JPH11304650A - Lens inspecting device with device for adjusting quantity of light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lens inspecting device with a device for adjusting quantity of light that causes no optical deterioration in a projected chart image, is inexpensive, and has simple structure and control. SOLUTION: A lens inspecting device judges whether a lens 11 to be inspected is conforming or not based on the images of axial and non-axial charts CA and CZ that are formed by the lens 11 to be inspected. In the lens inspecting device, luminous flux emitted from a light source lamp 20 is reflected by an axial light source mirror 21 and a non-axial light source mirror 22, axial and non-axial luminous flux through the axial and non-axial charts CA and CZ is applied to the lens 11 to be inspected, and axial and non-axial charge images being formed by the transmitted axial and non-axial luminous flux are received by axial and non-axial photodetectors 43 and 44. In this case, a device 23 for adjusting quantity of light that selectively allows either of beam attenuation filters 231 and 232 to advance into the optical path between the light source lamp 20 and the axial and non-axial light source mirrors 21 and 22 for retracting all is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens inspection apparatus capable of adjusting a light amount in an apparatus for inspecting a lens such as a photographing lens of a camera.

[0002]

2. Description of the Related Art As a method for measuring and inspecting the performance and characteristics of a photographing lens of a camera, there is a measuring method using an MTF. In this measurement, a light source, a chart, a lens to be inspected, and a light receiving element are arranged in the traveling direction of light used for measurement and inspection.

FIG. 15 shows an outline of an optical system of a conventional MTF inspection apparatus. Light source 102A, condenser lens 103A,
The on-axis chart CA and the test lens 101 are
The main luminous flux emitted from 2A is arranged so as to coincide with these centers and the optical axis. The light beam emitted from the light source lamp 102A is converged by the condenser lens 103A and illuminates the on-axis chart CA. The on-axis chart CA is a transmission type chart, and the lens to be tested 101 connects the image of the on-axis chart CA to the on-axis image plane 105A. Light source lamp 1
02Z and the condenser lens 102Z are arranged at a predetermined angle S2 with respect to the optical axis O101. Light source lamp 10
The light beam emitted from 2Z is converged by the condenser lens 103B and illuminates the off-axis chart CZ. Off-axis chart CZ
Is a transmission type chart, and the test lens 101 connects the image of the off-axis chart CZ to the off-axis image plane 105Z.

In order to inspect the images of the charts CA and CZ formed by the lens 101 to be inspected, image planes 105A and 105
An image sensor such as a CCD is arranged at 105Z to capture images of the charts CA and CZ. Then, by processing the picked-up chart image by an image processing device such as a computer, lens inspection and measurement of lens performance are performed.

In the case of a photographic lens of a camera, a finite distance measurement is generally performed using an object-image distance of 2 to 3 m. Therefore, when the test lens 101 is a photographing lens of a camera, the on-axis image plane 1 is obtained from the on-axis chart CA.
The distance to 05A is 2-3 m, and a space longer than this distance is required. Further, as shown in FIG. 15, the charts CA and CZ and the light sources 102A,
Since a space for installing 02Z is required, a longer distance is required.

Further, since the incident angle S2 and the exit angle S1 formed by the off-axis principal ray LZ with the optical axis O101 differ depending on the type of lens, an optical element (off-light source 102) for off-axis measurement is used.
Z, the condenser lens 103Z, and the chart CZ) have angles S2, S1
Needs to be rotated in the direction to change the direction. For example, if the focal length of the test lens is 20 mm to 400 mm and the image height h is 15 mm, the incident angle S2 is about 37.5 ° to 2.5 °, and the exit angle S is
1 varies depending on the lens, but is in the range of about 45 ° to 5 °. Therefore, the lens inspection device shown in FIG. 15 is also enlarged in the vertical direction in the figure, and is a large-sized device requiring an installation surface of about 4 m square. In addition, in the device in which the distance between the object and the image is infinite, in this conventional configuration, the light source, the condensing lens, and the distance between the chart and the image plane must be set at infinity,
This is virtually impossible.

Also, the focal length and the open F-number of the lens to be inspected change depending on the type, and the brightness changes. Therefore, light amount adjustment is required. It is desired that this light amount adjustment can be easily performed with a structure as simple as possible without affecting the image formation of the chart other than the brightness.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional lens inspection apparatus, and has been described in the related art. It is an object of the present invention to provide a lens inspection apparatus provided with a light amount adjustment device which is not deteriorated, has low cost, and is simple in structure and control.

[0009]

According to a first aspect of the present invention, there is provided a lens inspection apparatus for measuring a chart image formed by a test lens, wherein a light beam transmitted through the chart is incident on the test lens. A light source unit to be provided, and a light receiving unit for receiving a chart image formed by the light flux transmitted through the measurement lens, between the light source unit and the chart,
It is characterized by having a light amount adjusting device, which is provided with a dimming filter means for adjusting the light amount incident on the chart. Further, the present invention is a lens inspection apparatus that measures the contrast of a chart image formed by a lens to be inspected and determines the quality of the lens based on the measured value. On the axis transmitted through the off-axis chart, the light source unit that causes the off-axis light beam to enter the lens to be inspected, and on the axis transmitted through the measurement lens, on the corresponding axis by the off-axis light beam, on the off-axis light receiving means An on-axis, off-axis condenser lens for forming a subject image, and a dimming filter means for adjusting the amount of light incident on the on-axis, off-axis chart are provided between the light source unit and the on-axis, off-axis chart. be able to.

In an embodiment of the present invention, an on-axis light source mirror disposed on the optical axis, which reflects a part of the light beam from the light source along the optical axis of the lens to be inspected and transmits the rest, An off-axis light source mirror that reflects a light beam transmitted through the upper light source mirror at a predetermined angle with respect to the optical axis of the test lens, an on-axis chart through which the on-axis light beam reflected by the on-axis light source mirror passes, An off-axis chart through which an off-axis light beam reflected by the outer light source mirror is transmitted, wherein the dimming filter is disposed between the light source and the on-axis light source mirror. The dimming filter means includes a plurality of dimming filters having different dimming rates,
Either one of the neutral density filters is selectively advanced into the optical path or all of them are retracted to adjust the light amount.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a main part of an embodiment of the present invention. In this embodiment, in order to reduce the overall length of the apparatus, an on-axis and off-axis imaging lens is arranged between the lens to be inspected and the image plane to shorten the optical path length from the lens to be inspected to the image plane. One of the features is that measurement at an infinite object-image distance is also possible. Furthermore, the on-axis light beam and the off-axis light beam from the light source are each bent by a mirror arranged before and after the lens to be inspected, thereby shortening the overall length of the device and narrowing the width of the entire device for compactness. There are also features. In the embodiment of the present invention, since the MTF is measured by the back projection method, the traveling direction of the measuring light beam is opposite to that when the actual test lens is used. Therefore, in the description of the embodiments of the present invention, the angle (ie, the angle formed by the off-axis principal ray incident on the test lens with the optical axis of the test lens when the test lens is used, regardless of the traveling direction of the measurement light beam) Incident angle)
1. The angle (exit angle) formed by the off-axis principal ray passing through the test lens and the optical axis of the test lens is defined as S2.

The test lens 11 of the illustrated embodiment is a photographing lens of a camera. The traveling direction of the light beam in this lens inspection device is opposite to the original use state of the test lens 11. That is, the chart CA for on-axis measurement and the chart CZ for off-axis measurement are provided at positions corresponding to the film.
And these are placed on the on-axis light beam LA and off-axis light beam L from the light source mirror unit 2 disposed on the side opposite to the lens 11 to be measured.
Illuminated by Z, and transmitted on and off the axis of the test lens 11, the images of the on-axis and off-axis charts CA and CZ are transmitted through the on-axis and off-axis condensing lenses 41 and 42. Outside light receiving element 43,
An image of the chart CA, CZ is captured by the on-axis and off-axis light receiving elements 43, 44. In this embodiment, the principal rays of the on-axis light beam LA and the off-axis light beam LZ from the light source mirror unit 2 travel in parallel with the plane of FIG.

The light source mirror unit 2 splits the light source lamp 20 and the light beam emitted from the light source lamp 20 into charts CA and C.
An on-axis light source mirror 21 and a movable off-axis light source mirror 22 that reflect toward Z are provided. The on-axis light source mirror 21 is a half mirror, and reflects a part of the light beam emitted from the light source lamp 20 into an on-axis light beam LA, and transmits the remaining light beam as an off-axis light beam LZ. The on-axis light beam LA reflected by the on-axis light source mirror 21 illuminates the on-axis chart CA. The light beam transmitted through the on-axis light source mirror 21 is reflected by the movable off-axis light source mirror 22, becomes an off-axis light beam LZ, and illuminates the off-axis chart CZ. The movable off-axis light source mirror 22 is supported so as to be movable toward and away from the on-axis light source mirror 21 on a straight line, and is rotatably supported about an axis thereof by an axis extending in a direction perpendicular to the paper surface. I have. Further, the light source mirror unit 2 includes a dimming filter switching device 23 for adjusting the amount of light between the light source lamp 20 and the axial light source mirror 21.

The test lens 11 is mounted on a lens mount (not shown) of the lens mount unit 1. This lens mount is a known mechanism that supports the test lens 11 rotatably around its optical axis O11 and can be set to any direction. In the present embodiment, in FIG. 1, when the lens inspection apparatus assumes that a camera body or a photographic lens to which a lens to be inspected is attached is attached to the camera body, an index indicating the upper side of the camera body is above the paper surface. .

The rotation mechanism for rotating the test lens 11 is as follows:
Although not shown in detail, it has a structure that can be set at a predetermined angle in accordance with an instruction from the computer 6, and has a mount portion capable of attaching and detaching the test lens while maintaining sufficient mechanical rotation accuracy. Have. Further, a space is provided on the incident side and the exit side where light beams LA and LZ can pass in anticipation of changes in the incidence and exit angles S1 and S2. The rotating part of the rotating mechanism is made by quenching and polishing the SSK material and mounting a precision grade steel ball with a retainer, thereby ensuring mechanical accuracy such as inclination and displacement of the axis. In addition, a servo motor with an encoder is used for the rotational power, and a photo interrupter or a limit switch is installed so that the origin of rotation can be detected when the power is turned on.

The lens mount 1 includes a lens 11 to be measured.
On the light source mirror unit 2 side, an on-axis chart CA of 20 lines / mm and an off-axis chart CZ of 10 lines / mm are installed. The on-axis light beam LA transmitted through the on-axis chart CA passes through substantially the center of the lens 11 to be inspected, is reflected by the on-axis mirror 31 of the mirror unit 3, passes through the on-axis imaging lens 41, and passes through the on-axis chart CA. Is formed on the on-axis light receiving element 43. On the other hand, the off-axis light beam LZ transmitted through the off-axis chart CZ is incident on the peripheral portion of the lens 11 to be inspected and exits from the peripheral portion. Then, the light is reflected by the movable off-axis mirror 32 of the mirror section 3, passes through the off-axis condenser lens 42, and forms an image of the off-axis chart CZ on the light receiving surface of the off-axis light receiving element 44.

