JP2000230883A - Decentering measuring apparatus and its adjusting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decentering measuring apparatus by which the decentering of a lens system to be inspected can be measured easily and with high accuracy. SOLUTION: In this decentering measuring apparatus, a luminous flux which is emitted from a light source 1 is incident on illumination lens systems 19 to 3 comprising an index 20, the luminous flux which is transmitted through the illumination lens systems 19 to 3 is incident on a lens system 6 to be inspected, and the luminous flux which is transmitted through, or reflected by, the lens system 6 to be inspected is passed through a condensing lens system 7 so as to be incident on a position sensor 8. A rotation means 16 by which a part or the whole of the illumination lens systems 19 to 3 is turned around a shaft is provided. The decentering of the lens system 6 to be inspected is detected on the basis of the track 12 of an image 9 by the index 20 formed on the position sensor 8 due to the rotation of the rotation means 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentricity measuring apparatus for measuring transmission eccentricity and reflection eccentricity of a lens system used in an optical apparatus and the like, and an adjustment method therefor.

[0002]

2. Description of the Related Art Conventionally, in an eccentricity measuring apparatus, an eccentricity measurement of a lens system to be measured is performed by mounting the lens system to be measured on a high-precision rotary table and rotating the lens system to be measured by the rotary table. You are. Specifically, when measuring transmission eccentricity,
The collimator lens is adjusted so that the light beam emitted from the light source projects an index on the front focal plane of the lens system to be measured. Then, the light beam transmitted through the lens system to be detected is transmitted through the condenser lens, and the image of the target is projected on the position sensor. And
Based on the radius of the Lissajous (trajectory) of the image of this indicator,
The transmission eccentricity of the test lens system is measured. On the other hand, when measuring the reflection eccentricity, the collimator lens is adjusted so that the luminous flux emitted from the light source is projected on the center of curvature of the surface to be measured of the lens system to be measured. The light beam reflected by the surface to be measured of the lens system to be measured transmits through the condenser lens, and projects an image of the target on the position sensor, similarly to the transmission eccentricity measurement. Then, the reflection eccentricity of the surface to be measured is measured based on the radius of the Lissajous of the image of the index.

[0003]

In the above-described conventional eccentricity measuring apparatus, a test lens system in which the optical axis does not become one straight line, such as a refraction / reflection type test lens system having a plurality of lenses, is used. It was difficult to measure eccentricity. Normally, when measuring a test lens system composed of a plurality of such lenses with an eccentricity measuring device, the eccentricity of the test lens system is measured and at the same time, the eccentricity becomes an allowable value. ,
Also performs assembly adjustment. That is, the eccentricity measurement and the assembly adjustment are alternately repeated while the test lens system is mounted on the turntable. Therefore, in the case of a complex system such as a refraction-reflection type lens system to be inspected, the turntable becomes large and the adjustment work becomes complicated, and considerable work time is required. Further, in the conventional eccentricity measuring device, the runout of the rotary shaft of the turntable affects the measurement error of the eccentricity measurement, and there is a case where the measurement cannot be performed with high accuracy due to the error.

To solve these problems, FIG.
An eccentricity measuring device using an image rotator as shown in FIG. In this apparatus, the eccentricity of the lens system 6 to be measured can be measured without rotating the lens system 6 to be tested and instead rotating the image rotator 22. Specifically, a light beam emitted from the light source 1 passes through the collimator lens 2 and the index 20, and enters the beam splitter 21. The light beam transmitted through the split surface of the beam splitter 21 passes through the focus lens system 3 and the image rotator 22, and enters the lens system 6 to be measured. The light beam reflected from the surface of the lens system 6 to be measured passes through the image rotator 22 and the focus lens system 3 and enters the beam splitter 21. The light beam reflected by the split surface of the beam splitter 21 forms an image of the index 20 on the observation surface 24.

