JP2006177846A - Method of measuring lens decentration and device thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a position highly accurately without wrong recognition of a lens surface reflection spot of a test lens in lens reflection decentration measurement. <P>SOLUTION: When measuring a reflection spot on the test lens surface by using the first and second reflection measuring optical systems mutually opposite in the reverse direction relative to the optical axis of the test lens, since a curvature center position on the test lens surface viewed from the first reflection measuring optical system is different from a curvature center position on the same test lens surface viewed from the second reflection measuring optical system, either system having less wrong recognition is selected from between the first reflection measuring optical system and the second reflection measuring optical system, and measurement is performed. Hereby, the highly-accurate lens reflection decentration measurement having less wrong recognition wherein the reflection spot from the desired test lens surface is not confused with another reflection spot can be performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for measuring the amount of eccentricity of a lens, and to a technique for detecting the amount of lens eccentricity by observing reflected light from a lens surface and the apparatus.

  As a method and apparatus for optically measuring the eccentricity of each surface of a conventional lens, one shown in FIG. 15 is known (see FIG. 11.2 of Non-Patent Document 1).

In FIG. 15, the camera 7 having the collimator lens 2, the focus lens 3, and the imaging surface 8 is disposed on one and the same optical axis, and the optical axis is bent by the half mirror 6 to be substantially the same as the optical axis of the light source 1. Match. The center of the imaging surface 8 substantially coincides with the optical axis. The light emitting points of the imaging surface 8 and the light source 1 are almost coincident with the focal position of the collimator lens 2. 15, the light emitted from the light source 1 is turned back by the half mirror 6 to be collimated through the collimator lens 2 along the optical axis, passes through the focus lens 3, and passes through the focus lens 3. After converging at the focal position 9, the light enters the lens surface 5 to be tested supported by the support frame 4. When the focal point 9 and the center of curvature of the lens surface 5 to be tested are substantially coincident with each other on the optical axis, the light reflected by the lens surface 5 to be tested passes through the focus lens 3 along the same path as the incident light and passes through the collimator lens. 2, partially passing through the half mirror 6 and condensing on the imaging surface 8, the spot 11 can be confirmed at the center of the observation screen 10 of the camera 7. Here, when the test lens surface 5 is decentered in the direction of the arrow 13 while maintaining the perpendicular to the optical axis, the reflected light from the test lens surface 5 is shifted according to the decentering of the test lens surface 5. (Refer to FIG. 11.1 of Non-Patent Document 1) Since the light is condensed on the imaging surface 8 of the camera 7 through the path shown by the broken line in FIG. 15, the spot 12 shifted from the center is confirmed on the observation screen 10 of the camera 7 it can. Since the optical axis and the center of the observation screen 10 are substantially matched, the amount of eccentricity from the optical axis of the lens surface 5 to be measured can be measured from the amount of deviation of the spot from the center. Further, when there are a plurality of test lens surfaces along the optical axis direction, the focus lens 3 is moved along the optical axis, and the focal point 9 is made to substantially coincide with the center of curvature of the desired lens surface. The amount of eccentricity of each lens surface to be measured in an optical system composed of a plurality of lens surfaces can be measured. How much the spot shifts when a certain lens surface is decentered or tilted by a certain amount can be obtained by calculation if there is lens design data (see Non-Patent Document 2).
“Optical Technology Contact” Vol. 20 No. 4 (1982) (pages 35-42) “Optical Technology Contact” Vol. 20 No. 5 (1982) (pp. 40-47)

  The method shown in FIG. 15 has an advantage that the amount of eccentricity of a plurality of lens surfaces can be measured. However, the center of curvature of two or more test lens surfaces 14, 15, 16 as shown in FIG. In the case of concentrating on, the reflected spots of different test lens surfaces are simultaneously observed on the imaging surface 8 and overlap each other, so that it is not possible to determine which test lens surface each spot originates from. It causes misrecognition. Further, the reflection of the lens surface to be examined is reflected when the center of curvature of the lens surface 5 to be examined and the focal point 9 of the focus lens 3 substantially coincide with each other as shown in FIG. 17, and the lens to be examined as shown in FIG. There is reflection when the surface 5 and the focal point 9 of the focus lens 3 are substantially coincident. The aerial image condensed in the air shown in FIG. 16 is used for the eccentricity measurement, and the surface reflection image condensed on the lens surface 5 shown in FIG. 17 is not necessary for the measurement. When measuring a test lens group composed of a plurality of lens surfaces, the positions of the aerial image and the surface reflection image of different test lens surfaces may be concentrated at very close positions. In this case, an aerial image spot and a surface reflection image spot are observed at the same time and overlap each other, which causes a spot position misrecognition without distinguishing between the aerial image and the surface reflection image of each spot.

  The present invention solves the above-described conventional problems, and mitigates / prevents the overlapping of spot images corresponding to each lens surface when observing the reflected spot image from each lens surface in measuring the eccentricity of the lens surface. As a result, the test lens group in the state shown in FIG. 16 which is not possible with the conventional method without erroneous spot detection, or a surface reflection image and an aerial image are observed simultaneously. It is an object to enable decentration measurement of the lens group.

  In order to achieve the above object, the lens eccentricity measuring method of the present invention is a measurement system in which measurement light can be incident from both sides of two apertures in a test lens, and measurement is performed from both sides of the test lens surface. The lens eccentricity is measured with light incident. Each measurement system includes a light source that emits parallel light, a condensing lens, a moving unit that moves the condensing lens in the optical axis direction of the light source, and an emission light of the condensing lens that is disposed on the optical axis of the light source. And a light receiving unit that converts the reflected light from the lens surface of the lens to be collimated by the condenser lens and receives the light.

  Each measurement system is provided with an eccentricity amount calculation device for calculating the eccentricity amount of each lens to be measured from the measured reflected spot position data, and these two devices calculate the eccentricity amount of each measurement system. It is connected to an eccentricity calculation result judgment device that compares and recalculates the device data and the eccentricity calculation result to calculate the final result. The calculation of the eccentricity amount by the eccentricity measuring device can be performed by a known calculation method as shown in Non-Patent Document 2. Further, the center position of curvature of each lens surface to be used as a criterion for selecting the eccentricity data from the measurement optical systems of the eccentricity calculation result judging device can be calculated by a known means such as a ray tracing method.

