JP2012093116A - Lens checking apparatus and chart plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a chart plate capable of finding the position of an optical axis outside the range of observation and accomplishing prompt optical axis alignment, and a lens checking apparatus using the same.SOLUTION: A chart plate 10 has a transparent glass disk 11 on which a centering chart 12 and cross charts 13 to 15 are drawn; the centering chart 12 comprises twenty straight lines 16 of a constant width formed of transparent parts and radially extended at equal angles from the center toward the circumference and twenty sectors 17 formed by vapor-depositing metal films, which have a light intercepting property, between the twenty straight lines 16; on the cross charts 13 to 15, cross lines 18 to 20 formed of transparent parts and three circles each divided into four equal parts at equal angles by the cross lines 18 to 20 are formed, metal films with a light intercepting property being vapor-deposited onto the four quarter circles; and the cross lines 18 to 20 are formed in widths that increase in the order of 18, 19 and 20.

Description

  The present invention relates to a lens inspection device for measuring optical performance of a lens and a chart plate on which an optical axis center searching pattern for optical axis alignment is drawn.

  Generally, when an optical lens is shipped as a product, lens performance such as resolution is inspected. The lens performance inspection is performed, for example, by mounting a lens to be inspected on a camera, photographing a chart on which a performance measurement pattern such as a cross chart or a resolution chart is drawn, and observing the chart on a monitor (actual shooting) Method) or a method for observing the image of the performance measurement pattern after irradiating the lens with the performance measurement pattern from the incident surface (object plane) side of the lens and transmitting the lens (orthographic projection method) A method of illuminating a performance measurement chart placed on the imaging surface of the lens to be inspected from the opposite side of the lens and projecting the performance measurement pattern onto the screen through the lens (back projection method), etc. It has been known.

  When performing an inspection by the orthographic projection method, for example, image light having a cross chart pattern is applied to a plurality of incident surfaces of the lens to be inspected, and the cross image formed by the lens is enlarged with a microscope. The image is picked up by the image pickup device and the performance is measured. Since the lens has a plurality of aberrations such as spherical aberration, the position at which the image is formed shifts depending on the incident position of light. Therefore, every time the incident position of light on the lens changes, the microscope to be observed must be moved so that the center of the optical axis of the microscope coincides with the center of the image formed. In addition, since the magnification is different between the center and the periphery of the lens, there is an error if a chart with the same size is used depending on the lens. Therefore, depending on the position to be measured (view angle), the chart has a different size each time. Must be replaced.

  In Patent Document 1 below, when a photographing lens is mounted and fixed to a lens barrel of a camera, the amount of deviation of the position of the cross image formed by photographing the cross chart and forming an image on the image sensor is stored in the storage means as correction information. A method is described in which the position of the photographic lens is corrected after being corrected by the correction means for correcting the position of the photographic lens based on the correction information stored in the storage means. In Patent Document 2 below, the center of the optical axis of two lenses incorporated in a lens barrel is detected using a cross chart, and a correction amount for matching the two optical axes from the eccentricity is disclosed. A lens alignment device is shown that calculates and determines the optical axis by moving one of the two lenses. Patent Document 3 below discloses a method for adjusting the position of the light receiving element with respect to the lens in the optical axis direction and the rotation direction using a cross chart when assembling the light receiving element and a lens that forms an image of incident light on the light receiving element. Are listed.

JP 2008-257033 A Japanese Patent Laid-Open No. 2007-065365 JP 2003-031822 A

  As shown in Patent Documents 1 to 3, the method of aligning two optical axes using a cross chart is based on the premise that the intersection of the crosses, that is, the center of the cross chart pattern is within the observation range. . In order to increase the measurement accuracy, if the cross chart pattern is enlarged with a microscope or the like and the center position of the pattern is observed, the center position (intersection of the cross) may not be visible outside the observation range if it is enlarged from the beginning. Therefore, after performing the center alignment operation with a lower observation magnification, the observation magnification must be increased and the center alignment operation must be performed again. To achieve highly accurate alignment, several times Alignment work may be required. As described above, the conventional cross chart has a problem that it takes time and effort.

