JP2007218647A - Inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device capable of detecting not only an on-axis image but also an off-axis image with high precision, and measuring the optical characteristics of an optical member (a lens to be inspected). <P>SOLUTION: The inspection device 1, comprises a light source 2, a chart plate 3 having a chart for on-axis 3a and a chart for off-axis 3b, a test lens 4, a light-sensitive sensor for on-axis 13, and a light-sensitive sensor for off-axis 14, is constituted by providing a small stage driving section 12 which moves the light-sensitive sensor 14 within a flat surface intersecting perpendicular to a machine shaft 7, shakes this light-sensitive sensor 14 with respect to this flat surface, and makes the light-receiving surface of this light-sensitive sensor 14 approximately perpendicular to a principal beam of light emitted from the chart 3b, and a control device 16 for controlling this driving section 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inspection apparatus that measures OTF, PTF, and MTF of an optical member.

  An MTF measurement device in mass production inspection simultaneously captures an on-axis image and a plurality of off-axis images (peripheral images), and these images are used to make a determination in a short time. An enlargement projection type is used in which a chart plate having a plurality of slits or pinholes is placed at the corresponding position, and an image of these slits or pinholes is magnified by a test lens and received by a line sensor or area sensor. (For example, refer to Patent Document 1).

  When the test lens is a photographic lens, the magnification β when evaluating the MTF is generally from −1/50 to −1/30. The focal length f of the lens to be measured varies from about 10 mm to over 300 mm, so that the photographing distance l is approximately | β | · f. Therefore, when measuring a test lens having a short focal length, the angle of light incident on the off-axis image height line sensor or area sensor is greatly inclined with respect to the mechanical axis.

JP-A-56-2518

  Such a line sensor or area sensor is arranged in a case in which nitrogen gas is sealed in a space covered with a cover glass. When the angle of light incident on this sensor is greatly inclined, the sensor reflects the cover glass. There is a problem that the measurement accuracy decreases.

  The present invention has been made in view of such problems, and can inspect not only an on-axis image but also an off-axis image with high accuracy to measure an optical characteristic of an optical member (a lens to be tested). The purpose is to provide.

  In order to solve the above-described problems, an inspection apparatus according to the present invention includes a light source, a chart plate on which a chart is formed, a lens to be tested, and an imaging element arranged side by side on a mechanical axis, and passes through the chart. The projected light is projected onto the image sensor with the test lens to form a chart image, and the optical characteristics of the test lens are inspected using the chart image detected with the image sensor. The chart is arranged so as to include the mechanical axis, the luminous flux emitted from the light source passes, and the on-axis chart (for example, implementation) forms an on-axis image on the optical axis of the test lens by the test lens. The on-axis inspection chart 3a) in the form is arranged so as not to include the mechanical axis, the light beam emitted from the light source passes, and an off-axis image is formed outside the optical axis of the test lens by the test lens. Off-axis chart (eg, An off-axis inspection chart 3b) in the embodiment, and the image sensor detects an on-axis image (for example, the on-axis light receiving sensor 13 in the embodiment) and an off-axis image. Off-axis imaging device (for example, off-axis light receiving sensor 14 in the embodiment). The inspection apparatus includes a first moving mechanism (for example, the small stage drive unit 12 in the embodiment) that moves the off-axis imaging element in a plane orthogonal to the mechanical axis, and the off-axis imaging element with respect to the plane. A swing mechanism (for example, the small stage drive unit 12 in the embodiment) that makes the light receiving surface of the off-axis imaging device substantially perpendicular to the principal ray emitted from the off-axis chart, and a first moving mechanism And a control device for controlling the swing mechanism.

  Such an inspection apparatus according to the present invention has a second moving mechanism (for example, the large stage driving unit 10 in the embodiment) that moves the image sensor in a plane, and the control device detects a detection signal from the image sensor. Is preferably configured to detect the position of the optical axis of the lens to be tested by controlling the second moving mechanism to move the image sensor.

  Moreover, it is preferable that the inspection apparatus according to the present invention is configured to simultaneously detect an on-axis image and an off-axis image.

  Furthermore, in the inspection apparatus according to the present invention, the imaging elements extend so as to be orthogonal to each other, and a first line sensor for detecting a meridional image of the chart image (for example, the vertical line sensors 13a and 14a in the embodiment). And a second line sensor (for example, the horizontal line sensors 13b and 14b in the embodiment) for detecting a sagittal image, or an area sensor.