Here, a rotation axis parallel to the optical axis z of the image rotator 22 is a measurement reference axis. Then, the image of the index 20 is projected onto the position of the apparent center of curvature of the surface of the lens system 6 to be measured. Furthermore, Image Rotator 2
By rotating the lens 2, the observer 25 can measure the amount of eccentricity of the lens system 6 to be measured via the objective lens 23 based on the image of the index 20 formed on the observation surface 24. But,
In the eccentricity measuring device using the image rotator 22, the image rotator 22 processed with high precision is required in order to obtain high eccentricity measurement accuracy, and the device becomes expensive as a whole. Accordingly, an object of the present invention is to provide an eccentricity measuring device capable of easily and highly accurately measuring the eccentricity of a lens system to be inspected, and an adjustment method thereof.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. That is, when the reference numerals attached to the attached drawings are added in parentheses, the present invention starts from the light source (1). The luminous flux is incident on the illumination lens system (19-3) having the index (20), and the illumination lens system (19-3)
The light beam that has passed through the lens system enters the test lens system (6), and the light beam transmitted or reflected by the test lens system (6) passes through the condenser lens system (7) and enters the position sensor (8). The eccentricity measuring device includes a rotation unit (16) for rotating a part or all of the illumination lens system (19-3) around a rotation axis, and the position sensor (8) is rotated by the rotation of the rotation unit (16).
Trajectory (12) of the image (9) of the index (20) formed above
An eccentricity measuring device characterized in that the eccentricity of the lens system (6) to be detected is detected based on the following formula. In that case, the illumination lens system (19-3) has a focus lens system (3), and the rotating means (16) is formed so as to be able to rotate only the focus lens system (3) and the index (20), In the lens systems (19-18) other than the focus lens system (3) in the illumination lens systems (19-3), the optical axes of the lens systems (19-18) are the rotation means (1).
Preferably, it is formed so as to substantially coincide with the rotation axis of 6).

The present invention also provides a light source (1) and a light source (1)
An index (20) illuminated by a light beam emitted from the light source, and an illumination lens system (19 to 3) for guiding the light beam from the index (20) to a test lens system (6) mounted on a support plate (22). A condenser lens system (7, 27) for guiding a light beam reflected or transmitted from the test lens system (6) to a position sensor (8, 28).
In the method of adjusting the eccentricity measuring device, the light beam from the illumination lens system (19 to 3) is incident on the support plate (22) in a state where the lens system (6) is removed, and the illumination lens system ( The light of the illumination lens system (19-3) is rotated based on the rotation of the image (9) of the index (20) formed on the position sensor (8, 28) by rotating a part or the whole of 19-3). The axis (z) is matched with the rotation axis, and the illumination lens system (19 to
The support plate (22) is rotated based on the rotation of the image (9) of the index (20) formed on the position sensor (8, 28) by rotating a part or all of 3) and the support plate (22). And the optical axis (z) of the illumination lens system (19-3) are matched, and the corner prism (3) is used instead of the support plate (22).
1) is inserted, the position of the image (9) of the index (20) formed on the position sensor (8, 28) is specified, and the position of the image (9) obtained when the corner prism (31) is inserted. By matching the position with the position of the image (9) obtained when rotating the support plate (22) with a part or all of the illumination lens system (19-3), the index (20) Matching the proper position with the optical axis (z) of the illumination lens system (19-3);
An adjustment method for an eccentricity measuring device, characterized in that:

[0008]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a first embodiment of an eccentricity measuring device according to the present invention. FIG. 1 is a schematic diagram of an eccentricity measuring apparatus according to a first embodiment of the present invention, which is an apparatus for measuring transmission eccentricity of a lens system to be measured. A light beam emitted from the light source 1 is transmitted through the illumination lens 19, the index 20, and the collimator lens 2 in this order, and is incident on the variable stop 18. Variable aperture 18
Are transmitted through a focus lens system 3 including a front lens group 4 and a rear lens group 5 movable in the direction of the arrow in the drawing, and enter the lens system 6 to be measured. Here, the illumination lens system of the present apparatus includes an illumination lens 19, an index 20, a collimator lens 2, a variable diaphragm 18, and a focus lens system 3. The light beam transmitted through the lens system 6 to be inspected further passes through the condenser lens 7 and enters the position sensor 8. At this time, the focus lens system 3 forms an image of the index 20 at the front focal point of the lens system 6 to be measured. The light beam transmitted through the lens system 6 to be examined projects an apparent index 20 on the position sensor 8 by the condenser lens 7.

Here, the index 20, the collimator lens 2,
The variable aperture 18 and the focus lens system 3 are mounted on the turntable 16. The turntable 16 has a rotation axis parallel to the optical axis z, and thereby rotates the index 20, the collimator lens 2, the variable diaphragm 18, and the focus lens system 3 simultaneously. As a result, the image of the index 20 is accurately rotated around the rotation axis of the turntable 16. Then, based on the Lissajous image of the index 20 on the position sensor 8, the transmission eccentricity of the lens system 6 to be measured is measured. Note that the index 20 is disposed at a position slightly shifted from the focal plane of the illumination lens 19.
This is so that when the turntable 16 is rotated in a state where the optical axis of the index 20 does not coincide with the rotation axis of the turntable 16, the uneven light amount caused by the illumination lens 19 does not affect the center of the light amount at the index 20. To do that.

Next, a specific measurement procedure by the eccentricity measuring apparatus of the first embodiment will be described with reference to FIGS.
First, as a preparation before starting the measurement, the standard position of the image of the index 20 projected on the position sensor 8 is determined. The procedure for determining the standard position 11 shown in FIG. 2 is as follows. First, the focus lens system 3 is adjusted so that the target 20 is projected at infinity without placing the test lens system 6 on the apparatus. Then, rotate the turntable 16,
The center position of the Lissajous of the image of the index 20 projected on the light receiving surface of the position sensor 8 is detected. The center position of this Lissajous is the standard position 11. The information on the standard position 11 is held in the memory unit.

Thereafter, the test lens system 6 is mounted on the apparatus, and the eccentricity of the test lens system 6 is measured. First, index 20
Is formed at the front focal point of the lens system 6 to be inspected,
Adjust the focus lens system 3. At this time, the index image 9 is projected on the light receiving surface of the position sensor 8 by the lens system 6 to be measured and the condenser lens 7. Next, when the turntable 16 is rotated, the index image 9 on the light receiving surface of the position sensor 8 becomes
Moving in the direction of the arrow in FIG. 2, a circular Lissajous 12 is drawn. Then, the Lissajous center 10 which is the center position of the Lissajous 12 is detected. This Lissajous center 10
Then, the eccentric state of the lens system 6 to be inspected is obtained from the positional relationship with the standard position 11 determined above.

That is, the distance H between the Lissajous center 10 and the standard position 11 indicates the amount of eccentricity of the lens system 6 to be measured, and the direction of the Lissajous center 10 with respect to the standard position 11 indicates the eccentric direction of the lens system 6 to be measured. The distance between the Lissajous center 10 and the Lissajous 12, ie, the Lissajous radius 13, is
The optical axis shift of the optical system mounted on the turntable 16, that is, the optical axis shift of the index 20, the collimator lens 2, the variable diaphragm 18, and the focus lens system 3 is shown.

