JP2006349585A - Otf (optical transfer function) measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an OTF measuring instrument setting a plurality of examined lenses introduced while set in a lens tray to make those in parallel each other. <P>SOLUTION: In this OTF measuring instrument for introducing a plurality of specimens 1 with a lens 2 to be examined assembled in a lens holder 3, while setting those in the lens tray 100, for projecting a chart provided in a target, by the lens 2, for picking up a projected chart image, and for processing an image therein to measure an OTF value of the lens 2, the lens tray 100 has: a plurality of setting recesses for setting the plurality of specimens 1 under respective positioned conditions, a projection opening 121 is formed in each of the recesses to introduce projection light onto a bottom face, each specimen 1 is set using an edge part 121a of the projection opening 121 as a mounting face, and the mounting faces in the plurality of setting recesses are formed in parallel with each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an OTF measuring apparatus that measures an OTF value indicating the optical quality of a lens used in an optical product such as a digital camera.

Conventionally, in order to inspect the optical quality of a lens used in an optical product such as a digital camera mounted on a mobile phone, a chart image is projected by a lens to be inspected, and the projected chart image is captured by an imaging means (CCD 2. Description of the Related Art An OTF measurement device that captures an image with a camera and processes the image to measure an OTF value (Optical Transfer Function) of the lens to be measured is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 5-288642

  By the way, with the rapid increase in demand for optical products such as digital cameras in recent years, the production amount of camera modules and lenses mounted on them has also increased rapidly. For this reason, in order to continuously measure a plurality of subjects (in which a lens to be examined is incorporated in a lens holder) and increase the number of measurements per time, a plurality of subjects are provided with a lens tray to be introduced into a measuring apparatus. It is possible to set it.

  However, if the bottom surfaces of the plurality of set recesses on which the plurality of subjects are respectively set (subject placement surfaces) are inclined to each other, the plurality of subjects (test lenses) cannot be set in parallel to each other. . Therefore, a measurement error occurs due to a difference in set posture (inclination) among a plurality of subjects. That is, even if the test lens has the same OTF value, the obtained OTF value differs depending on which set concave portion is set.

  An object of the present invention is to provide an OTF measuring apparatus capable of setting a plurality of test lenses set and introduced on a lens tray in parallel to each other.

  The OTF measuring apparatus according to the present invention introduces a plurality of specimens in which a test lens is incorporated in a lens holder by being set on a lens tray, and projects and charts a chart provided on a target by each test lens. An OTF measuring apparatus that captures a chart image and performs image processing on the chart image to measure an OTF value of a test lens, wherein the lens tray has a plurality of set recesses for setting a plurality of subjects in a positioning state, respectively. Each set recess has a projection opening for introducing projection light on the bottom surface, and each subject is set with the edge of the projection opening as a placement surface, and the placement surfaces of the plurality of set recesses are: They are formed parallel to each other.

According to this configuration, since the plurality of placement surfaces on which the plurality of subjects are respectively placed are formed in parallel to each other, the plurality of subjects (test lenses) are set in parallel with each other. can do. Therefore, there is no measurement error due to the set position for a plurality of test lenses.
Here, the OTF value is a concept including an MTF value (Modulation Transfer Function) and a PTF value (Phase Transfer Function).

  In this case, the lens tray is formed with a plurality of projection openings, a placement plate on which a plurality of subjects are placed, and a plurality of positioning openings that are superposed on the surface of the placement plate to position each subject. Each set recess is constituted by each projection opening of the mounting plate and each positioning opening of the positioning plate, and the mounting plate is made of a plate material whose surface is adjusted in flatness. Preferably it is.

  According to this configuration, a plurality of placement surfaces on which a plurality of subjects are respectively placed are configured by the placement plates whose surfaces are adjusted so as to have flatness. For this reason, a plurality of mounting surfaces can be formed in parallel to each other without requiring complicated processing.

  In this case, each positioning opening is preferably partially chamfered on the peripheral edge on the front side.

  According to this configuration, when pinching the object with tweezers or a finger and setting it in the set recess or removing it from the set recess, the chamfered portion formed on the surface of each positioning opening is used to make each positioning on the tweezer or finger. Since the peripheral portion of the opening does not interfere (obstruct), the operability can be improved.

