JP2012002607A - Conical surface measuring device - Google Patents

Abstract

An object of the present invention is to obtain a conical surface measuring device capable of adjusting the alignment of a conical surface to be examined and a spherical measuring interferometer with high accuracy and improving the accuracy of diameter measurement of the conical surface to be examined.
A planar measurement interferometer, a biaxial tilt adjustment stage, an XY stage, and a Z stage adjust alignment of a test conical surface and a spherical measurement interferometer, and a reference lens. The test lens 90 is arranged at a reference position where the cat's eye point is located on the test conical surface 91. The test lens 90 is moved to the test cone surface measurement position where a part of the measurement light from the spherical surface measurement interferometer 10 enters perpendicularly to the arc-shaped region on the test cone surface 91, and the reference position and The distance from the test cone surface measurement position is obtained from the detection value of the laser length measuring device 41, and the measurement value of the diameter of the test cone surface 91 is calculated based on the distance.
[Selection] Figure 1

Description

  The present invention relates to a conical surface measuring apparatus for measuring a conical surface, and in particular, to a test conical surface comprising a right conical surface and a test plane formed perpendicular to the central axis of the conical surface. The present invention relates to a conical surface measuring apparatus suitable for measuring a diameter of a conical surface to be examined in a specimen.

  In recent years, in order to align a plurality of lenses in the optical axis direction without decentering them in a lens barrel, a plurality of adjacent lenses are each formed with a conical surface consisting of a right conical surface, and each fitting surface A lens (hereinafter referred to as a “fitting lens”) that enables positioning between the lenses by fitting them together has been put into practical use. Such a fitting lens usually has a flat surface formed perpendicular to the central axis of the fitting surface (which coincides with the lens optical axis in design), and this flat surface is disposed in the lens barrel. This is the reference plane for installation.

  In this type of fitting lens, unless the forming accuracy of the fitting surface is good, each lens cannot be installed at the correct position, and it becomes difficult to obtain the desired optical performance. Therefore, there is a demand to improve the forming accuracy by measuring the forming error (inclination angle, surface shape, and diameter error) of the fitting surface and feeding back the obtained forming error to the manufacturing process.

  Conventionally, a three-dimensional shape measuring apparatus (see Patent Documents 1 and 2 below) using a measurement probe such as an optical probe or an atomic force probe has been used to measure such a fitting lens. There is a problem that it takes a lot of time.

  On the other hand, a technique for measuring the radius of curvature of a spherical surface to be measured using a spherical surface measuring interferometer that emits a spherical wave as measurement light has been known (see Patent Document 3 below). This technique has two positions: when the apex of the test sphere is located at a point where the measurement light is focused (also called a cat's eye point) and when the measurement light is perpendicularly incident on the test sphere. Utilizing the formation of interference fringes, the measured value of the radius of curvature of the subject spherical surface is calculated based on the difference in distance between the two positions.

Japanese Patent Laid-Open No. 5-87540 JP 2005-156235 A Japanese Patent No. 3218723

  The technique for measuring the radius of curvature of the test spherical surface using the spherical surface measuring interferometer described above is also used for measuring the diameter of a right cylindrical surface such as a cylindrical lens. Therefore, it is conceivable to apply this technique to measure the diameter of a right conical surface such as the fitting surface described above.

  However, unlike a right circular cylinder surface in which each bus bar is parallel to the central axis, each bus bar of the right conical surface is inclined by a predetermined angle with respect to the central axis. Therefore, when measuring the diameter of a right circular cylinder surface, it is only necessary to align the measurement optical axis of the interferometer for spherical measurement and the central axis of the right circular cylinder surface to be perpendicular to each other. When measuring the diameter, the central axis of the right conical surface is more accurately tilted by a predetermined angle (the angle formed between the generatrix of the right conical surface and the central axis) with respect to the measurement optical axis of the interferometer for spherical measurement. Thus, it is necessary to align with high accuracy.