  The inspection apparatus according to the present invention preferably measures at least one of OTF, PTF, and MTF as the optical characteristic of the lens to be examined.

  When the inspection apparatus according to the present invention is configured as described above, not only an on-axis image but also an off-axis image can be detected with high accuracy, and the optical characteristics (OTF, PTF, MTF) of the lens to be measured can be measured. .

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The inspection apparatus according to the present invention is an OTF, PTF, MTF inspection apparatus that can measure a plurality of angles of view simultaneously with an enlarged projection type, and eliminates a shift structure between the chart and the lens to be detected, and the light receiving sensor is perpendicular to the mechanical axis. It is characterized by a structure that shifts in the plane (moves in this vertical plane) and tilts relative to this plane (swings relative to the vertical plane). First, the configuration of the inspection apparatus 1 according to the present embodiment will be described with reference to FIGS. The inspection apparatus 1 includes a light source 2 and a chart plate 3 inside, and includes an illumination unit 5 that holds a lens 4 to be tested, and a measurement unit 6 that can move relative to the illumination unit 5. Is done.

  The light source 2, the chart plate 3, and the test lens 4 are arranged side by side on the optical axis (hereinafter referred to as “mechanical axis 7” of the measuring device 1). Then, the measuring unit 6 has a flat plate shape in a plane perpendicular to the mechanical axis 7 on the light receiving side (opposite side of the light source 2 with the lens 4 to be tested) (hereinafter, this plane is referred to as “measurement plane”). The receiving part 8 is provided. On the surface of the receiving portion 8 on the light source 2 side, a large biaxial plate (hereinafter referred to as “large stage 9”) that can move relative to the receiving portion 8 in the measurement plane, and the large stage 9 Is provided with a large stage drive unit 10 for driving in the measurement plane, and further, a three-axis small drive stage (hereinafter referred to as “small stage 11”) that can be relatively moved and swung in the measurement plane of the large stage 9. ) And a small stage driving unit 12 for driving the small stage 9. A plurality of small stages 11 are provided on the large stage 9 (for example, FIG. 2 shows a case where four small stages 11 are provided in the diagonal direction of the rectangular large stage 9). In this case, as shown in FIGS. 2 and 3, the small stage 11 is configured to be movable relative to the large stage 9 in a diagonal direction, and swings in a plane that passes through the diagonal line and is orthogonal to the large stage 9. It is configured to be movable. The light beam emitted from the light source 2 is radiated onto the mechanical shaft 7 by the optical fiber 2a and a condenser lens (not shown), and is irradiated onto the chart plate 3.

  As shown in FIG. 2, a vertical line sensor 13a extending in the vertical direction with respect to the installation surface (ground) extends in the horizontal direction in a substantially central portion on the large stage 9 (on or near the mechanical shaft 7). An on-axis light receiving sensor 13 comprising a horizontal line sensor 13b is provided. The on-axis light receiving sensor 13 can also be configured by a single area sensor. Each small stage 11 has a vertical line sensor 14a extending in a diagonal direction of the large stage 9 (radially extending from the on-axis light receiving sensor 13) and a direction perpendicular to the diagonal line in the measurement plane. An off-axis light receiving sensor 14 including an extended horizontal line sensor 14b is provided. The off-axis light receiving sensor 14 can also be constituted by one area sensor. The vertical line sensors 13a and 14a and the horizontal line sensors 13b and 14b constituting the on-axis and off-axis light receiving sensors 13 and 14 are an M (meridional) image and an S (sagittal) image of the chart image. Used to detect.

  Further, on the chart plate 3, as shown in FIG. 6, the on-axis inspection chart 3a disposed so as to include the mechanical shaft 7 and the shaft disposed at a position apart from the mechanical shaft 7 without including the mechanical shaft 7. The outer inspection chart 3b is formed, and the light beam that has passed through these charts 3a and 3b is imaged on the on-axis and off-axis light receiving sensors 13 and 14 by the test lens 4. The on-axis inspection and off-axis inspection charts 3a and 3b are configured by slits or point image charts. Further, when the light receiving surface of the off-axis light receiving sensor 14 is orthogonal to the mechanical axis 7, the light receiving surfaces of all the sensors 13, 14 are arranged in the same plane (in the measurement plane).