  In view of the above problems, the present invention makes it possible to detect the position of the optical axis even when the center of the optical axis is not within the observation range, and even if the chart is observed at a high magnification from the beginning, the optical axis can be easily obtained. A chart having a dedicated pattern for centering that can be aligned is provided, and a lens inspection apparatus having the chart is proposed.

  The chart plate according to the present invention has a chart symbol imaged by the imaging unit, and moves the imaging unit within a plane orthogonal to the optical axis based on an imaging signal from the imaging unit to capture an imaging area of the imaging unit. A chart plate used when matching the center of the chart design with the center of the chart design, wherein the chart design has a plurality of straight lines formed with a constant width at the second density on the background of the first density. It is a radial pattern in which the angle formed by the straight lines extending from the center of the chart symbol toward the periphery and adjacent to each other is constant. Further, it is preferable to make one of the background and the plurality of straight lines transparent and the other opaque.

  A lens inspection apparatus according to the present invention includes a lens holding unit that holds a test lens, and a collimator that causes the chart plate to be positioned on a focal plane of a collimating lens and makes a light beam from the chart pattern a parallel light beam and enter the test lens. A collimator support means for supporting the collimator so that the collimator can move and swing in order to adjust the incident direction of the parallel light flux to the test lens, and an image of the chart symbol imaged by the test lens. An imaging unit for imaging the imaging unit, imaging unit support means for supporting the imaging unit in two directions orthogonal to each other within a plane orthogonal to the optical axis of the lens to be examined, and an imaging signal obtained from the imaging unit The image pickup unit support means adjusts the position of the image pickup unit based on the image to match the center of the image pickup area of the image pickup unit with the center of the chart symbol image. Characterized in that a settling unit.

  The lens inspection apparatus uses a resolving power chart plate arranged on a focal plane of the collimating lens instead of the chart plate after the adjustment means matches the center of the imaging area with the center of the chart symbol image. A light beam from the drawn evaluation symbol is converted into a parallel beam and incident on the lens to be examined, and an image of the evaluation symbol imaged by the lens to be examined is picked up by the image pickup unit, and the obtained image pickup signal is obtained. Based on this, the test lens is inspected.

  The adjustment means controls the collimator support means by calculating a luminance tendency in the horizontal direction of the chart symbol imaged by the imaging part, and the chart plate having the first density higher than the second density is used. If the chart plate having the second density higher than the first density is used, the luminous flux incident on the lens to be inspected is high in luminance. It is good to comprise from the control part moved to the direction.

  Alternatively, the adjustment unit is a calculation unit that obtains a luminance tendency in the horizontal direction and the vertical direction of the chart symbol imaged by the imaging unit, and the imaging unit support unit based on the respective calculation results in the horizontal direction and the vertical direction. And a control unit that moves the image pickup unit in the horizontal direction and the vertical direction. The control unit moves the imaging unit to a higher luminance when the chart plate having the first density higher than the second density is used, and the chart plate having the second density higher than the first density is used. When used, it is better to move to the lower luminance side.

  If the chart plate according to the present invention is used, the center position of the light transmitted through the lens can be observed at a high magnification, so that high-precision center alignment can be performed in one operation.

It is a figure which shows the chart board by this invention. It is a top view which shows the structure of the lens inspection apparatus by this invention. FIG. 3 is a central sectional view of FIG. 2. FIG. 3 is a schematic cross-sectional view showing a cross section of the first side collimator in FIG. 2 at the optical axis position. It is a horizontal sectional view showing the angle of the chart light incident on the test lens set in the lens holding part. It is a figure which shows the measurement location on the entrance plane of a to-be-tested lens. It is a block diagram which shows an electric structure. It is the figure which represented the movement of the position of the aerial image of the cross chart with respect to the visual field range of an expansion optical system on the basis of the cross chart. It is the figure which represented the movement of the position of the aerial image of the centering chart with respect to the visual field range of an expansion optical system on the basis of the centering chart. It is a schematic diagram for description which measures the brightness | luminance by scanning the partial range of the imaged centering chart vertically and horizontally. It is a flowchart which shows the procedure of centering using a chart board. It is a flowchart which shows another procedure. It is a schematic diagram for description which measures a brightness | luminance by scanning the partial range of the imaged centering chart horizontally. It is a figure which shows another chart board.

