JPH07140046A - Inspection equipment for lens performance - Google Patents

Abstract

PURPOSE:To make it possible to inspect the performance of lens without providing any rotary mechanism at the test pattern part. CONSTITUTION:A liquid crystal 2 for constituting a test pattern is interposed between a light source 1 and a lens 4 to be tested. An image scanning means 5 is disposed at the position for focusing the projection image of the test pattern and the image is analyzed by a signal processing means 6. A liquid crystal driver 3 controls the liquid crystal 2 to alter the test pattern depending on the inspection method, the inspecting direction of the lens to be inspected, etc. Since the liquid crystal 2 alters the test pattern, no rotary mechanism is required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the positional light intensity distribution of a test pattern projection image formed by a lens to be inspected to obtain a test pattern projection image of a plurality of image heights including on the axis of the lens to be inspected. The present invention relates to a lens performance inspection device that inspects an image formation state.

[0002]

2. Description of the Related Art A test pattern such as a slit provided in a chart is imaged through a test lens such as a photographic lens, and a positional light intensity distribution is converted into a time series signal by a light receiving element such as a CCD, Japanese Patent Publication No. 63-36449 discloses a conventional lens performance inspecting apparatus that analyzes a signal obtained from a light receiving element to inspect the imaging performance of a plurality of image heights including the axis of a lens to be inspected. This apparatus arranges chart patterns at a plurality of positions at arbitrary distances from the optical axis in a plane orthogonal to the optical axis of the lens to be inspected, and through the lens to be inspected, on the plurality of solid-state scanning elements, to the above-mentioned each The image of the chart pattern is formed, and the MTF inspection of the lens to be inspected is performed by the output signal from each solid-state scanning element. A plurality of solid-state scanning elements are mechanically rotated to the optical axis of the lens to be inspected. At the same time, the solid scanning element is rotated about the central portion or the vicinity thereof in the orthogonal plane by the same amount to change the arrangement direction of the solid scanning elements, and the solid scanning elements for the plurality of chart patterns are also changed. By rotating so as to match the arrangement direction after the rotation of or, or by arranging other chart patterns in advance, the image of each of these chart patterns is obtained by each solid scanning element. Create a relationship to be imaged in, M in at least two directions of the lens
Inspecting TF.

FIG. 9 shows this conventional apparatus, in which 110 is a light source, 111 is a disk-shaped chart plate holding a chart pattern, 112 is a lens to be inspected, 113, 114, 115.
Are mounting plates that support and mount the solid-state scanning elements. The light source 110, the chart plate 111, and the mounting plate 11
4 is located on the optical axis of the lens 112 to be inspected, and is placed on the mounting plate 11
3 and the mounting plate 115 are in a position facing each other with the mounting plate 114 in between. On each of the mounting plates 113, 114, 115, two ears are formed at positions facing each other with each center therebetween.

These ear-like portions are respectively 113L and 11
3R, 114L, 114R, 115L, 115R, the ear-like portions 113L, 114L, 115L on the same side and the ear-like portions 113R, 114R, 115R on the opposite side are continuously fixed in the middle of the wires 116, 117, respectively. Has been done. One end of each wire 116, 117 is fixed to the drive node 118, respectively. The center of the drive node 118 is integrally fixed to the drive shaft 119.
Depending on the rotation direction of 19, either one of the wires 116 and 117 is pulled and the other is loosened. Wires 116 and 11
Although not shown in the figure, the other end of 7 is wound around a pulley, for example. A pulley 120 is integrally provided with the drive shaft 119 at a position facing the chart plate 111 in the middle of the drive shaft 119, and the chart plate 111 and the pulley 120 are linked by a belt 121 so as to be interlocked with each other.

A rotation amount detector 1 is provided on the extension of the drive shaft 119.
22 is provided and detects the amount of rotation of the drive shaft 119 provided by a known drive means (not shown),
Obtain the switching signal of the measuring direction. This rotation amount detector 122
For example, a rotary encoder or a potentiometer is used, but in addition, the drive shaft 1
It is also possible to mechanically extract and display the rotation amount of 19.