  With this configuration, when measurement light is incident from one of the two apertures of the test lens, the reflected spot image from the test lens surface overlaps with the reflected spot image from the other lens surface. When measurement becomes difficult, it is possible to alleviate / prevent the overlap of reflected spot images from other lens surfaces by making measurement light incident from the other and measuring.

  By the method described above, the conventional method misrecognizes what was impossible to measure the eccentricity by misrecognizing the spot position when multiple reflected spot images from the lens surface of the test lens were observed simultaneously. It can be measured without doing.

  As described above, according to the lens eccentricity measuring method of the present invention, when measuring the eccentricity of each component lens of an optical system composed of a plurality of lenses with the above-described reflective optical system, conventionally, Eccentricity measurement can be performed for a lens to be measured in which reflected spot images from a plurality of lens surfaces that could not be measured overlap.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a conceptual diagram of an optical system configuration used in the lens eccentricity measuring method according to Embodiment 1 of the present invention.

  In FIG. 1, the lens center of the first focus lens 101 having an antireflection film formed on the lens surface is on the optical axis of the first LD laser light source 100, and an optical multilayer film is formed on the surface beyond that. The first half mirror 102 thus arranged is arranged so that the optical axis is folded back approximately 90 °. The lens center of the first imaging lens 103 in which an antireflection film is formed on the lens surface is on the first laser optical axis turned back by the half mirror 102.

  The rear focal position of the focus lens 101 and the front focal position of the imaging lens 103 are arranged so as to substantially coincide on the first laser optical axis. The focus lens 101 and the imaging lens 103 constitute a beam expander, the light emitted from the LD laser light source 100 is enlarged, and parallel light parallel to the first laser optical axis is emitted from the imaging lens 103. The lens center of the first condenser lens 104 with the antireflection film formed on the lens surface is on the first laser optical axis, and the first moving stage 105 on which the condenser lens 104 is disposed is the first laser. Since it is movable in parallel with the optical axis direction and is provided with a linear scale, it is possible to obtain current position information with respect to the direction along the optical axis of the moving stage 105.

  The imaging surface of the first CCD camera 106 is arranged so as to be the front focal position of the imaging lens 103 via the half mirror 102, and the first laser optical axis position is the center of the imaging surface. At the tip of the condensing lens 104 on the first laser optical axis turned back by the half mirror 102, there are test lenses 301, 302, 303, and 304 each having an antireflection film formed on the lens surface. Is held by. The central axis of the holding frame 305 is perpendicular to the positioning reference plane 306 and is disposed so as to pass through the center.

  Further, the center of the reference surface 306 is disposed so as to substantially coincide with the first laser optical axis. The first CCD camera 106 is arranged such that its imaging surface 110 is perpendicular to the first laser optical axis and the center portion substantially coincides with the optical axis. With the above configuration, the light emitted from the laser light source 100 is on the A side shown in FIG. 1 with respect to the test lenses 301, 302, 303, 304 along the first laser optical axis folded back to the half mirror 102. Incident from the (test lens 301 side). When viewed from the condenser lens 104 side, the first lens surface of the test lens 302 is 310, and the first lens surface of the test lens 303 is 311. Position information in the direction along the optical axis of the moving stage 105 on which the condenser lens 104 is disposed and image information of the CCD camera 106 are transmitted to the first eccentricity calculation device 107.

  On the other hand, on the optical axis of the second LD laser light source 200, there is a lens center of the second focus lens 201 in which an antireflection film is formed on the lens surface, and an optical multilayer film is formed on the surface beyond that. The second half mirror 202 is arranged so that the optical axis is turned back approximately 90 °. On the second laser optical axis folded back by the half mirror 202, there is the lens center of the second imaging lens 203 in which an antireflection film is formed on the lens surface.

  The rear focal position of the focus lens 201 and the front focal position of the imaging lens 203 are arranged so as to substantially coincide on the second laser optical axis. The focus lens 201 and the imaging lens 203 constitute a beam expander, the light emitted from the LD laser light source 200 is enlarged, and parallel light parallel to the second laser optical axis is emitted from the imaging lens 203. The center of the second condensing lens 204 having the antireflection film formed on the lens surface is on the second laser optical axis, and the second moving stage 205 on which the condensing lens 204 is disposed is the second laser. Since it is movable in parallel with the optical axis direction and has a linear scale, it is possible to obtain current position information in the direction along the optical axis of the moving stage 205.

  The imaging surface of the second CCD camera 206 is disposed so as to be the front focal position of the imaging lens 203 via the half mirror 202, and the second laser optical axis position is the center of the imaging surface. At the tip of the condensing lens 204 on the second laser optical axis turned back by the half mirror 202, there are test lenses 304, 303, 302, 301, which are held by a holding frame 305. The central axis of the holding frame 305 is perpendicular to the reference plane 306 and is disposed so as to pass through the center.

  Further, the center of the reference plane 306 is disposed so as to substantially coincide with the second laser optical axis. The second CCD camera 206 is arranged such that its imaging surface 210 is perpendicular to the second laser optical axis and the center portion substantially coincides with the optical axis. Position information in the direction along the optical axis of the moving stage 205 on which the condenser lens 204 is disposed and image information of the CCD camera 206 are transmitted to the second eccentricity calculation device 207.

  With the above configuration, the light emitted from the laser light source 200 is on the B side shown in FIG. 1 with respect to the test lenses 304, 303, 302, 301 along the second laser optical axis folded back to the half mirror 202. Incident from the side of the test lens 304.

  At this time, the moving range of the first moving stage 105 is that the focus of the focus lens 101 is from all the test lens surfaces of the test lens group including the test lenses 301, 302, 303, 304 and the holding frame 305. A sufficiently wide range can be moved so as to substantially coincide with the reflected spot image generation position. Similarly, the moving range of the second moving stage 205 is such that the focus of the focus lens 201 is the lens 304, 303, 302, 301, A sufficiently wide range can be moved so that the reflected spot image generation positions from all the test lens surfaces of the test lens group constituted by the holding frame 305 can be substantially matched.

  The two eccentricity calculation devices 107 and 207 are connected to the eccentricity calculation result determination device 320 so that information can be exchanged between them.

