JP2006047149A - Interference measuring method, and adjusting method for interference measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove an aberration caused by a positional shift of an auxiliary lens, and to precisely measure optical performance of an examined lens. <P>SOLUTION: In this interference measuring method for measuring the optical performance of the examined lens by observing an interference fringe obtained with a reference light reflected by a reference plane plate, and an examination light formed into a finite light by the auxiliary lens after transmitted through the reference plane plate, transmitted through the examined lens arranged in a prescribed position to be turned back by a concave mirror, and transmitted again through the examined lens, the auxiliary lens and the reference plane plate, a position of the examined lens is regulated to bring the interference fringe into one color, under the condition where a metal mirror having a curvature same to the examined lens is arranged in place of the examined lens at a position where the examined lens is arranged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an interference measurement method for measuring optical performance of a lens to be examined by interference measurement and an adjustment method for an interference device used therefor, and more particularly to an interference measurement method for measuring the optical performance of a finite light incident on the test lens. And an adjustment method of the interference measurement apparatus.

Conventionally, in order to measure the optical performance of a test lens having a spherical surface, a spherical original device having a spherical surface having the same curvature as the spherical surface of the test lens is arranged on the optical path of the measurement light of an existing interferometer. The device was used. In this apparatus, by arranging a spherical original device, a predetermined spherical wave can be incident on the lens to be examined.
Japanese Patent No. 3140498

  However, in the above-described apparatus, when the measurement target is switched to a test lens having a curved surface having a different curvature, the relative position between the spherical original device and the test lens is changed, or the test lens after switching is changed. It was necessary to replace it with a spherical prototype having the same curvature as Since these operations are required when switching the test lens, work efficiency is inevitably reduced.In particular, when changing the relative position of the spherical prototype and the lens to be measured, the curvature of the test lens is accurate. Therefore, there is a possibility that the optical performance of the test lens cannot be measured accurately.

  In order to solve the above-described problems, the interference measurement method of the present invention includes a reference light reflected by a reference plane plate, a test light that is transmitted through the reference plane plate and then converted into a finite light by an auxiliary lens and arranged at a predetermined position. Interference measurement method for measuring optical performance of a test lens by observing interference fringes obtained by passing through the lens, being folded back by a concave mirror, and again passing through the test lens, auxiliary lens and reference plane plate In the state where a metal mirror having the same curvature as the test lens is arranged instead of the test lens at the position where the test lens is arranged, the interference fringes are assisted so as to become one color. It is characterized by adjusting the position of the lens.

  The method for adjusting an interference measurement apparatus according to the present invention includes a reference mirror reflected by a reference plane plate and a finite light by an auxiliary lens after passing through the reference plane plate, and passes through a lens to be measured disposed at a predetermined position and is a concave mirror. And an interference measuring device adjustment method for measuring the optical performance of the test lens by observing the interference fringes obtained by the test light that is reflected by the test lens, the auxiliary lens, and the reference plane plate again. Then, in a state where a metal mirror having the same curvature as the test lens is arranged instead of the test lens at the position where the test lens is arranged, the auxiliary lens is arranged so that the interference fringes become one color. It is characterized in that the position of the test lens is adjusted by moving it.

  A concave lens or a convex lens can be used as the auxiliary lens.

  According to the present invention, it is possible to cope with a test lens having a different curvature only by replacing the auxiliary lens, so that the working efficiency is high and the optical performance of the test lens can be accurately measured. Furthermore, since the arrangement position of the auxiliary lens can be set accurately, it is possible to remove the aberration due to the positional deviation between the test lens and the auxiliary lens, and to measure the optical performance of the test lens with higher accuracy. .

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
<First Embodiment>
The first embodiment is an example in which a concave lens is used as an auxiliary lens of the interference measuring apparatus according to the present invention. The interference measuring apparatus includes a semiconductor laser (light source) 10, a reference plane plate 56, a concave mirror 59, and a CCD (solid-state imaging device) 40.

  As shown in FIGS. 1 and 2, the semiconductor laser 10 is driven by an LD driver 11, and emits a predetermined laser beam to the lens 80 to be tested through an optical system described below. In the traveling direction of the laser light emitted from the semiconductor laser 10, a condenser lens 50, a pinhole 51, and a half mirror 52 are sequentially arranged from the semiconductor laser 10 side. Laser light emitted from the semiconductor laser 10 is condensed into the pinhole 51 by the condenser lens 50. The traveling direction of the light that has passed through the pinhole 51 is bent 90 degrees by a half mirror 52 that is disposed at an inclination of 45 degrees with respect to the optical path.