Referring to FIG. 10, the mounting plate 113 is shown.
9 corresponds to the position where the solid-state scanning element P1 in FIG. 9 is arranged. Similarly, the mounting plate 114 corresponds to the solid-state scanning element P2, and the mounting plate 115 corresponds to the solid-state scanning element P3. A solid-state scanning element is attached to each.
On the other hand, the chart patterns held on the chart plate 111 are indicated by reference numerals z1 to z5, in which the image of the chart pattern z1 is placed on the solid-state scanning element of the placing plate 115 and the image of the chart pattern z2 is placed. An image is formed on each of the solid-state scanning elements of the plate 114.

After the MTF measurement in the radial direction is completed in the state shown in FIG. 10, the drive shaft 119 is rotated 90 ° in the clockwise direction. The control of the rotation angle of 90 ° is performed by the function of the rotation amount detector 122 described above. The state after such rotation corresponds to the state shown in FIG. 11, and the MTF in the tangential direction is the same.
Is measured.

[0008]

However, the above-mentioned conventional device has the following drawbacks. If the chart plate 111 is not parallel to the test lens 112, the distance of the chart pattern changes with respect to the test lens, which adversely affects the measurement value. Therefore, it is necessary to maintain the parallelism, but it is difficult to maintain the parallelism between the lens to be inspected and the chart when the chart pattern is mechanically rotationally moved or the chart is switched. Further, it is difficult to miniaturize the chart part because a rotation mechanism part and a switching mechanism part are required.

In view of the above problems, the present invention provides a lens performance inspecting apparatus capable of inspecting lens performance in an arbitrary direction at an arbitrary image height position of a lens to be inspected without providing a mechanism such as rotation in a test pattern portion. The purpose is to provide.

[0010]

FIG. 1 shows the basic structure of the present invention, in which 1 is a light source, 4 is a lens to be inspected, 2 is a liquid crystal constituting a test pattern, and the surface of the lens to be inspected is 4. Is arranged perpendicular to the optical axis of the lens 4 to be inspected. Reference numeral 3 is a liquid crystal driver for controlling the liquid crystal 2 to display various patterns, and 5 is installed at the image forming position of the projected image of the test pattern displayed on the liquid crystal 2 perpendicularly to the optical axis of the lens to be inspected. Image scanning means 6 and signal processing means 6 connected to the image scanning means 5, respectively.

In the above structure, the liquid crystal 2 is irradiated with the light flux emitted from the light source 1. The liquid crystal 2 displays a test pattern for inspecting the performance of the lens 4 to be inspected, and allows the light flux of the light source 1 to pass through the transmitted light portion. The test pattern formed by the liquid crystal 2 differs depending on the inspection method such as inspection based on the MTF value and visual inspection, the inspection direction such as the normal line and tangential direction of the lens to be inspected, and the position on the lens to be inspected. It is controlled and changed by the liquid crystal driver 3 depending on the difference. The light flux emitted from the test pattern formed by the liquid crystal 2 forms a projected image of the test pattern on a plane perpendicular to the optical axis of the lens 4 to be inspected due to the imaging action of the lens 4 to be inspected. The image scanning means 5 is arranged so that the light receiving part of the image scanning means 5 is located on the plane, and the positional light intensity distribution of the projected image of the test pattern generated by the lens 4 to be inspected is converted into a time series signal. Then, this signal is subjected to various calculations such as A / D conversion by the signal processing means 6, and the lens performance can be inspected by grasping the image formation state from the MTF value of the projected image and the image processing result output. .

