JP2007093243A - Inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device capable of measuring optical performance without being affected by transmission eccentricity of test lenses. <P>SOLUTION: The inspection device 1 where a light source 2 and a test lens 4, in which since a chart plate 3 on which a chart 3a for on-axis and a chart 3b for off-axis are formed and a light-sensitive sensor 13 is deployed in juxtaposition on a machine shaft 7, imageries of the charts 3a and 3b can be provided by implementing extended projection of light transmitted through the charts 3a and 3b on a light-sensitive sensor for on-axis 13 and a light-sensitive sensor for off-axis 14, are prepared, is equipped with a large stage driving section 10, a small stage driving section 12, and a controlling device 16 shifting the light-sensitive sensor for on-axis 13 and the light-sensitive sensor for off-axis 14 within a flat surface intersecting perpendicularly to a machine shaft 7, in order to acquire optical properties (OTF, PTF, and MTF) of the test lens 4 by processing the detected signals from the light-sensitive sensors 13 and 14 at the controlling device 16, by controlling both the driving sections 10 and 12 to shift the light-sensitive sensors 13 and 14, and by detecting on-axis imageries and off-axis imageries of the charts 3a and 3b. <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.

  In general, the configuration of an MTF measurement apparatus often takes an infinite distance reduced projection arrangement (see, for example, Patent Document 1). The light source is mainly a halogen lamp having a white spectrum. First, as shown in FIG. 6, an MTF measuring apparatus 100 using a collimator with reduced projection will be described. An image of the light source 101 is formed near the aperture stop 105 of the collimator lens 104 by the condenser lens 102. The image of the slit or pinhole 103 is converted into parallel light by the collimator lens 104 and reduced and projected onto the primary imaging plane (field stop 107) by the test lens 106, and further enlarged by the objective lens 108 to form an image on the sensor 109. To do.

  As shown in FIG. 7A, in this MTF measuring apparatus 100, when a collimated light beam is applied from the right to the collimator lens 104 and a parallel light beam is input from the left to the test lens 106, the paraxial image plane 110, The best image plane can be obtained due to the influence of aberration at a distance of Δfc and Δft from 111. Next, as shown in FIG. 7B, when light is applied from the left of the slit or pinhole 103 and this slit or pinhole 103 is used as an object, the aberration Δ appearing on the primary imaging plane 107 is as follows. It is represented by Formula (1).

                      Δ = α · Δfc + Δft (1)

Here, fc is the focal length of the collimator lens 104, ft is the focal length of the lens 106, and α is the vertical magnification from the slit or pinhole 103 to the primary imaging plane 107. The object to be measured is the aberration Δft of the lens 106 to be measured, but it is measured by adding an amount obtained by multiplying the aberration Δfc of the collimator lens 104 by the vertical magnification. In general the lateral magnification as said | beta | aberration Δfc collimator lens 104 since the longitudinal magnification α if it ≒ 5 or more is beta ² becomes negligible order.

  The next objective lens 108 is optically close to the diffraction limit because its own aberrations are directly applied. Enlarging the spatial frequency on the primary imaging plane 107 with the objective lens 108 lowers the spatial frequency on the sensor 109, and the pitch of the sensor 109 is increased and a wide dynamic range can be obtained.

  Further, the sampling time Δt is limited by the illuminance E on the sensor 109. If Δt can be made sufficiently small, it is strong against vibrations and can cope with a high spatial frequency. Furthermore, the high illuminance E can also increase the S / N of the LSF to be acquired, leading to an improvement in low-frequency reliability. In the case of orthographic projection, the illuminance E can be expressed by the following equation (2), assuming that the luminance B of the light source, the transmittance T of the optical system, the brightness Fno of the test lens, and the relay magnification βr of the objective lens 108 as shown in FIG. ).

E = πTB / (4Fno ² · | βr |) (2)

  The luminance B of the light source cannot be increased beyond a certain value due to restrictions. The illuminance E on the sensor 109 of the orthographic projection device 100 is substantially determined by the F number Fno of the lens 106 to be tested and the lateral magnification βr of the objective lens 108 if the luminance B is constant. Since the magnification βr of the objective lens 108 is at most about −20 times, the illuminance E on the sensor 109 can be sufficiently secured.