This lens inspection apparatus includes a condenser lens 41,
Since the images of the charts CA and CZ are formed at a shorter distance by the convergence action of the test lens 11 than when the test lens 11 is used alone,
The optical path length of the lens inspection device is shortened.

The images of the charts CA and CZ projected on the light receiving elements 43 and 44 are converted into electric pixel signals by the light receiving elements 43 and 44, and are converted into voltages corresponding to the contrast by the contrast detection circuit 5. The digital signal is processed by the computer 6 by the / D conversion circuit. The computer 6 inspects the quality of the lens 11 to be inspected by comparing the contrast values of the on-axis and off-axis chart images obtained in this way with the quality judgment values set and stored in advance. . That is, the contrast value of the image of the on-axis chart CA and the contrast value of the image of the off-axis chart CZ are measured, and the quality of the test lens 11 is determined by comparing the contrast value with the quality determination value. In the illustrated embodiment, in order to measure the focus error of the lens 11 to be measured, the light receiving elements 43 and 44 are moved stepwise around a design focus position (reference position) within a predetermined distance range before and after. The contrast is measured at the step moving position, and the focus error is measured.

The contrast refers to the sharpness. In the present embodiment, a value obtained by dividing the difference between the light amounts of the brightest and dark portions of the image by the sum of the light amounts of the bright and dark portions is used as the contrast. I do. “MTF” is a transfer function of contrast, that is, a quotient obtained by dividing the contrast of the output image by the contrast of the input image. For example, in this lens inspection apparatus, a chart having a contrast near 1 at 20 lines / mm on the axis and 10 lines / mm off the axis is used as an input image, so that the contrast in the ideal state and the MTF are the same.

Test lens 11 and on-axis condenser lens 41
Accordingly, the image of the on-axis chart CA is projected on the on-axis light receiving element 43. Although the spatial frequency of the on-axis chart CA is 20 lines / mm, an image having a size obtained by multiplying the on-axis chart CA by the projection magnification is projected on the on-axis light receiving element 43. If the focal length of the on-axis condenser lens 41 is 250 mm and the focal length of the lens 11 to be measured is 50 mm, and the measurement is performed in the ∞ state, the magnification of the image plane (the optical system composed of the lens 11 and the condenser lens 41) Is 5 times, and the on-axis light receiving element 43 has 4 lines /
mm image is projected. Therefore, the on-axis light receiving element 43
It suffices if a sinusoidal light quantity distribution of 4 lines / mm can be electrically converted. In this embodiment, a general-purpose facsimile CCD line sensor having a pixel pitch of 14 μm can be used, so that the on-axis and off-axis light receiving elements 43 and 44 can be configured at low cost. The on-axis and off-axis light receiving elements 43 and 44 are S / S
The better the N, the temperature characteristic, the linearity of the light amount, and the like are better, but the temperature characteristic can be corrected by a circuit or software.

The contrast detecting means of the illustrated embodiment calculates the contrast by analog signal processing.
The output of D may be immediately subjected to A / D conversion to perform digital signal processing. Analog signal processing is inexpensive and operates quickly, but noise tends to be applied to the processing circuit portion (OP amplifier), and the MTF changes greatly due to temperature fluctuations. Digital signal processing is expensive and slow in operation, but noise is less likely to occur in the processing circuit portion, and the change in MTF due to temperature is small. Select either one according to the specifications of the entire device.

In the illustrated embodiment, the on-axis and off-axis light receiving elements 4
The image signals output from the image processing units 3 and 44 are processed by an image processing apparatus (computer 6) to obtain contrast and MTF.
The lens characteristics and pass / fail are determined. One embodiment of the contrast detecting means will be described with reference to FIG. Since on-axis and off-axis contrast detection can be performed by an apparatus having the same configuration, an embodiment of an apparatus for detecting on-axis contrast will be described in this specification. The measurement conditions of this embodiment are as follows. Focal length of lens to be tested: 50 mm Focal length of on-axis focusing lens: 250 mm Distance between object images: ∞

On-axis and off-axis light receiving elements 43 and 44 are CCDs
In the line sensor, a large number of light receiving elements are arranged in a vertical direction with the light receiving surface facing the left side of FIG. In one embodiment, 2048 pixels (light receiving elements) are arranged at a pitch of 14 μm and have a total length of about 29 mm.

The on-axis light receiving element 43 includes a signal generation circuit 530.
Integration, transfer, and clocks such as reset clock, transfer clock, and transfer clock output by 0
Read operation is performed. Each pixel charge integrated and output by the on-axis light receiving element 43 is converted into a voltage signal proportional to the light quantity distribution of the image projected on the on-axis light receiving element 43 by the sample and hold circuit 5301 and output. (A) of FIG.
FIG. 17 is a graph showing an output signal of the sample hold circuit 5301 in a graph. On-axis chart CA of this embodiment
Is a grating consisting of a light-shielding part and a light-transmitting slit,
The output signal of the on-axis light receiving element 43 is a SIN-shaped AC signal, and corresponds to a portion where the peak voltage a is the brightest (a light transmitting slit portion) and a portion where the bottom voltage b is the darkest (a light shielding portion). Therefore, the contrast is calculated by the formula: (ab) / (a + b).

This AC signal is supplied to a high-pass filter 530.
2 to obtain an AC signal having an intermediate value of ± 0 (FIG. 2).
(B)), the full-wave rectification circuit 5303 performs full-wave rectification into a plus-only signal (FIG. 2C). The full-wave rectified signal is integrated by the integration circuit 5304 for a preset time. The integration is performed on the absolute value signal shown in FIG.

Similarly, the output signal (S) shown in FIG.
The IN-shaped AC signal) is divided through the resistor block 5305, and then integrated by the integration circuit 5306 for the same time as the integration time by the integration circuit 5304. Then, a dividing circuit 5307 including an analog element forms an integrating circuit 5304.
Is divided by the output signal of the integration circuit 5306 to obtain M
Find the TF.

As described above, in the present embodiment, the AC component of the voltage signal corresponding to the chart image is taken out, converted into an absolute value, and the integrated signal is divided by the signal obtained by integrating the original voltage signal. A signal proportional to the MTF is obtained. The MTF obtained as a voltage by the division is converted into a digital value and written into the storage means 7 of the computer 6. The contrast detection circuit shown in FIG. 2 is provided with two sets of on-axis and off-axis for this lens inspection apparatus.

In the embodiment of the present invention, a master lens manufactured with high precision was measured with high precision using a higher-precision measuring device, and the measured known MTF and the actual measured value were measured with the illustrated lens inspection device. Master lens M
The characteristics of the lens inspection device are calibrated, corrected, or adjusted based on the TF measurement value. For example, a value obtained by dividing the known MTF of the master lens by the MTF measurement value actually measured by the lens inspection apparatus of the present embodiment is used as an MTF correction value, and the MTF correction value is multiplied by the MTF measurement value of the lens to be inspected.
In another embodiment, the measured MTF of the master lens is known M
The output of the lens inspection device is corrected to match the TF.

In this embodiment, a resistance block 5305 having a plurality of resistance rows is provided to correspond to different types of lenses to be inspected. Resistance block 5305
As shown in FIG. 3, a resistor R, a variable resistor VR, and a switch SW are connected in series, and three resistor columns are provided in parallel. In the measurement using the MTF correction value, the resistance value of the resistance block 5305 is selected by switching the connection of the resistance line by ON / OFF of the switch SW according to the type of the lens to be inspected, and the input current to the integration circuit 5306 is determined. Adjustment. In the measurement without using the MTF correction value, the accurate MT
F, that is, the variable resistor VR is adjusted so that the known MTF of the master lens and the MTF measurement value of the master lens match.

The purpose of switching the resistance string in the measurement using the MTF correction value is to improve the S / N ratio, so that a precise resistance value is not required, and the resistance value is switched in steps of a multiple of two. To improve the S / N ratio, a 1.5 times series (1,
1.5, 2.2,...), And a quadruple series (1,
4, 16,...) Are suitable. In the measurement using the MTF correction value, the variable resistor VR is unnecessary. That is, in the method of setting the MTF correction value so that the MTF measured value of the master lens matches the known characteristic data of the master lens, the adjustment by the variable resistor VR is unnecessary.

Further, the resistor blocks 5305 are provided with the resistor rows as many as the types of the measuring lenses. Although three rows are shown in FIG. 3, resistor rows are provided in a number corresponding to the type of lens to be measured. In the method using the MTF correction value, at least one type of resistor row is required, and a resistor row corresponding to the number of types becomes unnecessary.

In the embodiment of the present invention, a master lens having a known characteristic is measured by the lens inspection device, and the mechanical and electrical characteristics of the lens inspection device are adjusted so that the measured value matches the known characteristic value of the master lens. Calibrate the characteristic or measured value. Next, measurement is performed by the lens inspection device after the calibration, so that measurement accuracy can be maintained regardless of the type of the lens to be inspected.

FIG. 12 is a view for explaining the measurement azimuth of the lens to be inspected in this lens inspection apparatus. Rectangle 51
Indicates a photographing range on the imaging plane when the test lens is normally used. For example, in the case of a photographing lens of a 35 mm film camera, the photographing range is 36 mm wide and 24 mm long on a film. The symbol C51 indicates the center of the rectangle 51 that displays the outline of the shooting screen, and the circle 52 indicates that the image height h is 15 mm.
Shows the off-axis measurement position corresponding to.

Line segments 0-4 and 2-6 are diagonal lines and line segment 1-5
Is a horizontal bisector, and line segment 3-7 is a vertical bisector. Reference numerals 0 to 7 indicate azimuths radially divided into eight from the center of the shooting screen. In other words, the first off-axis azimuth indicates the position 53 on the circle 52 in FIG.
F indicates the radial or meridional MTF at the position 53. In the lens inspection apparatus of the present embodiment, the MTF in the meridional direction is measured for all off-axis directions. Also, the direction of the axial MTF, for example, the axial MTFA
1 is the direction of the line segment 1-5, and is optically on-axis MTFA
It is equivalent to 5.

In this specification, MTF is used for MTF-related variables, "PP" is used for image plane-related variables, "A" is used for on-axis related variables or angle variables, and off-axis related variables are used. Alternatively, the angle variable is identified by adding “Z”. The variables related to the azimuth centered on the optical axis of the lens to be inspected are 0 to 7 described above.
And the number of bearings. For constants such as standard values, "S
TD ”. Then, terms are defined by combining the above symbols and numbers. For example, MTFZ1 is the MTF in the first off-axis azimuth, and in FIG.
Is the MTF.