[0012]

Embodiment 1 FIGS. 2, 3 and 4 show Embodiment 1 of the present invention. In FIG. 2, 4 is a lens to be inspected, 8 is a cold cathode tube as a light source, and 9 is a light guide, which uniformly irradiates the liquid crystal 2 with light emitted from the cold cathode tube 8. Reference numeral 2 denotes a liquid crystal for forming a transmitted light opening as a test pattern, and a slit transmitted light opening is provided at a position corresponding to an image height to be inspected on-axis and off-axis as shown in FIG. Controlled by 3. The slit transmitted light opening of the liquid crystal 2 is the lens 4 to be inspected.
The pattern is switched as shown in FIG. 3A or 3B depending on which of the normal direction and the tangential direction is measured. 3 (a) and 3 (b) show all of the slit transmitted light apertures 2-1a, b to 2-5a, b corresponding to the measurement points, but depending on the points to be inspected at the time of inspection. As shown in FIG. 3C, the slit transmitted light opening is displayed only at the position corresponding to the inspection location.

The surface of the liquid crystal 2 is oriented toward the lens 4 to be inspected, and is installed perpendicularly to the optical axis of the lens to be inspected. Opal glass 10 as a diffusing plate for uniformly irradiating the light is arranged in a close contact state.

Reference numeral 13 is an optical path switching means rotatable about the optical axis of the lens 4 to be inspected, and is a mirror 13a arranged so as to be able to advance and retreat on the on-axis optical path 4a and a mirror 13b arranged on the off-axis optical path 4b. With. The mirror 13a has an off-axis image inspection position 13 which is 45 degrees with respect to the optical axis of the lens 4 to be inspected and which is free from eclipse of the off-axis light flux passing through the off-axis optical path 3b.
a "or off-axis optical path On-axis image inspection position 13 retracted so as not to cause eclipse on the on-axis light flux passing through the on-axis optical path 4a
It can be appropriately switched to a '. The off-axis optical path 4a is formed by the mirror 13b arranged on the off-axis optical path 4b of the lens 4 to be inspected.
A direction intersecting at right angles to the axial optical path 4a (optical path 4
b ′), and further converted by the mirror 13a in a direction coinciding with the on-axis optical path 4a.

A collimator lens 14 is installed so that its optical axis coincides with the optical axis of the lens 4 to be tested. 11
Is a one-dimensional CCD as an image scanning means provided on the image forming surface of the collimator lens 14. The CCD 11 is installed perpendicularly to the optical axis of the lens 4 to be inspected, and the optical path switching means is arranged so that the scanning direction intersects perpendicularly with the projected image of the test pattern with the optical axis of the lens 4 to be inspected as the center. It can be rotated according to the rotation of 13 or the position of the mirror 13a. 12 is connected to CCD 11 and FF
It is a signal processing means including a signal processing device 12a capable of T and a monitor 12b.

In the above structure, the light beam emitted from the cold cathode tube 8 is applied to the liquid crystal 2 by the light guide 9. The liquid crystal 2 has a slit transmitted light opening as a test pattern for inspecting the performance of the lens 4 to be inspected, and a part of the light flux from the cold cathode tube 8 passes through this opening, and the opal glass 10
Are diffused by and are uniformly emitted toward the entire surface of the lens 4 to be inspected. When inspecting the on-axis performance of the lens 4 to be inspected, the liquid crystal 2 is controlled by the liquid crystal driver 3, and either the test pattern 2-1a or 2-1b shown in FIG. On-axis image inspection position 13
Install at a '.

Test pattern 2 for on-axis image inspection of liquid crystal 2
The on-axis light flux emitted from 1a or 2-1b passes through the on-axis optical path 4a, and the collimating lens 14 condenses the test pattern 2-1a or 2-on the CCD 11.
Generate a projected image of 1b. At this time, the scanning direction of the CCD 11 is set to a rotational position perpendicular to the projected image of the test pattern 2-1a or 2-1b.