  Next, consider the setting error of the test lens 106. As shown in FIG. 9, if the test lens 106 is attached in a shifted state (the center of which is shifted from the optical axis), the shift amount of the image on the primary imaging plane 107 is as follows. The amount of shift 106 becomes the actual amount, and if this satisfies the field of view of the objective lens 108 and is within the range of the object side NA (numerical aperture), the measurement is not affected. If the objective lens 108 restricts the light flux of the lens 106, the objective lens 108 and the sensor 109 may be moved in a plane perpendicular to the mechanical axis. Errors in the machine axis direction also appear on the primary image plane 107 in a one-to-one relationship. Therefore, these errors are considered to be quite small, and in most cases, measurement is possible without moving the objective lens 108 and the sensor 109 in a plane perpendicular to the mechanical axis.

  Although it is a reduction projection MTF measuring apparatus 100 that is quite popular, it measures one angle of view and cannot measure multiple image heights in the measurement area at the same time. Because there is no area sensor that covers the measurement area and determines the frequency range with an appropriate pitch and has a sufficiently wide dynamic range, the measurement surface is once relayed with an objective lens and a line sensor with a wide dynamic range for measurement is placed.

  As described above, the reduction projection measuring apparatus 100 has many advantages, but if it is evaluation of a lens such as a prototype, it may be sufficient to measure one angle of view by taking a sufficient amount of time. It is not suitable for mass production inspection of new products. Therefore, as shown in FIG. 10, an MTF measuring apparatus 200 for finite distance expansion projection that evaluates a plurality of angles of view of the lens 206 to be examined at once using a plurality of slits 203 and a linear sensor 209 can be considered. In the case of a photographic lens, the lateral magnification β to be evaluated is generally about −1/50 to −1/30. The infinite reduction projection has the following disadvantages in terms of the configuration of the apparatus.

  One is that a part of the image at the center image height deviates from the sensor 209 due to the transmission declination error of the test lens 206. As shown in FIG. 11, when the transmission declination error of the test lens 206 is expressed by a shift, the principal ray that has exited the center slit 203 ′ goes straight toward the shifted principal point of the test lens 206. In magnified projection, the amount of deviation Δy ′ on the sensor side is expressed by the following equation (3).

                        Δy ′ = (| β | +1) · d (3)

  If the test lens 206 is shifted with respect to the slit 203 for alignment on the sensor 209, the movable range of the apparatus 200 can be reduced. However, the center position of the image circle of the test lens 206 changes, and the peripheral image height with the origin as the origin also changes. In the case of infinite reduction projection, the amount is not so large, but in the case of finite enlargement projection, it is an amount that cannot be ignored.

  The other is that the peripheral image height changes greatly due to distortion of the lens 206 to be examined, and cannot be captured by the sensor 209. Many of the distortions of photographic lenses, such as wide-angle zoom lenses, are about -5%. When this is back-tracked and enlarged and projected, the distortion is about + 5%, and a line image or point image cannot be captured unless the position of the sensor 209 is moved greatly. FIG. 12A shows a lens 301 having a 1 / β magnification and a negative distortion. FIG. 12B shows a lens 301 having a positive distortion at β times by reversing the object image relationship.

  In addition, since the image plane illuminance is considerably smaller than the above-described relational expression between the luminance B and the illuminance E compared to the reduced projection type due to the enlarged projection, the sensor accumulation time must be lengthened.

  The slit width and pinhole size to be projected must be increased to a certain extent due to the illuminance relationship on the sensor. This limits the measurement limit frequency. However, since the frequency of MTF evaluation of a photographic lens is generally sufficient up to about 40 lp / mm, there is no problem in mass production inspection.

  As described above, when an inspection apparatus for mass-produced products is assumed, an enlarged projection type apparatus structure is formed because of the requirement to measure a plurality of angles of view simultaneously. However, since the test lens generally has transmission eccentricity, the chart, the test lens, and the light receiving sensor do not line up in a straight line. Therefore, a structure for capturing an image by moving either of them in a plane perpendicular to the optical axis direction is required. Conventional inspection apparatuses that can measure a plurality of angles of view at the same time have used a chart or a lens to be measured shifted in a plane perpendicular to the optical axis. This is because in the case of enlargement projection, the shift amount can be smaller than when the light receiving sensor is shifted. However, if the chart or the test lens is shifted in a plane perpendicular to the optical axis, a shift occurs between the chart and the test lens, which makes it difficult to measure the image height that is originally desired to be measured.