  In these cases, the positioning plate is preferably provided with a plurality of temporary placement portions for temporarily placing the subject corresponding to the positioning openings.

  According to this configuration, for example, if a test lens whose OTF value deviates from the standard as a result of measurement is temporarily placed in the corresponding temporary placement unit, the test lens conforming to the standard and the non-standard test lens And can be easily identified. Thus, usability can be improved.

  Hereinafter, an OTF measuring apparatus to which the present invention is applied will be described with reference to the accompanying drawings. This OTF measuring apparatus measures an OTF value by capturing a chart image back-projected by a test lens in order to evaluate the optical quality of a lens used in an optical product such as a digital camera mounted on a mobile phone. This device is mainly incorporated in a mass production line for lens assembly, and is used for shipping inspection and quality control. Therefore, first, a lens to be measured that is a measurement target will be described.

  As shown in FIG. 1, a test lens 2 to be measured is incorporated in a lens holder 3 so that it can be installed in a camera module such as a digital camera. Hereinafter, the lens holder 3 in which the test lens 2 is incorporated will be referred to as “subject 1” and the description will proceed.

  The lens holder 3 is made of resin, and includes a small cylindrical portion 6 in which the test lens 2 is incorporated so as to be molded, and a large large cylindrical portion 7 that is continuous with the lower end side of the small cylindrical portion 6. ing. The large cylindrical portion 7 includes a cylindrical holder recess 8 having an opening at the lower end side, into which the emission side end portion of the target 14 is inserted (details will be described later). That is, the focal length of the lens 2 to be examined is extremely short, and the focal point is located inside the holder recess 8.

  Then, the OTF measuring apparatus which concerns on this embodiment is demonstrated. As shown in FIG. 2, the OTF measuring device 11 is installed on the machine base 12 and the machine base 12 and moves the lens tray 100 on which a plurality of subjects 1 can be set in the X-axis direction and the Y-axis direction. The XY moving table 13, the target 14 provided with the chart 45 on the upper end surface, the measurement light irradiation device 15 that irradiates the chart 45 with the measurement light incident from the lower end surface of the target 14, and the lens 2 to be projected (connected). An image pickup unit 16 for picking up the image of the chart image from above, and a control device (not shown) that performs image processing on the picked-up chart image to calculate an OTF value and controls the various parts of the apparatus. ing.

  Further, the OTF measuring apparatus 11 picks up the focus moving table 17 for moving the target 14 in the vertical direction for focusing, and the subject 1 for which the obtained OTF value is determined to be out of the standard. A pickup mechanism (not shown) is provided. The focus movement table 17 is fixed to a bracket (not shown) suspended from the lower surface of a support base 22 (described later) of the machine base 12, while the pickup mechanism straddles the XY movement table 13 on the machine base 12. It is arranged.

  The machine base 12 is a machine base body (not shown) with casters framed by a channel material, and a plate-like support base 22 that is placed on the machine base body and supports the XY moving table 13, the imaging unit 16, and the like. And have. Although the machine base body is not shown, it is configured in a cabinet type having a side plate panel and an opening / closing door, and the measurement light irradiation device 15 and the focus moving table 17 are provided in a storage chamber (not shown) formed therein. Is housed.

  A bracket to which the focus movement table 17 is fixed is suspended from the lower surface of the support base 22. A target opening 23 for inserting the target 14 connected to the measuring light irradiation device 15 is formed in the center of the support base 22, and the target 14 is attached to the lens tray 100 through the target opening 23. It faces the set subject 1 (details will be described later). Although not shown, the XY moving table 13 and the imaging unit 16 on the support base 22 are covered from above with a protective cover having a work opening for accessing the front surface from the outside.

  The XY movement table 13 includes a set table 31 on which the lens tray 100 is directly mounted, an X-axis table (not shown) for moving the set table 31 in the X-axis direction, and the set table 31 via the X-axis table. And a Y-axis table (not shown) that moves in the axial direction, and each table can move the lens tray 100 in the X and Y-axis directions in the horizontal plane via the set table 31 by motor drive. It is configured.