The positional light intensity distribution of the projected image of the test pattern 2-1a or 2-1b generated on the CCD 11 is converted into a time-series signal by the CCD 11, and this signal is A / D converted by the signal processor 12a. It is stored and stored, and MTF calculation by FFT is performed, and the monitor 12
b displays the MTF value. Thereby, the test pattern 2-1a or 2-1b generated by the lens 4 to be inspected
It is possible to inspect the image formation state of the projected image of. Depending on the eccentricity of the lens 4 under test, the test pattern 2-1a or 2
When -1b is disengaged from the CCD 11, the position of the slit transmitted light opening is adjusted by the liquid crystal driver 3 as shown in 2a 'and 2a "of FIG. The projection image of 2-1b is generated.

When inspecting the off-axis performance of the lens 4 to be inspected, the liquid crystal 2 is controlled by the liquid crystal driver 3, and the test patterns 2-2a to 2a shown in FIG.
5a or any of 2-2b to 5b is displayed, and the mirror 13a is placed at the off-axis image inspection position 13a ". The off-axis light flux emitted from the test patterns 2-2a to 5a or 2-2b to 5b. After being diffused by the opal glass 10 placed on the image plane A of the lens 4 to be inspected, it becomes a parallel light beam by the lens 4 to be inspected. The optical path is switched by the mirror 13a and the mirror 13b, passes through the on-axis optical path 3a, and the condensing action of the collimator lens 14 produces a projected image of the test pattern 2-2a to 5a or 2-2b to 5b on the CCD 11. At this time, the scanning direction of the CCD 11 is set to a rotation position perpendicular to the test pattern.

The positional light intensity distribution of the projected image of the test patterns 2-2a to 5a or 2-2b to 5b generated on the CCD 11 is converted by the CCD 11 into a time series signal. This signal is A / D converted by the signal processing device 12a and stored, and MTF calculation by FFT is performed, and the monitor 12b displays the MTF value. As a result, the test patterns 2-2a-
It is possible to inspect the image formation state of the projected image of 5a or 2-2b to 5b. Due to the eccentricity of the lens 4 to be inspected, the test patterns 2-2a to 5a or 2-2b to 5b are CCDs.
When it deviates from 11, the liquid crystal driver 3 is used.
As shown in (a), the position of the slit transmitted light aperture is adjusted so that a projected image of the test pattern 2-2a to 5a or 2-2b to 5b is generated on the CCD 11.

Further, by the Fno of the lens 4 to be inspected, the liquid crystal 2
The slit width of the upper slit transmitted light portion is changed to adjust the amount of light passing therethrough. With the mirror 13a still installed at the off-axis image inspection position, the optical path switching means is rotated by every α1 to α3 (see FIG. 3), and the CCD 11 is synchronized with it to make the test patterns 2-2a to 5a or 2-2b to 5b. By rotating so that the scanning direction is perpendicular to the projected image of 1, the inspection state of the image formation state of the projected image of the test pattern of a plurality of image heights including the axis of the lens 4 to be inspected becomes possible.

According to this embodiment, the cold cathode fluorescent lamp 8
Can be arranged parallel to the plane of the liquid crystal 2, and the light guide 9 can be made thin so that the liquid crystal 2 and the opal glass 10 can be brought into close contact with each other. Therefore, the cold cathode tube 8, the light guide 9, the liquid crystal 2 The part including the opal glass 10 can be downsized. Also,
Since the optical path of the test pattern projection image is a parallel light beam between the lens 4 to be inspected and the collimator lens 14, there is flexibility in the arrangement of the lens 4 to be inspected, the optical path switching means 13, and the collimator lens 14.

[0023]

Second Embodiment FIGS. 5 and 6 show a second embodiment of the present invention. Reference numeral 4 is a lens to be inspected, 15 is an ELD as a light source, and 2 is a liquid crystal for forming a transmitted light portion as a test pattern, which is shown in FIG. 6 at a position corresponding to an image height to be inspected on-axis and off-axis. As shown, the pinhole transmitted light openings 2-1 and 2-2
-5 is controlled by the liquid crystal driver 3. In FIG. 6, the pinhole transmitted light openings 2-1 and 2-2 corresponding to the measurement points are shown.
Although all of -5 are shown, the pinhole transmitted light apertures are displayed only at the positions corresponding to the inspection points during inspection. The position of the transmitted light opening of the pinhole transmitted light opening is finely adjusted as shown by the arrow, and the area of the transmitted light opening is changed to change the amount of light applied to the lens 4 to be inspected. be able to.