The following two types of run-out of the rotary shaft of the turntable 16 can be considered. One is a case where the rotation of the rotation axis draws a circular shape and the frequency thereof matches the rotation frequency of the turntable 16. When this kind of shaft runout occurs, the Lissajous radius 13 of the index image 9 detected by the position sensor 8 does not change. The other is a case where the rotation of the rotary shaft does not draw a circular shape and its frequency does not match the rotation frequency of the turntable 16, that is, the shaft is different from the above. When this kind of shaft runout occurs, the shape of the Lissajous 12 on the position sensor 8 does not become a circle,
The shape of the Lissajous 12 and the Lissajous center 10 can be obtained by analyzing the frequency of the measurement error caused by the shaft runout. As described above, in the first embodiment, since the optical axis deviation of the optical system mounted on the turntable 16 and the eccentric state of the test lens system 6 can be detected separately, the eccentricity of the test lens system 6 can be detected. Can be measured easily and with high accuracy.

Next, an eccentricity measuring apparatus according to a second embodiment of the present invention will be described with reference to FIG. While the device of the first embodiment is a device for measuring the transmission eccentricity of the lens system to be measured, the device of the second embodiment is a device for measuring the reflection eccentricity. A light beam emitted from the light source 1 is transmitted through the illumination lens 19, the index 20, and the collimator lens 2 in this order, and is incident on the variable stop 18. The light beam transmitted through the variable stop 18 transmits through the mirror 17, further transmits through the focus lens system 3, and enters the lens system 6 to be measured. The light beam reflected on the surface to be measured of the lens system 6 to be measured passes through the focus lens system 3 again and is incident on the mirror 17. Mirror 1
The light beam reflected by 7 passes through the condenser lens 7 and enters the position sensor 8. At this time, the focus lens system 3 places the index 2 on the center of curvature of the surface to be measured of the lens system 6 to be measured.
A zero image is formed. Further, the light beam reflected by the test lens system 6 projects an apparent index 20 on the position sensor 8 by the condenser lens 7.

Here, in the second embodiment, the focus lens system 3 and the index 20 are mounted on the turntable 16. And, as in the first embodiment, the turntable 16 is
It has a rotation axis parallel to the optical axis z, and thereby rotates the focus lens system 3 and the index 20. As a result, the image of the index 20 is accurately rotated around the rotation axis of the turntable 16. Then, based on the Lissajous image of the index 20 on the position sensor 8 at this time, the reflection eccentricity of the lens system 6 to be measured is measured. In the second embodiment, before starting the eccentricity measurement, the optical axes of the illumination lens 19, the index 20, and the collimating lens 2 are set so as to coincide with or be parallel to the rotation axis of the turntable 16. Will be adjusted.

In the second embodiment, similarly to the first embodiment, the deviation of the optical axis of the optical system mounted on the turntable 16 and the eccentric state of the lens system 6 can be detected separately. In addition, the eccentricity of the test lens system 6 can be measured easily and with high accuracy. In the second embodiment, the image of the index 20 is formed by the focus lens system 3 at the center of curvature of the surface of the lens system 6 to be measured.
The image of the index 20 may be formed at the paraxial focal point.

Next, an eccentricity measuring apparatus according to a third embodiment of the present invention will be described with reference to FIGS. While the lens system to be tested mounted on the eccentricity measuring apparatus of the first and second embodiments is a single lens, the lens system to be tested of the third embodiment has a plurality of lenses. It is a reflective lens system. Further, in the third embodiment, both the eccentricity measurement and the assembly adjustment are performed while the lens system to be inspected is mounted on the apparatus. A light beam emitted from the light source 1 is transmitted through the illumination lens 19, the index 20, and the collimator lens 2 in this order, and is incident on the variable stop 18. The light beam transmitted through the variable aperture 18 is transmitted through the focus lens system 3 and enters the beam splitter 21.
The light beam transmitted through the split surface of the beam splitter 21 enters the lens system 6 to be measured. The light beam that has passed through the lens system 6 to be examined passes through the condenser lens 7 and enters the position sensor 8.