  The present invention has been made in view of such circumstances, and performs alignment adjustment between a test cone surface to be measured and a spherical measurement interferometer with high accuracy, thereby improving the accuracy of diameter measurement of the test cone surface. An object of the present invention is to provide a conical surface measuring device that can be improved.

  In order to achieve the above object, a conical surface measuring apparatus according to the present invention has the following features.

That is, the conical surface measuring device according to the present invention is
A subject holding means for holding a subject comprising a test conical surface composed of a right conical surface and a test plane formed perpendicular to the central axis of the test conical surface;
A spherical measurement interferometer that emits measurement light composed of spherical waves focused on the measurement optical axis toward the test cone surface and causes return light from the test cone surface to interfere with reference light;
An inclination detecting means for detecting an inclination of the test plane with respect to the measurement optical axis;
The relative angle of the subject and the spherical surface measurement interferometer is such that the angle of inclination of the test plane with respect to the measurement optical axis coincides with the angle formed by the generatrix of the test cone surface and the central axis. An inclination adjusting means for adjusting the inclination;
The subject and the spherical measurement interference after the relative inclination adjustment so that the measurement optical axis intersects the central axis and the measurement light condensing point is located on the test conical surface. Position adjusting means for adjusting the relative position of the meter;
The measurement optical axis of the subject and the spherical measurement interferometer after the relative position adjustment so that a part of the measurement light is perpendicularly incident on an arc-shaped region on the test conical surface A separation distance adjusting means for adjusting a separation distance in the direction;
And a separation distance difference detecting unit for detecting a difference between the separation distances before and after the adjustment of the separation distance.

  In the present invention, the parallel light beam is emitted toward the test plane, and the return light from the test plane is made to interfere with the reference light to obtain an interference fringe carrying the tilt information of the test plane. An interferometer can be provided as the tilt detection means.

  The conical surface measuring apparatus according to the present invention has the above-described features, and thus has the following effects.

  That is, according to the conical surface measuring apparatus of the present invention, the inclination detecting means for detecting the inclination of the test plane with respect to the measurement optical axis of the spherical measurement interferometer, and the relative inclination adjustment of the subject and the spherical measurement interferometer By providing the tilt adjusting means for performing the alignment, the alignment adjustment between the test conical surface and the spherical surface measuring interferometer can be performed with high accuracy.

  A position adjusting unit that adjusts a relative position between the subject and the spherical measurement interferometer; a separation distance adjusting unit that adjusts a separation distance in the measurement optical axis direction of the subject and the spherical measurement interferometer; By providing the separation distance difference detecting means for detecting the difference between the separation distances before and after the distance adjustment, the diameter of the test cone surface can be measured with high accuracy.

It is a schematic block diagram of the conical surface measuring apparatus which concerns on one Embodiment. It is the schematic which shows the aspect at the time of the measurement of a conical surface measuring apparatus. It is the schematic which shows the aspect at the time of alignment adjustment of a cone surface measuring apparatus. It is the schematic for demonstrating the calculation method of the diameter of a to-be-tested conical surface.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the above-mentioned drawings. In addition, each figure used for description of embodiment is rough explanatory drawing, and does not show a detailed shape and structure, The size of each member, the distance between members, etc. are changed suitably and shown. . In particular, in FIGS. 2 and 4, the configuration of the test lens 90 is simplified.

(Device configuration)
As shown in FIG. 1, the conical surface measuring apparatus according to the present embodiment measures a test lens 90 (the subject in the present embodiment), and includes a spherical surface measuring interferometer 10 and a flat surface measuring interferometer 20. The object alignment adjustment unit 30, the separation distance difference detection unit 40, and the measurement analysis unit 50 (shown only in FIG. 1) are provided.

The test lens 90 is a test cone surface 91 having a right conical surface and a test cone formed perpendicular to the central axis C ₉₁ of the test cone surface ₉₁ (which is also the optical axis of the test lens 90). A plane 92. The test lens 90 is a fitting lens used in combination with another lens (not shown), and a test conical surface 91 is formed as a contact surface with the other lens.