  A pair of positioning guides 32 and 32 that are spaced apart in the Y-axis direction and two lens trays 100 that are guided by the pair of positioning guides 32 and 32 and slide-mounted in the X-axis direction abut on the surface of the set table 31. Positioning pins 33, 33 are provided. Each positioning guide 32 is provided with a pair of fixing pieces 34 and 34 for fixing the lens tray 100 in a state where it abuts against the two positioning pins 33 and 33 (see FIG. 3). That is, the lens tray 100 is slid and set by the pair of positioning guides 32 and 32 in a slightly floating state, and the two positioning pins 33 and 33 and the pair of fixing pieces 34 and 34 are used in an XY plane in the horizontal plane. Positioned and set in the axial direction.

  On the other hand, the XY moving table 13 receives the control from the control device, while the set table 31 includes a set area (not shown) where the lens tray 100 is introduced (replaced) and a measurement area (not shown) facing the target 14. Are moved back and forth in the X-axis direction, and moved in the X and Y-axis directions within the measurement region so that the plurality of test lenses 2 set on the lens tray 100 sequentially face the target 14.

  The measurement light irradiation device 15 includes a halogen lamp or the like, and includes a light source 51 that irradiates measurement light (white light) and an optical fiber (bundle) that optically connects the light source 51 and the incident surface 43 of the target 14. The light guide 52 guides the measurement light from the light source 51 to the incident surface 43 of the target 14. The monochromatic light filtered to a specific wavelength by interposing a filter in the optical path of the light source 51 may be used as measurement light.

  As will be described in detail later, the measurement light from the light source 51 is incident on the incident surface 43 of the target 14 via the light guide 52, and is further irradiated on the chart 45 provided on the emission surface 44. A chart image is projected by the lens 2.

  The imaging unit 16 is provided in front of each CCD camera 61 and a plurality of CCD cameras 61, and forms a plurality of imaging images on the CCD light-receiving surface of the CCD camera 61 by the chart image projected by the test lens 2. A lens 62, a camera mounting dome 63 to which a plurality of CCD cameras 61 and a plurality of imaging lenses 62 are detachably attached, and a camera stand (illustrated) that is provided on the support base 22 and supports the camera mounting dome 63. (Omitted).

  Although not shown, the camera stand includes a mounting frame in which a circular camera mounting opening is formed in the center, and four support columns that support four corners of the mounting frame. The camera mounting dome 63 has a dome (substantially hemispherical) shape, and is configured to be mountable in a posture in which the camera mounting opening of the camera stand is convex. That is, the outer periphery of the camera mounting dome 63 and the edge of the camera mounting opening are screwed and mounted at a plurality of locations.

  As the camera mounting dome 63, a plurality of types having different dome shapes are prepared. When the camera mounting dome 63 is mounted on a camera stand, the dome shape is such that the center point of the dome becomes the pupil position of the set lens 2 to be tested. By selecting the camera mounting dome 63, it is possible to deal with a wide variety of test lenses 2.

  A maximum of nine CCD cameras 61 can be mounted on the camera mounting dome 63, and nine camera mounting openings are formed, one of which is arranged at the apex position of the camera mounting dome 63 and the remaining eight. Are arranged on the concentric circles four by four, equally distributed in the circumferential direction and arranged at the same position in the circumferential direction. The CCD camera 61 is attached to each camera attachment opening so that its optical axis is substantially perpendicular to the dome surface. Therefore, the pupil position of the test lens 2 and the optical axis of each CCD camera 61 overlap.

  In the present embodiment, the five CCD cameras 61 are arranged at the apexes so that the image pickup unit 16 can pick up the projected center point image and four peripheral point images (described later) for each lens 2 to be examined. The camera is mounted on a total of five camera mounting openings, including four places on the outer circumference. That is, among the five CCD cameras 61, those attached to the apex portion take a central point image, and those located on the outer circumference take a corresponding peripheral point image. Therefore, the OTF values at the five measurement locations of the test lens 2 can be collectively measured, and the imaging performance of the entire test lens 2 can be inspected quickly and efficiently.

  The focus moving table 17 is a slide guide 71 fixed to the bracket, a slider 72 provided on the slide guide 71, and a guide fixed to the slider 72 to detachably attach the tip end portion (light emitting side end portion) of the light guide 52. It has a holder 73, and is configured such that the target 14 connected to the tip of the light guide 52 via the guide holder 73 can be moved minutely in the vertical direction by motor drive.