  Here, the structure of the line sensor used for the on-axis and off-axis light receiving sensors 13, 14 will be described with reference to FIG. This line sensor LS covers the case 22 having a space 22 with an open top, the sensor element 22 attached to the bottom surface of the case member 21 in the space 22, and the opening of the case 21 so as to seal the space 22. And a cover glass 23. Nitrogen gas or the like is sealed in the space 22 sealed with the cover glass 23.

  FIG. 5A shows an ideal imaging state in the inspection apparatus 1, and an image of the on-axis inspection chart (center slit) 3 a formed on the chart plate 3 (this is referred to as an “axial image”). Is formed on the on-axis light receiving sensor 13, and an image of the off-axis inspection chart 3b (referred to as an "off-axis image") is formed on the corresponding off-axis light receiving sensor 14. However, when the test lens 4 is a lens with a large distortion, as shown in FIG. 5B, even if the on-axis image can be captured by the on-axis light receiving sensor 13 on the axis, Then, the off-axis image may deviate from the off-axis light receiving sensor 14. In such a case, the off-axis image can be captured by moving the off-axis light receiving sensor 14 in the radial direction.

  On the other hand, if the test lens 4 has a transmission eccentricity, the chart image is deviated from the on-axis and off-axis light receiving sensors 13 and 14 as shown in FIG. Therefore, the large stage drive unit 10 operates the large stage 9 in the measurement plane, and the axial image (center slit position) is scanned by the axial light receiving sensor 13 (in this case, as shown in FIG. 6B). The on-axis light receiving sensor 13 and the off-axis light receiving sensor 14 are simultaneously aligned in the same amount and direction). As in the case of FIG. 5, the off-axis light receiving sensor 14 (actually the small stage 11) is operated in the radial direction by the small stage drive unit 12 to scan the off-axis image and align it with the off-axis light flux. State (state shown in FIG. 6C). In this way, by aligning the on-axis and off-axis light receiving sensors 13 and 14 in two stages, the objects that can be measured at high speed are expanded. Further, in FIG. 6B, if the coordinate system of the on-axis light receiving sensor 13 has a global coordinate system and the off-axis light receiving sensor 14 has a local coordinate system, It is not always necessary to move the off-axis light receiving sensor 14 at the same time. FIG. 6 shows a case where two off-axis light receiving sensors 14 are provided to simplify the description.

  By the way, as shown in FIG. 7, the light beam emitted from the off-axis inspection chart 3b of the chart plate 3 is a sensor element 20 of the off-axis light receiving sensor 14 (only the horizontal line sensor 14b is shown in FIG. 7). Incidently with respect to the light receiving surface. Then, since a part of the light beam reflected by the cover glass 23 is also incident on the sensor element 20, a component reflected by multiple reflections is placed on the skirt portion of the line image intensity distribution detected by the sensor element 20. The accuracy will be lowered. Therefore, in the inspection apparatus 1 according to the present embodiment, the small stage 11 is shaken by the small stage driving unit 12 so that the light receiving surface of the sensor element 20 is substantially perpendicular to the principal ray emitted from the off-axis inspection chart 3b. It is configured to move. Note that the off-axis light receiving sensor 14 swings with respect to the small stage 11 (in the measurement plane, orthogonal to the diagonal of the large stage 9 connecting the position where the small stage 11 is disposed and the center of the large stage 9. The axis extending in the direction in which the sensor element 20 is disposed is located near the center of the light receiving surface of the sensor element 20 when viewed from the light source 2 side so that the light receiving surface of the sensor element 20 is substantially perpendicular to the principal ray. Preferably it is.

  The small stage 11 is swung in this manner so that the light receiving surface of the off-axis light receiving sensor 14 is substantially perpendicular to the principal ray emitted from the off-axis inspection chart 3b. In addition, the luminous flux emitted from the aperture of the sensor element 20 is reduced and the chief ray is incident on the light receiving surface of the sensor element 20 substantially perpendicularly, so that the chart image can be detected efficiently.