  Next, a lens reflection eccentricity measuring method using the optical system configured as described above will be described.

  The parallel light emitted from the laser light source 100 is magnified by the focus lens 101 and the imaging lens 103. The light that has passed through the imaging lens 103 is converted from a plane wave to a spherical wave by passing through the condenser lens 104. The curvature of this spherical wave is determined by the distance from the focal position of the condensing lens 104, the position of the stage 105 is moved, and the focal position of the condensing lens 104 is moved to move the spherical wave on each lens surface of the lens 301 under test. The curvature can be changed.

  When the lens surface of the test lens is not decentered with respect to the first laser optical axis, the light is applied to the entire lens surface when the curvature of the test lens surface wave substantially matches the lens surface curvature of the test lens. It will be incident vertically. At this time, the light reflected by the lens surface of the test lens returns along the same optical path as the incident light beam. The light reflected by the lens surface of the test lens is converted into parallel light parallel to the optical axis by the condenser lens 104 and passes through the imaging lens 103.

  By moving the moving stage 105 to an appropriate position obtained by calculation in advance, as shown in FIG. 2, the light incident on the lens group to be examined from the condenser lens 104 is perpendicular to the lens surface 310 to be examined. Reflected and the reflected light returns along the same path as the incident light. The reflected light that has passed through the imaging lens 103 via the condenser lens 104 is condensed at a focal position on the first laser optical axis. As shown in FIG. 3, since the imaging surface 110 of the CCD camera 106 is at the focal position of the imaging lens 103, the spot image 108 derived from the reflection of the lens surface 310 to be imaged by the CCD camera is located near the center of the screen. Will do.

  On the other hand, if the center of the test lens surface of the test lens 302 is decentered with respect to the first laser optical axis, the light is applied to the entire surface of the test lens surface 310 at the position of the moving stage 105 when there is no decentering. It is incident at a certain angle that is not perpendicular to it. This incident angle is proportional to the amount of eccentricity of the lens surface 310 to be examined. Therefore, the reflected light from the lens surface 310 is converted into parallel light by the condensing lens 104, but has an angle proportional to the lens eccentricity with respect to the first laser optical axis.

  Accordingly, the light collected by the imaging lens 103 forms a spot 109 at a position away from the center by a distance corresponding to the amount of eccentricity, as shown in the background art.

  By the way, when the center of curvature 313 of the desired lens surface 310 when viewed from the A side and the center of curvature 314 of the other lens surface 311 are adjacent to each other as shown in FIG. When the condenser lens 104 is moved so that the focal point of the condenser lens 104 substantially coincides with the curvature center position 313 of the lens surface 310 to be examined, it also substantially coincides with the curvature center position 314 of the other lens surface 311 to be examined. .

  Therefore, the light emitted from the condenser lens 104 to the test lens is incident on the entire surface of the test lens surface 310 at a uniform angle, and at the same time, the light is incident on the entire surface of the other test lens surface 311 at a substantially uniform angle. Therefore, the spot 108 derived from the reflection from the lens surface 310 and the spot 109 derived from the reflection from the other lens surface 311 are simultaneously present on the imaging surface 110 of the CCD camera 106 shown in FIG. Observed. It is difficult to separate or distinguish between the desired spot 108 and the unnecessary spot 109, which causes spot misdetection.

  On the other hand, as shown in FIG. 4, using the second measurement optical system that makes the light emitted from the laser light source 200 incident on the lens to be examined from the B side, the same procedure as described above for making the light incident from the A side. By moving the condensing lens 204 in the above procedure, the focal position of the condensing lens 204 and the center of curvature position 315 of the lens surface 310 to be tested are substantially matched, and a spot image resulting from the reflection of the lens surface 310 to be examined is formed. Observation can be performed using a CCD camera 206.

  At this time, the subject lens surface of interest is the same subject lens surface 310 as when laser light is incident from the A side, but the direction in which the laser light is incident is different, so that the incident laser light is Other lens configurations arranged in the optical path up to the lens surface 310 to be examined are different. For this reason, the relationship between the positions of the curvature centers of the test lens surfaces viewed from the incident B side is different from that viewed from the incident A side. That is, when the light is incident from the A side, the curvature center position 313 of the test lens surface 310 and the curvature center position 314 of the other lens surface 311 are 315 and 316, respectively, when viewed from the B side. Because of the positional relationship, the light emitted from the condenser lens 204 and incident from the B side to the lens group to be tested is reflected at a uniform angle only on the entire surface of the lens surface 310, and the other lenses The reflection angle is not uniform over the entire lens surface 311.

  For this reason, as shown in FIG. 5, only the spot 208 derived from the reflection of the lens surface 310 to be measured is formed on the imaging surface 210 of the CCD camera 206. For this reason, it is possible to suppress reflection from unnecessary lens surfaces other than the lens surface 310 to be tested, and to prevent spot detection errors. Therefore, from unnecessary lens surfaces that are simultaneously observed when light is incident from the A side. It is possible to erase, separate or discriminate by switching the reflected spot to observation by light incidence from the B side.

  After measuring each lens surface to be measured, the position information of the moving stage 105 and the image information of the CCD camera 106 are sent to the eccentricity calculation device 107 as measurement data from the A side, and the spot position / collection obtained from the information is obtained. Using the position of the optical lens 104 and each test lens surface data, the decentering amount and the tilt amount of each test lens with respect to the optical axis are automatically calculated.

  Similarly, the position information of the moving stage 205 and the image information of the CCD camera 206 are also sent as measurement data from the B side to the decentration amount calculation device 207, and the decentering amount and inclination amount of each test lens with respect to the optical axis are automatically determined. To calculate.

  The center of curvature of each lens surface to be tested in the lens group can be obtained by a known calculation procedure using the lens design value of the lens group, so that the condensing lens when spot measuring the lens surface It can be predicted for each of the lens surfaces to be measured whether the position of 104, 204 or the measurement from the A side or the measurement from the B side is suitable for spot measurement of each lens surface.

  For example, plotting the curvature center position of the lens surface to be measured on the optical axis for the two cases when the measurement light is incident from the A side and the measurement light is incident from the B side, and further, the curvature center position of the other lens surface And plotting the lens surface position and comparing the two, it can be said that the measurement light incident direction is more suitable when there are fewer points relating to other lens surfaces near the center of curvature of the lens surface to be examined.