  The focus movement table 17 is controlled by the control device so that the chart 45 provided on the upper end surface of the target 14 is positioned at the best focus position and the predetermined defocus position of the lens 2 to be tested. 14 is moved minutely.

  As shown in FIG. 3, the lens tray 100 includes a tray main body 101 on which a plurality of subjects 1 are set, a frame body 102 in which a shallow groove for setting the tray main body 101 is formed, and sides of the frame body 102. And a pair of handles 103 provided at both left and right ends of the unit. The left and right handles 103, 103 serve as parts to be held when the operator places a plurality of subjects 1 on the lens tray 100 outside the apparatus and then places them on the set table 31.

  Further, the frame body 102 is formed with a pair of positioning recesses 104 and 104 that contact the pair of positioning pins 33 and 33 of the set table 31 on the side opposite to the pair of handles 103 and 103. Yes. That is, the tray main body 101 is positioned and set (fixed) on the set table 31 via the frame 102.

  The tray main body 101 is configured to be able to set a maximum of 32 subjects 1, and each of the 32 set recesses 106 for setting the subject 1 in a positioning state is arranged in rows of 8 in the X-axis direction (Y-axis 4 columns in the direction). Furthermore, 32 temporary placement recesses 107 for temporarily placing the subject 1 are arranged in rows in the X-axis direction so as to be adjacent to each set recess 106 (4 rows in the Y-axis direction). . The temporary placement recess 107 is shown only in FIG.

  As shown in FIG. 4, the tray main body 101 includes a substantially rectangular mounting plate 111 and a positioning plate 112 that is formed in the same size as the mounting plate 111 and is polymerized (screwed) on the surface of the mounting plate 111. It is configured.

  The mounting plate 111 is made of a slightly thick plate (for example, 10 mm) made of stainless steel, and eight circular projection openings 121 for introducing projection light from the target 14 are arranged in rows (four rows). A maximum of 32 subjects 1 are placed on the surface, with the front edge 121a of 121 being the placement surface of the subject 1. Further, the surface 111a of the mounting plate 111 is subjected to flatness processing such as lapping, and is adjusted to a high flatness (for example, 5 μm or less).

  Each projection opening 121 includes a small-diameter hole 123 having a small diameter opened on the front surface 111a of the mounting plate 111, and a large-diameter hole 124 formed in a larger diameter than the small-diameter hole 123 and communicating with the small-diameter hole 123 and opening on the back surface. It is composed of The small-diameter hole 123 is formed to have a smaller diameter than the large cylindrical portion 7 of the lens holder 3 so that the subject 1 is placed on the front side edge portion 121a, and the emission side end portion of the target 14 is inserted. Thus, it is formed larger in diameter than the target 14. Therefore, the chart 45 can be positioned on the front side (the test lens 2 side) with respect to the back surface of the mounting plate 111, and the chart image can be appropriately displayed even for the test lens 2 having an extremely short focal length. Can be projected.

  The large-diameter hole 124 is a target in which a chart plate in which a chart is formed and a diffuser plate that equalizes measurement light from a light source are housed in a metal cylindrical case instead of the target 14 of the present embodiment. As described above, this is used when a target having a larger diameter than the small-diameter hole 123 is used. That is, in this case, the target is inserted up to the large-diameter hole 124 so that the front end surface of the cylindrical case is brought into contact with the back side edge 121 b of the small-diameter hole 123. Therefore, when only the target 14 of this embodiment is used, the projection opening 121 may be formed as a through hole having the same diameter from the front surface 111a to the back surface.

  On the other hand, the positioning plate 112 is made of a plate material made of resin and having a thickness approximately the same as the height of the large cylindrical portion 7 of the lens holder 3, and corresponds to the 32 projection openings 121 of the mounting plate 111. Each positioning opening 126 is formed, and 32 temporary placement openings (not shown) are formed adjacent to each positioning opening 126. That is, 32 positioning openings 126 and 32 temporary placement openings are arranged in 4 examples, each of 8 pieces, and a row composed of 8 positioning openings 126 and a row composed of 8 temporary placement openings, They are alternately arranged.