The surface of the liquid crystal 2 is oriented toward the lens to be inspected 4 and is perpendicular to the optical axis of the lens to be inspected. The light flux emitted from the pinhole transmitted light opening is provided on the surface of the lens to be inspected 4. Opal glass 10 as a diffusion plate for uniformly irradiating the entire surface is arranged in a close contact state.

Numeral 16 is a two-dimensional CCD as an image scanning means which is installed on the image plane of the lens 4 to be inspected and which is perpendicular to the optical axis of the lens 4 to be inspected.
A plurality of them are installed on the image forming plane corresponding to the off-axis measurement positions. Reference numeral 17 is a signal processing means connected to the CCD 16 and provided with a signal processing device 17a capable of two-dimensional FFT and a monitor 17b.

In the above structure, the ELD 15 irradiates the liquid crystal 2. The liquid crystal 2 has a pinhole transmitted light opening as a test pattern for inspecting the performance of the lens 4 to be inspected. A part of the light from the ELD 15 passes through this opening and is diffused by the opal glass 10. It is uniformly ejected toward the entire surface of the lens 4 to be inspected.

When inspecting the on-axis and off-axis performances of the lens 4 to be inspected, the liquid crystal 2 is controlled by the liquid crystal driver 3 and any one of the test patterns 2-1 to 5 shown in FIG. indicate. The on-axis and off-axis light fluxes emitted from the test pattern of the liquid crystal 2 pass through the on-axis optical path 4a and the off-axis optical path 4b, and due to the imaging action of the lens 4 under test,
A projected image of the test pattern is generated on the CCD 16.

The positional light intensity distribution of the projected image of the test pattern generated on the CCD 16 is converted into a time series signal by the CCD 16, and this signal is A / D converted by the signal processing device 17a and stored. Two-dimensional MTF calculation in the tangential direction and the normal direction by FFT is performed. Then, the monitor 17b displays this two-dimensional MTF value. This makes it possible to inspect the two-dimensional image formation state in the tangential direction and the normal direction of the projected image of the test pattern generated by the lens 4 to be inspected. Lens to be inspected 4
When the test pattern deviates from the CCD 16 due to the eccentricity, the position of the pinhole transmitted light opening is adjusted by the liquid crystal driver 3 to generate a projected image of the test pattern on the CCD 16, as shown in FIG. The area of the pinhole opening on the liquid crystal 2 is changed by Fno of the lens 4 to be inspected, and the amount of light passing therethrough is adjusted.

In this embodiment, as the light source, E
Since it is possible to make the LD 15 thin and make it adhere to the liquid crystal 2 and the opal glass 10, the ELD 1
5, the part including the liquid crystal 2 and the opal glass 10 can be miniaturized. Further, the imaging performance in the tangential direction and the normal direction at the arbitrary image height position of the test lens 4 can be inspected without rotating the CCD 16.

[0030]

Third Embodiment FIGS. 7 and 8 show a third embodiment of the present invention, in which 4 is a lens to be inspected, 19 is a halogen light source as a light source, and 20 is a lens which directs the light emitted from the halogen light source 19 to the liquid crystal 2. Irradiate evenly. Reference numeral 2 denotes a liquid crystal for forming a transmitted light opening as a test pattern, and a slit transmitted light opening is provided at a position corresponding to an image height to be inspected on-axis and off-axis as shown in FIG. Controlled by. The pattern of the slit transmitted light opening of the liquid crystal 2 is switched depending on whether the normal direction or the tangential direction of the lens 4 to be inspected is inspected. Further, the off-axis image inspection position is also arbitrarily changed as in the first embodiment shown in FIG. Although all of the slit transmitted light openings corresponding to the measurement points are shown in FIG. 8, the slit transmitted light openings are displayed only at the corresponding positions according to the points to be inspected at the time of inspection.