  FIG. 13 shows a case where the image of the chart 303 is formed on the light receiving sensor 309 by the test lens 306. In FIG. 13, the light receiving sensor 309 includes one on-axis sensor 309a and two off-axis sensors 309b. FIG. 13A shows an ideal imaging state without transmission eccentricity. Actually, since the test lens 306 has transmission eccentricity, when the test lens 306 is mounted on a measuring machine, the image may be detached from the light receiving sensor 309 as shown in FIG. Therefore, in the conventional apparatus, the chart 303 is moved so that the image is on the light receiving sensor 309 (the state shown in FIG. 13C).

Japanese Patent Laid-Open No. 58-736

  However, if the chart is moved so that an image is placed on the light receiving sensor, a shift occurs between the chart and the lens to be measured in this state, so that the image height to be originally measured is not measured.

  The present invention has been made in view of such problems, and an object thereof is to provide an inspection apparatus capable of measuring optical performance without being affected by transmission eccentricity of a lens to be examined.

  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, and an image sensor (for example, the on-axis light receiving sensor 13 in the embodiment) arranged on a mechanical axis. A test lens is arranged to form a chart image by expanding and projecting the light beam transmitted through the chart onto the image sensor, and inspecting the optical characteristics of the test lens using the image detected by the image sensor A moving mechanism (for example, the large stage drive unit 10 in the embodiment) that moves the image pickup device in a plane orthogonal to the mechanical axis, and a detection signal from the image pickup device is processed, and the moving mechanism is controlled to control the image pickup device. And a control device for detecting the position of the optical axis of the lens to be examined.

  Such an inspection apparatus according to the present invention includes an on-axis chart in which a chart plate is disposed on a mechanical axis and passes through a test lens to form an on-axis image on an image sensor on the optical axis of the test lens. An off-axis chart that is arranged outside the mechanical axis and forms an off-axis image outside the optical axis of the test lens through the test lens so that the on-axis image and the off-axis image are detected simultaneously. Preferably, it is configured.

  In such an inspection apparatus, it is preferable that the imaging device includes an on-axis light receiving sensor for detecting an on-axis image and an off-axis light receiving sensor for detecting an off-axis image.

  At this time, it is arranged on the surface of the large stage, which is disposed so as to be orthogonal to the mechanical axis, and is disposed on the surface of the large stage, the large stage having the on-axis light receiving sensor disposed substantially at the center of the surface orthogonal to the mechanical axis. It is preferable to have a small stage that can move radially around the on-axis light receiving sensor and on which the off-axis light receiving sensor is disposed.

  The large stage is configured to be movable in a plane orthogonal to the mechanical axis, and the large stage is moved to move the on-axis light receiving sensor on the optical axis of the lens to be detected to detect the on-axis image. It is preferable to be configured as described above. Further, it is preferable that the small stage is moved and an off-axis image is detected by the off-axis light receiving sensor.

  Further, it is preferable that the image sensor extends so as to be orthogonal to each other and includes a first line sensor for detecting a meridional image of the chart image and a second line sensor for detecting a sagittal image. Or it is preferable that an image pick-up element is comprised by one area sensor.

  Further, it is preferable that the inspection apparatus according to the present invention is configured to measure at least one of OTF, PTF, and MTF as optical characteristics of the test lens from the chart image.

  In order to explain the present invention in an easy-to-understand manner, the constituent elements of the embodiment have been described, but it goes without saying that the present invention is not limited thereto.

  When the inspection apparatus according to the present invention is configured as described above, a test lens such as a photographic lens having a relatively large transmission eccentricity is evaluated for optical performance of an image height defined with reference to the mechanical axis of the inspection apparatus. be able to.

  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 MTF, PTF, OTF 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. First, the configuration of the inspection apparatus 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. The inspection apparatus 1 includes a light source 2 and a chart plate 3 inside, an illumination unit 5 that holds a lens 4 to be examined, and a measurement unit 6 that can move relative to the illumination unit 5. .

  The light source 2, the chart plate 3, and the test lens 4 are arranged side by side on the mechanical axis 7 of the measuring device 1. The measuring unit 6 has a flat plate-like receiving unit in a plane perpendicular to the mechanical axis 7 (hereinafter referred to as “light receiving surface”) on the light receiving side (opposite the light source 2 with the lens 4 to be tested). 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 light receiving surface, and the large stage 9 Is provided with a large stage drive unit 10 that drives the light receiving surface within the light receiving surface, and a small bistage driving stage (hereinafter referred to as “small stage 11”) and a small stage that are relatively movable within the light receiving surface of the large stage 9. A drive unit 12 is provided. 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, the small stage 11 is configured to be slidable in the diagonal direction with respect to the large stage 9. 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 of the small stages 11 includes a vertical line sensor 14a extending in a diagonal direction (extending radially from the on-axis light receiving sensor 13) and a horizontal line sensor 14b extending in a direction perpendicular to the diagonal. An off-axis light receiving sensor 14 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 plate 3, respectively. Used to detect an image.