[Setting of Mirror Position and Angle] When measuring and changing the lens to be inspected, that is, when measuring a different lens to be inspected (hereinafter simply referred to as “model change”), the angles S1 and S2 are set. Need to be changed.

The first is a case where a large amount of the same type of zoom lens is inspected, and corresponds to the production process of the zoom lens itself, a compact camera equipped with the zoom lens, and a digital camera. In the case of a zoom lens, MTF measurement is performed at different focal lengths, for example, at two points (a short focal length and a long focal length) on the wide angle side and the telephoto side. The two points on the wide-angle side and the telephoto side are not necessarily two points on the wide-angle end and the telephoto end, and may be measured at an appropriate focal length that can maintain the quality of the lens. Hereinafter, corresponding to the first case is referred to as “zoom compatible”.

The second is a case where a plurality of completely different types of single focus lenses are measured. In this case, once switching is performed, it is often the case that a plurality of lenses of the same type are measured in succession. At this time, the switching may take a certain amount of time, but it is desired to support three or more types, as many as possible. Hereinafter, the response to the second case is referred to as “multi-model response”. The present invention provides a lens inspection device that supports this zoom and that supports various types.

[Light Source Mirror Unit for "Zoom"] One embodiment of the light source mirror unit 2 for zoom is shown in FIGS.
This will be described with reference to FIG. In the case of zooming, the change of the off-axis light beam LZ required when changing the model is realized by switching the position KP and the angle KA of the movable off-axis light source mirror 22. FIG. 4 shows a half mirror 21 of the light source mirror unit 2 of FIG.
FIG. 3 is a diagram showing details of a periphery of a movable off-axis light source mirror 22; FIG. 4 shows an embodiment in which the angle S2 is switched between 20 ° on the telephoto side and 45 ° on the wide-angle side as an example of zooming. The light source mirror section 2 has a mechanism for switching the angle S2 corresponding to the wide angle side and the telephoto side in about one second. In FIG. 4, the movable off-axis light source mirror 22 in the telephoto state is indicated by a solid line, and the movable off-axis light source mirror 22 in the wide-angle state is indicated by a dashed line on the right side. As can be seen from this figure, in the telephoto state and the wide-angle state, the movable off-axis light source mirror position KP changes and the movable off-axis light source mirror angle KA also changes. The on-axis light source mirror 2
1 is fixed at an angle of 45 ° with the optical axis O11.

FIG. 5 shows the movable off-axis light source mirror 22 shown in FIG.
, The half mirror 21 is omitted when viewed from the left side. The movable off-axis light source mirror 22 is
The rotation center KPT of the reflection surface 22a is fixed so as to coincide with the axis of the rotation shaft 2201. The rotation shaft 2201 is
Brackets 22 whose both ends are arranged in parallel at predetermined intervals
11, 2212, and brackets 2211, 22
Between 12, there is formed a recess 2202 whose flat surface exceeds the axis. The movable off-axis light source mirror 22 is provided in the concave portion 2202,
The reflection surface 22a is attached in a state where the reflection surface 22a substantially coincides with the rotation center of the rotation shaft 2201. However, FIG. 5 shows a state where the movable off-axis light source mirror angle KA is 0 ° for easy understanding of the shape of the concave portion 2202.

The rotating shaft 2201 has brackets 2211 and 2211 at both ends thereof via bearing members 2214 and 2215 having low friction, for example, made of Teflon or the like.
12 is rotatably supported. This bracket 22
11 and 2212 are fastened and fixed by a connecting member 2213 and are integrated.

At one end of the rotating shaft 2201, a stopper bar 2203 extending in a direction perpendicular to the axis is attached. When the off-axis light source mirror 22 moves to the wide angle side, the stopper bar 2203
06, and when it moves to the telephoto side, it comes into contact with the rotation stopper 2204 to set the rotation angle KA of the movable off-axis light source mirror 22. In the illustrated embodiment, the movable off-axis light source mirror angle KA is set so that S2 becomes 20 ° on the telephoto side.
Is set to 45 ° + S2 / 2 = 55 °, and S is set on the wide-angle side.
The movable off-axis light source mirror angle KA is set to 45 ° + S2 / 2 = 67.5 ° so that 2 becomes 45 °. In a measuring device that measures each MTF using a light beam transmitted on the axis of the test lens 11 and off-axis, the movable off-axis light source mirror angle KA when the light source light beam is deflected by the movable off-axis light source mirror is determined. , 45 ° ± S2 / 2. S2 / 2
Is shown in FIG.

The brackets 2211 and 2212 are attached to a pair of shafts 2221 and 2222 arranged in parallel with the principal ray from the light source lamp 20 by a bearing member 222 with little friction.
It is slidably supported via 3, 2224. The brackets 2211 and 2212 are connected to the shaft 222.
It moves linearly along the sides 1 and 2222 (in the left-right direction in FIG. 4) to enable the position of the movable off-axis light source mirror 22 to be adjusted. The stoppers 2231 and 2233 are members that regulate the position on the telephoto side and the position on the wide angle side of the movable off-axis light source mirror 22, are movably mounted on the shaft 2221, and are fixed and loosened by tightening the screws 2232 and 2234. It is configured to be movable. Note that the shafts 2221, 2222
Are fixed at both ends to a support plate 2200 (only one is shown) attached to a fixing part (not shown).

The movable off-axis light source mirror 22 is urged to rotate clockwise in FIG. 4 by a spring (not shown). When the movable off-axis light source mirror 22 is at the telephoto side movable off-axis light source mirror position KP regulated by the stopper 2231 by the urging force of the spring, the stopper bar 22
03 is in contact with the rotation stopper 2204 to set the movable off-axis light source mirror angle KA on the telephoto side, and when the movable off-axis light source mirror position KP on the wide-angle side is restricted by the stopper 2233, the stopper bar 2203 moves the rotation stopper 2204.
, And abuts against the rotation stopper 2206 to set the movable off-axis light source mirror angle KA. Rotation stopper 2204,
Reference numeral 2206 denotes a screw, which can set and adjust the angle KA of the movable off-axis light source mirror by moving the distal end portion due to its rotation. The rotation stopper 2204 is screwed into a stopper holding block 2205 attached to the fixed portion, and the rotation stopper 2206 is screwed into the support plate 2200. The movable off-axis light source mirror 22 is connected to a connecting member 2213.
The shaft 22 is connected to an actuator (not shown) such as a single air cylinder or an electromagnetic plunger.
11 and 2212.

The thus configured zoom-compatible light source mirror section 2 uses a single actuator to move the off-axis movable light source mirror 22 to the stoppers 2231 and 22 at the telephoto end and the wide-angle end.
The position KP of the movable off-axis light source mirror 22 that can support the measurement on the telephoto side and the wide-angle side is set by simply moving the mirror 33 (the left and right moving end in FIG. 4). Off-axis light source mirror 2
The angle KA of 2 is also set. Therefore, the switching time is shortened, and since the positioning is performed by mechanical application, sufficient accuracy can be obtained. Further, since only a single actuator needs to be controlled, the structure and control are easy.

In this embodiment, the movable off-axis light source mirror 22 is disposed at a position farther from the light source lamp 20 than the on-axis light source mirror 21. However, as shown in FIG. Movable off-axis light source mirror 2 on the 20 side
When 2 is arranged, the sign of S2 / 2 is negative. In the mirror arrangement shown in FIG. 6, the movable off-axis light source mirror 22
Is a half mirror, and the on-axis light source mirror 21 is a normal mirror. When one end of the stopper bar 2203 comes into contact with the rotation stopper 2206, the movable off-axis light source mirror angle KA is set to 55 ° on the telephoto side, and the other end of the stopper bar 2203 is set to the rotation stopper 2204.
The stoppers 2204, 2206, 2232, and 2234 are set so as to be set at 20 ° on the wide-angle side when they come into contact with.

[Zoom Compatible Off-Axis Mirror Unit] When the angles S1 and S2 change due to model change, it is necessary to change the position and angle of the off-axis mirror 32 of the mirror unit 3. The support mechanism of the mirror unit 3 for the zoom-compatible off-axis mirror 32 is similar to the support mechanism of the zoom-compatible light source mirror unit 22. One embodiment of the mirror unit 3 for zooming will be described with reference to FIG. FIG. 7 shows details around the movable off-axis mirror 32 in the mirror section 3 of FIG. The movable off-axis mirror section 32 is a mechanism for zooming, and is a mechanism for switching the off-axis light flux between the wide-angle side and the telephoto side in about one second. In the figure, the movable off-axis mirror 32 in the wide-angle state is indicated by a solid line, and the movable off-axis mirror 32 in the telephoto state is indicated by a dashed line on the right side.

FIG. 7 shows that the angle of incidence S1 is 20 at the telephoto side.
゜, on the wide angle side, the movable off-axis mirror 32 corresponding to the case of 40 ° is shown. The movable off-axis mirror 32 is fixed to a rotating shaft 320 extending in a direction perpendicular to the paper surface such that the axis of the rotating shaft 320 and the reflecting surface 32a coincide.
The rotating shaft 320 is rotatably supported by plate-like brackets 328 arranged in parallel at a predetermined interval, although both ends, only one of which is not shown.

Similarly to the light source mirror section 2, the rotation angle MA of the movable off-axis mirror 32 is normally 45 ° ± S1 / 2, where the rotation angle of the on-axis mirror rotation 31 is 45 °.
The position MP of the movable off-axis mirror 32 is (J−I) × tanS
1 + H. Here, J is the distance from the optical axis of the off-axis condenser lens 42 to the charts CA and CZ, and I is the lens 11 to be measured.
Is the distance from the surface closest to the mirror portion 3 to the charts CA and CZ, and h is the optical axis O11 of the test lens 11 of the off-axis principal ray at the position of the frontmost end surface of the test lens 11 closest to the mirror portion 3 , Which corresponds to H (off-axis principal ray incident height) shown in FIG.

Two stopper bars 321 and 322 are fixed to one end of the rotating shaft 320 in the radial direction, and are extended by a tension spring 324 suspended between one of the stopper bars 322 and the bracket 328. Are biased in the counterclockwise rotation direction. On the wide angle side where the incident angle S1 is 40 °, the stopper bar 321 is
, The off-axis mirror angle MA becomes 45
{+ S1 / 2 = 65} is set. On the other hand, the incident angle S
On the telephoto side where 1 becomes 20 °, the movable bar off-axis mirror angle MA is set to 45 ° + S1 / 2 = 55 ° by the stopper bar 322 abutting against the rotation stopper 325.

The rotation stoppers 323, 32 according to the present embodiment
Since each of the screws 5 is a screw, the movable off-axis mirror angle MA can be set by moving the distal end portion by its rotation. Since the stopper piece 326 on which the rotation stopper 325 is raised is slidably mounted on the shaft 329 and is configured to be movable and fixed by the screw 327, even if the amount of change of the movable off-axis mirror position MPZ is large. By moving the stopper piece 326, the angle can be easily set while allowing the movable off-axis mirror 32 to move. Stopper 32
Reference numeral 1 stands on a flange protruding from a bracket 328 that rotatably supports the rotating shaft 320 of the movable off-axis mirror 32.