The surface of the liquid crystal 2 is directed toward the lens 4 to be inspected, and is installed perpendicularly to the optical axis of the lens 4 to be inspected. Is irradiated.

Reference numeral 21 denotes a two-dimensional CCD as an image scanning means installed on the image forming surface of the lens 4 to be inspected and perpendicularly to the optical axis of the lens 4 to be inspected. The CCD 21 is installed on an XY table 23 that can move on the same plane while maintaining a positional relationship that is always perpendicular to the axial optical path 4a of the lens 4 to be inspected and that can rotate about the CCD 21.
Reference numeral 22 denotes a signal processing unit which is connected to the CCD 21 and includes a signal processing device 22a capable of performing two-dimensional FFT and a monitor 22b.

In the above structure, the light emitted from the halogen light source 19 is diffused by the lens 20 and applied to the liquid crystal 2. The liquid crystal 2 has a slit transmitted light opening as a test pattern for inspecting the performance of the lens 4 to be inspected,
Part of the light from the halogen light source 19 passes through this opening and is uniformly emitted toward the entire surface of the lens 4 to be inspected.

When inspecting the axial performance of the lens 4 to be inspected, the liquid crystal 2 is controlled by the liquid crystal driver 3, and the on-axis image inspection test patterns 2-1c, 1d, 1e, 1f, shown in FIG.
Either 1g or 1h is displayed, the XY table 23 is driven, and the center of the CCD 21 is aligned with the on-axis optical path 4a of the lens 4 to be inspected.

Test pattern for on-axis image inspection of liquid crystal 2-
The on-axis light fluxes emitted from 1c, 1d, 1e, 1f, 1g, 1h pass through the on-axis optical path 4a and the test pattern 2-1c, 1 is formed on the CCD 21 by the imaging action of the lens 4 to be inspected.
The projected images of d, 1e, 1f, 1g, and 1h are generated. At this time, the scanning direction of the CCD 21 is the test pattern 2-1c, 1
The rotation positions are set perpendicular to the projected images of d, 1e, 1f, 1g, and 1h.

The positional light intensity distribution of the projected images of the test patterns 2-1c, 1d, 1e, 1f, 1g, 1h generated on the CCD 21 is converted into a time series signal by the CCD 21, and this signal is converted into a signal processing device. 22a is A / D converted and stored, the MTF is calculated by the FET, and the monitor 22b displays the MTF value. Thereby, the test pattern 2-1 generated by the lens 4 to be inspected
It is possible to inspect the image formation state of the projected images of c, 1d, 1e, 1f, 1g, 1h. Due to the eccentricity of the lens 4 to be tested, test patterns 2-1c, 1d, 1e, 1f, 1g,
If 1h is off the CCD 21, the liquid crystal driver 3 adjusts the position of the slit transmitted light opening,
21 on the test patterns 2-1c, 1d, 1e, 1f,
The projected images of 1g and 1h are generated. Further, in the case of visual inspection, 2-1g and 1h shown in FIGS. 8 (e) and 8 (f), which are slit transmitted light opening portions for on-axis visual image inspection, are provided on the liquid crystal 2.
The projected image is converted into a time series signal by the CCD 21, the signal is displayed on the monitor 22b, and the inspector observes and judges the signal.

When inspecting the off-axis performance of the lens 4 to be inspected, the liquid crystal 2 is controlled by the liquid crystal driver 3 and the off-axis image inspection test patterns 2-2c and 2d shown in FIG. , 2e, 2f, 2g, 2h to 5c, 5
Display any of d, 5e, 5f, 5g, 5h,
The XY table 23 is driven and installed so that the center of the CCD 21 coincides with the off-axis optical path 4b of the lens 4 to be inspected. Off-axis image inspection test patterns 2-2c, 2d, 2e, 2f,
The off-axis light fluxes emitted from 2g, 2h to 5c, 5d, 5e, 5f, 5g, 5h generate a projected image of the off-axis image inspection test pattern on the CCD 21 by the imaging action of the lens 4 to be inspected. At this time, the scanning direction of the CCD 21 is set to a rotation position perpendicular to the projected image of the test pattern.