  Based on such prediction, the eccentricity amount calculation result judging device 320 selects an appropriate one of the eccentricity amount and inclination amount data of each lens calculated by the eccentricity amount calculating devices 107 and 207, and the display device 321. To display the result. With the above method, it is possible to automatically measure the amount of lens eccentricity of the lens group to be observed such that reflection spots from a plurality of lens surfaces that have been impossible to measure conventionally are observed simultaneously.

  Note that a CMOS, PSD, or photomultiplier may be used instead of the CCD used in this embodiment.

  The half mirrors 102 and 202 used in the present embodiment may be a metal vapor deposition film or a pellicle mirror.

  Although the optical axis of the laser light source is folded back approximately 90 ° by the half mirror, the CCD side may be folded back by the half mirror without folding the laser light source side.

  The LD laser light sources 100 and 200 used in the present embodiment may be a parallel laser beam of an incoherent light source such as a gas laser, a solid laser, a liquid laser, an LED, an EL, or a halogen lamp.

  The focus lenses 101 and 201, the imaging lenses 103 and 203, and the condensing lenses 104 and 204 constituting the measurement optical system may not have an antireflection film on the surface.

  In this embodiment, the test lens group has a four-lens configuration and the test lens surface 310 is a measurement target. However, the test lens group may not have a four-lens configuration, and the test lens surface may be a test lens. Any surface of the lenses constituting the group may be used.

  In this embodiment, in order to scan the lens surface of the lens group to be measured, the condenser lens 104 is moved by the stage 105 and the condenser lens 204 is moved by the stage 205. good.

  In this embodiment, in order to scan the lens surface of the lens group to be examined, the condenser lens 104 is moved by the stage 105 and the condenser lens 204 is moved by the stage 205. However, the focal points of the condenser lenses 104 and 204 are variable. A mechanism may be provided to change the focal positions of the condenser lenses 104 and 204 without changing the positions of the condenser lenses 104 and 204.

  In this embodiment, in order to scan the lens surface of the lens group to be examined, the condenser lens 104 is moved by the stage 105 and the condenser lens 204 is moved by the stage 205. However, the LD light source 100, the focus lens 101, and the half are moved. The entire first measurement optical system including the mirror 102, the imaging lens 103, the condenser lens 104, the moving stage 105, and the CCD camera 106, the LD light source 200, the focus lens 201, the half mirror 202, the imaging lens 203, the collection lens The entire second measurement optical system including the optical lens 204, the moving stage 205, and the CCD camera 206 may be moved with respect to the lens group to be examined.

  In the present embodiment, the first laser optical axis and the second laser optical axis are substantially aligned, but the central axis of the holding frame 305 is disposed so as to be perpendicular to the reference plane 306 and through the center thereof. If the center of the reference surface 306 is arranged so as to substantially coincide with the first and second laser optical axes, the first laser optical axis and the second laser optical axis may not coincide with each other. .

  Although the CCD camera 106 is disposed at the focal position of the imaging lens 103 and the CCD camera 206 is disposed at the focal position of the imaging lens 203, a magnifying optical system for enlarging the imaging surface of the CCD cameras 106 and 206 is added to provide a spot image. May be enlarged.

  In the present embodiment, the reference surface 306 that supports the holding frame 305 is disposed only on the B side of the two lens group openings. However, even if the reference surface 306 is disposed on the A side, it is disposed on both the A side and the B side. Also good.

  A lens for assisting measurement may be arranged on the reference surface 306. In that case, the center of curvature position of the lens surface to be measured including the measurement auxiliary lens is calculated in advance.

  Note that the eccentricity calculation devices 107 and 207 and the eccentricity calculation result determination device 320 do not have to be separated as individual devices as long as the functions equivalent to those of the present embodiment can be realized.

  The eccentricity calculation devices 107 and 207 and the eccentricity calculation result determination device 320 may be configured by a general-purpose electronic computer application program instead of a dedicated device.

  It should be noted that the position information management of the moving stages 105 and 205 using the linear scale arranged on the moving stages 105 and 205 can be performed by managing the rotational speed of the moving stage drive motor as long as it can be transmitted to the eccentricity calculation devices 107 and 207 as the stage position information. good.

  If the optical system including the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, and the CCD camera 106 has the same function as that described in this embodiment, an autocollimator or the like It may be replaced with a single device.

  The optical system including the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, the condenser lens 104, the moving stage 105, and the CCD camera 106 is equivalent to that described in this embodiment. If it has a function, it may be replaced with a single device.

  If the optical system including the LD light source 200, the focus lens 201, the half mirror 202, the imaging lens 203, and the CCD camera 206 has equivalent functions, it can be replaced with a single device such as an autocollimator. good.

  An optical system including the LD light source 200, the focus lens 201, the half mirror 202, the imaging lens 203, the condenser lens 204, the moving stage 205, and the CCD camera 206 is equivalent to that described in this embodiment. If it has a function, it may be replaced with a single device.

(Embodiment 2)
FIG. 6 is a conceptual diagram of an optical system configuration used in the lens eccentricity measuring method according to Embodiment 2 of the present invention. 6, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 6, reference numeral 501 denotes a rotation stage for fixing the positioning reference surface 306, which has a rotation axis in a direction perpendicular to the laser optical axis and a mechanism capable of changing the direction of the holding frame 305 with respect to the laser optical axis. The rotation stage 501 can change the direction of the holding frame 305 with respect to the laser optical axis by approximately 180 °. Even if the orientation of the holding frame 305 is changed by the rotary stage 501, the laser optical axis is arranged so as to substantially coincide with the optical axes of the test lenses 301, 302, 303, and 304. A position sensor is attached to the rotary stage 501, and information on the current rotary stage orientation is transmitted to the eccentricity calculation device 801. Similarly, the position information of the moving stage 105 on which the condenser lens 104 is arranged and the image information of the CCD camera 106 are also transmitted to the eccentricity amount calculation device 801.