A bracket 328 for holding the movable off-axis mirror 32 is slidably mounted on a pair of parallelly arranged shafts 330a and 330b via a bearing member with little friction. The shafts 330a and 330b are arranged in parallel with the optical axis of the condenser lens 42, and guide the movable off-axis mirror 32 so as to be linearly movable along the optical axis of the condenser lens 42. The position MP of the movable off-axis mirror 32 is set by position stoppers 331 and 332 mounted on the shaft 330b and abutting on the bracket 328. Position stoppers 331 and 332 for setting the positions on the telephoto side and the wide angle side of the bracket 328 are fixed by tightening screws (not shown).
The position stopper 331 is formed so as to be loosened and movable.
Is the off-axis mirror position MP on the telephoto side of the bracket 328
And the position stopper 332 sets the movable off-axis mirror position MP on the wide angle side of the bracket 328.

A piston rod 325 of a reciprocating air cylinder 333 is connected to the bracket 328 by the connecting member 3.
36. Compressed air is sent to the air cylinder 333 via a speed controller 334, the piston rod 325 is pushed out, and the bracket 328 and the movable off-axis mirror 32 are moved through the shaft 335 connected to the piston rod 335 to the right in the figure. The bracket 328 is moved in the direction until the bracket 328 contacts the position stopper 331. Bracket 328 is position stopper 331
In a state where the mirror is stopped by contact with the stopper, the stopper bar 322 contacts the stopper 325, and the movable off-axis mirror angle MK becomes five.
Set to 5 °.

Conversely, when moving leftward in the figure from the telephoto side to the wide-angle side, compressed air is sent to the air cylinder 333 via the speed controller 337 in a direction in which the piston rod 325 is drawn. Then, the movable off-axis mirror 32 moves leftward in the figure until the bracket 328 contacts the position stopper 332. When the support member is in contact with the position stopper 332 and stopped, the stopper bar 321 is in contact with the rotation stopper 323 and the movable off-axis mirror angle M
K is set to 65 °.

The “zoom-ready” mirror unit 3 thus configured can simultaneously switch both the position and the angle on the telephoto side and the wide angle side of the movable off-axis mirror 32 by the operation of the single air cylinder 333. Therefore, the switching operation can be completed in a short time. In addition, since the position and angle of the movable off-axis mirror 32 are determined by mechanical application, high accuracy can be maintained.

[Light Source Mirror Unit for "Multiple Models"] The embodiment described above corresponds to the zoom. Next, an embodiment corresponding to multiple models will be described with reference to FIG. The position KP of the movable off-axis light source mirror 22 is determined by setting the off-axis height (image height) to 1
Assuming that the distance from the chart CA, CZ to the optical axis of the light source is 5 mm and K is KP = 15 + K × tanS2, S2
It can be seen that it changes depending on. That is, the off-axis movable light source mirror position KZ is changed according to the focal length of the lens to be measured. In order to measure a plurality of types of lenses to be inspected having different focal lengths as described above, it is necessary that the movable off-axis light source mirror position KP and the rotation angle KA can be arbitrarily set, and that the settings are easy. It is.

The light source mirror section of "multi-model compatible" which has such a demand does not require the high-speed operation as the light source mirror section of "zoom compatible", but the setting range of the position and angle of the movable off-axis light source mirror is wide. It is necessary. One embodiment of a light source mirror unit compatible with various types will be described with reference to FIG.

FIG. 8 is a diagram showing a main part of a movable off-axis light source mirror driving mechanism for various models. Off-axis light source mirror 2
2 is held on a rotating shaft 2241 similarly to the embodiment of FIG. 2, and the rotating shaft 2241 is a pair of brackets 2251,
It is rotatably supported between 2252. A step motor 2261 is supported on one of the brackets 2251 via a support member (not shown).
Are connected to a rotating shaft 2241. By controlling the number of drive pulses of the step motor 2261, the rotation angle of the movable off-axis light source mirror 22 can be controlled. In the illustrated embodiment, for example, the step motor 226
When one is driven by one pulse, the rotating shaft 2241 is configured to rotate by 0.1 °.

In the figure, the movable off-axis light source mirror angle KA is 4
At 5 °, the limit bar 2263 fixed to the rotating shaft 2241 pushes the contact 2265 of the limit switch 2264 fixed to the bracket 2251 to turn on the limit switch 2264. The position where this ON signal is generated is set as a reference point at 45 ° of the movable off-axis light source mirror angle KA,
If the movable off-axis light source mirror angle KA to be set is, for example, 55 °, the number of driving pulses is (55−45) /0.1=
8, that is, in FIG. 8, when the step motor 2261 is driven counterclockwise by 100 pulses, the movable off-axis light source mirror angle KA can be set to 55 °.

When changing the setting of the movable off-axis light source mirror 22 (movable off-axis light source mirror angle KA), in this embodiment, the stepping motor 226 is used in order to increase the accuracy after the change.
1 to rotate the off-axis movable light source mirror 22 until the limit switch 2264 is turned ON (clockwise rotation in the figure). When the limit switch 2264 is turned on, the step motor 2261 is stopped, and the step motor 2261 is driven from that position by the number of pulses corresponding to the new off-axis light source mirror angle KA.

The off-axis light source mirror 22
To set the movable off-axis light source mirror angle KA after returning to the start position where the limit switch 2264 is turned on, for example, when the movable off-axis light source mirror angle KA is changed from 60 ° to 55 °, the step motor 2261 is turned off. When driving at 240 pulses / sec, ((60-4
5) + (55−45)) / 0.1 / 240 = 250/2
40 ≒ 1, that is, the time required from the start to the end of the change of the movable off-axis light source mirror angle KA is about 1 second.

A bracket 225 for supporting a rotary drive unit such as the movable off-axis light source mirror 22 and the step motor 2261
1, 2252 are integrated by a connecting member 2253,
A shaft 2271, similar to the zoom-compatible light source mirror unit,
It is formed so as to be able to move linearly along 2272. The connecting member 2253 is provided with a female screw, and a feed screw 2282 connected to the rotating shaft of the step motor 2281 is screwed into the female screw. That is, the step motor 2261 and the off-axis movable light source mirror 22 are
251 and 225 and the connecting member 2253 are linearly moved by a step motor 2281.

A stopper plate 2273 is fixed to the bracket 2251. When the feed screw 2282 rotates clockwise, the bracket 2251 moves together with the stopper plate 2273 to the left in the figure, and the stopper plate 2273 is By pressing 2275, the limit switch 2274 is turned on. The off-axis light source mirror position KP is set using the position where the limit switch 2274 changes from OFF to ON as a reference position.

The pitch of the feed screw 2282 is 1 mm, the step motor 2281 is 10 revolutions / second, the currently set movable off-axis light source mirror position KP is 40 mm, the new movable off-axis light source mirror position KP is 50 mm, and the limit switch 2274 is OFF.
Assuming that the reference position that changes from ON to ON is 20 mm, ((40
−20) + (50−20)) / 10 = 5, that is, the movable off-axis light source mirror position KP can be changed in 5 seconds.

[Movable Off-Axis Mirror Unit for "Multiple Models"]
The mirror unit of "multi-model compatible" does not require a high-speed operation as the mirror unit of "zoom compatible", but the position and angle must be freely set. The configuration to detect and set the reference position and angle with a switch using a step motor for setting the angle MA and a motor or actuator for setting the position MP with a relatively high speed is a "multi-model compatible" movable off-axis light source mirror unit. It becomes possible with the same thing as.

[Adjustment of Light Amount] The brightness of the test lens varies depending on the type. Therefore, when the brightness of the light source is the same, the light receiving elements 43, 44,
The amount of received light at 42 is different, and the output levels of the light receiving elements 43 and 44 fluctuate greatly. In other words, even when the maximum output level of the light receiving elements 43 and 44 is close to the maximum value of the dynamic range of the light receiving elements 43 and 44 in the case of a bright test lens, the same maximum output level is obtained in the case of a dark test lens. It becomes near the minimum value of the dynamic range, and the accuracy is reduced due to the influence of noise. Conversely, if the brightness of the light source is set so that the maximum output level is a value near the middle value of the dynamic range in the case of a dark test lens,
In the case of a bright test lens, the maximum output level may exceed the maximum value of the dynamic range, making measurement impossible. Therefore, it is necessary to adjust the amount of light in order to keep the output levels of the light receiving elements 43 and 44 within the dynamic range and maintain a good S / N ratio. Therefore, in the embodiment of the present invention, a light-attenuating filter having a transmittance capable of obtaining an appropriate light amount based on the result of the light amount measurement of the on-axis and off-axis light receiving elements 43 and 44 which is an intermediate measurement value of the MTF measurement. Switched to the configuration.

In the optical system shown in FIG. 1, when the light amount of the light source lamp 20 and the F value of the lens under test and the condenser lens are constant, the sensor surface (light receiving element) is proportional to the square of the focal length of the lens under test. The illuminance of the light receiving surfaces 43 and 44 changes. For example, the ratio of the light amounts of the test lenses having the focal lengths of 20 mm and 400 mm is 400 times.

On the other hand, the dynamic range of a CCD sensor is only about 1000 times at room temperature. Therefore, in order to effectively use the dynamic range of the CCD sensor,
It is necessary to adjust the amount of light incident on the sensor or the illuminance on the sensor surface. Therefore, in the embodiment of the present invention, the light amount adjusting device for limiting the illuminance of the sensor surface is provided.

A light amount adjusting device 23 is arranged between the light source 20 of the light source unit 2 and the on-axis light source mirror 21 in FIG. FIG. 9 shows an embodiment of the light amount adjusting device 23. The desolate stretching device 23 includes first and second neutral density filters 231 and 2
32. The first neutral density filter 231 is a filter having a flat transmittance and a colorless transmitted light, and a light transmittance of 10%. The second neutral density filter 232 is formed by stacking two first neutral density filters 231 and has a light transmittance of 1
%.

The neutral density filters 231 and 232 are provided at predetermined intervals on the neutral density filter support plate 234, and in the illustrated embodiment, 6 mm.
The main light 241 of the light source lamp 20 is held at an interval of 0 mm.
In a direction that can be received almost vertically. In the embodiment shown in FIG. 9, the dimming filter support plate 234 is connected to the piston rods at the tips of a plurality of cylinders connected in multiple stages, and the dimming is selectively performed by the expansion and contraction of the piston rod of each cylinder. The filters 231 and 232 are advanced into the optical path, or all of them are retracted from the optical path. That is, the neutral density filter support plate 234 is fixed to the first slider 237, and is movably supported by two actuators arranged in parallel, for example, air cylinders 235 and 236.