Off-axis image inspection test patterns 2-2c, 2d, 2e, 2f, 2g, 2h generated on the CCD 21.
The positional light intensity distributions of the projected images of 5c, 5d, 5e, 5f, 5g, and 5h are converted into time series signals by the CCD 21, and the signals are A / D converted by the signal processing device 22a and stored. , MFT calculation by FFT is performed, and the monitor 22b displays the MTF value. This makes it possible to inspect the image formation state of the projection image of the off-axis image inspection test pattern generated by the lens 4 to be inspected. Due to the eccentricity of the lens 4 to be inspected, the projected image of the test pattern is CC
If it deviates from D21, the position of the slit opening is adjusted by the liquid crystal driver 3 to generate a projected image of the test pattern on the CCD 21.

In the case of visual inspection, 2-2g, 3g, 4g, 5g or 2-2h in FIGS. 8 (e) and 8 (f), which are slit transmitted light openings for visual off-axis image inspection,
3h, 4h, 5h slit transmitted light apertures are provided on the liquid crystal 2, the projected image thereof is converted into a time series signal by the CCD 21, and this signal is displayed on the monitor 22b, which the observer observes and makes a judgment. .

According to this embodiment as described above, the monitor 22
It is also possible to perform a visual inspection with b. In addition, the slit transmitted light opening on the liquid crystal 2 is installed at an arbitrary position, and CC
By moving the center of D21 by the XY table 23 so as to match the off-axis optical path, it is possible to inspect the imaging performance of the lens 4 to be inspected at an arbitrary image height position.

[0041]

As described above, according to the present invention, it is possible to inspect the imaging performance in an arbitrary direction at an arbitrary measurement position of the lens to be inspected without using a mechanism such as rotation in the test pattern portion. . When the inspection lens is inspected by the MTF value and the Fno of the inspection lens is large, the amount of light radiated to the inspection lens is adjusted by increasing the width of the transmitted light aperture of the liquid crystal and adjusting the passing light amount. Can be increased. Further, at the time of the inspection, the test pattern is displayed only at the position corresponding to the inspection position, the projected image thereof is captured by the image scanning means, the signal processing device performs the processing such as A / D conversion, and is recorded, and then the test is performed. The signal of the image scanning means is fetched in a state where all the patterns are not displayed, the A / D conversion is similarly performed, and the noise is generated in the image scanning means by the subtraction from the previously recorded data. Since the influence of light can be calibrated, more accurate inspection can be performed.

[Brief description of drawings]

FIG. 1 is a side view showing a basic configuration of the present invention.

FIG. 2 is a side view showing the first embodiment.

FIG. 3 is a front view of the liquid crystal of Example 1.

FIG. 4 is a front view of a transmitted light portion of FIG.

FIG. 5 is a side view showing a second embodiment.

6 is a front view of the liquid crystal of Example 2. FIG.

FIG. 7 is a front view of the third embodiment.

8 is a front view of the liquid crystal of Example 3. FIG.

FIG. 9 is a perspective view of a conventional device.

FIG. 10 is a plan view showing measurement of a conventional device.

FIG. 11 is a plan view showing measurement of a conventional device.

[Explanation of symbols]

 1 light source 2 liquid crystal 3 liquid crystal driver 4 lens to be inspected 5 image scanning means 6 signal processing means

Claims (1)

[Claims] 1. A light source, a test pattern illuminated by a light beam from the light source, a lens to be examined for forming a projected image of the test pattern, and a positional light intensity distribution of the projected image converted into a time-series signal. Image scanning means and signal processing means for processing a signal from the image scanning means, the test pattern is made of liquid crystal, and the liquid crystal can be driven and controlled by a liquid crystal driver. Performance inspection device.