  In such an inspection apparatus 1, the imaging position of the off-axis light beam is sensed by the off-axis light receiving sensor 14, and the asymmetry in all directions can be determined by changing the deviation from the ideal image height and the actual angle of view. Further, when the M image and S image line sensors (vertical line sensors 13a and 14a and horizontal line sensors 13b and 14b) are used as in this embodiment, the actual image height can be determined from the M image sensor. In this embodiment, as shown in FIG. 2, by providing a small stage 11 that can be operated radially, the angle of view due to manufacturing errors, such as a lens having a large eccentricity such as a photographic lens or a lens having a large distortion, can be obtained. It is also possible to measure lenses with large changes. In this embodiment, the vertical line sensor 14a and the horizontal line sensor 14b for detecting the M image and the S image of the off-axis light receiving sensor 14 are arranged on the small stage 11 so as to move integrally. The sensor 14a and the horizontal line sensor 14b may be arranged on independent plates, and may be configured to operate independently.

  The receiving portion 8 is provided with a measurement driving portion 15 for moving the measuring portion 6 along the mechanical axis 7 (moving in the left-right direction in FIG. 1). The large stage driving unit 10, the small stage driving unit 12, the measurement driving unit 15, the on-axis light receiving sensor 13, and the off-axis light receiving sensor 14 are electrically connected to the control device 16, and the large stage driving unit 10, the small stage drive unit 12 and the measurement drive unit 15 are controlled to control the operation of the measurement unit 6 and the large and small stages 9 and 11, and from the on-axis and off-axis light receiving sensors 13 and 14. The detection signal is processed.

  When the test lens 4 is set on the illumination unit 5 as described above, the center of the large stage 9 (the point where the large stage 9 and the mechanical shaft 7 intersect with each other by the transmission eccentricity, and the on-axis light receiving sensor 13 is It is formed at a location deviated from the arranged part). The large stage 9 is operated to scan in the vertical and horizontal directions within the light receiving surface, and the control device 16 receives detection signals from the vertical line sensor 13a and the horizontal line sensor 13b (or area sensor) of the on-axis light receiving sensor 13. Processing is performed to detect the image position of the on-axis image of the chart plate 3. As an image position detection method, for example, the center of gravity of a point image or a line image or the coordinates of the pixel with the highest output is detected as the image position. When the transmission eccentricity error of the test lens 4 is large, the chart image may deviate from the pair of line sensors 13a and 13b (on-axis light receiving sensor 13). Therefore, the procedure for searching for the large stage 9 needs to be set in the control device 16 in advance. For example, the search time can be saved by configuring the large stage 9 so as to search efficiently by operating a rectangular area with a spiral shape from the outside to the inside. After the search, the control device 16 moves the large stage 9 so that the on-axis inspection chart image is positioned at the center of each of the vertical and horizontal line sensors 13a and 13b (or the center of the area sensor), and the position is set as the origin. Store and end centering.

  The control device 16 also operates the small stage 11 in the diagonal direction of the large stage 9, and the off-axis image is converted from the detected value of the off-axis light receiving sensor 14 in the same manner as the on-axis light receiving sensor 13. The small stage 11 is operated so as to be positioned at the center of the external light receiving sensor 14. Finally, the control device 16 swings the small stage 11 so that the light receiving surfaces of the vertical and horizontal line sensors 14a and 14b are perpendicular to the principal ray emitted from the off-axis inspection chart 3b. . Here, the control device 16 determines the swing angle A of the small stage 11, that is, the angle A formed by the principal ray emitted from the off-axis inspection chart 3b and the mechanical shaft 7 as shown in FIG. It can be calculated from the distance D on the mechanical axis 7 from the diaphragm 4 a of the lens 4 to the measurement plane Y and the image height H of the off-axis image detected by the off-axis light receiving sensor 14. As shown in FIG. 2, the small stage 11 is not only configured to operate in the diagonal direction (slant 45 °) of the rectangular large stage 9, but also configured to operate with two axes in the vertical direction and the horizontal direction. It is also possible to do.

