JPH1194700A - Measuring device and method for lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make measurable an afocal lens with high accuracy by measuring and correcting the inclination and displacement of the optical axis of a lens to be examined relative to the optical axis of a measuring device. SOLUTION: A light beam from a light source 11 is transmitted through a patterned plate 13 and converted by a collimator 14 into a parallel beam, and the parallel beam is made incident upon a moving lens 18 and focused on the center P1 of curvature of the first face of a lens O to be examined, and the light beam reflected by the first face of the lens O to be examined is reflected by a half mirror 15 and is focused as P12 on an area sensor 16 provided in a position where it becomes symmetrical to the patterned plate. Then, the lens O to be examined is rotated about the center of the optical axis to describe a first circle using the image on the area sensor 16. Next, the image on the moving lens 18 is focused on the center of curvature of the final face o of the lens O to be examined, and a second circle is described similarly. From the center positions of the first and second circles and the moving distance of the moving lens, the inclination and amount of displacement of the optical axis of the lens O to be examined are calculated to correct the optical axis of the lens O to be examined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an MTF for an afocal optical system such as a camera viewfinder, binoculars or a telescope.
More particularly, the present invention relates to a technique capable of matching an optical axis of a lens to be measured with an optical axis of measurement.

[0002]

2. Description of the Related Art As a device for measuring a lens system such as a viewfinder of a camera, there is known a telescope measuring device of Ealing Company, UK shown in FIG. This measures the MTF of the lens to be measured.

In FIG. 4, light emitted from a light source 1 passes through a slit 2, is converted into a parallel light beam by a collimating lens 3, and is converted into a virtual image P by a test lens 4 such as a finder lens.
And the divergent light beam emitted from ′ is formed at the point P by the imaging lens 5. This image is formed on the light receiving element 7 by the magnifying lens 6, and the light quantity distribution is Fourier-transformed by the microcomputer to measure the MTF of the afocal optical system.

In the above-mentioned measurement, it is necessary to superpose the optical axis of the measuring device and the optical axis of the lens to be measured. However, in the above-described apparatus, the position of the optical axis of the lens to be measured can be adjusted to the optical axis of the measuring apparatus, but the inclination of both axes cannot be adjusted.

[0005]

SUMMARY OF THE INVENTION The present invention has been conceived in view of the above facts. The present invention measures the tilt angle of the optical axis of a lens to be measured with high accuracy, corrects the tilt, and measures the performance of a lens such as MTF. It is an object of the present invention to provide an apparatus and a method capable of performing the following.

[0006]

To achieve the above object, a lens measuring apparatus according to the present invention comprises a light source, a pattern plate receiving light from the light source, a collimator having the pattern plate as a front focal position, A half mirror provided between the pattern plate and the collimator; an area sensor provided at a position symmetrical to the pattern plate with respect to the half mirror; and a lens to be inspected in the light beam from the collimator. A sample stage movable in a plane orthogonal to the axis, a movable lens detachably provided between the sample stage and the collimator and movably provided in the optical axis direction, and a lens to be measured centered on the optical axis. A rotating stage that rotates, an automatic goniometer that adjusts the optical axis of the lens to be inspected, an imaging lens into which the light beam emitted from the lens to be incident enters, and an image that is placed near the imaging point of the imaging lens lens And retractably photodetectors in the optical axis direction, is characterized by a control device for controlling the entire apparatus.

A first arithmetic circuit for analyzing the output of the area sensor, a second arithmetic circuit for analyzing the output of the light receiving element, and a controller for controlling the sample stage, the automatic gonio stage, and the rotating stage are provided. It can be configured to be connected to the control device.

It is preferable that a detachable shielding plate for shielding a light beam emitted from the lens to be inspected is provided.