  Each positioning opening 126 is formed in a circular shape having a slightly larger diameter than the large cylindrical portion 7 of the lens holder 3. In the state where the positioning plate 112 is superposed on the mounting plate 111, the inner peripheral surface 126a of the positioning opening 126 and the surface 111a of the mounting plate 111 constitute the set recess 106 described above. The sample 1 is set in the positioning state. Although not shown, each positioning opening 126 has a peripheral edge on the front side that is partially edged. Accordingly, when the subject 1 is picked up by the tweezers or fingers and set in the set recess 106 or taken out from the set recess 106, the peripheral portion on the front side of the positioning opening 126 does not interfere with the tweezers or fingers.

  Furthermore, as described above, the surface of the mounting plate 111 serving as the mounting surface of the 32 subjects 1 is adjusted so that the flatness is obtained, so that the 32 subjects 1 are respectively placed. The front edge portions 121a of the 32 projection openings 121 can be formed in parallel to each other. For this reason, the 32 test objects 1 (test lens 2) are set in a mutually parallel state. Therefore, no measurement error due to the set position occurs for the plurality of test lenses 2.

  On the other hand, each temporary placement opening is formed in a substantially square shape whose one side is slightly longer than the large cylindrical portion 7 of the lens holder 3. In the state where the positioning plate 112 is superposed on the mounting plate 111, the temporary placement recess 107 is formed by the inner peripheral surface of the temporary placement opening and the surface 111a of the placement plate 111. Sample 1 is temporarily placed.

  As shown in FIG. 1, the target 14 includes a cylindrical optical waveguide member 41 connected to the tip of the light guide 52 and a light shielding film body 42 coated on the outer peripheral surface of the optical waveguide member 41. Yes.

  The optical waveguide member 41 is made of white glass or the like, and has an incident surface 43 that is connected to the light guide 52 and receives measurement light from the light source 51, and an output surface 44 that forms a chart 45. Further, a light diffusing member 46 made of opal glass or the like is integrally incorporated in the optical path intermediate portion of the optical waveguide member 41. According to this, since the measurement light from the light source 51 is irradiated on the chart 45 in a uniformly diffused state, a uniform chart pattern without unevenness in illuminance can be formed on the emission surface 44, and the OTF value Measurement reliability can be improved.

  The chart 45 includes nine cross slits (one center slit 45a, four inner circumferential slits 45b, and four outer circumferential slits 45c described later), and an etching process is performed on the metal film formed on the emission surface 44. The pattern is formed by the above. This metal film is made of, for example, a chromium vapor-deposited film, and has an inner surface that is a mirror surface and a thickness of 0.8 μm. According to this, since the chart 45 is patterned on the thin metal film, an appropriate chart image can be projected. Note that this metal film may be formed by electroless plating, sputtering, or the like in addition to the metal vapor deposition method.

  Further, by forming the chart 45 with cross slits 45a, 45b, 45c, the sagittal direction (radiation direction) OTF value and the meridional direction (concentric direction) OTF value at each measurement location of the lens 2 to be measured are obtained. Can do.

  Nine cross slits 45a, 45b, 45c are a central slit 45a (center point) formed at the center of the exit surface 44, and four inner peripheries formed on the circumference thereof in a circumferentially distributed manner. A slit 45b (peripheral point), four inner peripheral slits 45b, and four outer peripheral slits 45c (peripheral points) formed concentrically and uniformly distributed in the circumferential direction are provided, and four inner peripheral slits. 45b and the four outer peripheral slits 45c are formed at the same position in the circumferential direction. That is, the nine cross slits 45a, 45b, and 45c correspond to the arrangement of the camera mounting openings. The slits extending in the radial direction of the inner peripheral slits 45b are continuous with the slits extending in the radial direction of the outer peripheral slits 45c.