  As shown in FIG. 1, a chart plate 10 according to the present invention comprises a disk 11 made of transparent glass, a chart pattern for searching the optical axis center (hereinafter referred to as a centering chart) 12 and a resolution evaluation pattern (hereinafter referred to as a cross). (Referred to as a chart) 13 to 15 are drawn. The centering chart 12 is formed of a transparent portion and radially extends from the center to the periphery at an equal angle with 20 straight lines 16 having a constant width, and a metal such as chromium having a light shielding property between the 20 straight lines 16. It is composed of 20 sectors (first density background) 17 formed by depositing a film. The cross charts 13 to 15 are cross-shaped lines 18 to 20 formed of a transparent portion (the milky white having the second concentration) and a light-shielding metal film that is equally divided into four by the cross lines 18 to 20 at equal angles. Three circles having four quarter circles deposited are formed, and the cross lines 18 to 20 are formed in the order of 18, 19, and 20 with a wide line width.

  As shown in FIGS. 2 to 4, the lens inspection device 21 according to the present invention is fixed to a pedestal 41 provided on a surface plate 40, and the lens 22 to be tested for performance measurement inspection rotates around the optical axis 24. The lens holding unit 23 that is freely held, the light source unit 33 that projects light onto the chart plate 10 via the light diffusing plate 38, and the collimating lens 37, and the test lens 22 held by the lens holding unit 23 A center collimator 25 is provided for inspecting the performance of the lens 22 to be tested with respect to the on-axis beam by allowing a parallel beam to which any of the cross charts 13 to 15 is applied from above the optical axis 24. The center collimator 25 is fixed to the surface plate 40 by a fixed frame 42. The lens holding unit 23 is rotated around the optical axis 24 by 45 ° by a lens holding unit motor 95 (see FIG. 7).

  On the surface plate 40, first and second guides 48 and 49 are linearly arranged at positions that are line-symmetric with respect to the output optical axis 43 of the center collimator 25, and from the center collimator 25 side to the lens holding unit 23 side. Is extended to a position exceeding the lens holding portion 23 in the shape of a letter C so as to move away from the optical axis 24. The first and second guides 48 and 49 have a feed screw and a guide rail, and movably support the first and second slide stages 30 and 31, and the first and second slide stage motors 93 and 94 are used for the first. The second slide stages 30 and 31 are driven.

  First and second rotary stages 28 and 29 on which first and second side collimators 26 and 27 are placed are fixed to the first and second slide stages 30 and 31, respectively. 27 is supported rotatably about an axis perpendicular to the surface plate 40. The first and second side collimators 26 and 27 are rotated by first and second rotary stage motors 91 and 92 (see FIG. 7). The first and second side collimators 26 and 27 are caused to enter a parallel light beam to which one of the cross charts 13 to 15 is applied from outside the optical axes 44 and 45 to the test lens 22 held by the lens holding unit 23. The performance of the inspection lens 22 with respect to the off-axis light beam is inspected.

  In the first and second side collimators 26 and 27, one of the cross charts 13 to 15 is selected depending on the incident angle (see FIG. 5) of the light incident from the collimating lens 37 to the incident surface 60 of the lens 22 to be examined. . As the center collimator 25, for example, a cross chart 13 is used. Alternatively, a cross chart having a crosshair pattern slightly thinner than the cross chart 13 may be used. The chart plate 10 used for the center collimator 25 may use a pattern different from the cross charts 13 to 15 used for the first and second side collimators 26 and 27, and an appropriate one is used depending on the lens to be measured. You can do that.

  The light source unit 33 includes an LED 34, a heat sink 35, and a condenser lens 36, and irradiates the chart plate 10. Any one of the cross charts 13 to 15 is set on the optical path of the chart plate 10, and the chart light to which any one of the cross charts 13 to 15 is applied from the collimating lens 37 focused on the position of the chart plate 10. Parallel light is emitted toward the lens 22 to be examined.

