanism 84. After tilt adjustment and shift adjustment,
The laser outer diameter measuring devices 76 and 77 use the outer peripheral portion 81 of the lens.
Measure the lens outer peripheral runout at the location. The measurement result is
Sent to the personal computer 63 in the control / arithmetic unit, the tilt shift of the lens outer peripheral axis with respect to the spindle axis is calculated, and the eccentricity of the lens with respect to the lens outer peripheral axis is obtained from the result.

In this way, even if there is a tilt of the lens holder 79 itself or a tilt when the lens 78 is chucked, it is possible to correct the tilt. Therefore, the amount of eccentricity of the lens with reference to the lens outer peripheral axis is obtained. It becomes possible. In the eccentricity measuring apparatus of this embodiment, the laser outer diameter measuring device 77 is omitted, and a mechanism for moving the laser outer diameter measuring device 76 in the direction along the spindle axis is provided.
The shake of the outer periphery of the lens may be measured at two points (1).

Fourth Embodiment The eccentricity measuring apparatus of this embodiment has almost the same configuration as that of the third embodiment, except that one laser outer diameter measuring device as an outer eccentricity measuring unit mounted on the lens holder unit 32 is provided. The difference is that only one mechanism is provided and no mechanism or the like for moving in the spindle axis direction is provided. FIG. 21 shows a schematic configuration of the lens holder unit 32 and the laser outer diameter measuring device 76 provided in the eccentricity measuring apparatus of the present embodiment.

In FIG. 21, a rod lens 85 is held and fixed by a lens holding member 87 of a lens holder 86 so that a lens outer peripheral portion 88 is sandwiched therebetween. Adjustment of tilt and shift of the lens holder 86 with respect to the spindle shaft 89 is performed by a tilt adjustment mechanism 90 and a shift adjustment mechanism 91. The outer peripheral shake of the lens is measured by a laser outer diameter measuring device 76. The measurement result here is sent to the personal computer 63 in the control / arithmetic unit.

Hereinafter, a method for measuring a lens to be inspected using the eccentricity measuring apparatus of this embodiment will be described. First, the tilt adjustment is performed by the method described in the first embodiment. Next, shift adjustment is performed in the same manner as described in the first embodiment. By performing such shift adjustment, when the rod lens 85 is mounted, the shift of the center axis of the lens outer periphery with respect to the spindle shaft 89 at the lower end (the chucked portion) of the rod lens 85 becomes almost zero.

After the tilt adjustment and the shift adjustment, the rod lens 85 is mounted on the lens holder 86, and the deflection of the lens outer peripheral portion 88 is measured by the laser outer diameter measuring device 76. The measurement result is transmitted to the personal computer 63 in the control / measurement unit, and the tilt shift of the lens outer peripheral axis with respect to the spindle shaft 89 is calculated based on the equation (16). From this result, the amount of eccentricity of the lens with respect to the lens outer peripheral axis can be obtained.

With such a method, the eccentricity measuring apparatus of this embodiment can correct the tilt of the lens holder 86 itself and the chuck tilt when the lens 85 is chucked, so that it can be corrected. Can be used to determine the amount of eccentricity of the lens.

As described above, the eccentricity measuring apparatus of the present invention has the following features (1) to (5) in addition to the features described in the claims.

(1) The eccentricity measuring apparatus according to claim 1 or 3, wherein the eccentricity of the aspherical surface is obtained from the eccentricity of two or more local curvature centers.

(2) The aspheric surface is obtained from the eccentricity of the local center of curvature in the meridional plane at the first peripheral portion on the aspherical surface and the eccentricity of the local center of curvature within the spherical surface at the first peripheral portion on the aspherical surface. The eccentricity measuring device according to claim 1, wherein the eccentricity is determined.

(3) The eccentricity of the local center of curvature in the meridional plane at the first peripheral part on the aspherical surface and the eccentricity of the local center of curvature in the meridional plane at the second peripheral part on the aspherical surface are determined. The eccentricity measuring device according to claim 1, wherein the eccentricity is obtained.

(4) In at least two or more portions of the aspherical surface, by measuring the eccentricity of the center of curvature of the spherical surface closest to the aspherical shape within the range of the incident light beam diameter,
The eccentricity measuring apparatus according to claim 1 or (1), wherein the eccentricity of the aspherical axis is determined.

(5) means for causing a light beam to enter the lens to be inspected, means for rotating the lens to be inspected, means for detecting a reflected image from the lens to be inspected, and rotation of the lens to be inspected A reference jig comprising: means for determining the eccentricity of the lens to be measured from the locus of the obtained reflected image; means for measuring the shake of the lens to be measured; and a holding member for holding the outer periphery of the lens to be measured. An eccentricity measuring apparatus characterized in that the tilt of the outer periphery of the test lens is obtained from the centering adjustment of the lens holding member to be tested using the method and the measurement of the deflection of the outer periphery of the test lens at one or more locations. .

[0106]

As described above, according to the eccentricity measuring device of the present invention, the eccentricity of the aspherical axis can be measured with high accuracy without any marking for aspherical eccentricity measurement at the same time as completely non-contact and aspherical processing. can do. In addition, the center of the local curvature of curvature is determined with high accuracy because the coordinates of the center of gravity of the reflected image in the direction in which the reflected image is elongated due to astigmatism are not used for measurement, and as a result, the eccentricity of the aspheric surface is also accurately determined. It is possible to ask.

Further, according to the eccentricity measuring apparatus of the present invention, even if the aspherical surface has a large paraxial radius of curvature and a large amount of change in the amount of aspherical surface, a large spherical aberration does not occur in the reflected image, and a high spherical aberration can be obtained. The eccentricity of the aspherical axis can be accurately measured. In particular, when measuring a rod lens, even if there is a tilt of the lens holder itself or a chuck tilt when chucking the lens, it is hardly affected by the tilt. You can easily find it.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method of measuring the eccentricity of an aspherical axis.