  In the measurement, using the lens data of the ideal magnification β times of the lens 4 to be tested, the ray distance is traced from the film surface to the object surface, and the photographing distance and the actual object height are obtained. The control device 16 controls the distance between the chart plate 3 (slit chart or point image chart) of the inspection device 1 and the on-axis and off-axis light receiving sensors 13 and 14 by controlling the measurement drive unit 15 to make the measurement unit 6 a mechanical axis. 7 to match the calculated shooting distance. Then, as described above, the deviation of the optical axis due to the transmission eccentricity error of the lens 4 to be tested is centered. Next, the test lens 4 is focused. A signal is sent from the inspection device 1 side (control device 16) to the lens 4 to be tested, and a motor (not shown) in the lens 4 is driven to move the focusing lens to a position where the output of the center image is high. The centering of the inspection apparatus 1 may be performed once again after the focusing is completed. Further, as described above, the small stage 11 is moved in the radial direction in order to search and align the peripheral image, and then the current position of the measurement unit 6 (the position of the measurement plane and the image height of the off-axis image). ) To determine the swing angle A and swing the small stage 11.

  In the inspection of the lens 4 to be inspected by the inspection apparatus 1, as shown in FIG. 10, the inspection chart 3 is slightly moved back and forth with respect to the optical axis (mechanical axis 7) by the control device 16 (for example, about ± 0.5 mm). ) Defocus, measure the best image plane and its front and back areas with on-axis and off-axis sensors 13 and 14, and calculate OTF, PTF, and MTF from these measured values. Therefore, in the swing control of the small stage 11 described above, the control is performed so that the angle formed between the principal ray emitted from the off-axis inspection chart 3b and the perpendicular of the light receiving surface of the off-axis light receiving sensor 14 is within ± 30 °. It is preferred that In this inspection apparatus 1, since the on-axis image and the off-axis image can be detected simultaneously, the optical characteristics (OTF, PTF, MTF) of the lens 4 to be examined can be inspected in a short time.

  A conceptual diagram of a chart image captured by the light receiving sensors 13 and 14 is shown in FIG. In FIG. 11, the off-axis image M image and the S-image LSF captured by the off-axis light receiving sensor 14 are shown. In general, a photographic lens has a large netting, and the M image has an S image due to coma aberration. It is wider than the statue. If this is captured by one sensor at the same S / N, the accumulation time is determined in accordance with the S image, and the resolution of the M image is reduced. Therefore, in order to detect the LSF with the same accuracy for the M image and the S image, as shown in this embodiment, it is desirable that the M image and the S image are composed of individual sensors including the vertical and horizontal line sensors 14a and 14b. When capturing a chart image (line image or point image), it is necessary to decide how far the length of the line image or the spread of the point image is to be detected. Thereby, the detection accuracy of the flare component of the test lens 4 is determined. This also determines the frequency increment in the computation after detecting the LSF.

  By the way, in this inspection apparatus 1, since the measurement is performed by swinging the small stage 11, that is, the off-axis light receiving sensor 14, the detection value of the vertical line sensor 14a is a plane perpendicular to the mechanical shaft 7 (described above). It is necessary to project onto the measurement plane (surface Y in FIG. 9). In order to project the line image or point image captured by the vertical line sensor 14a onto the measurement plane, the sensor pitch having a dimension of length, the sensor opening, the line image or point image capture length is set to cosA (unit of angle A). Must be multiplied by “°”. FIG. 12A shows the chart image and length L at the time of capture, and FIG. 12B shows the chart image after projection and the length L ′ (= L × cos A). The inspection apparatus 1 is configured to calculate OTF, PTF, and MTF using such a chart image after projection.

  By configuring the inspection apparatus 1 according to the present embodiment as described above, an on-axis image and an off-axis image of the chart plate 3 can be detected at the same time. It can be measured and used for mass production inspection. In addition, a product such as a photographic lens having a relatively large transmission eccentricity can be evaluated based on the optical performance of the image height defined with the mechanical axis 7 as a reference. Furthermore, by making the off-axis light receiving sensor 14 operable independently of the on-axis light receiving sensor 13, the inspection apparatus 1 can be highly versatile. In particular, in this inspection apparatus 1, the light receiving surface of the off-axis light receiving sensor 14 is substantially perpendicular to the principal ray emitted from the off-axis inspection chart 3b by swinging the small stage 11 with respect to the measurement plane. Therefore, the measurement accuracy can be improved by suppressing the light rays reflected by the cover glass constituting the sensor 14 and entering the sensor element.