  The lens inspection device 21 includes an imaging unit 32 that images the chart light transmitted through the lens 22 to be examined. The imaging unit 32 magnifies and observes the aerial image of the cross charts 13 to 15 formed by the lens 22 to be examined, and the camera unit 52 captures the cross charts 13 to 15 observed by the magnification optical system 51. Are mounted on a three-axis stage (imaging unit support means) 55 and fixed to the surface plate 40. The triaxial stage 55 includes a Y stage 56 that moves the imaging unit 32 in a vertical direction within a plane orthogonal to the optical axis 24, and an X stage 57 that moves the Y stage 56 in a horizontal direction within a plane orthogonal to the optical axis 24. And a Z stage 58 that moves the X stage 57 in a direction parallel to the optical axis 24.

  As shown in FIG. 5, the first and second side collimators 26, 27 are configured so that the outgoing optical axes 44, 45 are placed on the incident surface 60 of the test lens 22 by the first and second rotary stages 28, 29. The light is incident obliquely horizontally on the optical axis 24 from the left-right direction of the test lens 22 at an arbitrary position in the horizontal direction passing through 24. The chart light is alternately incident from the first and second side collimators 26 and 27 on the incident surface 60 of the test lens 22 rotated every 45 ° by the lens holding unit 23, and the test lens 22 shown in FIG. MTF measurement can be sequentially performed at eight positions 72 to 79 on the incident surface 60.

  The eight measurement positions 72 to 79 and the center position 71 (the position of the optical axis 24) where the chart light is incident from the center collimator are all input to the memory 83 (see FIG. 7). The rotation of the lens holding portion 23 is 180 ° with respect to the 360 ° measurement of the lens 22 to be measured, and the measurement accuracy is improved by reducing the rotational positioning number of the lens 22 having a large influence on the measurement accuracy. Can do.

  As shown in FIG. 7, the control device 80 includes a CPU (control unit) 82, a memory 83, a calculation unit 84, and a motor driver 85. The CPU 82 and the calculation unit 84 constitute the adjusting means described in the claims. The CPU 82 drives and controls eight motors 91 to 98 via eight drivers 85. As shown in FIG. 8, the center position of the aerial image of the cross line of the cross chart that has passed through the test lens 22, for example, the cross line 19 of the cross chart 14, is shifted with respect to the optical axis 53 of the magnifying optical system 51. In the case where the magnifying optical system 51 is present, the aerial image of the crosshair 19 is not captured in the range (the imaging area of the imaging unit 32) 63 observed by the magnifying optical system 51. In this case, the chart plate 10 rotates and the centering chart 12 is set on the optical axis of the collimator instead of the cross chart 14.

  As shown in FIG. 9, the portion of the range 62 in the aerial image of the centering chart 12 is imaged by the camera unit 52 by the magnifying optical system 51. This imaging information is transferred from the camera unit 52 to the calculation unit 84. As shown in FIG. 10, the light intensity for each pixel is stored in the memory for the detection area 64 and the detection area 65, the respective sums are obtained by the calculation unit, and the detection area 64 and the detection area 65 are compared. The luminance in the horizontal direction is obtained, and the luminance in the detection area 66 and the luminance in the detection area 67 are similarly compared to obtain the luminance in the vertical direction. The CPU 82 controls the X stage 57 based on the calculation result in the horizontal direction, and moves the imaging unit 32 by a predetermined amount toward the higher luminance. Further, the Y stage 56 is controlled based on the calculation result in the vertical direction, and the imaging unit 32 is moved by a predetermined amount to the higher luminance side.

  By repeating the imaging of the chart symbol by the imaging unit 32 to the movement of the X stage 57 and the Y stage 56 by the CPU 82, the center of the chart symbol can be matched with the center of the range 62 observed by the magnifying optical system 51. When the center of the chart symbol coincides with the center of the range 62, the calculation unit 84 notifies the CPU 82 of the calculation result with no luminance difference. When the CPU 82 receives the result of no luminance difference in both the horizontal direction and the vertical direction, Then, the chart plate 10 is rotated to change the centering chart 12 to any one of the cross charts 13 to 15.