Here, the test lens system 6 is supported on a support plate 22. The lens system 6 includes a first lens 6 a, a second lens 6 b, and a third lens 6.
c, fourth test lens 6d, test reflecting mirror 15, mirror 14
a and 14b. The optical path of the lens system 6 described above will be described in detail. The light beam transmitted through the split surface of the beam splitter 21 is reflected by the mirror 14a and the first
The light passes through the test lens 6a and the second test lens 6b and enters the test reflecting mirror 15. The light beam reflected by the test reflecting mirror 15 passes through the second test lens 6b and the first test lens 6a again, and is incident on the mirror 14a. The light beam reflected by the mirror 14a is further reflected by the mirror 14b, passes through the third lens 6c and the fourth lens 6d, passes through the condenser lens 7, and enters the position sensor 8. Here, in the third embodiment, the collimator lens 2, the variable aperture 18, and the focus lens system 3 are mounted on the turntable 16. Then, the turntable 16 is rotated to sequentially assemble the test lens systems 6 while measuring the transmission eccentricity of the test lens system 6 based on the Lissajous image of the index 20 on the position sensor 8. Will be.

The procedure for assembling the lens system 6 to be inspected by the apparatus according to the third embodiment will be described below with reference to FIGS. First, the optical axis z of the illumination lens system matches the rotation axis of the turntable 16. Specifically, first, as shown in FIG. 5, the light beam transmitted through the beam splitter 21 is directly incident on the support plate 22 without mounting the lens system 6 to be inspected on the apparatus. The light beam reflected by the support plate 22 enters the beam splitter 21 again. The light beam reflected by the split surface of the beam splitter 21 passes through the condenser lens 27,
The light enters the position sensor 28. Then, the turntable 16 is rotated, and based on the Lissajous image of the index 20 formed on the position sensor 28 at that time, the illumination lens 19,
The optical axis z of the illumination lens system including the index 20, the collimator lens 2, the variable diaphragm 18, and the focus lens system 3.
And the rotation axis of the turntable 16 are matched.

Next, the direction of the normal to the support plate 22 is made to coincide with the optical axis z of the illumination lens system. That is, the adjustment is performed so that the surface of the support plate 22 is orthogonal to the optical axis z of the illumination lens system. Specifically, after the above-described adjustment process, the turntable 16
The support plate 2 is rotated based on the Lissajous image of the indicator 20 formed on the position sensor 28.
Adjustment is performed so that the two surfaces are orthogonal to the optical axis z of the illumination lens system.

Next, the proper position of the index 20 is matched with the optical axis z of the illumination lens system. Specifically, the corner prism 31 is inserted before the optical path reaching the support plate 22. Then, the light beam reflected by the corner prism 31 is reflected by the beam splitter 21, passes through the condenser lens 27, and then enters the position sensor 28 to specify the position of the index image. Then, the position of the image 9 obtained when the corner prism 31 is inserted is matched with the position of the image 9 obtained when the turntable 16 and the support plate 22 are rotated without inserting the corner prism 31. adjust. Thereby, the proper position of the index 20 and the optical axis z of the illumination lens system
Can be matched.

Thereafter, the constituent lenses are assembled while measuring the eccentricity of the lens system 6 to be measured. First, the reflection mirror to be tested 15 is placed on the support plate 22. Then, the reflection eccentricity of the reflection surface of the test reflecting mirror 15 is measured, and the inclination of the test reflecting mirror 15 is adjusted so that the eccentric amount is within an allowable range.
Similarly, reflection eccentricity is measured in the order of the second lens 6b and the first lens 6a, and the inclination of each lens is adjusted so that the amount of eccentricity is within an allowable range. Next, the turntable 16 is rotated to form an index image on the position sensor 8. That is, a Lissajous of the index image formed by the first lens 6a, the second lens 6b, the reflection mirror 15, and the mirrors 14a and 14b is formed on the position sensor 8, and the center of the Lissajous is formed. As a standard position,
Store in memory.