  At this time, by rotating the holding frame 305 with the rotation stage 501, the laser beam is incident from the test lens 301 side and the laser beam is incident from the test lens 304 side. In addition, the focal point of the condenser lens 104 is substantially matched with the center of curvature of all the test lens surfaces of the test lens group including the test lenses 301, 302, 303, 304 and the holding frame 305. It is assumed that the moving range of the moving stage 105 can move within a sufficiently wide range.

  As shown in FIG. 7, when light is incident from the side of the test lens 301, the curvature center position 313 of the desired lens surface 310 and the curvature center position 314 of the other lens surface 311 are adjacent to a very close position. In this case, as described in the first embodiment, when the condenser lens 104 is moved so that the focal point of the condenser lens 104 substantially coincides with the curvature center position 313 of the lens surface 310 to be examined, another lens surface 311 is simultaneously obtained. This also almost coincides with the center of curvature position 314.

  At this time, since the lens surface 310 and the other lens surface 311 are incident on the entire lens surface at a substantially uniform angle, as shown in FIG. 8, the light is incident on the imaging surface 110 of the CCD camera 106. The spot 108 derived from the reflection from the lens surface 310 and the spot 109 derived from the reflection from the other lens surface 311 are observed simultaneously. For this reason, it is difficult to separate and distinguish the spot 108 due to the reflection of the lens surface 310 to be originally observed and the unnecessary spot 109 due to the reflection of the other lens surface 311, which causes spot detection errors.

  Therefore, when the holding frame 305 arranged so that light is incident from the side of the test lens 301 is rotated 180 ° with respect to the laser optical axis using the rotation stage 501, the test is performed as shown in FIG. The arrangement is such that light enters from the lens 304 side. Similar to the first embodiment, even if the target lens surface to be noticed is the same surface, if the incident direction of the laser beam is different, other lens configurations arranged in the optical path to the target lens surface 310 Is different.

  Accordingly, the relationship between the curvature center positions of the test lens surface 310 and the other lens surface 311 when light is incident from the test lens 301 side is different from that when light is incident from the test lens 304 side. When the condenser lens 104 is moved in the arrangement as shown in FIG. 9 so that the focal position of the condenser lens 104 and the curvature center position 315 of the lens surface 310 to be tested are substantially matched, the curvature center position 316 of the other lens surface 311 is obtained. Does not match.

  Therefore, the spot due to the reflection of the other lens surface 311 is not observed on the imaging surface 110 of the CCD camera 106 as shown in FIG. 10, and only the spot 111 due to the reflection of the lens surface 310 to be examined is observed. For this reason, reflection spot separation / distinguishment from unnecessary lens surfaces other than the lens surface 310 to be measured can be performed, so that erroneous detection of the spot position can be prevented. As in the first embodiment, after the measurement of each lens surface to be examined, the position information of the moving stage 105, the image information of the CCD camera 106, and the orientation information of the rotary stage 501 are sent as measurement data to the eccentricity calculation device 801. From each spot lens surface data composed of the spot position on the screen, the position of the condenser lens 104, and the incident direction of the measurement light, the amount of eccentricity and inclination of each subject lens with respect to the optical axis are measured. The calculation is automatically performed separately for the case where the light enters from the lens 301 side and the case where the light enters from the lens 304 side.

  Since the center of curvature position of each lens surface to be measured can be obtained from the design data of the lens system to be measured, it is possible to perform spot measurement when light is incident from the lens 301 side or from the 304 side. It can be predicted in advance for each lens surface to be tested. For example, when the measurement light is incident on the lens group to be measured from the test lens 301 side and the measurement light is incident on the test lens 304 side, the center position of curvature of the test lens surface on the optical axis And plot the center of curvature of the other lens surface and the position of the lens surface and compare the two. It is better that there are fewer points related to the other lens surface near the center of curvature of the lens surface to be tested. It can be said that it is the measurement light incident direction.

  Based on these predictions, the decentering amount calculation result judging device 320 selects an appropriate amount of decentering amount and tilt amount data for each of the two lenses depending on the light incident direction, and finally the decentering amount of the lens to be examined. The inclination amount data is determined, and the result is displayed on the display device 321.

  According to the above procedure, it is possible to automatically measure the amount of lens eccentricity of the lens group to be measured such that reflection spots from a plurality of lens surfaces to be measured that could not be measured conventionally are observed simultaneously. While obtaining the same effects as those of the first embodiment, fewer optical components are required to configure the apparatus than in the first embodiment, and the apparatus cost can be reduced and the apparatus volume can be reduced. It is possible to measure the amount of lens eccentricity even in a lens group having a configuration in which there is no movable part such as a zoom mechanism.

  Note that a CMOS, PSD, or photomultiplier may be used instead of the CCD used in this embodiment.

  The half mirror 102 used in this embodiment may be a metal mirror film or a pellicle mirror.

  Although the optical axis of the laser light source is folded back approximately 90 ° by the half mirror, the CCD side may be folded back by the half mirror without folding the laser light source side.

  Note that the LD laser light source 100 used in this embodiment may be a parallel laser beam of an incoherent light source such as a gas laser, a solid laser, a liquid laser, an LED, an EL, or a halogen lamp.

  Note that the focus lens 101, the imaging lens 103, and the condenser lens 104 constituting the measurement optical system may not have an antireflection film on the surface.

  In this embodiment, the test lens group has four lenses and the test lens surface 310 is the object to be measured. However, the test lens group may not have four lenses, and the test lens surface may not be tested. Any surface of the lenses constituting the lens group may be used.

  In this embodiment, the condenser lens 104 is moved by the stage 105 in order to scan the lens surface of the lens group to be tested. However, the lens side to be tested may be moved.

  In the present embodiment, the condensing lens 104 is moved by the stage 105 in order to scan the lens surface of the lens group to be examined. However, the condensing lens 104 is provided with a variable focus mechanism, and the position of the condensing lens 104 is changed. The focal position of the condensing lens 104 may be changed without changing.

  In this embodiment, the condensing lens 104 is moved by the stage 105 in order to scan the lens surface of the lens group to be examined. However, the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, the converging lens, The entire measurement optical system including the optical lens 104, the moving stage 105, and the CCD camera 106 may be moved with respect to the lens group to be examined.

  In this embodiment, in order to change the incident direction of the measurement light, the measurement optical system is fixed and the holding frame 305 that holds the lens group to be measured is rotated. However, the holding frame 305 is fixed and the measurement optical system side is fixed. May be rotated.