  Alternatively, the change in luminance is measured while moving the detection area 64 and the detection area 66 in the directions of arrows 68 and 69 by the calculation unit 84, and the detection area 64 or 65 has a higher luminance than the detection area 64 or 65. If there is a difference in luminance in the horizontal direction, and if there is a luminance higher than the detection area 66 or 67 between the detection areas 66 and 67, it is transmitted to the CPU 82 as no luminance difference in the vertical direction. Anyway.

  The camera unit 52 transmits focus information from the imaging result to the CPU 82, and the CPU 82 drives the X stage motor 96, the Y stage motor 97, and the Z stage motor 98 via the driver 85 to set the focus position of the camera unit 52. Can be adjusted. In the focus adjustment, the position of the imaging unit 32 is adjusted by the Z stage 58. However, when the chart light is obliquely incident on the incident surface 60 of the lens 22 to be examined, if the position in the Z-axis direction changes, the X-axis The position of the image pickup unit 32 is adjusted by the X stage 57 and the Y stage 56 because the direction and the position in the Y-axis direction also change.

  The CPU 82 moves the Z stage 58 in the Z-axis direction so that the imaging unit 32 captures not only the image initially formed on the camera unit 52 but also several points whose focus positions have been changed. The MTF value at the focus position can be obtained. Even when there are no best focus positions in the picked up images, the best focus position and the MTF value at that time can be interpolated from the obtained data.

  Next, the function and effect of the present invention will be described through the MTF measurement procedure. For example, the cross chart 13 is set on the chart plate 10 of the center collimator 25, and the cross chart 14 is set on the chart plates 10 of the first and second side collimators 26 and 27. The test lens 22 is set on the lens holding portion 23, and the chart light (emitted optical axis 43) to which the pattern of the cross chart 13 is applied from the center collimator 25 is the center of the entrance surface 60 of the test lens 22 (71 in FIG. 6). The position is incident on. The cross chart 13 that has passed through the center of the lens 22 to be examined is observed by the magnifying optical system 51, and the design is imaged by the camera unit 52.

  When a cross image is detected and confirmed in the image captured by the camera unit 52, the image information of the captured cross chart 13 is transmitted to the CPU 82, and the MTF at the center 71 of the lens 22 to be measured is measured. . Here, since the light incident on the test lens 22 is parallel light, the light of the center collimator 25 forms an image on a plane orthogonal to the optical axis 24, and the optical axis 53 of the magnifying optical system 51 is the test lens. 22 are used in parallel with the optical axis 24. Further, since the light (44, 45) emitted from the first and second side collimators 26, 27 is imaged on a plane orthogonal to the optical axis 24, the optical axis 53 of the magnifying optical system 51 is the lens 22 to be examined. This is used in a state parallel to the optical axis 24, thereby enabling stable measurement at all times.

  The CPU 82 drives the first and second rotary stages 28 and 29 and the first and second slide stages 30 and 31 based on the data stored in the memory 83, and from the first and second side collimators 26 and 27. The first and second side collimators 26 and 27 are set so that the outgoing optical axes 44 and 45 of the emitted chart light enter a predetermined position (positions indicated by 72 and 73) of the lens 22 to be examined.

  First, the test lens 22 from a position (see FIG. 5) in which the chart light (emitted optical axis 44) to which the pattern of the cross chart 14 is applied from the first side collimator 26 is inclined by 45 ° in the horizontal direction with respect to the optical axis 43 is obtained. The light is emitted toward the pupil position and irradiated on the position indicated by 72 in FIG. A part of the aerial image of the cross chart 14 that has passed through the test lens 22 is observed by the magnifying optical system 51, and the design is imaged by the camera unit 52. When a cross image is detected and confirmed in the image captured by the camera unit 52, the image information of the captured cross chart 14 is transmitted to the CPU 82, and the MTF at the position 72 of the lens 22 to be measured is measured. The

  Next, the chart light (emitted optical axis 45) provided with the cross chart 14 pattern from the second side collimator 27 is inclined by 45 ° in the horizontal direction from the side opposite to the first side collimator 26 with respect to the optical axis 43. The light is emitted toward the pupil position of the lens 22 to be examined at the position (see FIG. 5), and is irradiated onto the position indicated by 73 in FIG. A part of the aerial image of the cross chart 14 that has passed through the test lens 22 is observed by the magnifying optical system 51, and the design is imaged by the camera unit 52. When a cross image is detected and confirmed in the image captured by the camera unit 52, the image information of the captured cross chart 14 is transmitted to the CPU 82, and the MTF at the position 73 of the lens 22 to be measured is measured. The