  FIG. 3A shows an ideal imaging state in the inspection apparatus 1, and the image of the on-axis inspection chart (center slit) 3 a formed on the chart plate 3 is the on-axis light receiving sensor 13. The image on the off-axis inspection chart 3b is formed on the corresponding off-axis light receiving sensor 14. However, when the test lens 4 is a lens having a large distortion, as shown in FIG. 3B, the image can be captured on the axis by the on-axis light receiving sensor 13, but the image is off-axis. May deviate from the off-axis light receiving sensor 14. In such a case, the image can be captured by moving the off-axis light receiving sensor 14 in the radial direction.

  On the other hand, if there is a transmission eccentricity error in the lens 4 to be examined, 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 within the light receiving surface, and the axial chart image (center slit position) is scanned by the axial light receiving sensor 13 (in this case, as shown in FIG. 4B). Thus, 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. 3, 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 chart image and align it with the off-axis light flux. (The state shown in FIG. 4C). 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. 4B, if the coordinate system of the on-axis light receiving sensor 13 is a global coordinate and the coordinate system of the off-axis light receiving sensor 14 is a local coordinate system, It is not always necessary to move the off-axis light receiving sensor 14 at the same time. FIG. 4 shows a case where two off-axis light receiving sensors 14 are provided in order to simplify the description.

  By sensing the imaging position of the off-axis light beam by the off-axis light receiving sensor 14, the deviation from the ideal image height and the actual angle of view can be known, and the asymmetry in all directions can be determined. In addition, 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 the present embodiment, as shown in FIG. 2, by providing a small stage 11 that can move radially, the angle of view due to manufacturing errors, such as a lens with a large eccentricity such as a photographic lens or a lens with a large distortion, can be reduced. 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 on the small stage 11 and are configured to move together. 14a and the horizontal line sensor 14b may be disposed 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.

  As described above, when the test lens 4 is set on the illumination unit 5, an image is formed at a position deviated from the center of the large stage 9 (a point where the large stage 9 and the mechanism shaft 7 intersect) due to transmission eccentricity error. The 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 center 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, it is possible to efficiently search and save search time by operating a rectangular range with a large stage 9 spirally from the outside to the inside. After the search, the large stage 9 is moved to the center of each of the vertical and horizontal line sensors 13a and 13b (or the center of the area sensor), and the centering is ended with the position as the origin. Further, the small stage 11 can be configured not only to be operated in a diagonal direction (diagonal 45 °) as shown in FIG. 2 but also to be operated with two axes in the vertical direction and the horizontal direction.

  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 distance between the chart plate 3 (slit chart or point image chart) of the inspection apparatus 1 and the on-axis and off-axis light receiving sensors 13 and 14 is calculated by moving the measuring unit 6 along the mechanical axis 7 by the measurement driving unit 15. Match the 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 apparatus 1 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. Centering may be performed 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.

  FIG. 5 shows a conceptual diagram of the chart image captured by the light receiving sensors 13 and 14. In FIG. 5, the MSF and LSF of the peripheral image captured by the off-axis light receiving sensor 14 are shown. In general, a photographic lens has a large vignetting, and the M image is an S image due to the influence of coma aberration. More spread. If this is captured with the same S / N by one sensor, the accumulation time is determined in accordance with the S image, and the resolution of the M image becomes small. Therefore, in order to detect the LSF for the M image and the S image with the same accuracy, it is desirable that the image is composed of individual sensors including the vertical and horizontal line sensors 14a and 14b as shown in this embodiment. When taking 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. As a result, the detection accuracy of the flare component of the lens 4 is determined. This also determines the frequency increment in the computation after detecting the LSF.

  By configuring the inspection apparatus 1 according to the present invention as described above, a plurality of angles of view can be simultaneously measured with high accuracy in a short measurement time, and can be used for mass production inspection and the like. 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.

  Further, the conventional enlargement 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, in the inspection apparatus 1 according to the present embodiment, since the shift mechanism of the apparatus 1 between the chart plate 3 and the lens 4 to be examined can be omitted, it is possible to adopt an apparatus structure that is resistant to disturbance.