The first air cylinder 235 is slidably guided through a fixed block 239 fixed to a fixed structure of the lens inspection device, and is slidably guided.
1 is fixed through the second slider 238.
The tip of the piston rod 2351 is the first slider 2
37 is slidably penetrated and supported. The second air cylinder 236 penetrates through the fixed block 239 and is fixed to the second slider 238, and the second piston rod 2361 is fixed to the first slider 238. FIG. 9 shows a state where the piston rod 2361 of the second air cylinder 236 has been fully extended.

First and second air cylinders 235 and 23
6, the movement amounts of the piston rods 2351 and 2361 are set to 60 mm. FIG. 9 shows that the first piston rod 2351 is retracted and the second piston rod 2351 is retracted.
61 extends 60 mm, and the filter 231
1 shows a first-stage extended state that has advanced between 0 and the on-axis light source mirror 21.

When the first piston rod 2351 extends 60 mm from the first stage extended state, the second slider 23
8 moves 60 mm integrally with the first piston rod 2351, so that the second cylinder 236
Move 60mm with 38. That is, the piston rod 2361, the first slider 237, and the filter support plate 234 also move by 60 mm, and the second filter 232 advances between the light source lamp 20 and the on-axis light source mirror 21.
It becomes a step extension state.

The first cylinder 235 and the second cylinder 236 are both retracted and the piston rod 2351,
When the 2361 is retracted, the sliders 237 and 238 move to a reference position where they contact each other and the fixed block 239, and retract the filters 231 and 232 from the optical path between the light source lamp 20 and the on-axis light source mirror 21.

FIG. 9 shows a state in which only one air cylinder 236 is extended, and the first slide member 237 is separated from the second slide member 238 by 60 mm. % ND filter 231 is inserted. The two air cylinders 235 and 236 are extended and the second slider 238 is fixed to the fixed block 239.
60 mm away from the filter support plate 23
4 is shifted 60 mm to the left, and the light-attenuating filter 23 having a light transmittance of 1%.
2 is inserted into the optical path. Air cylinder 23
5, 236 are both contracted, and the first and second sliders 2
In a state where the fixing blocks 37 and 238 are in contact with the fixing block 239, the neutral density filter supporting plate 234 is moved from the state of FIG.
It moves to the right by mm and both the neutral density filters 231 and 232 are retracted outside the optical path, that is, the light transmittance becomes 100%.

The above two air cylinders 235, 23
With the six configurations, it is possible to set three types of positions: a contracted state, a stretched state, and a stretched state. That is, the neutral density filter support plate 234 is moved in the length direction of the piston rods 2351 and 2361 in steps of 60 mm and set at three positions, and according to the set positions, the light transmittance is 100%, 10%, It has been switched to 1%.

The light-attenuating filter installed in the light source mirror unit 2 of the present embodiment is disposed closer to the light source than the chart, and illuminates the chart with the luminous flux transmitted through the light-attenuating filter. There is no danger of image deterioration, and it is possible to use an inexpensive frosted glass or the like diffusion surface instead of an expensive ND filter. Also,
In the example of FIG. 9, three types of light amount switching of 100%, 10%, and 1% light transmittance are shown. However, by increasing or decreasing the same configuration, N + 1 sliding members and actuators are combined. It is possible to switch the amount of light. In the illustrated embodiment, since an air cylinder is used as an actuator, the structure is simple, small, and high-speed operation is possible as compared with a driving mechanism using a motor. Furthermore, since the ON / OFF of the pneumatic control solenoid valve for extending and retracting the air cylinder may be controlled by the computer 6, the control is simplified.

[Detection of Light Amount] The output of the integration circuit 5306 is proportional to the amount of light received by the sensor 43, and can be used for detecting the amount of transmitted light of the lens to be measured. Information for light intensity adjustment
The output of the integration circuit 5306 is supplied to the bypass 5311, A /
Digital conversion is performed via the D converter 5308 and the digital conversion is performed by the microcomputer 5309. If the amount of light is out of the appropriate range, the microcomputer 5309 switches the neutral density filter so that the amount falls within the appropriate range.

When performing the aperture inspection of the lens to be inspected by the lens inspection apparatus, the on-axis light amount MLIG of the master lens data is used.
By using the HTA and the off-axis light amount MLIGHTTZ and comparing the on-axis measured value LIGHTTA and the off-axis measured value LIGHTTZ, the measurement and inspection of the aperture or off-axis vignetting can be performed simultaneously with the MTF measurement.

[Adjustment of Reference Position of Light-Receiving Element (Adjustment of Image Surface Position)] Next, the fluctuation was caused by expansion and contraction of the structure of the lens inspection apparatus due to temperature fluctuation, aging, or expansion and contraction of an optical element such as a condenser lens. An embodiment of a mechanism and a method for adjusting and setting the reference positions of the light receiving elements 43 and 44 according to the image plane position (focus position) will be described.

In the present embodiment, the position of the light receiving element is adjusted by adjusting the master lens M measured by the lens inspection apparatus.
The measured values of the on-axis image plane position (on-axis focus position) and the off-axis image plane position (off-axis focus position) of the master lens M
This is a process of adjusting the positions of the light receiving elements (on-axis light receiving element 43 and off-axis light receiving element 44) so as to match the known characteristic data of L. In the embodiment of the present invention, the master lens ML
Sensor for detecting the start position of the on-axis and off-axis light receiving elements 43 and 44 such that the start position is located at a fixed distance from the on-axis and off-axis chart image (focus position), that is, the reference position. Adjust the position of. This start position is a start position at which the light receiving elements 43 and 44 are scanned and moved to measure the image plane position of the lens to be measured.

One embodiment of a mechanism for adjusting the reference position of the light receiving element will be described with reference to FIG. In the illustrated embodiment, the on-axis image plane position of the master lens ML is 0, and the off-axis image plane position is -100 μm. In this specification, the condensing lenses 41 and 42 are provided on the image plane side of the condensing lenses 41 and 42.
Is defined as “plus”, and the direction approaching the condenser lens 41 is defined as “minus”.

FIG. 10 shows the on-axis condenser lens 41, the on-axis light receiving element 43 and its peripheral structure in FIG. The on-axis condenser lens 41 is fixed so that its optical axis O41 substantially coincides with the on-axis light flux LA (principal ray). The off-axis condenser lens 42, the off-axis light receiving element 44 and the peripheral structure are the same as those shown in FIG.

The on-axis light receiving element 43 is mounted on the CCD drive circuit board 430 and is mounted on the CCD holding member 433 via the CCD drive circuit board 430. The CCD holding member 433 is slidably supported by two guide shafts 431 and 432 arranged in parallel with the axial light beam LA. Both ends of the guide shafts 431 and 432 are supported by bridges 404 and 405 connecting the pair of side plates 401 and 402 of the light receiving unit frame 40, respectively.

A feed screw 435 is disposed between the guide shafts 431 and 432 in parallel with them, and one end of the feed screw 435 is screwed to the CCD holding member 433. The other end of the lead screw 435 is the bridge 40
5 is connected to the rotating shaft of a step motor 434 mounted on the motor. That is, the CCD holding member 433 is moved forward and backward by the rotation of the feed screw 435 which is rotated and driven by the step motor 434.

Between the CCD holding member 433 and the bridge 405, a position where the rear end face of the CCD holding member 433 contacts the contact point, that is, a light receiving means reference position for setting a reference position of the light receiving surface of the axial light receiving element 43. A limit switch 436 is provided as setting means. Limit switch 43
6 is a guide shaft 431 via the substrate 4361
And is screwed to a feed screw 438 arranged in parallel with the shafts 431 and 432. The feed screw 238 is connected to a rotation shaft of a step motor 437 mounted on the bridge 405, and is rotationally driven by the step motor 437 to move the limit switch 436 along the guide shaft 431.

Step motor 434 for moving the image pickup device
Rotates once in 20 pulses (18 ° in one pulse),
Since the pitch of the feed screw 435 is set to 2 mm,
When the step motor 434 rotates by one pulse, the on-axis light receiving element 43 moves by 0.1 mm in parallel with the on-axis light beam LA. On the other hand, the step motor 437 and the feed screw 438 for the limit switch rotate the step motor 437 by one pulse, that is, the feed screw 438.
Is rotated by one pulse, the step angle of the step motor 437 and the pitch of the feed screw 438 are set so that the limit switch 436 moves by 4 μm.

The limit switch 436 is a switch for detecting and setting the reference position of the on-axis light receiving element 43. When setting the position of the axial light receiving element 43, first,
The step motor 434 is rotated in the plus direction so that the on-axis light receiving element 43 approaches the limit switch 436, and waits until the limit switch 436 is turned on. When the limit switch 436 is turned on, the step motor 434 is stopped, and the step motor 434 is moved in the minus direction (on-axis condenser lens 41) by a predetermined step with the stop position as a reference position.

When inspecting the lens to be inspected, every time the stepping motor 434 is driven one step, the image data is taken in from the axial light receiving element 43, the MTF is calculated and recorded. Hereinafter, the driving of the step motor 434 is referred to as “scanning”, the driving steps are referred to as “scanning steps”, and the number thereof is referred to as “scanning step number WSS”. FIG. 11 shows the MTF data recorded in this way, with the horizontal axis representing the number of steps and the vertical axis representing the MTF. In this figure,
It can be seen that the image plane (focus position) exists at the position of 160 steps.

Here, for example, the focal length of the test lens is 50 mm, the measurement at infinity, and the focal length of the condenser lens is 250 mm.
mm, the movement amount of the on-axis light receiving element 43 for one step of 0.1 mm is 1/25 of the chart position of the lens to be inspected.
× 0.1 = 4 μm only. Therefore, when it is necessary to expect variation of the focal length of the lens to be inspected by ± 0.5 mm including aberration and ± 125 in steps,
Must be able to move more than 250 steps (1mm). Therefore, in the present embodiment, the number of scanning steps WSS is set so that the light receiving elements 43 and 44 can be moved by 250 steps or more when measuring the lens under test.
Is set to, for example, 300. In order to reduce the measurement time, it is desirable that the number of scanning steps WSS be a necessary minimum value in consideration of the variation of the lens to be inspected. Therefore, it is desirable to determine the number of scanning steps WSS for each model.

In the lens inspection apparatus of this embodiment, the number of scanning steps W is set so that the position of the image plane can be measured efficiently.
The adjustment is performed so that the on-axis image plane position (= 0) of the master lens ML, which is a reference of the on-axis image plane position, is located at a position of 1/2 step of SS. For example, when the image plane is detected at the position of 160 steps in the on-axis image plane position measurement of the master lens ML, it is corrected (corrected) to 150 steps which is WSS / 2. For this purpose, in the present embodiment, the step motor 437 for the limit switch is rotated by 10 steps in the minus direction in terms of the number of steps of the step motor 434 for the image sensor.