  On the optical path of the light reflected by the half mirror 52, a collimator lens 53, a reference plane plate 56, a cover glass 58, and a concave mirror (reflection reference concave mirror) 59 are arranged in this order from the half mirror 52 side. The light reflected by the half mirror 52 is collimated by the collimator lens 53, and the test lens 80 is placed on the stage 81 placed on the optical path of the parallel light and in front of the cover glass 58. Is done. The stage 81 is disposed so as not to prevent the light entering the lens 80 to be examined.

  The reference flat plate 56 is a flat glass plate whose surface is polished with high accuracy, and a reference surface 56 a is provided on a surface far from the collimator lens 53. The reference surface 56a has a property of transmitting part of the light incident on the reference flat plate 56 and reflecting the rest. By utilizing this property, it is possible to obtain interference fringes between the light reflected by the reference surface 56a and the light that has passed through the reference surface 56a and then passed through the lens 80 to be tested.

  The light (reference light) reflected by the reference surface 56 a passes through the half mirror 52 through the collimator lens 53. The light transmitted through the half mirror 52 forms an image on the CCD 40 through the pinhole 57 arranged on the optical path. On the other hand, the light (test light) that has passed through the reference surface 56 a passes through the test lens 80 and the cover glass 58 and then enters the concave mirror 59. The light reflected by the concave mirror 59 having a focal point on the optical axis of the collimator lens 53 follows the same optical path as the incident light, passes through the reference plane plate 56 again, and then follows the same optical path as the light reflected by the reference surface 56a. An image is formed on the CCD 40. Therefore, on the CCD 40, interference fringes are generated by light transmitted through the lens 80 to be measured and light reflected by the reference surface 56a. The interference fringes are converted into electrical signals by the CCD 40, imaged by the image scanner 32 connected thereto, and input to the computer 33, where processing described later is performed.

  Between the reference plane plate 56 and the test lens 80, a drive unit 72 (for example, an air) is provided in an optical path direction of light that passes through the reference plane plate 56 and travels toward the test lens 80 and in a plane perpendicular to the optical path direction. A grip portion 71 that is movable by a cylinder) is provided. The grip portion 71 is movable in the optical path direction of the light passing through the reference plane plate 56 and traveling toward the lens 80 to be tested while holding the concave lens (auxiliary lens) 70 on the upper surface thereof. It is possible to move in a plane perpendicular to the optical path direction of the test light including a predetermined measurement position (FIG. 1) and a lens replacement position outside the optical path (FIG. 2). The measurement position where the concave lens 70 is disposed is a position where the front focal position B of the concave lens 70 coincides with the front focal position A of the lens 80 shown in FIG. In a state where the concave lens 70 is arranged at the measurement position, the light transmitted through the reference plane plate 56 becomes a spherical wave as a finite light having the same front focal position A as shown in FIG. 80 is incident.

  In the interference measuring apparatus of the present embodiment, a metal mirror 100 is prepared for the adjustment. The metal mirror 100 is placed on the stage 81 in place of the test lens 80 when the interference measuring apparatus is adjusted. The metal mirror 100 has a mirror surface having the same curvature as that of the lens 80 to be tested, and the reflected light from the mirror surface is focused on the front focal position A of the lens 80 to be tested. That is, the center of curvature C of the metal mirror 100 coincides with the front focal position A.

In the interference measuring apparatus having the above configuration, the optical performance of the test lens 80 is measured as follows.
First, light having the same characteristics as the measurement light is emitted from the semiconductor laser 10 to adjust the position of the concave lens 70. In this adjustment, as shown in FIG. 4, the metal mirror 100 is placed on the stage 81, and the gripping portion 71 holding the concave lens 70 is set at the measurement position based on the design value data of the concave lens 70 and the test lens 80. Deploy.

  Of the light emitted from the semiconductor laser 10, the light (test light) that is bent 90 degrees by the half mirror 52 through the condenser lens 50 and the pinhole 51, and transmitted through the reference plane plate 56 through the collimator lens 53 is The concave lens 70 enters the metal mirror 100 as predetermined finite light. The reflected light from the metal mirror 100 follows the same path as the incident light, becomes parallel light by the concave lens 70, and passes through the reference plane plate 56. Thereafter, an image is formed on the CCD 40 through the collimator lens 53, the half mirror 52, and the pinhole 57.

  On the other hand, light (reference light) reflected by the reference surface 56 a out of the light emitted from the semiconductor laser 10 forms an image on the CCD 40 through the collimator lens 53 and the half mirror 52.