  In this embodiment, in order to change the incident direction of the measurement light, the holding frame 305 that holds the test lens is rotated by an axis perpendicular to the optical axis. However, the rotational axis may not be perpendicular to the optical axis.

  Although the CCD camera 106 is disposed at the focal position of the imaging lens 103, a spot image may be enlarged by adding an enlargement optical system for enlarging the imaging surface of the CCD camera 106.

  In this embodiment, the reference surface 306 that supports the holding frame 305 is disposed only on the side closer to the lens to be tested 304 out of the two lens group apertures. You may arrange in both.

  A lens for assisting measurement may be arranged on the reference surface 306. In that case, the center of curvature position of the lens surface to be measured including the measurement auxiliary lens is calculated in advance.

  Note that the eccentricity amount calculation device 801 and the eccentricity amount calculation result determination device 320 do not have to be individually separated as devices as long as the functions equivalent to those of the present embodiment can be realized.

  The eccentricity amount calculation device 801 and the eccentricity amount calculation result judgment device 320 may be configured by an application program of a general-purpose electronic computer instead of a dedicated device.

  Note that the position information management of the moving stage 105 by the linear scale arranged on the moving stage 105 may be the rotation number management of the moving stage drive motor as long as it can be transmitted to the eccentricity amount calculation device 801 as the stage position information.

  If the optical system including the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, and the CCD camera 106 has the same function as that described in this embodiment, an autocollimator or the like It may be replaced with a single device.

  The optical system including the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, the condenser lens 104, the moving stage 105, and the CCD camera 106 is equivalent to that described in this embodiment. If it has a function, it may be replaced with a single device.

(Embodiment 3)
FIG. 11 is a conceptual diagram of an optical system configuration used in the lens eccentricity measuring method according to Embodiment 3 of the present invention. In FIG. 11, the same components as those in FIGS. 1, 2, 6, 7, and 15 are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 11, reference numeral 601 denotes a first lens group constituting a lens group to be examined having a zoom function, and 602 denotes a second lens group constituting a lens group to be examined having a zoom function, which has a function of moving in the optical axis direction. . Reference numeral 603 denotes a third lens group that constitutes a test lens group having a zoom function.

  Further, the lens groups 601, 602, and 603 to be examined are fixed as shown in FIG. 11 by a lens barrel 604 that can be fixed with their optical axes substantially matched. However, the lens group 602 to be tested can slide in the optical axis direction within the lens barrel 604, and the moving stage 502 has a function of moving the lens group 602 in the optical axis direction and includes a linear gauge. The current position information of the moving stage 502 can be transmitted to the eccentricity calculation device 802. Position information of the moving stage 105 and image information of the CCD camera 106 can also be transmitted to the eccentricity calculation device 802. The second lens surface of the lens group 602 when viewed from the condenser lens 104 side is denoted by 610, and the first lens surface of the lens group 603 is denoted by 611.

  At this time, regardless of the position of the lens group 602 that can move in the optical axis direction within the movable range of the lens group 602, all of the lens groups that are formed from the lens groups 601, 602, and 603 are used. It is assumed that the moving range of the moving stage 105 can be moved within a sufficiently wide range so that it substantially matches the curvature center position of the lens surface to be examined.

  As shown in FIG. 11, by moving the condenser lens 104 so that the focal position of the condenser lens 104 and the center of curvature 317 of the lens surface 610 are substantially matched, the CCD camera 106 is shown in FIG. A spot 701 derived from reflection from the test lens surface 610 can be formed on the imaging surface 110.

  However, when the curvature center position 318 of the lens surface 611 other than the lens surface 610 is close to the curvature center position 317 of the lens surface 610, as shown in FIG. Since the spot 702 due to reflection is also observed at the same time, it is difficult to separate or distinguish between the desired spot 701 and the unnecessary spot 702, which causes spot misdetection.

  Therefore, as shown in FIG. 13, by moving the lens group 602 in the optical axis direction, the curvature center position 317 of the lens surface 610 to be measured can be shifted from the vicinity of the curvature center position 318 of the other lens surface 611. is there. Thereafter, the condensing lens 104 is moved again so that the focal position of the condensing lens 104 and the curvature center position 317 of the lens surface 610 to be tested are substantially matched. As a result, the lens surface that substantially coincides with the condenser lens at the center of curvature is only the lens surface 610 to be tested, so that the imaging surface 110 of the CCD camera 106 reflects from the lens surface 610 as shown in FIG. Only the spot 701 is observed. For this reason, it is possible to suppress reflection from unnecessary lens surfaces other than the lens surface 610 to be detected, and to reduce spot position detection errors.

  As in the first embodiment, the center of curvature of each lens surface to be measured can be obtained from the design data of the lens system to be measured by calculation. Whether the measurement can be performed well can be predicted in advance by calculating for each lens surface. For example, the center of curvature of the lens surface to be tested on the optical axis is plotted, the center of curvature of the other lens group and the lens surface position are plotted, and the movable range of the lens group 602 movable in the optical axis direction. Do similar plots for several locations.

  It can be said that the position of the lens group 602 that has few points relating to other lens surfaces in the vicinity of the center of curvature of the test lens surface is the position of the lens group 602 suitable for the measurement of the test lens surface. From these results, the optimum position of the moving stage 502 with respect to each lens surface to be examined is determined in advance, spot measurement data on each lens surface to be examined, position information of the moving stage 502, and position information of the moving stage 105. Is transmitted to the decentration amount calculation device 802, and the decentering amount and tilt amount data of each test lens is calculated based on them, and the result is displayed on the display device 321.

  By the above procedure, the eccentricity measurement of the test lens group having a zoom mechanism that was impossible to measure by observing multiple reflection spots from the test lens surface at the same time due to the positional relationship of the test lens. Is possible.

  In addition, while obtaining the same effect as that of the second embodiment, the number of equipment mechanisms constituting the apparatus is less than that of the second embodiment, and the same effect as that of the second embodiment can be achieved without rotating the holding frame or the lens barrel. Therefore, even a lens group having a structure that is long in the optical axis direction can be configured with a smaller area, so that the cost of the apparatus can be reduced and the volume of the apparatus can be reduced.