In this embodiment, the limit switch 4
By moving 36 in the minus direction (left direction in the figure) by 1 mm, the axial image plane position with respect to the limit switch 436 changes by 10 steps (1 mm / 0.1 mm = 10). The moving distance of one step of the step motor 437 is 4μ.
m, the step motor 437 is driven in the minus direction by 250 pulses (1 mm / 4 μm = 250).
In this way, the axial image plane of the master lens ML is changed from the start position by 160 steps to 150 steps, and the axial image plane reference position is adjusted. By this operation, the on-axis image plane position of the master lens ML becomes a position driven by 150 steps in the minus direction from the start position detected by the limit switch 436, and the measured lens is accurately measured using the 150 steps as a reference position. Is adjusted to be able to.

In the calibration of the detected value of the off-axis image plane position, the mechanical structure for moving the off-axis light receiving element 44 is the same, but it is not uniform to WSS / 2 as on the axis.
The curvature of field MDM of the master lens data (here,-
The position of the off-axis limit switch is adjusted so as to coincide with 100 μm). Assuming that the position shifted by 150 steps as on the axis is 0 (reference position), the image plane formed by the master lens ML is shifted by -100 μm.
That is, since the off-axis image plane of the master lens ML is displaced by 25 steps (100 μm / 4 μm = 25) toward the test lens, the off-axis image plane position is located at a position shifted by 175 steps from the start position. Adjust the position of the off-axis limit switch. “MDM” is an abbreviation for Defocus Meridional of a master lens.

[Lens Inspection] Inspection and measurement of a photographing lens using this lens inspection apparatus will be described. In this embodiment, before measuring a test lens, a master lens corresponding to the test lens is measured.

[Automatic Adjustment of Inspection Apparatus Using Master Lens] In the lens inspection apparatus of the present invention, automatic adjustment (calibration and correction) can be performed using the master lens in changing the measurement model and performing other calibrations. The processing in that case will be described in more detail.

In order to automatically adjust the lens inspection device,
A master lens ML having known characteristics is prepared. The master lens ML includes: 1-1 on-axis contrast (MTF: MMTFA1) 1-2 off-axis contrast (MTF: MMTFZ1) 1-3 on-axis contrast peak position (on-axis image plane position: MPPA1) 1 -4 Off-axis contrast peak position (off-axis image plane position: MPPZ1) Four items are precisely measured by a higher-order measuring instrument. The above measured values are written in advance in the storage means 7 of the computer 6 as master lens data, input by an operator when measuring the corresponding lens, or read from a removable medium. The measurement value of the master lens ML by the higher-level measuring device is identified by attaching a symbol “M” before the symbol of the measurement value as master lens data.

In the case of inspecting the light amount of the lens, two additional items are added as measurement items of the master lens ML: 1-5-axis light amount: MLIGHTTA, 1-6 off-axis light amount: MLIGHTTZ. These light amounts are used for light amount adjustment such as selection of a neutral density filter.

The data to be written into the storage means 7 are: 1-3 on-axis contrast peak position (on-axis image plane position) and 1-4 off-axis contrast peak position (off-axis image plane position). (MPPA1-MPPZ1) may be used. The difference between the on-axis image plane position and the off-axis image plane position is defined as a field curvature amount MDM.

When the master lens ML is used also as a reference lens for focusing, in order to adjust the on-axis image plane position with sufficient accuracy, the on-axis image plane position is set to the reference = 0 and the off-axis image plane position is set to the master. It can be lens data.
In this case, the off-axis image plane position is equal to the field curvature.

[Measurement of Master Lens] The worker mounts the master lens ML corresponding to the lens to be inspected on the mount unit 1. Then, the type of the master lens ML, known data, the type of the corresponding lens to be inspected, characteristic data, a calibration instruction command, and the like are input to the computer 6. The computer 6 uses the type information of the master lens ML, the information written in the storage means 7 in advance,
2 position MP and angle MA, movable off-axis light source mirror 22
Position KP and angle KA, filter information LV according to the amount of light, pass / fail threshold values STDMNLA, STDMNLZ,
The scanning amounts WWS and WSH for scanning the image plane are read.

The computer 6 reads the on-axis and off-axis chart image data while moving the on-axis and off-axis light receiving elements 43 and 44 stepwise, and reads the on-axis MTF (MTFA1) and off-axis MTF (MTF) of the master lens ML. MTFZ1),
The MTF correction value, the field curvature amount MDM, and the direction of the field curvature
It is calculated as master lens information necessary for measurement inspection and stored. Then, the lens inspection apparatus is automatically calibrated so that the on-axis MTF of the master lens ML and the off-axis MTF measured by the lens inspection apparatus match the master lens data. For example, the master lens ML
The lens to be inspected is actually measured as the on-axis and off-axis MTF correction value obtained by dividing the high-precision known on-axis and off-axis MTF by the on-axis and off-axis MTF measurement values measured by this lens inspection apparatus. To the on-axis and off-axis MTF measurements.
Multiply by the F correction value. Alternatively, for example, when the resistance block circuit shown in FIG. 3 is provided, the variable resistor VR is adjusted so that the on-axis and off-axis MTF measurement values of the master lens coincide with the on-axis and off-axis MTF. The output levels of 43 and 44 are adjusted.

As described above, the lens inspection apparatus according to the embodiment of the present invention adjusts the lens inspection apparatus based on the above data, or sets calibration and correction data. Upon completion of the processing performed by the lens inspection device, the user
The master lens ML is removed from the lens mount 1. The adjustment and calibration of the lens inspection device for changing the model are completed by the above processing and operations.

Thereafter, without changing the above settings, the test lens 11 is mounted on the lens mount 1, and the image plane position measurement and the MTF measurement are performed. The computer 6 writes the positions of the movable off-axis light source mirror 22 and the movable off-axis mirror 32 corresponding to the lens type,
The rotation angle data is read in, the movable off-axis light source mirror 22 and the movable off-axis mirror 32 are set, and the reference positions of the on-axis and off-axis light receiving elements 43 and 44 obtained by the master lens measurement, the adjustment of the start position, the dimming filter Set, select, and prepare for measurement and inspection. Then computer 6
Executes the MTF measurement while moving the light receiving elements 43 and 44 stepwise from the start position.

Data that can be measured by the lens inspection apparatus according to the embodiment of the present invention includes, for example, the following items. On-axis MTF: MTFAn (n = 0 to 7 azimuths, the same applies hereinafter), Off-axis MTF: MTFZn, On-axis MTF on axis average image plane: MTFLan, Off-axis MTF on axis average image plane: MTFLZn The amount of curvature of field: DMn, the amount of on-axis and off-axis light: LIGHTTA, LIGHTTZ, the on-axis image plane position: PPAn, and the off-axis image plane position: PPZn. The judgment data includes a judgment result of good or bad of the lens to be inspected. Further, the correction data includes an on-axis MTF correction value: HMTFA1, an off-axis MTF correction value: HMTFZ1, and other variables indicating the measurement state.

The inspection operation of the lens to be inspected will be described in more detail with reference to FIG. The measurement direction of the lens is set to the first direction. By rotating the lens mount by a predetermined angle with a rotation mechanism not shown,
The test lens is oriented in the normal use (first orientation).

For the image plane scanning, the on-axis and off-axis light receiving elements 43 and 44 are set at the mechanical start positions. The on-axis light receiving element 43 is moved to a position where the limit switch 436 is turned on by driving the step motor 434. Similarly, the off-axis light receiving element 44 is moved by a moving mechanism (not shown) to a position where a limit switch (not shown) similar to the limit switch 436 is turned on. By the above processing,
The off-axis light receiving elements 43 and 44 are set at reference positions for image plane scanning. The image plane scanning referred to here means that the on-axis and off-axis light receiving elements 43 and 44 are moved stepwise in the direction of the optical axis and the principal ray, and the on-axis and off-axis light receiving elements 43 and 4 are moved at each step movement position.
4 is to read the chart image data, measure the contrast, and search for a peak position where the contrast is maximum.

While the on-axis MTF is measured from the output of the on-axis light receiving element 43, the stepping motor 434 is driven to drive the on-axis light receiving element 43.
Is step-moved from right to left in the figure by the set image plane scanning amount WSS. Similarly, while measuring the off-axis MTF from the output of the off-axis light receiving element 44, the off-axis light receiving element 44 is step-moved from right to left in the figure by the set image plane scanning amount WSS. By the above processing, the MTF in the on-axis horizontal direction: MTFA1, the maximum position of the MTF in the on-axis horizontal direction: PPA1, the MTF in the off-axis horizontal direction: MTFZ1, the maximum position of the MTF in the off-axis horizontal direction: PPZ1, are obtained. .

Third azimuth image plane scanning The lens mount 1 is turned by a predetermined angle,
Is rotated, for example, in the vertical direction (third direction). Then, while measuring the on-axis MTF from the output of the on-axis light receiving element 43, the stepping motor 434 is driven to drive the on-axis light receiving element 4
3 is moved stepwise from left to right in the figure by the measured axial image plane position PPA1 + WSH in the first azimuth. Similarly,
While measuring the off-axis MTF from the output of the off-axis light receiving element 44, the off-axis light receiving element 44 is moved stepwise from left to right in the figure by the measured off-axis image plane position PPZ1 + WSH in the first azimuth. By the above processing, the MTF in the on-axis vertical direction: MTFA3, the maximum position of the MTF in the on-axis vertical direction: PPA3, the MTF in the off-axis vertical direction: MTFZ3, and the maximum position of the MTF in the off-axis vertical direction: PPZ3. .

The on-axis and off-axis light receiving elements 43 and 44 are set at the average on-axis image plane position. Next, the axis is set on the average on-axis image plane position HKNPPA in two horizontal and vertical directions defined by (PPA1 + PPA3) / 2. Upper and off-axis light receiving elements 43 and 44 are set.

On-axis and off-axis MTF measurement at the average on-axis image plane position The test lens is rotated to a predetermined azimuth 0, 1, 2, 3,
The MTF when facing (angle) at 4, 5, 6, 7 is measured and stored. By this measurement, eight MTFALs (0, 1, 2,...) Which are the MTF values on the axis at the average on-axis image plane position are obtained.
3, 4, 5, 6, 7) value, off-axis M at average on-axis image plane position
Eight MTFZLs (0, 1, 2, 3, 4,
5, 6, 7) The values are measured.

Pass / Fail Judgment The on-axis MTF minimum value at the eight average on-axis image plane positions is calculated, and the minimum value MTFMNLA is set to the standard value STDMNL.
Compare with A. If MTFMNLA> STDMNLA, the shaft is regarded as good. The minimum value of the off-axis MTF at the eight average on-axis image plane positions is calculated and the minimum value MTFMNL is calculated.
Z is compared with a standard value STDMNLZ. If MTFMNLZ> STDMNLZ, off-axis is regarded as good. If both on-axis and off-axis are good,
The test lens shall be non-defective. In addition, the pass / fail judgment reference value and the reference are arbitrary.