The spherical measurement interferometer 10 includes an interferometer body 11, a reference lens 12 for generating a spherical wave installed on the interferometer body 11 via a biaxial tilt adjustment mechanism 13, and a spherical measurement interference. A flat reference plate 14 (see FIG. 2) installed in place of the reference lens 12 at the time of alignment adjustment of the meter 10 and the flat surface measurement interferometer 20 is provided, and its measurement optical axis C ₁₀ (reference lens 12 after alignment adjustment) A spherical wave condensed on the optical axis) is emitted from the reference lens 12 toward the test cone surface 91 as measurement light, and return light from the test cone surface 91 is used as reference light. Interference fringes corresponding to a predetermined region of the test conical surface 91 are obtained by interference.

The plane measuring interferometer 20 includes an interferometer body 21 and a plane reference plate 23 attached to the interferometer body 21 via a biaxial tilt adjusting mechanism 22, and its measurement optical axis C _20. A parallel light beam is emitted toward the test plane 92 along the line, and the return light from the test plane 92 is made to interfere with the reference light, so that an interference fringe carrying the tilt information of the test plane 92 is obtained. It is configured. The plane measuring interferometer 20 is held by a θ stage 25 via a biaxial tilt adjustment stage 24.

  The subject alignment adjustment unit 30 includes a holding base 31 that holds the test lens 90 by suction, a biaxial inclination adjustment stage 32 that holds the holding base 31, and a support base 33 that supports the biaxial inclination adjustment stage 32. And an XY stage 34 that holds the support base 33, a Z stage 35 that holds the XY stage 34, and the spherical measurement interferometer 10 and the planar measurement interferometer 20 are arranged on the XY stage 34 during alignment adjustment. And a two-axis position adjusting stage 36 (see FIG. 2).

  The separation distance difference detection unit 40 includes a laser length measuring device 41 and a corner cube 42 installed on the XY stage 34 in order to retroreflect the laser light from the laser length measuring device 41.

  The measurement analysis unit 50 includes an analysis device 51 including a computer, a monitor device 52 that displays an interference fringe image and the like, and an input device 53 for performing various inputs to the analysis device 51. The analysis device 51 includes a storage unit such as a CPU and a hard disk, and a circuit unit for executing a program stored in the storage unit, and is configured to perform interference fringe analysis and various calculations.

  In the present embodiment, the plane measuring interferometer 20 constitutes an inclination detecting means, and the biaxial inclination adjusting stage 32 constitutes an inclination adjusting means. Further, the XY stage 34 and the Z stage 35 described above constitute a position adjustment means, the Z stage 35 constitutes a separation distance adjustment means, and the laser length measuring device 41 constitutes a separation distance difference detection means. Yes.

Hereinafter, the operation of the conical surface measuring apparatus according to the present embodiment will be described. Prior to performing the measurement, alignment adjustment of the spherical surface measuring interferometer 10 and the flat surface measuring interferometer 20 is performed. First, the procedure will be described. For this alignment adjustment, an adjustment jig 60 shown in FIG. 3 is used. The adjustment jig 60 includes a first plane 61 and a second plane 62 that are respectively formed in an optical flat, and an angle β ₂ formed between the first plane 61 and the second plane 62 is a generatrix of the conical surface 91 to be examined. The angle β ₁ (for example, 105 degrees (design value), see FIG. 4) formed by the angle between the surface 92 and the test plane 92 is configured to coincide with high accuracy.

(Alignment adjustment)
<1> As shown in FIG. 4, a flat reference plate 14 is attached to the spherical measurement interferometer 10, the measurement optical axis C _{10 of} the spherical measurement interferometer _10, and a reference reference plane (not shown) of the flat reference plate 14. The inclination of the plane reference plate 14 is adjusted so that the two are perpendicular to each other. The tilt adjustment is formed, for example, by irradiating a collimated light beam from a spherical surface measuring interferometer 10 by placing a corner cube (not shown) on the measuring optical axis C _10, the reference light and the returning light from the corner cube The operator manually operates the biaxial tilt adjustment mechanism 13 so that the interference fringes are in a null fringe state.