  Needless to say, by combining the present embodiment and the first embodiment, it is possible to measure the amount of lens eccentricity in a test lens group having a complicated configuration.

  Needless to say, by combining the present embodiment and the second embodiment, it is possible to measure the amount of lens eccentricity in a test lens group having a complicated configuration.

  Note that a CMOS, PSD, or photomultiplier may be used instead of the CCD used in this embodiment.

  The half mirror 102 used in this embodiment may be a metal mirror film or a pellicle mirror.

  Although the optical axis of the laser light source is folded back approximately 90 ° by the half mirror, the CCD side may be folded back by the half mirror without folding the laser light source side.

  Note that the LD laser light source 100 used in this embodiment may be a parallel laser beam of an incoherent light source such as a gas laser, a solid laser, a liquid laser, an LED, an EL, or a halogen lamp.

  Note that the focus lens 101, the imaging lens 103, and the condenser lens 104 constituting the measurement optical system may not have an antireflection film on the surface.

  In this embodiment, the test lens group has a three-group configuration, the movable group by the zoom mechanism is the lens group 602, and the test lens surface 610 is the measurement target. However, the test lens group may not have the three-group configuration. The movable group may be any lens group, and the test lens surface may be any surface of the lens constituting the test lens group.

  In this embodiment, the condenser lens 104 is moved by the stage 105 in order to scan the lens surface of the lens group to be tested. However, the lens group side may be moved.

  In the present embodiment, the condensing lens 104 is moved by the stage 105 in order to scan the lens surface of the lens group to be examined. However, the condensing lens 104 is provided with a variable focus mechanism, and the position of the condensing lens 104 is changed. The focal position of the condensing lens 104 may be changed without changing.

  In this embodiment, the condensing lens 104 is moved by the stage 105 in order to scan the lens surface of the lens group to be examined. However, the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, the converging lens, The entire measurement optical system including the optical lens 104, the moving stage 105, and the CCD camera 106 may be moved with respect to the lens group to be examined.

  Although the CCD camera 106 is disposed at the focal position of the imaging lens 103, a spot image may be enlarged by adding an enlargement optical system for enlarging the imaging surface of the CCD camera 106.

    The eccentricity calculation device 802 may be configured by a general-purpose electronic computer application program instead of a dedicated device.

  It should be noted that the position information management of the moving stages 105 and 502 using the linear scale disposed on the moving stages 105 and 502 may be the rotation number management of the moving stage drive motor as long as it can be transmitted to the eccentricity calculation device 802 as the stage position information.

  If the optical system including the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, and the CCD camera 106 has a function equivalent to that described in the present embodiment, an autocollimator or the like It may be replaced with a single device.

  The optical system including the LD light source 100, the focus lens 101, the half mirror 102, the imaging lens 103, the condenser lens 104, the moving stage 105, and the CCD camera 106 is equivalent to that described in this embodiment. If it has a function, it may be replaced with a single device.

  According to the lens reflection eccentricity measuring method of the present invention, the reflected light from each lens surface of the lens to be examined is condensed on a small spot on the evaluation surface, and the reflected light corresponding to each lens surface is individually evaluated as an evaluation target. Since measurement can be performed with distinction, it is possible to measure with high accuracy without misrecognizing the spot light position of the eccentricity measurement.

  For this reason, the present invention can be applied to assembly, adjustment, inspection of a lens assembly of a camera, lens assembly, adjustment, inspection of a CD or DVD optical pickup.

Schematic diagram of the lens eccentricity measuring apparatus in Embodiment 1 of the present invention The figure which showed the light ray of the test lens vicinity when measurement light injects from the A side in FIG. 1 in Embodiment 1 of this invention Schematic diagram of imaging surface 110 in the state of FIG. 2 in Embodiment 1 of the present invention The figure which showed the light ray of the test lens vicinity when measurement light injects from the B side in FIG. 1 in Embodiment 1 of this invention 4 is a schematic diagram of the imaging surface 210 in the state of FIG. 4 in Embodiment 1 of the present invention. Schematic diagram of the lens eccentricity measuring optical system in Embodiment 2 of the present invention The figure which showed the test lens and the light ray state of a test lens vicinity when measurement light injects from the test lens 301 side described in FIG. 6 in Embodiment 2 of this invention Schematic diagram of imaging surface 110 in the arrangement of FIG. 7 in Embodiment 2 of the present invention. The figure which showed the test lens and the light ray state of a test lens vicinity when measurement light injects from the test lens 304 side described in FIG. 6 in Embodiment 2 of this invention Schematic diagram of imaging surface 110 in the arrangement of FIG. 9 in Embodiment 2 of the present invention. Schematic diagram of the lens eccentricity measuring apparatus in Embodiment 3 of the present invention Schematic diagram of imaging surface 110 with the test lens arrangement of FIG. 11 in Embodiment 3 of the present invention. Schematic diagram of lens eccentricity measurement in a state where the position of the lens group 602 to be tested is changed compared to FIG. 11 in Embodiment 3 of the present invention. Schematic diagram of imaging surface 110 with the test lens arrangement of FIG. 13 in Embodiment 3 of the present invention. Schematic diagram of conventional lens eccentricity measuring device and imaging surface 8 The figure which showed a mode that the focus 9 of the focus lens 3 substantially corresponded with respect to the curvature center position of the lens surfaces 14, 15, and 16 which have a curvature center position in the very near position. The figure which showed a mode that the focus 9 of the focus lens 3 substantially corresponded to the curvature center position of the lens surface 5 The figure which showed a mode that the focus 9 of the focus lens 3 substantially corresponded to the lens surface 5