  The four inner slits 45b correspond to the test lens 2 for a small size (for example, 1/7 inch) CCD, and the four outer peripheral slits 45c are for a large size (for example, 1/4 inch) CCD. This corresponds to the lens 2 to be tested. That is, when measuring the OTF value of the former test lens 2, the center slit 45 a is projected onto the center of the optical axis of the test lens 2, and the inner peripheral slit 45 b is the center of the optical axis of the test lens 2. When the OTF value of the latter lens 2 is measured, the central slit 45a is the optical axis of the lens 2 to be tested. In addition to being projected to the center, the inner circumferential slit 45b is projected to the periphery of the center of the optical axis of the lens 2 to be examined. Thereby, it is possible to correspond to two kinds of test lenses 2 by one target 14.

  On the other hand, the light shielding film 42 is made of a metal film (chrome) whose inner surface is a mirror surface. This metal film is formed by a metal vapor deposition method in the same manner as the metal film formed on the emission surface 44. In this case, other methods such as electroless plating and sputtering can be used. . In addition, the light shielding film body 42 can be formed thin and with high strength by forming the metal film with chromium.

  Then, the outer peripheral surface of the optical waveguide member 41 is covered with a metal film (light-shielding film body 42) whose inner surface is a mirror surface, and the emission surface 44 of the optical waveguide member 41 is covered with a metal film whose inner surface is a mirror surface as described above. Thereby, the light reflectance of the inner surface of the optical waveguide member 41 can be easily increased. For this reason, the measurement light incident from the incident surface 43 can be efficiently transmitted to the emission surface 44, and the power consumption of the light source 51 can be suppressed. In addition, the measurement light incident from the incident surface 43 reaches the output surface 44 by being repeatedly reflected by the metal film. Therefore, a uniform chart pattern with no illuminance unevenness can be formed on the exit surface 44, and the measurement light from the exit surface 44 can have orientation characteristics that are not angle-dependent. Therefore, the measurement accuracy of the OTF value can be improved.

  Furthermore, the optical waveguide member 41 in which the chart 14 is formed on the emission surface 44 of the target 14 is covered with the light-shielding film body 42 so that the diameter of the target 14 as a whole can be reduced. Since it becomes almost equal to the diameter, the target 14 can be made as small as possible as compared with the case where the chart plate is incorporated in the cylindrical case.

  Although not shown, the pickup mechanism is arranged between the lens suction hand for sucking and holding the subject 1 and each set concave portion 106 of the lens tray 100 and the corresponding temporary placement concave portion 107 via the lens suction hand. A lens moving mechanism for moving the subject 1.

  When the control device determines that the OTF value of the lens 2 to be measured is out of specification, the pickup mechanism sucks the subject 1 set in the set recess 106 with the lens suction hand. It is held and taken out from the set recess 106 and temporarily placed in the corresponding temporary placement recess 107. Thereby, the test lens 2 conforming to the standard and the test lens 2 not conforming to the standard can be easily identified, and the usability can be improved.

  Although not shown, the control device is composed of a personal computer equipped with a keyboard, a monitor, etc., and includes a program storage unit, an OTF arithmetic processing unit, an image display processing unit, an input / output control unit, a control control unit, have.

  The program storage unit is composed of a hard disk or the like, and includes measurement condition data for measuring the OTF value, a program for calculating the OTF value, a program for outputting the measurement result of the OTF value as an image, and the OTF measurement device 11 A control program for controlling each unit is stored.

  The OTF calculation processing unit executes an OTF value calculation process based on the imaging data sent from the CCD camera 61 and the data or program stored in the program storage unit. That is, the OTF value is obtained by Fourier transforming the light intensity distribution of the chart image. The image display processing unit is configured by a CPU, a VRAM, and the like, and displays the measurement conditions and measurement results of the OTF value on a monitor and stores image information.

  The input / output control unit includes a logic circuit for handling interface signals with various peripheral circuits. For example, the input / output control unit captures input data from a keyboard, imaging data from the CCD camera 61, and the like into the control device, and also an OTF. Control data necessary for controlling each part of the measuring apparatus 11 is output to each part, and image data and the like from the image display processing part are output to the monitor. The control supervision unit is constituted by a CPU and controls the processing operation of the entire control device.

  Here, a series of measurement operations by the OTF measurement apparatus 11 of the present embodiment will be described. First, the operator sets 32 subjects 1 on the lens tray 100 taken out from the OTF measuring apparatus 11. Then, the operator introduces the lens tray 100 into the apparatus through the work opening and places it on the set table 31 located in the tray setting area.