  When the measurement of the positions 72 and 73 shown in FIG. 6 is completed, the CPU 82 drives the lens holding unit motor 95 via the driver 85, and the lens holding unit 23 is moved based on the data stored in the memory 83. Rotate 45 °. The test lens 22 moves from the positions 74 and 75 shown in FIG. 6 to the positions 72 and 73, and the chart light of the cross chart 14 moves from the first and second side collimators 26 and 27 to the positions 74 and 75. And MTF at each position is measured. The lens holding unit 23 repeats the rotation of 45 °, and the MTFs at positions 72 to 79 on the incident surface 60 are measured. As the lens holding portion 23 is rotated about the optical axis 24, the axial symmetry of the lens 22 to be tested can also be inspected. Axisymmetric testing is particularly useful in the case of plastic lenses.

  A method for centering a chart image according to the present invention will be described with reference to a flowchart shown in FIG. 11 when a cross image cannot be detected in an aerial image captured by the camera unit 52. As shown in FIG. 8, the crosshair 19 is not detected from the range 62 observed by the magnifying optical system 51. Based on this information, the CPU 82 rotates the chart plate 10 to set the centering chart 12 on the optical axis of the collimator, and the range 62 observed by the magnifying optical system 51 shown in FIG. .

  As shown in FIG. 10, the luminance of the detection area 64 and the luminance of the detection area 65 are measured and calculated from the imaged range 62 image to obtain the luminance difference between the left and right. If there is a difference between the left and right luminances, the imaging unit 32 is moved by a predetermined amount toward the higher luminance by the X stage 57, an aerial image is captured again by the imaging unit 32, and the luminance measurement by the arithmetic unit 84 is performed. Made. When there is no difference between the luminances of the detection areas 64 and 65, the luminance of the detection area 66 and the luminance of the detection area 67 are measured and calculated to obtain the difference between the upper and lower luminances. If there is a difference between the upper and lower luminances, the imaging unit 32 is moved by a predetermined amount to the higher luminance by the Y stage 56, an aerial image is captured again by the imaging unit 32, and the luminance measurement by the arithmetic unit 84 is performed. Made.

  The aerial image capturing, the luminance measurement of the captured image, and the movement of the imaging unit 32 by the X stage 57 and the Y stage 56 are repeated, and the observation range of the magnifying optical system 51 is the position of the range 61 shown in FIG. Thus, the center of the magnifying optical system 51 coincides with the center of the centering chart 12. When it is confirmed that there is no luminance difference between the left and right sides, the chart plate 10 is rotated and changed from the centering chart 12 to, for example, the cross chart 14, and an aerial image of the cross chart 14 is captured by the imaging unit 32. Is imaged. Since the captured image is an image in the range 61 shown in FIG. 8, the MTF can be measured because the cross line 19 of the cross chart 14 is captured.

  If only the position in the horizontal direction is shifted, the positions of the first and second side collimators 26 and 27 are adjusted to adjust the first and second side collimators 26 to the center of the range observed by the magnifying optical system 51. , 27 may be made to coincide with each other. As shown in FIG. 12, for example, the chart light of the cross chart 14 is incident on the test lens 22 from the first side collimator 26, and an aerial image of the cross chart 14 by the test lens 22 is observed by the magnifying optical system 51. When there is no cross line crossing point in the observed range 63, the chart plate 10 rotates and the centering chart 12 is set. An aerial image of the centering chart 12 is observed by the magnifying optical system 51, and for example, an image in the range 63 is captured by the imaging unit 32.