The lens measuring method of the present invention includes:
The light from the light source is transmitted to the pattern plate, the transmitted light is converted into a parallel light by a collimator, and the parallel light is incident on a moving lens to form an image on the center of curvature of the first surface of the lens to be measured. The light beam reflected by the first surface is reflected by a half mirror to form an image on an area sensor provided at a position symmetrical with the pattern plate, and the test lens is rotated about the optical axis to obtain a second image based on the image of the area sensor. (1) a step of drawing a circle, and the parallel light beam from the collimator is incident on the moving lens to form an image on the center of curvature of the second surface of the test lens, and the light beam reflected on the final surface of the test lens is converted into the half light beam. Reflecting on a mirror to form an image on the area sensor, rotating the test lens about the optical axis, and drawing a second circle on the image of the area sensor;
Calculating the inclination and displacement of the optical axis of the test lens from the center positions of the first and second circles and the moving distance of the moving lens at that time, and correcting the optical axis of the test lens. It is characterized by:

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of one embodiment of the measuring device of the present invention. The light source 11 is supported by a cylindrical body 12 parallel to the optical axis XX.
And the collimator 14 are integrated. A slit 13 a is formed in the pattern plate 13, and the slit 13 a overlaps a front focal point of the collimator 14.

A half mirror 15 is disposed between the light source 11 and the collimator 14, and the half mirror pattern plate 1 is provided.
An area sensor 16 is provided at a position which is mirror-symmetrical to the position 3. A moving lens 18, a test lens O, an imaging lens 19, and a light receiving element 20 are sequentially arranged behind the collimator 14.

The collimator 14 is mounted on the mounting body 21 by the apparatus main body 2.
2 and the moving lens 18 is a moving lens stage 24.
And the movable lens 18 can be moved back and forth on the optical axis XX of the measuring device by the movable lens stage 24.

The test lens O is mounted on a sample stage 25 which can move up, down, left and right, that is, in a plane orthogonal to the optical axis XX, and the sample stage 25 is rotatable about the optical axis XX. The rotary stage 26 is mounted on a stage 26, and the rotary stage 26 is mounted on an automatic gonio stage 28, and the automatic gonio stage 28 is fixed to the apparatus main body 22.

On the imaging lens 19 side of the lens O to be inspected, there is a detachable shielding plate 29. The imaging lens 19 is fixed to the apparatus main body 22 by an imaging lens mounting base 30, the light receiving element 20 is mounted on a light receiving element holding base 31, and the light receiving element holding base 31 is mounted on the apparatus main body via an automatic stage 32. I have.

The area sensor 16 is connected via a first arithmetic circuit 34, and the light receiving element 20 is connected via a second arithmetic circuit 35 to a control device 36 comprising a microcomputer.
5. The moving lens stage 24, the automatic stage 32, the automatic goniometer stage 28, and the rotary stage 26 are connected to a control device 36 via a controller 38. Control device 36
Is provided with a display 39 for showing control contents and the like.

Next, a method for adjusting the optical axis of the lens to be inspected according to the present invention will be described. The light beam emitted from the light source 11 passes through the slit 13 a of the pattern plate 13 and
At 4, the light beam becomes a parallel light beam, passes through the moving lens 18 and forms an image. The controller 36 moves the movable lens stage 24 in the optical axis XX direction via the controller 38, and the image by the movable lens 18 is moved to the center of curvature P1 of the first surface of the lens O to be measured.
Adjust to form an image. Light from the image forming point is reflected by the first surface, and the reflected light flux returns to the half mirror 15 by returning along the optical path. Then, the light is reflected by the half mirror 15 and forms an image as a point P12 on an area sensor 16 provided at a position symmetrical to the pattern plate 13.

Next, the controller 36 drives the rotary stage 26 via the controller 38, and the rotary stage 26 rotates the lens O to be measured about the optical axis. Then
The point P12 imaged on the area sensor 16 draws a circle having an eccentric amount of a rotation radius Z1, as shown in FIG.

Next, the controller 36 drives the movable lens stage 24 via the controller 38 so that the image of the movable lens is formed on the center of curvature P2 of the final surface of the lens to be inspected. A point P22 forms an image on the area sensor 16. Then, the rotation stage 26 is rotated, and the rotation radius Z of the eccentric amount is
Draw a circle of 2.

As shown in FIG. 3, the coordinates of the eccentric centers O1 and O2 of the first surface and the final surface of the lens O to be inspected are obtained, and the moving amount L of the moving lens 18 when moving from O1 to O2 is obtained. The inclination θz between the optical axis XX of the apparatus and the optical axis of the lens O to be inspected can be determined by the following formula: θz = (coordinate of O1−coordinate of O2) / movement amount L. In addition, the amount of axis deviation δ is O
It can be obtained from the distance between the midpoint of 1, O2 and the optical axis.