  Subsequently, when the operator gives an instruction to start measurement from the control device, the lens tray 100 is moved from the tray set area to the measurement area by the XY movement table 13, and the first object to be measured, that is, the first row / 1 is measured. The subject 1 set in the set recess 106 at the stage is caused to face directly above the target 14.

  Next, the focus moving table 17 causes the target 14 to be inserted into the holder recess 8 of the lens holder through the projection opening 121 and to move the target 14 to the focus position of the lens 2 to be examined. In this state, the chart image projected by the test lens 2 is picked up using the five CCD cameras 61 of the image pickup unit 16, and the OTF value at the focus position is measured. Further, the target 14 is moved (defocused) at a predetermined distance pitch from the focus position by the focus movement table 17, and the OTF value is measured each time.

  From the focus position thus obtained and the OTF values at a plurality of defocus positions, an OTF-defocus characteristic diagram at each measurement location is created and displayed on the monitor, and whether or not it conforms to the standard. judge.

  If it is determined that it conforms to the standard, the target 14 is temporarily retracted from the lens tray 100 by the focus movement table 17 and the subject 1 to be measured next, that is, one row by the XY movement table 13. The subject 1 set in the eye / second stage setting recess 106 is caused to face directly above the target 14. If it is determined that it does not conform to the standard, the pickup 1 moves the subject 1 from the set concave portion 106 to the temporary placement concave portion 107, and then similarly sets the subject 1 to be measured next as the target 14. Let it face directly above. In the unlikely event that the temporary placement (automatic discharge) of the non-standard test lens 2 fails, a warning is displayed on the monitor.

  In the same manner, the measurement is sequentially performed for all the test lenses 2 set on the lens tray 100. When the measurement is completed for all the test lenses 2 on the lens tray 100, the lens tray 100 is moved from the measurement area to the tray set area by the XY movement table 13. Finally, the operator removes the lens tray 100 from the work opening, and the series of measurement processes is completed.

  As described above, according to the OTF measuring apparatus 11 of the present embodiment, by providing the lens tray 100 described above, the OTF values are continuously measured for the plurality of test lenses 2 without any measurement error due to the set position. can do.

(A) is a schematic front view of a target and a test object, (b) is a top view of a target. It is a typical front view of an OTF measuring device. It is a typical front view of a set table and a lens tray. It is a typical top view of a lens tray.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Subject 2 ... Test lens 3 ... Lens holder 13 ... XY moving table 14 ... Target 45 ... Chart 100 ... Lens tray 106 ... Set recessed part 107 ... Temporary placing recessed part 111 ... Mounting plate 111a ... Surface (mounting plate) DESCRIPTION OF SYMBOLS 112 ... Positioning plate 121 ... Projection opening 121a ... Front side edge part 126 ... Positioning opening

Claims (4)

A plurality of subjects in which a test lens is incorporated in a lens holder are set and introduced into a lens tray, and a chart provided on the target is projected by each of the test lenses, and a projected chart image is captured, And this is an OTF measuring device for image processing to measure the OTF value of the lens to be examined,
The lens tray has a plurality of set recesses for setting the plurality of subjects in a positioning state,
In each set recess, a projection opening for introducing projection light is formed on the bottom surface, and each subject is set with the edge of the projection opening as a mounting surface.
The mounting surface of the plurality of set recesses is formed in parallel to each other, and the OTF measuring device. The lens tray is
A mounting plate on which the plurality of projection openings are formed, and the plurality of subjects are mounted on a surface;
A positioning plate that is polymerized on the surface of the mounting plate and has a plurality of positioning openings for positioning each subject;
Each set recess is constituted by each projection opening of the mounting plate and each positioning opening of the positioning plate,
The OTF measuring apparatus according to claim 1, wherein the mounting plate is made of a plate whose surface is adjusted for flatness.   The OTF measuring apparatus according to claim 2, wherein each of the positioning openings is partially chamfered at a peripheral portion on the front side.   The OTF measuring apparatus according to claim 2 or 3, wherein the positioning plate is provided with a plurality of temporary placement portions for temporarily placing the subject corresponding to the positioning openings. .

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