MTFPP measured by the above processing
The value and the pass / fail judgment value are written to the storage unit 7 of the computer 6. The basic operation for measuring the lens to be inspected has been described above, but it is also possible to measure the image plane position in all directions. In this case, by repeating the image plane scanning in all eight directions, MT
F, measured values in all eight directions of the on-axis and off-axis image planes are obtained. When measuring eccentricity, field curvature, coma, and astigmatism,
Eight direction measurements are performed. For calibration and pass / fail determination, MTF measurement on the average image plane on the vertical and horizontal axes described above may be used. In this case, the measurement time is short since the image plane scanning needs to be performed twice. In the lens production process, the off-axis MTF is a meridional (radial direction) because changes and deterioration due to the process can be managed.
Only measurement is required.

In the above embodiment of the present invention, before measuring the lens to be measured, first, the master lens corresponding to the lens to be measured is measured, and the measured value is compared with the highly accurate known data of the master lens. By providing each part of the lens measuring device or a means for correcting the measured value so as to match, it is possible to transfer to some extent the cost and the measurement accuracy of the higher-ranking measuring device which took much time for one measurement. In addition, when there are a plurality of lens production processes and a plurality of lens inspection devices, calibration can be performed under the same conditions by calibrating them with the same master lens. Furthermore, when calibrating a plurality of lens inspection devices installed at a plurality of locations, by using a plurality of master lenses measured under the same measurement conditions by a higher-level measuring device,
Many products can be measured with the same measurement accuracy, which is very effective in quality control.

In a lens measurement / inspection apparatus used in a lens production process, the validity of the measurement / inspection ability is required. In principle, the MTF simply needs to be able to measure the spatial distribution of the amount of light of the image by the lens to be inspected, but it takes time and cost to achieve high accuracy. Therefore, the MTF measuring device having the capability of automatic calibration by the master lens as in the present embodiment can maintain the accuracy by performing the calibration by the master lens, and can maintain the IS090.
The adaptability to quality control such as 01 is improved. In this case, the contents to be calibrated using the master lens are the image plane position, the MTF, and the light amount.

[Automatic Lens Inspection] According to the lens inspection apparatus of the present invention, if the model of the lens and the master lens can be specified, the model change can be automated. For example, on the master lens, a part or structure that can specify the model of the lens is provided, or a member having the information is provided,
The corresponding master lens information is selected from these, and the characteristics of the lens inspection device are calibrated and adjusted.

FIG. 14 is a diagram showing a state of an embodiment of a process by this automation. The test lens on the belt 111 moves from right to left toward the lens mount 13 of the lens inspection device. Although not shown in FIG. 15, the SCARA robot 116 attaches and detaches the lens to be inspected to and from the lens mount 13 of the lens inspection apparatus shown in FIG. The lens to be inspected is a different model for every fourth lens. The first lens 112M, 113M, 114M, 115M of each group is a master lens, and the subsequent lenses 112, 113, 11
Reference numerals 4 and 115 are test lenses.

Although not shown in detail, an identification tag for identifying the model of the lens is affixed to the master lens 112M. Known techniques such as a barcode and a magnetic tape can be used as the identification tag. The master lens data may be read from the identification table of the master lens 112M, or may be obtained from the model and the master lens number by accessing a database of the lens inspection device or a database to which the lens inspection device is connected. As described above, according to the present invention, so-called mixed flow production, in which a plurality of types of lenses can be produced on the same line, which has been impossible in the conventional lens inspection automation process, has become possible.

[Evacuation of the Movable Off-Axis Mirror Outside the On-Axis Light Beam]
Since the lens inspection apparatus of the present invention has an on-axis and off-axis measurement system, on-axis and off-axis MTF can be measured at the same time. However, depending on the internal space of the apparatus, on-axis and off-axis light beams may not be separated. It may not be possible. In this case, by controlling the position or angle of the movable off-axis mirror, the luminous flux of the on-axis and off-axis measurement systems is switched, and the focal length of a large-diameter, ultra-wide-angle lens is 400
Enables measurement of super-telephoto lenses of mm or more.

When measuring a large-aperture telephoto lens with the optical system of FIG. 1, the following problems occur. As an example, assume a case where an F5.6 lens is measured at a focal length of 300 mm. The incident angle S1 of the off-axis chief ray is 2.8 °, the distance L from the off-axis chart CZ illuminated with the off-axis chief ray to the front end of the test lens is 200 mm, and the distance H between the incident position of the test lens and the optical axis. Is 17.5 mm, the on-axis light beam diameter φA is 54 mm, the off-axis light beam diameter φZ is 38 mm measured in a direction parallel to the paper surface, and the distance J from the off-axis chart CZ to the optical axis of the off-axis focusing lens 42 is 2
If the distance is 40 mm, the on-axis light beam and the off-axis light beam emitted from the lens to be inspected overlap, so that they cannot be separated.

FIG. 13 is an enlarged view showing a state in which this problem occurs. In such a case, if the distance J is increased to the position where the off-axis light flux is separated on the axis, the apparatus becomes large. In this example, the distance J becomes longer by about 200 mm. In order to avoid this, the present invention provides a time difference between on-axis and off-axis measurements. For example, first, the movable off-axis mirror 32 shown by the broken line is retracted to a position where the on-axis light flux is not shielded (the middle off-axis mirror 32). That is, in FIG. 13, the end portion 32a of the movable off-axis mirror 32 is separated (retracted) from the optical axis to a position where the end portion 32a does not cross the on-axis light beam diameter φA.
In this retracted state, measurement is performed with the on-axis light flux, and the measured value is stored. Then, the center of the movable off-axis mirror 32 is moved to the correct center position MP indicated by the dashed line, and measurement is performed with the off-axis light flux. Perform inspection with the above measured values. It goes without saying that the measurement order on the axis and off-axis may be reversed.

In the above embodiment, the movable off-axis mirror 32
Was moved in parallel with the optical axis of the off-axis converging lens and retracted, but the movable off-axis mirror 32 may be rotated and retracted around the outside of the on-axis light flux diameter φA. For example, end 32
It is rotated about the end 32b opposite to a. Also,
If the center position MP is outside the on-axis light beam diameter φA, the center position MP
Rotate around. Further, when the lens to be inspected is attached to the lens inspection apparatus, when the lens is to be removed and the movable off-axis mirror 32 is close to the lens, it is difficult to perform the operation. To be larger.

[Measurement of Mechanical Change] In a zoom lens, an autofocus lens, and a lens having a plastic lens barrel, the mechanical rigidity tends to be reduced particularly. Therefore, in the embodiment of the present invention, the lens to be measured is rotated around the optical axis thereof by the lens rotation driving device 103 via the rotation mount 101 to execute MTF measurement in a plurality of directions to reduce the mechanical rigidity. Measure.

MTFA1 is the MT in the 1-5 direction at the axial position.
Since it is F, it is optically the same as MTFA5. Optical means that when the lens is rotated by a half rotation around the optical axis and measured by the optical system shown in FIG. 1, the measured values MTFAl and MTF which are generally obtained due to a mechanical change or a measurement error of the lens.
This is because A5 has a different value. If the acceleration, vibration and the like applied to the lens at the time of measurement are kept constant, it can be used for measuring the mechanical change of the lens. For example, based on the data of MTFA0 to MTFA7 obtained by the measurement, the difference between MTFA0 and MTFA4, the difference between MTFAl and MTFA5, the MTF
The difference between A2 and MTFA6, the difference between MTFA3 and MTFA7,
By measuring either, it is possible to measure the MTF change caused by the mechanical configuration of the lens.

The lens inspection apparatus repeats the same operation unless the set operation command is changed. Therefore, the acceleration change mainly due to the acceleration / deceleration in the rotation direction applied to the lens causes the autofocus mechanism of the zoom lens to be not rotationally symmetric, so that the zoom lens moves in accordance with the acceleration change, deforms and optically changes the MTF. Sometimes. According to the lens inspection apparatus of the present invention, which can measure the MTF quickly and accurately, even with such a lens, the mechanical stability of the lens, the lens barrel, the axial blur, the lens Inspection and evaluation of the rigidity of the lens barrel became possible.
It is desirable that the rotation mount 101 be rotated at each acceleration of one rotation per second or more.

[0125]

As is apparent from the above description, the first aspect of the present invention is directed to a chart formed by a light source unit for causing a light beam transmitted through a chart to enter a test lens, and a light beam transmitted by the measurement lens. Light-receiving means for receiving an image; and, between the light source unit and the chart, light-reducing filter means for adjusting the amount of light incident on the chart, so that the optical performance of the light-reducing filter affects the chart image. This makes it possible to form the neutral density filter with a relatively inexpensive material.
According to a sixth aspect of the present invention, the dimming filter means includes a plurality of dimming filters having different dimming rates, and one of the dimming filters is selectively advanced into the optical path, or all of the dimming filters are retracted. Since the light amount can be adjusted by adjusting the light amount, the light amount can be adjusted with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of an embodiment of a lens inspection apparatus to which the present invention is applied.

FIG. 2 is a block circuit diagram showing an example of a contrast detecting means in the embodiment and a diagram showing waveforms of main parts in a graph.

FIG. 3 is a diagram showing one embodiment of a resistance block of the contrast detecting means.

FIG. 4 is a diagram showing an outline of a main part of a light source mirror unit of the lens inspection apparatus.

FIG. 5 is a front view of the light source mirror unit of FIG. 5;

FIG. 6 is a diagram showing an embodiment in which the movable off-axis light source mirror is arranged closer to the light source lamp than the on-axis light source mirror in the light source mirror unit.

FIG. 7 is a diagram showing an outline of a main part of a mirror unit of the lens inspection apparatus.

FIG. 8 is a diagram showing an outline of a main part of a light source mirror unit corresponding to various models as another embodiment of the light source mirror unit of the lens inspection apparatus.

FIG. 9 is a diagram showing an embodiment of a light amount adjusting device of the lens inspection device.

FIG. 10 is a diagram showing an embodiment of a position adjusting mechanism of an imaging means of the lens inspection apparatus.

FIG. 11 is a graph showing MTF data measured by the lens inspection apparatus.

FIG. 12 is a diagram illustrating a measurement direction of a lens to be inspected in the lens inspection apparatus.

FIG. 13 is a diagram illustrating a state in which an on-axis light beam and an off-axis light beam cannot be separated.

FIG. 14 is a diagram illustrating an outline of a case where measurement of a plurality of types of lenses to be inspected is automated in the lens inspection apparatus of the present invention.