  <2> The biaxial position adjusting stage 36 is installed on the XY stage 34, the above-described adjusting jig 60 is placed on the biaxial position adjusting stage 36, and the first plane 61 is opposed to the interferometer 10 for spherical measurement. The second plane 62 is installed so as to face the plane measuring interferometer 20.

<3> The inclination of the adjustment jig 60 is adjusted so that the measurement optical axis C10 of the spherical surface interferometer ₁₀ and the first plane 61 of the adjustment jig 60 are perpendicular to each other. In this tilt adjustment, for example, the first plane 61 is irradiated with a parallel light beam from the interferometer 10 for spherical measurement, and the interference fringes formed by the return light from the first plane 61 and the reference light are in a null fringe state. As described above, the operator manually operates the biaxial position adjustment stage 36.

<4> As the measurement optical axis C ₂₀ of the planar measurement interferometer 20 and the second plane 62 of the adjustment jig 60 are perpendicular to each other, to adjust the tilt of the planar measurement interferometer 20. For example, the tilt adjustment is performed by irradiating the second plane 62 with a parallel light beam from the interferometer 20 for plane measurement, and the interference fringes formed by the return light from the second plane 62 and the reference light are in a null fringe state. As described above, the operator manually operates the biaxial tilt adjustment stage 24 and the θ stage 25.

<5> Remove the flat reference plate 14 a spherical measurement interferometer 10, fitted with a standard lens 12 shown in FIG. 1, the inclination adjustment of the optical axis of the reference lens 12 with respect to the measurement optical axis C _10. This tilt adjustment is performed, for example, when the first plane 61 is located at the cat's eye point of the reference lens 12 (the condensing point of the spherical wave emitted from the reference lens 12) and interference fringes due to the return light from the cat's eye point The operator manually operates the XY stage 34, the Z stage 35, and the biaxial tilt adjustment mechanism 13 so as to be formed.

The above alignment adjustment, no measurement optical axis C ₁₀ and the angle (two measuring optical axis C ₁₀ of the measurement optical axis C ₂₀ of the planar measurement interferometer _20, C ₂₀ spherical measuring interferometer 10 intersect each other If, the angle of each direction vector), so that the matching angle beta ₁ and the high accuracy between the bus and the test plane 92 of the test conical surface 91. If the alignment cannot be adjusted completely, the alignment error is obtained, and the measurement error due to the alignment error is corrected at the time of analysis.

  After the alignment adjustment is completed, the diameter of the test conical surface 91 is measured. Hereinafter, the measurement procedure and the operation during measurement will be described.

(Measurement procedure and action)
<1> The biaxial position adjustment stage 36 and the adjustment jig 60 are removed from the XY stage 34, and the holding base 31, the biaxial tilt adjustment stage 32, and the support base 33 are placed on the XY stage 34 as shown in FIG. After the installation, the test lens 90 is installed on the holding table 31. At this time, coarse adjustment by visual observation or the like is performed so that the test plane 92 of the test lens 90 faces the interferometer 20 for plane measurement.

<2> Interference fringes (hereinafter referred to as “hereinafter referred to as“ interference fringes ”) formed by irradiating a parallel light beam from the plane measuring interferometer 20 toward the test plane 92 of the test lens 90 and returning light from the test plane 92 and reference light. the phase information of the called test plane interference fringes ") (striped lines), detecting the inclination of the test plane 92 with respect to the measurement optical axis C ₂₀ of the planar measurement interferometer 20. In the present embodiment, the test plane interference fringes are analyzed by the analysis device 51 and the tilt of the test plane 92 is calculated. However, the operator can determine the tilt of the test plane 92 based on the test plane interference fringes. It is also possible to determine whether or not there is a state or inclination.