  In addition, the conventional enlarged projection type inspection apparatus has a disadvantage that it is weak against disturbance because disturbances such as vibrations to the chart and the lens to be examined are enlarged and projected. However, the inspection apparatus according to this embodiment 1, the shift mechanism of the device 1 between the chart plate 3 and the lens 4 to be examined can be omitted, so that it is possible to adopt a device structure that is resistant to disturbances.

It is a side view which shows the structure of the inspection apparatus which concerns on this invention. It is a figure which shows arrangement | positioning of the sensor for light reception. It is a side view showing a state when the off-axis light receiving sensor is swung in the inspection apparatus according to the present invention. It is a figure which shows the structure of the sensor for light reception, (a) is a top view, (b) is a sectional side view. It is explanatory drawing which shows the scanning of the sensor for light reception, (a) is a figure which shows an ideal image formation state, (b) is a figure which shows the state remove | deviated from the light sensor for off-axis. It is explanatory drawing which shows the scanning of the sensor for light reception, (a) is a figure which shows the state which the image shifted from the sensor for light reception by the transmission decentration error of a to-be-tested lens, (b) is a figure by the light reception sensor for axes. It is a figure which shows the state which scanned the on-axis image, (c) is a figure which shows the state which scanned the off-axis image with the light receiving sensor for off-axis. It is a figure which shows the incident state of the light ray before rocking the off-axis light receiving sensor. It is a figure which shows the incident state of the light ray after rocking the off-axis light receiving sensor. It is explanatory drawing of the calculation method of the angle which rocks the off-axis light-receiving sensor. It is a figure which shows the state of a light beam when moving a chart board and defocusing. It is a conceptual diagram of the chart image taken in by the light receiving sensor. It is a conceptual diagram of the chart image taken in with the off-axis light receiving sensor, (a) is a conceptual diagram of the chart image at the time of taking in, (b) is a conceptual diagram of the chart image after projection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 Light source 3 Chart board 3a On-axis inspection chart (on-axis chart)
3b Off-axis inspection chart (off-axis chart)
4 Test lens 10 Large stage drive unit (second moving mechanism)
12 Small stage drive unit (first moving mechanism, swing mechanism)
13 On-axis light receiving sensor (On-axis image sensor)
14 Off-axis light receiving sensor (off-axis image sensor)
13a, 14a Vertical line sensor (first line sensor)
13b, 14b Horizontal line sensor (second line sensor) 16 Control device

Claims (6)

A light source, a chart plate on which a chart is formed, a test lens, and an image sensor are arranged side by side on the mechanical axis, and light beams that have passed through the chart are projected onto the image sensor by the test lens. An inspection apparatus that forms an image of the chart and inspects optical characteristics of the lens to be inspected using the image detected by the imaging device,
The chart formed on the chart plate is disposed so as to include the mechanical axis, and a light beam emitted from the light source passes through, and an axial image is formed on the optical axis of the test lens by the test lens. The on-axis chart to be formed and the mechanical axis are arranged so as not to include the mechanical axis, the light beam emitted from the light source passes, and an off-axis image is formed outside the optical axis of the test lens by the test lens. It consists of an off-axis chart and
The image sensor is composed of an on-axis image sensor for detecting the on-axis image and an off-axis image sensor for detecting the off-axis image,
A first moving mechanism for moving the off-axis imaging device in a plane orthogonal to the mechanical axis;
A swing mechanism that swings the off-axis image sensor with respect to the plane and makes the light receiving surface of the off-axis image sensor substantially perpendicular to the principal ray emitted from the off-axis chart;
An inspection apparatus comprising: a control device that controls the first moving mechanism and the swing mechanism. A second moving mechanism for moving the image sensor in the plane;
The control device is configured to process a detection signal from the image sensor, control the second moving mechanism to move the image sensor, and detect the position of the optical axis of the lens to be tested. The inspection apparatus according to claim 1.   The inspection apparatus according to claim 1, wherein the on-axis image and the off-axis image are detected simultaneously.   The imaging device extends so as to be orthogonal to each other, and includes a first line sensor for detecting a meridional image of the image of the chart and a second line sensor for detecting a sagittal image. The inspection apparatus according to any one of claims 1 to 3.   The inspection apparatus according to claim 1, wherein the image sensor is an area sensor.   The inspection apparatus according to claim 1, wherein at least one of OTF, PTF, and MTF is measured as the optical characteristic of the test lens.

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