FIG. 15 is a diagram showing an outline of an optical system of a conventional apparatus for measuring MTF of a lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens mount part 101 Rotation mount 103 Lens rotation drive device 11 Lens under test 2 Light source mirror part 20 Light source lamp 21 On-axis light source mirror 22 Off-axis light source mirror 2201 Rotation axis 2203 Stopper bar 2204 2206 Stopper 2211 2212 Support member 2214 2215 Bearing Member 2221 2222 Shaft 2231 2233 Stopper 2232 2234 Screw 2241 Rotation axis 2251 2252 Support member 2253 Connection member 2261 Step motor 2262 Rotation axis 2263 Limit bar 2264 Limit switch 2273 Stopper plate 2281 Step motor 2282 Feed screw 231 First light reduction filter 232 2 neutral density filter 31 on-axis mirror 32 off-axis mirror 320 rotating member 321 322 Top bar 323 Stopper 324 Tension spring 325 Stopper 326 Stopper piece 327 Shaft 328 Support member 329 Shaft 330a 330b Shaft 331 332 Stopper 333 Air cylinder 335 Shaft 336 Connection member 40 Light receiving unit frame 401 402 Side plate 404 405 Bridge Bridge Outer condenser lens 43 On-axis light receiving element 431 432 Guide shaft 433 CCD holding member 434 Step motor 435 Feed screw 436 Limit switch 437 Step motor 438 Feed screw 44 Off-axis light receiving element 5 Contrast detection circuit 5300 Signal generation circuit 5301 Sample hold circuit 5302 High-pass filter 5303 Full-wave rectifier circuit 5304 Integrator circuit 5305 Resistor block 5306 Min circuit 5308 A / D converter 5311 Bypass 6 computer (computing, evaluation means) 7 storing means

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 18, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 7

[Correction method] Change

[Correction contents]

FIG. 7 ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 10, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

Further, since the incident angle S1 and the exit angle S2 formed by the off-axis principal ray LZ with the optical axis O101 differ depending on the type of lens, an optical element (off-light source 102) for off-axis measurement is used.
Z, the condenser lens 103Z, and the chart CZ) have angles S1, S2 around the optical center of the lens to be inspected substantially at the center of rotation.
Needs to be rotated in the direction to change the direction. For example, when the focal length of the lens to be inspected is 20 mm to 400 mm and the image height h is 15 mm, the incident angle S1 is about 37.5 ° to 2.5 °, and the exit angle S is
2 varies depending on the lens, but is in the range of about 45 ° to 5 °. Therefore, the lens inspection device shown in FIG. 15 is also enlarged in the vertical direction in the figure, and is a large-sized device requiring an installation surface of about 4 m square. In addition, in the device in which the distance between the object and the image is infinite, in this conventional configuration, the light source, the condensing lens, and the distance between the chart and the image plane must be set at infinity,
This is virtually impossible.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction contents]

A piston rod 335 of a reciprocating air cylinder 333 is connected to the bracket 328 by the connecting member 3.
36. The air cylinder 333, compressed air is fed via the speed controller 334, the piston rod 335 is pushed, Pisutonro
Bracket bracket 328 and the movable shaft outer mirror 32 connected to the head 335, in the right direction in FIG. 328
Is moved until it comes into contact with the position stopper 331. When the bracket 328 abuts on the position stopper 331 and stops, the stopper bar 322 abuts on the stopper 325 and the off-axis mirror angle MA is set to 55 °.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction contents]

[0054] moving backwards from the telephoto side to the left direction in view of the wide-angle side, sends the compressed air in a direction to retract the piston rod 335 to the air Siri <br/> Sunda 333 via the speed controller 337. Then, the movable off-axis mirror 32 moves leftward in the figure until the bracket 328 contacts the position stopper 332. The support member is a position stopper 332
When the stopper bar 321 is in contact with the rotating stopper 323 and the movable off-axis mirror angle
MA is set to 65 °.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of an embodiment of a lens inspection apparatus to which the present invention is applied.

FIG. 2 is a block circuit diagram showing an example of a contrast detecting means in the embodiment and a diagram showing waveforms of main parts in a graph.

FIG. 3 is a diagram showing one embodiment of a resistance block of the contrast detecting means.

FIG. 4 is a diagram showing an outline of a main part of a light source mirror unit of the lens inspection apparatus.

FIG. 5 is a front view of the light source mirror unit of FIG. 5;

FIG. 6 is a diagram showing an embodiment in which the movable off-axis light source mirror is arranged closer to the light source lamp than the on-axis light source mirror in the light source mirror unit.

FIG. 7 is a diagram showing an outline of a main part of a mirror unit of the lens inspection apparatus.

FIG. 8 is a diagram showing an outline of a main part of a light source mirror unit corresponding to various models as another embodiment of the light source mirror unit of the lens inspection apparatus.

FIG. 9 is a diagram showing an embodiment of a light amount adjusting device of the lens inspection device.

FIG. 10 is a diagram showing an embodiment of a position adjusting mechanism of an imaging means of the lens inspection apparatus.

FIG. 11 is a graph showing MTF data measured by the lens inspection apparatus.

FIG. 12 is a diagram illustrating a measurement direction of a lens to be inspected in the lens inspection apparatus.

FIG. 13 is a diagram illustrating a state in which an on-axis light beam and an off-axis light beam cannot be separated.

FIG. 14 is a diagram illustrating an outline of a case where measurement of a plurality of types of lenses to be inspected is automated in the lens inspection apparatus of the present invention.

FIG. 15 is a diagram showing an outline of an optical system of a conventional apparatus for measuring MTF of a lens.

DESCRIPTION OF SYMBOLS 1 Lens mount unit 101 Rotation mount 103 Lens rotation drive device 11 Lens to be inspected 2 Light source mirror unit 20 Light source lamp 21 On-axis light source mirror 22 Off-axis light source mirror 2201 Rotation axis 2203 Stopper bar 2204 2206 Stopper 2211 2212 Supporting member 2214 2215 Bearing member 2221 2222 Shaft 2231 2233 Stopper 2232 2234 Screw 2241 Rotating shaft 2251 2252 Supporting member 2253 Connecting member 2261 Step motor 2262 Rotating shaft 2263 Limit bar 2264 Limit switch 2273 Stopper plate 2281 Stepping motor 2281 Feed screw Dimming filter 232 Second dimming filter 31 On-axis mirror 32 Movable off-axis mirror 320 Rotating member 321 322 Stopper bar 323 Stopper 324 Tension spring 325 Stopper 326 Stopper piece 327 Screw 328 Support member 329 Shaft 330a 330b Shaft 331 332 Stopper 333 Air cylinder 335 Piston rod 336 Connection member 40 Light receiving portion frame 401 402 Side plate 404 405 Bridge Optical lens 42 Off-axis condenser lens 43 On-axis light receiving element 431 432 Guide shaft 433 CCD holding member 434 Step motor 435 Feed screw 436 Limit switch 437 Step motor 438 Feed screw 44 Off-axis light receiving element 5 Contrast detection circuit 5300 Signal generation circuit 5301 Sample hold circuit 5302 High-pass filter 5303 Full-wave rectifier circuit 5304 Integrator circuit 5305 Resistance block Click 5306 integration circuit 5308 A / D converter 5311 Bypass 6 computer (computing, evaluation means) 7 storing means

Claims (12)

[Claims] 1. A lens inspection apparatus for measuring a chart image formed by a lens to be inspected, comprising: a light source unit for illuminating the chart; and a light receiving unit for receiving a chart image formed by a light beam transmitted through the lens to be inspected. Means for adjusting the amount of light incident on the chart, between the light source unit and the chart. 2. An on-axis light source mirror arranged on an optical axis, wherein a part of a light beam from a light source is reflected along an optical axis of a lens to be inspected and the rest is transmitted. When,
An off-axis light source mirror that reflects the light beam transmitted through the on-axis light source mirror at a predetermined angle with respect to the optical axis of the lens to be inspected, and an on-axis chart through which the on-axis light beam reflected by the on-axis light source mirror is transmitted. An off-axis chart through which an off-axis light beam reflected by the off-axis light source mirror is transmitted; and the dimming filter unit includes a light amount adjusting device disposed between the light source and the on-axis light source mirror. Lens inspection equipment. 3. The lens inspection apparatus according to claim 1, wherein a part of the light beam from the light source is reflected at a predetermined angle with respect to the optical axis of the lens to be inspected, and the remaining light is transmitted. An off-axis light source mirror, an on-axis light source mirror that reflects a light beam transmitted through the off-axis light source mirror along an optical axis, an off-axis chart through which an off-axis light beam reflected by the off-axis light source mirror passes, A lens provided with an on-axis chart through which an on-axis light beam reflected by the upper light source mirror is transmitted, wherein the dimming filter means includes a light amount adjusting device disposed between the light source and the off-axis light source mirror. Inspection equipment. 4. The lens inspection apparatus according to claim 2, wherein the on-axis and off-axis light beams transmitted through the lens to be inspected are shifted in a direction in which the off-axis chief ray forms a right angle with the optical axis. On-axis and off-axis light condensing lenses including on-axis and off-axis mirrors that reflect on-axis and off-axis mirrors, and on-axis and off-axis light condensing lenses that collect off-axis main light beams A lens inspection device provided with an on-axis and off-axis light receiving means for receiving the on-axis and off-axis chart images respectively connected by the above. 5. The lens inspection device according to claim 1, wherein the light-reducing filter means includes a plurality of light-reducing filters having different light-reducing rates, and any one of the light-reducing filters is provided. A lens inspection device provided with a light amount adjusting device that adjusts the light amount by alternatively entering the optical path or retreating the whole. 6. The lens inspection apparatus according to claim 5, wherein said neutral density filter means includes a plurality of neutral density filters arranged at predetermined intervals on said neutral density filter support plate, and moves said neutral density filter support plate. A lens inspection device including a light amount adjusting device that adjusts the light amount by causing any of the neutral density filters to advance into the optical path, or by retracting all the neutral density filters. 7. The lens inspection apparatus according to claim 6, wherein the neutral density filter support plate is supported by an actuator at a tip end of a plurality of actuators connected in multiple stages, and a stroke of each of the actuators is any one of the plurality of actuators. A lens inspection device in which a neutral density filter is set to an amount that can be selectively advanced into an optical path. 8. The lens inspection apparatus according to claim 7, wherein the actuator is a cylinder, and the dimming filter support plate is connected to a piston rod of a tip cylinder, and a stroke of each cylinder is equal to that of the adjacent cylinder. A lens inspection device provided with a light amount adjustment device set to be equal to the interval between matching neutral density filters. 9. The lens inspection apparatus according to claim 1, wherein the light reduction filter includes a light amount adjustment device that is a diffusion transmission member. 10. The lens inspection apparatus according to claim 9, further comprising: a light amount adjusting device that is a neutral density filter that transmits the same amount of light as the number of the same diffused and transmissive members. 11. The lens inspection apparatus according to claim 1, wherein the neutral density filter means comprises:
A lens inspection device including a light amount adjusting device that switches a neutral density filter based on an output signal from the light receiving unit. 12. The lens inspection apparatus according to claim 1, wherein the light receiving unit includes a light amount adjustment device that is a CCD line sensor.