  As described above, in the CCD 40, the light transmitted through the reference plane plate 56 and reflected by the metal mirror 100 and the light reflected by the reference surface 56a are incident, so that interference fringes by these lights are obtained. Can do.

  This interference fringe includes information on the deviation between the front focal position B of the concave lens 70 and the center of curvature C of the metal mirror 100. That is, when the front focal position B and the center of curvature C are shifted in the optical path direction of the test light, the interference fringes are concentric circles of a plurality of colors (FIG. 5). On the other hand, when the front focal position B of the concave lens 70 and the center of curvature C of the metal mirror 100 are deviated in a plane perpendicular to the optical path direction of the test light, parallel lines of a plurality of colors are formed (FIG. 6). . On the other hand, when the front focal position B and the center of curvature C coincide with each other, the interference fringes become one color (monochromatic pattern) (FIG. 7). 5 to 7 simultaneously show a circular field frame 110 in which interference fringes are displayed and a rectangular display frame 111 in which no interference fringes are displayed around the same.

  Therefore, when the interference fringes are not one-color, the position of the concave lens 70 is obtained by operating the driving unit 72 and moving the gripping unit 71 in the optical path direction of the test light and / or in a plane perpendicular thereto. Adjust. When the interference fringes become one color, the operation of the driving unit 72 is stopped and the position adjustment of the concave lens 70 is finished. Thus, by adjusting the position of the concave lens 70 using the interference fringes, the concave lens 70 can be aligned in the wavelength order. Therefore, the aberration due to the positional deviation of the concave lens 70 can be removed, and the optical performance of the test lens 80 can be measured with higher accuracy. Note that the position of the concave lens 70 may be adjusted by the operator operating the drive unit 72, but the interference fringe information obtained by the CCD 40 is analyzed by the computer 33, and the computer 33 drives the drive unit 72 according to the result. On the other hand, it can also be performed automatically by outputting a signal instructing the moving direction and moving amount of the grip portion 71.

  Subsequently, the optical performance of the test lens 80 is measured. In this measurement, the test lens 80 is placed on the metal mirror 100 as shown in FIG. 4 in a state where the position of the concave lens 70 whose position has been adjusted is held, and then the measurement light is emitted from the semiconductor laser 10. . Of the light emitted from the semiconductor laser 10, the light that has been bent 90 degrees by the half mirror 52 through the condenser lens 50 and the pinhole 51, and transmitted through the reference plane plate 56 through the collimator lens 53, is given by the concave lens 70. The light enters the lens 80 as finite light, passes through the lens 80, and is folded back by the concave mirror 59. This light passes through the test lens 80 again, and then becomes parallel light by the concave lens 70 and passes through the reference plane plate 56. Thereafter, an image is formed on the CCD 40 through the collimator lens 53, the half mirror 52, and the pinhole 57.

  On the other hand, the light reflected from the reference surface 56 a out of the light emitted from the semiconductor laser 10 forms an image on the CCD 40 through the collimator lens 53 and the half mirror 52.

  Therefore, in the CCD 40, the light transmitted through the test lens 80 and the light reflected by the reference surface 56a are incident, so that interference fringes due to these lights can be obtained. The interference fringes are converted into electrical signals by the CCD 40 and output, and are imaged by the image scanner 32. The optical performance (for example, wavefront aberration, spherical aberration, eccentricity coma) of the test lens 80 is calculated by the computer 33 by a known calculation method. Aberration) is calculated.

  As described above, the concave lens 70 can be exchanged by moving it to the lens exchange position shown in FIG. Therefore, when measuring a test lens having a different curvature, the concave lens 70 can be moved to the replacement position and replaced with a concave lens having a curvature that matches the curvature of the test lens to be newly measured. it can. For this reason, it is possible to provide an interference measuring device and an interferometer side method that can measure the optical performance of the lens to be measured more accurately and with high work efficiency.

  Furthermore, the interference fringes can be set to one color, so that the position of the auxiliary lens can be set accurately, so that aberrations due to misalignment of the auxiliary lens can be removed, and the optical performance of the test lens can be improved with higher accuracy. Can be measured.

Second Embodiment
Next, a second embodiment of the present invention will be described. The second embodiment shown in FIG. 8 is different from the first embodiment in that a convex lens (auxiliary lens) 90 is used instead of the concave lens 70 of the first embodiment. The convex lens 90 is an optical path direction of light that passes through the reference flat plate 56 and travels toward the lens 80 to be tested, and a gripping section that is movable by a driving section 92 (for example, an air cylinder) in a plane perpendicular to the optical path direction. 91. The grip portion 91 is movable in the optical path direction of light that passes through the reference plane plate 56 and travels toward the lens 80 to be tested while holding the convex lens (auxiliary lens) 90 on the upper surface thereof. It is possible to move in a plane perpendicular to the optical path direction of the test light including a predetermined measurement position (solid line in FIG. 8) and a lens replacement position outside the optical path (dotted line in FIG. 8).