FIGS. 2A and 2B are diagrams showing a basic configuration of an eccentricity measuring device of the present invention.

FIG. 3 is a graph showing the relationship between the direction of a reflected image of a test lens and its light intensity distribution.

FIG. 4 is a diagram for explaining a method of calculating the eccentricity of the aspherical axis by the eccentricity measuring device of the present invention.

FIG. 5A is a graph showing a measurement result of a test lens at a reference position. (B) is a graph showing the result when the test lens is rotated by an arbitrary amount from the state of (a).

FIGS. 6A and 6B are diagrams showing a configuration of a generally used lens holder.

FIG. 7 is a diagram illustrating an overall configuration of an eccentricity measuring device according to the first example.

FIG. 8 is a diagram illustrating a detailed configuration of a lens surface eccentricity measuring unit 29 included in the eccentricity measuring device of the first embodiment.

FIG. 9 is a diagram showing a configuration of a lens holder unit 32 provided in the eccentricity measuring device of the first embodiment.

FIG. 10A is a diagram for explaining a configuration of a rod lens used as an example of a test lens. (B)
3 is a graph showing the shape of the first surface aspherical surface of the rod lens shown in FIG.

FIGS. 11A and 11B are diagrams for explaining the effect of the eccentricity measuring device of the first embodiment.

FIG. 12 is a diagram for explaining a method for avoiding an obstacle that occurs when a small and strong lens is measured using the eccentricity measuring device of the first embodiment.

FIG. 13 is a diagram illustrating a state of a monitor image displayed immediately after measurement is performed using the eccentricity measurement device of the first embodiment.

FIG. 14 is a diagram for explaining a shift adjustment method of the lens holder unit 32.

FIGS. 15A and 15B are diagrams for explaining an error in observation magnification due to focus adjustment of a reflected image.

16 is a diagram showing the trajectory of the center of gravity position of the reflected image W _L of the lens after rotating the sample lens.

FIG. 17 is a diagram showing a state of a screen of a monitor 62 displayed when the position of the lens outer peripheral eccentricity measurement unit 30 is adjusted.

FIG. 18 is a diagram illustrating an overall configuration of an eccentricity measuring device according to a second embodiment.

FIG. 19 is a diagram illustrating an overall configuration of an eccentricity measuring apparatus according to a third embodiment.

FIG. 20 shows a lens holder unit 32 and a laser outer diameter measuring device 76 provided in the eccentricity measuring device of the third embodiment.
It is a figure which shows the schematic structure of 77.

FIG. 21 is a view showing a schematic configuration of a lens holder unit 32 and a laser outer diameter measuring device provided in an eccentricity measuring apparatus of a fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aspherical lens 2, 8, 14, 16 Aspherical axis 3 Light emitting means 4, 31 Test lens 5, 26, 59 Rotation axis 6 Detecting means 7 Calculation means 9 Reflected image 10, 11 Light intensity distribution 12, 17 Reflection Image trajectory 13 Non-eccentric aspheric surface 15 Eccentric aspheric surface 18, 20 Oblique incident reflection image 19, 21 Vertical incident reflection image 22, 79, 86 Lens holder 23 Lens 24, 81, 88 Lens outer peripheral portion 25, 57, 80, 87 Holding member 27, 61, 83, 90 Tilt adjusting mechanism 28, 84, 91 Shift adjusting mechanism 29 Lens surface eccentricity measuring unit 30 Lens outer eccentricity measuring unit 32 Lens holder unit 33 Measurement / arithmetic unit 34 Light source 35, 41 Microscope Objective lens 36 Point light source 37 Half prism 38 Projection / imaging lens 39 Rotating mirror 40 Observation optical system 4 2 Triangular prism 43 Zoom lens 44, 56 CCD camera 45, 46, 48 Stepping motor 47, 49 Guide rail 50, 60 XY stage 51, 55 Guide stage 52 Base 54 Stage 58 Rotating means 62 Monitor 63 Personal computer 64 Lens surface eccentricity measurement unit Control unit 65 Lens peripheral eccentricity measurement unit control unit 66 Spindle rotation control unit 67 Manual controller 68 Lens 69 First surface 70 Second surface 71 Ball lens 72 Ball lens center position 73, 74 Image plane 75 Ring illumination unit 76, 77 Laser Outer diameter measuring machine 78,85 Rod lens 82,89 Spindle shaft

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kota Ogawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industrial Co., Ltd. (72) Kimihiko Nishioka 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (3)

[Claims] At least one of lenses to be inspected including an aspheric surface
The eccentricity of the aspherical surface is obtained from a trajectory of a reflected image obtained by rotating a lens to be inspected by irradiating a light beam to two or more portions including a portion other than two aspherical axes. measuring device. 2. A means for causing a light beam to enter a test lens;
Means for rotating the test lens, means for detecting a reflection image from the test lens, means for determining the eccentricity of the test lens from the locus of the reflection image obtained by rotating the test lens, Means for measuring the shake of the outer periphery of the test lens, and a holding member for holding the outer periphery of the test lens, and An eccentricity measuring device characterized in that a tilt is obtained. 3. A light beam is incident on a portion other than the aspherical axis,
When the eccentricity of the local center of curvature is obtained from the locus of the reflection image obtained by rotating the test lens, the direction in which the reflection image of the reflection image coordinates in at least three or more different directions of the test lens is shorter. 2. The eccentricity measuring apparatus according to claim 1, wherein the eccentricity of the local center of curvature is obtained by obtaining the reflection image locus from the component coordinates.