Therefore, the shift amount δ and the inclination θz are corrected between the sample stage 25 and the automatic gonio stage 28. Specifically, the first arithmetic circuit 34 outputs O1,
The coordinates of O2 are detected, and the controller 38 calculates the movement amount L. The controller 36 calculates θz and δ from the result, and issues an instruction to the sample stage 25 and the automatic goniostage 28 via the controller 38. By doing so, the optical axis of the lens O to be inspected and the optical axis XX- of the measuring device completely overlap. Thereafter, the moving lens 18 and the shielding plate 29 are removed, the light beam from the collimator 14 is made incident on the lens O to be tested, and the light beam emitted from the lens O is formed on the light receiving element 20 to form the light image P0. Is subjected to Fourier transform to measure the MTF of the lens to be measured.

[0021]

According to the present invention as described above,
Since the inclination of the optical axis of the test lens with respect to the optical axis of the measuring device can be accurately measured and corrected, the measurement of the test lens can be performed with high accuracy.

With the configuration in which the shielding plate is provided, it is possible to shield reflected light from the lens other than the lens to be inspected, and it becomes easy to measure the inclination of the optical axis.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a lens measuring device of the present invention.

FIG. 2 is an enlarged view of an area sensor.

FIG. 3 is a diagram for explaining a method of obtaining a tilt θz of an optical axis of a test lens.

FIG. 4 is a diagram showing a configuration of a conventional lens measuring device.

[Explanation of symbols]

 O lens to be inspected 11 light source 13 pattern plate 14 collimator 15 half mirror 16 area sensor 18 moving lens 19 imaging lens 20 light receiving element 25 sample table 26 rotation stage 28 automatic goniometer stage 29 shielding plate 34 first operation circuit 35 second operation circuit 36 control device 38 controller

Claims (4)

[Claims] 1. A light source, a pattern plate receiving light from the light source, a collimator having the pattern plate as a front focal position, a half mirror provided between the pattern plate and the collimator, An area sensor provided at a position symmetrical with respect to the pattern plate, a sample table in a light beam from the collimator, the sample lens being movable in a plane orthogonal to the optical axis, and the sample table and the collimator A movable lens provided detachably between the lens and the optical axis direction, a rotating stage that rotates the test lens around the optical axis, and an automatic gonio stage that adjusts the optical axis of the test lens, An imaging lens on which a light beam emitted from a lens to be detected enters, a light receiving element placed near an imaging point of the imaging lens and capable of moving back and forth in the optical axis direction of the imaging lens, and a control device for controlling the entire apparatus Have An apparatus for measuring a lens, comprising: 2. A first method for analyzing the output of the area sensor.
2. The controller according to claim 1, wherein an arithmetic circuit, a second arithmetic circuit for analyzing an output of the light receiving element, and a controller for controlling the sample stage, the automatic gonio stage, and the rotary stage are connected to the control device. The lens measuring device according to the above. 3. The lens measuring apparatus according to claim 1, further comprising a detachable shielding plate for shielding a light beam emitted from the lens to be inspected. 4. A light from a light source is transmitted through a pattern plate, the transmitted light is converted into a parallel light by a collimator, and the parallel light is incident on a moving lens to form an image on the center of curvature of the first surface of the lens to be measured. A light beam reflected by the first surface of the test lens is reflected by a half mirror to form an image on an area sensor provided at a position symmetrical to the pattern plate, and the test lens is rotated around the optical axis to form the area. Drawing a first circle with the image of the sensor; and projecting a parallel light beam from the collimator into the moving lens to form an image at the center of curvature of the second surface of the lens to be inspected and reflected by the final surface of the lens to be inspected. Reflecting the reflected light beam by the half mirror to form an image on the area sensor, rotating the test lens about the optical axis, and drawing a second circle on the image of the area sensor; The position of the center of the circle and the movement of the moving lens at that time Distance calculated slope and shift amount of the optical axis of the lens and a method of measuring a lens, characterized in that and a step of correcting the optical axis of the lens.