It is a side view which shows the structure of the inspection apparatus which concerns on this invention. It is a figure which shows the structure of the sensor for light reception. It is explanatory drawing which shows the scanning of a light reception sensor, (a) is a figure which shows an ideal image formation state, (b) is a figure which shows the state from which the image remove | deviated from the off-axis light reception sensor. It is explanatory drawing which shows the scanning of a light reception sensor, (a) is a figure which shows the state which the image shifted from the sensor for light reception by the transmission eccentricity error of a to-be-tested lens, (b) is an axis | shaft by the light reception sensor for an axis. It is a figure which shows the state which scanned the upper image, (b) is a figure which shows the state which scanned the off-axis image with the light-receiving sensor for off-axis. It is a conceptual diagram of the chart image taken in by the light receiving sensor. It is a figure which shows arrangement | positioning of an infinite distance reduction projection apparatus. It is a figure which shows the longitudinal aberration of a collimator lens and a test lens. It is a figure which shows the relationship between a brightness | luminance and illumination intensity. It is a figure which shows the image formation state when a to-be-tested lens shifts. It is a figure which shows arrangement | positioning of a finite distance expansion projection apparatus. It is a figure which shows the image formation state when a to-be-tested lens shifts. It is a figure which shows the image formation state of the lens which has a distortion, (a) is an image formation state of a 1 / (beta) lens, (b) is an image formation state at the time of reversing an object image relationship. It is a figure which shows the case where a chart image is imaged with a to-be-tested lens, (a) is a figure which shows an ideal state, (b) is an imaging position having shifted | deviated by the transmission eccentricity error of the to-be-tested lens. It is a figure which shows a state, (c) is a figure which shows the state which adjusted the imaging position by moving a chart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 Light source 3 Chart board 3a On-axis chart 3b Off-axis chart 4 Test lens 7 Mechanical axis 9 Large stage 10 Large stage drive part (movement mechanism)
11 Small stage 12 Small stage drive unit 13 On-axis light receiving sensor (image sensor)
13a Vertical line sensor 13b Horizontal line sensor 14 Off-axis light receiving sensor 14a Vertical line sensor 14b Horizontal line sensor 16 Controller

Claims (9)

A test object in which a light source, a chart plate on which a chart is formed, and an image sensor are arranged side by side on a mechanical axis, and a light beam transmitted through the chart is enlarged and projected onto the image sensor to form an image of the chart. An inspection apparatus in which a lens is arranged and inspects optical characteristics of the lens to be inspected using the image detected by the imaging device,
A moving mechanism for moving the image sensor in a plane perpendicular to the mechanical axis;
An inspection apparatus comprising: a control device that processes a detection signal from the image sensor, moves the image sensor by controlling the moving mechanism, and detects a position of an optical axis of the lens to be examined. An on-axis chart that forms an on-axis image on the image sensor on the optical axis of the test lens by passing through the test lens and the chart plate is disposed on the mechanical axis; An off-axis chart that is disposed and passes through the test lens to form an off-axis image outside the optical axis of the test lens;
The inspection apparatus according to claim 1, wherein the on-axis image and the off-axis image are detected simultaneously.   The inspection apparatus according to claim 2, wherein the imaging device includes an on-axis light receiving sensor that detects the on-axis image and an off-axis light receiving sensor that detects the off-axis image.   A large stage that is disposed so as to be orthogonal to the mechanical axis, and the axial light-receiving sensor is disposed at a substantially central portion of the surface orthogonal to the mechanical axis, and is disposed on the surface of the large stage; The inspection apparatus according to claim 3, further comprising a small stage that is radially movable around the on-axis light receiving sensor and on which the off-axis light receiving sensor is disposed. The large stage is configured to be movable in a plane perpendicular to the mechanical axis;
5. The inspection according to claim 4, wherein the large stage is moved to move the on-axis light receiving sensor on the optical axis of the lens to be detected to detect the on-axis image. apparatus.   The inspection apparatus according to claim 4, wherein the small stage is moved, and the off-axis image is detected by the off-axis light receiving sensor.   The image sensor extends perpendicularly to each other and includes a first line sensor for detecting a meridional image of the chart image and a second line sensor for detecting a sagittal image. The inspection apparatus according to claim 1.   The inspection apparatus according to claim 1, wherein the image sensor is configured by a single area sensor. The inspection apparatus according to claim 1, wherein at least one of OTF, PTF, and MTF is measured from the image as the optical characteristic of the test lens.

Images