<3> The angle α ₂ (see FIG. 4) of the inclination of the test plane 92 with respect to the measurement optical axis C ₁₀ of the spherical surface measuring interferometer 10 is the angle α formed between the generatrix of the test conical surface 91 and the central axis C _{91. 1} (for example, 15 degrees (design value), see FIG. 4), the inclination of the lens 90 is adjusted. This tilt adjustment is performed, for example, based on the detected tilt of the test plane 92 so that the test plane interference fringe is in a null fringe state, that is, the measurement optical axis C _{20 of the} plane measurement interferometer _20. On the other hand, the biaxial tilt adjustment stage 32 is manually operated so that the test plane 92 is vertical.

<4> the measurement optical axis C ₁₀ of the spherical measuring interferometer 10 intersects with the center axis C ₉₁ of the test conical surface 91, and Cat's eye point of the reference lens 12 (reference lens 12 measurement light emitted from the (spherical The position of the test lens 90 is adjusted so that the condensing point of the wave) is located on the test conical surface 91 (see FIG. 2A). In this position adjustment, the operator manually operates the XY stage 34 and the Z stage 35 so that when the test conical surface 91 is positioned at the cat's eye point, interference fringes due to the return light from the cat's eye point are actually formed. Operate to do. Hereinafter, the position of the test lens 90 at this time is referred to as a reference position.

  <5> The laser length measuring device 41 detects the distance between the XY stage 34 and the laser length measuring device 41 when the test lens 90 is at the reference position. Hereinafter, the detected value of the distance at this time is referred to as a first distance value.

<6> Spherical measurement interferometer so that part of the measurement light from the spherical measurement interferometer 10 is perpendicularly incident on the arc-shaped region on the test conical surface 91 (see FIG. 2B). for 10 and the measurement optical axis C ₁₀ direction of adjustment of the distance between the subject lens 90. The adjustment of the separation distance is performed by the operator so that an interference fringe (hereinafter referred to as “cone fringe interference fringe”) is actually formed by returning light from the arcuate region on the conical face 91 to be examined. The stage 35 is manually operated. Hereinafter, the position of the test lens 90 when the test conical surface interference fringes are formed is referred to as a test conical surface measurement position. When the test lens 90 is at the test cone surface measurement position, the cat's eye point of the reference lens 12 is located on the central axis C ₉₁ of the test cone surface 91.

  <7> The laser length measuring machine 41 detects the distance between the XY stage 34 and the laser length measuring machine 41 when the test lens 90 is at the test cone surface measurement position. Hereinafter, the detected value of the distance at this time is referred to as a second distance value.

<8> The diameter of the test conical surface 91 is calculated based on the first distance value and the second distance value described above. Specifically, first, an absolute value of a difference between the first distance value and the second distance value is obtained. The absolute value of the difference between this time corresponds to the distance shown in FIG. 4 D (distance from the intersection P between the measurement optical axis C ₁₀ and the central axis C ₉₁ to test the conical surface 91). Radius L of the test conical surface 91 (strictly speaking, when the test conical surface 91 is cut perpendicularly to the measurement optical axis C ₁₀ at the intersection point Q between the measurement optical axis C ₁₀ and the test conical surface 91) ) Has a relationship expressed by the following formula (1) with respect to the distance D. Therefore, the radius L is calculated by the following formula (1), and the calculated value is doubled to calculate the radius of the test conical surface 91. Find the diameter.
L = D / cosα ₁ (1)

  The calculation of the diameter of the test conical surface 91 is configured to be automatically calculated in the analysis device 51. However, the operator can calculate the diameter of the test conical surface 91 based on the first distance value and the second distance value. You may make it calculate using.

In this embodiment, since the width of the test cone surface 91 is extremely short, the position in the width direction on the test cone surface 91 where the intersection point Q of the measurement optical axis C ₁₀ and the test cone surface 91 is located. However, the calculation result of the diameter of the test conical surface 91 is not affected. When the test cone surface 91 has a certain width, it is preferable to include means for detecting which position in the width direction of the intersection point Q is on the test cone surface 91.