  As illustrated in FIG. 13, the luminance of the detection area 64 and the detection area 65 is measured and calculated from the image in the range 63 by the calculation unit 84, and the luminance difference between the left and right is obtained. When there is a difference in luminance between the left and right, the position of the first side collimator 26 is moved by a predetermined amount by the first rotary stage 28, and the position of the optical axis 44 that is incident on the incident surface 60 of the lens 22 to be measured is lower. Moved by a predetermined amount. Thereafter, the aerial image is picked up again by the image pickup unit 32, the luminance is measured by the calculation unit 84, and the process is repeated until there is no difference between the luminance of the detection area 64 and the luminance of 65. When it is confirmed that there is no luminance difference, the centering chart 12 of the chart plate 10 is changed to the cross chart 14, and an aerial image of the cross chart 14 is captured by the imaging unit 32, and the MTF is measured.

  Further, a chart plate 100 shown in FIG. 14 may be used instead of the chart plate 10 described above. The chart plate 100 is formed by depositing a light-shielding metal film on the straight line 16 of the centering chart 12 and the cross lines 18 to 20 of the cross charts 13 to 15. Although the number of straight lines 16 of the centering chart 12 is 20 for the sake of explanation, it is preferable to have 40 or more.

  Although it seems to be cramped, it is important that the straight line 16 of the centering chart 12 has a certain width, and as shown in the well-known Siemens star chart, it consists of a plurality of fan-shaped patterns that radiate from the center toward the periphery. Must not be black and white striped. In the Siemens Star chart, when an arbitrary part is enlarged, there is no change in luminance in both the vertical and horizontal directions, and the central direction cannot be found. When the chart plate 100 is used, when there is a luminance difference between the detection areas 64 and 65 and when there is a luminance difference between the detection areas 66 and 67, the imaging unit 32 is moved to a lower luminance. Alternatively, when there is a luminance difference between the detection areas 64 and 65, the emission optical axis 44 or 45 of the side collimator is moved toward the higher luminance.

  The chart plate may be composed of a milky white and translucent disk made of black paint having a light shielding property. In this case, since the light is diffused when it is transmitted, the light diffusing plate arranged in front of the chart plate can be omitted. Further, the light transmittances of the light shielding part and the light transmitting part in the chart plate do not necessarily have to be 0% and 100%, as long as there is a clear difference between them. For example, the chart board which formed the said chart design using a liquid crystal device, EL (electroluminescence), etc. may be sufficient.

  The lens inspection device 21 may include two chart plates, and the centering chart 12 and the cross charts 13 to 15 may be formed on different chart plates. Or you may make it install the chart board in which the cross charts other than the cross charts 13-15 other than the chart board 10 were formed.

  In the embodiment, the light emitted from the light source unit is transmitted through the chart plate and emitted from the collimating lens. However, the light emitted from the light source unit is reflected by the chart plate and the reflected light is emitted from the collimating lens. You may comprise so that it may do. In this case, it is preferable that the pattern of the chart plate is formed by a black and white pattern.

  The incident angle of the chart light and the incident point (measurement point) of the incident surface 60 of the test lens 22 in the embodiment may be determined according to the properties of the lens to be measured. 23 may be rotated 360.degree., So it may be selected in consideration of the property of the lens to be measured. In the above-described embodiment, the optical axis of the lens to be examined is a horizontally placed type inspection apparatus, but the entire apparatus such as a center collimator and an imaging unit is vertically arranged, and the optical axis of the lens to be examined is vertical. You may make it the structure arrange | positioned so that it may become a direction.

  The chart plate and centering chart according to the present invention may be used in other lens inspection apparatuses such as CTF inspection and projection resolution inspection. The optical axis alignment of a plurality of lenses, members such as a lens barrel and an image sensor, and a lens It may be used to align the center of the optical axis.