Thereafter, the third lens 6c to be inspected is incorporated into the lens system 6 to be detected, and the Lissajous center on the position sensor 8 at that time is detected. Then, the amount of eccentricity of the third lens 6c is detected from the Lissajous center and the previously obtained standard position, and the assembly is adjusted so that the amount of eccentricity is within an allowable range. Similarly, assembling adjustment is performed for the fourth lens 6d to be inspected. As described above, in the third embodiment, similarly to the first and second embodiments, the eccentricity of the lens system 6 to be measured can be measured easily and with high accuracy. Also,
Even if the test lens system 6 includes a plurality of lenses,
Assembly adjustment by eccentricity measurement can be easily performed.

[0024]

As described above, according to the present invention, it is possible to provide an eccentricity measuring apparatus capable of easily and highly accurately measuring the eccentricity of a lens system to be inspected and a method of adjusting the eccentricity. In addition, it is possible to provide an eccentricity measuring apparatus and an adjusting method thereof that are easy to assemble and adjust by eccentricity measurement even for a lens system to be inspected including a plurality of lenses.

[Brief description of the drawings]

FIG. 1 is a diagram showing an eccentricity measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a Lissajous figure on a position sensor according to a first embodiment of the present invention;

FIG. 3 is a diagram showing an eccentricity measuring device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an eccentricity measuring device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing an adjustment state of an eccentricity measuring device according to a third embodiment of the present invention.

FIG. 6 is a diagram showing an eccentricity measuring device using an image rotator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Collimating lens 3 ... Focus lens system 4 ... Focus lens front group 5 ... Focus lens rear group 6 ... Test lens system 6a ... 1st test lens 6b ... 2nd test lens 6c ... 3rd test Lens 6d Fourth test lens 7, 27 Condensing lens 8, 28 Position sensor 9 Index image 10 Lissajous center 11 Standard position 12 Lissajous 13 Lissajous radius 14a, 14b, 17 Mirror 15 Reflecting mirror 16 ... Rotating table 18 ... Variable aperture 19 ... Illumination lens 20 ... Index 21 ... Beam splitter 22 ... Support plate 31 ... Corner prism z ... Optical axis H ... Eccentricity

Claims (3)

[Claims] 1. A light beam emitted from a light source is made incident on an illumination lens system having an index, and the light beam passed through the illumination lens system is made incident on a lens system to be inspected, transmitted or reflected by the lens system to be inspected. An eccentricity measurement device that passes the light beam through a condenser lens system and enters a position sensor, comprising: a rotation unit configured to rotate a part or all of the illumination lens system around a rotation axis. An eccentricity measuring device, wherein the eccentricity of the lens system to be inspected is detected based on the trajectory of the image of the index formed on the position sensor. 2. The illumination lens system has a focus lens system, and the rotating means is formed so as to be able to rotate only the focus lens system and an index, and the illumination lens system other than the focus lens system is included in the illumination lens system. 2. The eccentricity measuring device according to claim 1, wherein the lens system is formed such that an optical axis thereof substantially coincides with a rotation axis of the rotation unit. 3. A light source, an index illuminated by a light beam emitted from the light source, an illumination lens system for guiding the light beam from the index to a test lens system mounted on a support plate, and the test lens system. A condensing lens system that guides a light beam reflected or transmitted from the illumination lens system to the position sensor. Injecting a light beam, rotating part or all of the illumination lens system, and aligning the optical axis and the rotation axis of the illumination lens system based on the rotation of the image of the index formed on the position sensor. Rotating a part or all of the illumination lens system and the support plate, based on the rotation of the image of the index formed on the position sensor, the normal direction of the support plate and the illumination lens system Align the optical axis and support Inserting a corner prism instead of a plate, specifying the position of the image of the index formed on the position sensor, the position of the image obtained when the corner prism is inserted, and a part of the illumination lens system Or, by matching the position of the image obtained when rotating all of the support plate and the support plate, the proper position of the index and the optical axis of the illumination lens system are matched. How to adjust the wick measuring device.