As shown in FIG. 9, the adjustment of the position of the convex lens 90 is performed by measuring the metal mirror 100 on the stage 81, the grip portion 91 holding the convex lens 90, and the measurement position based on the design value data of the convex lens 90 and the test lens 80. In addition, the light having the same characteristics as that of the measurement light is emitted from the semiconductor laser 10 in a state where they are arranged. When the interference fringes obtained by the CCD 40 are not one color, the interference fringes obtained by the CCD 40 are made one color by operating the driving unit 92 and adjusting the position of the convex lens 90. Thereby, the rear focal position D of the convex lens 90 can be made to coincide with the front focal position A of the lens 80 to be measured in FIG. Thus, by adjusting the position of the convex lens 90 using the interference fringes, the convex lens 90 can be aligned in the wavelength order. Therefore, the aberration due to the positional deviation of the convex lens 90 can be removed, and the optical performance of the test lens 80 can be measured with higher accuracy.
Other operations, effects, and modifications are the same as those in the first embodiment.

Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or modified within the scope of the purpose of the improvement or the idea of the present invention.

It is an interference measuring device which concerns on 1st Embodiment of this invention, Comprising: It is a figure which shows a structure when a concave lens exists in a measurement position. It is an interference measuring device concerning a 1st embodiment of the present invention, and is a figure showing composition when a concave lens is in a lens exchange position. It is a figure which shows the focus position A of a to-be-tested lens. It is a figure which shows the structure which replaced with the to-be-tested lens and has arrange | positioned the metal mirror when adjusting the position of a concave lens in 1st Embodiment of this invention. It is a figure which shows the interference fringe when the position of the concave lens has shifted | deviated to the optical axis direction of the test light in 1st Embodiment of this invention. It is a figure which shows the interference fringe when the position of the concave lens has shifted | deviated in the surface perpendicular | vertical to the optical axis direction of to-be-tested light in 1st Embodiment of this invention. It is a figure which shows the interference fringe by which the concave lens was arrange | positioned in the correct position and became one color in 1st Embodiment of this invention. It is a figure which shows the structure of the interference measuring device which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure which replaced with the to-be-tested lens and has arrange | positioned the metal mirror when adjusting the position of a convex lens in 2nd Embodiment of this invention.

Explanation of symbols

10 Semiconductor laser (light source)
40 CCD (solid-state image sensor)
56 Reference plane plate 59 Concave mirror (Reflection reference concave mirror)
70 Concave lens (auxiliary lens)
72 Drive unit 80 Test lens 81 Stage 90 Convex lens (auxiliary lens)
92 Driving part A Front focal position B Front focal position C Center of curvature D Rear focal position

Claims (6)

The reference light reflected by the reference plane plate and the finite light by the auxiliary lens after passing through the reference plane plate, transmitted through the test lens placed at a predetermined position and folded back by the concave mirror, again the test lens, An interference measurement method for measuring optical performance of the test lens by observing interference fringes obtained by the auxiliary lens and the test light transmitted through the reference plane plate,
In the state where a metal mirror having the same curvature as that of the test lens is arranged instead of the test lens at the position where the test lens is arranged, the auxiliary fringe is arranged so that the interference fringes become one color. An interference measurement method comprising adjusting a lens position. The interference measurement method according to claim 1, wherein the auxiliary lens is a concave lens. The interference measurement method according to claim 1, wherein the auxiliary lens is a convex lens. The reference light reflected by the reference plane plate and the finite light by the auxiliary lens after passing through the reference plane plate, transmitted through the test lens placed at a predetermined position and folded back by the concave mirror, again the test lens, A method of adjusting an interference measuring apparatus for measuring optical performance of the test lens by observing interference fringes obtained by the test light transmitted through the auxiliary lens and the reference plane plate,
In the state where a metal mirror having the same curvature as that of the test lens is arranged instead of the test lens at the position where the test lens is arranged, the auxiliary fringe is arranged so that the interference fringes become one color. A method for adjusting an interference measuring apparatus, comprising: adjusting a position of the lens to be examined by moving a lens. The method of adjusting an interference measuring apparatus according to claim 4, wherein the auxiliary lens is a concave lens. The method for adjusting an interference measuring apparatus according to claim 4, wherein the auxiliary lens is a convex lens.

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