Further, the shape of the test cone surface 91 can be measured based on the test cone surface fringes. In this case, by further providing a mechanism for rotating the test cone surface 91 about the central axis C ₉₁ , the shape of each arcuate region in the circumferential direction of the test cone surface 91 is measured, and the shape of each arcuate region is measured. It is also possible to measure the shape of the entire conical surface 91 in the circumferential direction and the roundness by connecting them together.

  When performing shape measurement, if it is difficult to observe the test cone surface fringes because the width of the test cone surface 91 is extremely short, the test cone surface interference fringes are connected to a screen such as ground glass. And the image may be magnified and observed with a microscope or the like. In this case, the shape of the entire region may be measured by moving the microscope and connecting the interference fringes of the regions observed in an enlarged manner to each other.

  As mentioned above, although embodiment of this invention was described, an aspect of this invention is not limited to the above-mentioned embodiment, The thing of a various aspect can be made into embodiment.

  For example, in the above embodiment, the plane measurement interferometer 20 is used as the tilt detection means, but an autocollimator can also be used as the tilt detection means.

  In the above embodiment, the test lens 90 made of a fitting lens is used as the test object. However, the conical surface measuring apparatus of the present invention is formed perpendicular to the right conical surface and the central axis of the right conical surface. The present invention can be applied to the measurement of the diameter or shape of the right conical surface of various subjects having a flat surface.

  In addition, as the interferometer (for spherical surface measurement and plane measurement) in the present invention, it is preferable to use an interferometer (for example, Fizeau type) using a high coherence light source, but interference using a low coherence light source. It is also possible to use a meter (for example, Michelson type).

DESCRIPTION OF SYMBOLS 10 Spherical measurement interferometer 11,21 Interferometer main-body part 12 Reference lens 13,22 Biaxial inclination adjustment mechanism 14,23 Plane reference board 20 Plane measuring interferometer 24 Biaxial inclination adjustment stage 24
25 θ stage 30 subject alignment adjustment unit 31 holding stand 32 biaxial tilt adjustment stage 33 support stand 34 XY stage 35 Z stage 36 biaxial position adjustment stage 40 separation distance difference detection unit 41 laser length measuring device 42 corner cube 50 measurement analysis Unit 51 Analysis device 52 Monitor device 53 Input device 60 Adjustment jig 61 First plane 62 Second plane 90 Test lens 91 Test cone surface 92 Test plane C ₁₀ , C ₂₀ Measurement optical axis C ₉₁ Central axis P, Q Intersection point α ₁ , α ₂ , β ₁ , β ₂ angle D distance L radius

Claims (2)

A subject holding means for holding a subject comprising a test conical surface composed of a right conical surface and a test plane formed perpendicular to the central axis of the test conical surface;
A spherical measurement interferometer that emits measurement light composed of spherical waves focused on the measurement optical axis toward the test cone surface and causes return light from the test cone surface to interfere with reference light;
An inclination detecting means for detecting an inclination of the test plane with respect to the measurement optical axis;
The relative angle of the subject and the spherical surface measurement interferometer is such that the angle of inclination of the test plane with respect to the measurement optical axis coincides with the angle formed by the generatrix of the test cone surface and the central axis. An inclination adjusting means for adjusting the inclination;
The subject and the spherical measurement interference after the relative inclination adjustment so that the measurement optical axis intersects the central axis and the measurement light condensing point is located on the test conical surface. Position adjusting means for adjusting the relative position of the meter;
The measurement optical axis of the subject and the spherical measurement interferometer after the relative position adjustment so that a part of the measurement light is perpendicularly incident on an arc-shaped region on the test conical surface A separation distance adjusting means for adjusting a separation distance in the direction;
A conical surface measuring device comprising: a separation distance difference detecting unit configured to detect a difference between the separation distances before and after the adjustment of the separation distance. A plane measuring interferometer that emits a parallel light beam toward the test plane, causes the return light from the test plane to interfere with the reference light, and obtains an interference fringe carrying the tilt information of the test plane. The conical surface measuring device according to claim 1, wherein the conical surface measuring device is provided as the inclination detecting means.

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