10,100 chart board 11 disk 12 centering chart (chart pattern of claim)
13 to 15 cross chart (resolving power evaluation design described in claims)
16 straight lines (multiple straight lines of constant width formed radially from the center at the second concentration)
17 Fan (Background of the first concentration)
18 to 20 Crosshair 21 Lens inspection device 22 Test lens 23 Lens holder 24 Optical axis (optical axis of the test lens)
25 Center collimator 26 1st side collimator 27 2nd side collimator 28 1st rotation stage (collimator support means)
29 Second rotation stage (collimator support means)
30 First slide stage (collimator support means)
31 Second slide stage (collimator support means)
32 Imaging unit 33 Light source unit 34 LED
35 Heat sink 36 Condensing lens 37 Collimating lens 38 Light diffusion plate 40 Surface plate 41 Base 42 Fixed frame 43 Outgoing optical axis of center collimator 44 Outgoing optical axis of first side collimator 45 Outgoing optical axis of second side collimator 48 First guide 49 Second Guide 51 Magnifying Optical System 52 Camera Unit 53 Optical Axis of Magnifying Optical System 55 Triaxial Stage (Imaging Unit Supporting Means)
56 Y stage (imaging part support means)
57 X stage (Imaging unit support means)
58 Z stage (Imaging unit support means)
60 Incident surface (of the test lens) 61 to 63 range (observation range of the magnifying optical system 51)
64 to 67 Detection area 68, 69 Arrow 71 to 79 MTF measurement position on the incident surface 60 80 Controller 82 CPU (control unit) (Adjustment means)
83 Memory 84 Calculation unit (Adjustment means)
85 Driver (for motor) 91 Motor for first rotation stage 92 Motor for second rotation stage 93 Motor for first slide stage 94 Motor for second slide stage 95 Motor for lens holding portion 96 Motor for X stage 97 For Y stage Motor 98 Z stage motor

Claims (6)

A chart symbol to be imaged by the imaging unit is drawn, and based on an imaging signal from the imaging unit, the imaging unit is moved in a plane orthogonal to the optical axis, and the center of the imaging area of the imaging unit and the chart symbol A chart plate used to match the center,
The chart symbol is formed by extending a plurality of straight lines formed at a constant width at a second density on the background of the first density from the center to the periphery of the chart symbol, and the straight lines adjacent to each other are formed. A chart plate having a radial pattern with a constant angle.   2. The chart board according to claim 1, wherein one of the background and the plurality of straight lines is transparent and the other is opaque. Lens holding means for holding the test lens;
A collimator, wherein the chart plate according to claim 1 or 2 is positioned on a focal plane of a collimator lens, and a light beam from the chart design is converted into a parallel light beam and incident on the lens to be examined;
Collimator support means for movably and swingably supporting the collimator in order to adjust the incident direction of the parallel light flux to the test lens;
An imaging unit that captures a part of the image of the chart symbol formed by the test lens;
Imaging unit support means for supporting the imaging unit so as to be movable in two directions orthogonal to each other within a plane orthogonal to the optical axis of the test lens;
An adjustment unit that adjusts the position of the imaging unit by the imaging unit support unit based on the imaging signal obtained from the imaging unit and matches the center of the imaging area of the imaging unit with the center of the image of the chart symbol. A lens inspection apparatus comprising:   After adjusting the center of the imaging area and the center of the image of the chart symbol by the adjusting means, the light beam from the resolution evaluation symbol arranged on the focal plane of the collimating lens instead of the chart symbol is converted into a parallel beam. The image of the resolution evaluation pattern that is incident on the test lens and imaged by the test lens is captured by the imaging unit, and the test lens is inspected based on the obtained imaging signal. The lens inspection device according to claim 3.   The adjustment means controls the collimator support means by calculating a luminance tendency in the horizontal direction of the chart symbol imaged by the imaging part, and the chart plate having the first density higher than the second density is used. If the chart plate having the second density higher than the first density is used, the luminous flux incident on the lens to be inspected is high in luminance. The lens inspection device according to claim 3, further comprising a control unit that moves the lens toward the side. The adjusting means includes
A calculation unit for obtaining a luminance tendency in a horizontal direction and a vertical direction of the chart symbol imaged by the imaging unit;
The image pickup unit support means is controlled based on the horizontal calculation result, and the image pickup unit is horizontally set to a higher luminance when a chart plate having the first density higher than the second density is used. When the chart plate having the second density higher than the first density is used, the chart plate is moved horizontally to the lower luminance side, and the imaging unit support means is controlled based on the calculation result in the vertical direction, When the chart plate having a higher density when the first density is higher than the second density is used, the brightness is higher when the chart board having the second density higher than the first density is used. A control unit that moves to the lower of the
The lens inspection device according to claim 3, wherein the lens inspection device comprises:

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