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 1st LD laser light source 101 1st focus lens 102 1st half mirror 103 1st imaging lens 104 1st condensing lens 105 1st moving stage 106 1st CCD camera 107 1st polarization Core amount calculation device 108 Reflected spot image from test lens surface 310 109 Reflected spot image from test lens surface 311 110 Imaging surface of first CCD camera 106 200 Second LD laser light source 201 Second focus lens 202 Second half mirror 203 Second imaging lens 204 Second condenser lens 205 Second moving stage 206 Second CCD camera 207 Second eccentricity calculation device 208 Reflected spot from lens surface 310 to be examined Image 210 Imaging surface of CCD camera 206 301 Test lens 302 Test lens 303 Test Lens 304 Test lens 305 Holding frame 306 Positioning reference surface 310 Test lens surface 311 Test lens surface 313 Position of the center of curvature of the test lens surface 310 when viewed from the A side in FIG. 1 314 Viewed from the A side in FIG. 315 curvature center position of the test lens surface 311 when viewed 315 curvature center position of the test lens surface 310 when viewed from the B side in FIG. 1 316 curvature of the test lens surface 311 when viewed from the B side in FIG. Center position 317 Curvature center position of lens surface 610 318 Curvature center position of lens surface 611 320 Eccentricity amount calculation result judgment device 321 Display device 501 Rotation stage 502 Moving stage 601 Test lens group 602 Test lens group 603 having a moving mechanism Test lens group 604 Lens barrel 610 Test lens surface 611 Test lens surface 701 Reflection spot from test lens surface 610 702 Reflected spot image from the lens surface 611 to be examined 801 Eccentricity calculation device 802 Eccentricity calculation device 1 Light source 2 Collimator lens 3 Focus lens 4 Support frame 5 Lens surface 6 Half mirror 7 Camera 8 Imaging surface 9 Focus lens 3 focal point 10 observation screen 11 spot by light shown by solid line in FIG. 15 spot by light shown by broken line in FIG. 15 13 eccentric direction of lens surface 5 14 lens surface 15 lens surface 16 lens surface

Claims (6)

A lens group to be tested;
A test lens surface constituting the test lens group; and
A first light source that emits parallel light;
A first condensing lens that condenses the light emitted from the first light source;
First moving means for moving the first condenser lens in the optical axis direction of the first light source;
A second light source that emits parallel light;
A second condenser lens that condenses the light emitted from the second light source;
Second moving means for moving the second condenser lens in the optical axis direction of the second light source;
A group of test lenses arranged so that the light emitted from the first condenser lens is the first incident light and the light emitted from the second condenser lens is the second incident light;
A first imaging lens that collimates the reflected light from the test lens surface of the test lens group with the first condenser lens and collects the light;
A first light receiving unit that receives light collected by the first imaging lens;
A second imaging lens that collimates the reflected light from the lens surface to be tested of the lens group to be examined by the second condenser lens and condenses the light;
A second light receiving portion for receiving the light collected by the second imaging lens;
The first test lens group is arranged so that the first incident light is incident from one side of the two apertures of the first test lens group and the second incident light is incident from the remaining one side, and the test lens is disposed. The optical axes of the groups are arranged so as to substantially coincide with the optical axis of the first incident light,
Further, by using a measurement optical system that is arranged so that the optical axis of the lens group to be tested is substantially coincident with the optical axis of the second incident light,
Spot position information when the first condenser lens is adjusted so that the reflected light from each lens surface of the lens group to be detected becomes a spot on the first light receiving portion, and the first light receiving portion Position information of the first moving means when a spot is formed and the second light condensing so that reflected light from each lens surface of the lens group to be examined becomes a spot on the second light receiving unit. From the position information of the lens when the lens is adjusted and the position information of the second moving means when the spot is formed on the second light receiving portion, the light of each lens to be tested that constitutes the lens group to be tested Calculate the amount of eccentricity and inclination from the shaft,
Compare the lens eccentricity and inclination data of each of the two test lenses calculated from the measurements of the first and second light-receiving units, and select the appropriate data according to the predetermined conditions. To measure the lens eccentricity of the lens group to be measured. A lens reflection eccentricity measuring apparatus that measures the amount of lens eccentricity by the lens reflection eccentricity measuring method according to claim 1. A light source that emits parallel light;
A condensing lens that condenses the light emitted from the light source;
Moving means for moving the condenser lens in the optical axis direction of the light source;
A test lens group disposed on the optical axis of the light source and disposed so that the light emitted from the condenser lens is incident light and the optical axis of the incident light is substantially coincident with its own optical axis;
The test lens group is rotated about a rotation axis perpendicular to the optical axis of the light source, and the incident light is incident along the optical axis of the test lens group from either of the openings on both sides of the test lens group. A rotating means to allow
An imaging lens that collimates the reflected light from the test lens surface of the test lens group with the condenser lens and condenses the light,
A light receiving portion for receiving the light collected by the imaging lens,
The spot position when the condensing lens is adjusted so that the reflected light from each lens surface of the lens group to be tested becomes a spot on the light receiving unit and the spot when the spot is formed by the light receiving unit From the positional information of the moving means and information on the orientation of the rotating means with respect to the optical axis, the amount of eccentricity and the amount of inclination from the optical axis of each lens to be tested are calculated,
The test lens group is rotated by the rotating means, light is incident from two directions of the test lens group aperture, and measured and calculated for two types of test lens eccentricity / tilt data. A lens reflection eccentricity measuring method, comprising: measuring an amount of lens eccentricity of each of the test lenses constituting the test lens group by selecting appropriate data in accordance with a predetermined condition. A lens reflection eccentricity measuring apparatus, wherein the lens eccentricity is measured by the lens reflection eccentricity measuring method according to claim 3. A light source that emits parallel light;
A condensing lens that condenses the light emitted from the light source;
Moving means for moving the condenser lens in the optical axis direction of the light source;
A lens that is arranged on the optical axis of the light source and that is configured such that the light emitted from the condenser lens is incident light, and the optical axis of the incident light is substantially coincident with its own optical axis. A lens group to be tested having a mechanism for moving a part in the optical axis direction;
A moving means that acts on a moving mechanism of the lens group to be tested and moves the movable lens group of the lens group to be tested;
A light receiving unit that receives light obtained by collimating the reflected light from the lens surface to be tested of the lens group to be examined by the condenser lens;
Spot position information and position information of the moving means when the condensing lens and the movable lens group are adjusted so that the reflected light from each lens surface of the lens group to be tested becomes a desired spot on the light receiving unit. And calculating the decentering amount / inclination amount of each test lens constituting the test lens group from the position information of the movable lens group,
A lens reflection decentering measurement method, comprising: measuring a lens decentering amount of each test lens constituting the test lens group. A lens reflection eccentricity measuring apparatus, wherein the lens reflection eccentricity is measured by the lens reflection eccentricity measuring method according to claim 5.

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