JP2003270093A - Lens inspecting apparatus and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens inspecting apparatus and a lens inspecting method capable of appropriately evaluating optical characteristics in relation to optical equipment. <P>SOLUTION: The lens inspecting apparatus which makes image light including a specific test pattern incident on a lens 160 for inspecting the lens 160 used for optical equipment, and detects irradiation light from the lens 160 for inspection, is provided with a light source 410 for emitting reference luminous flux for inspection, an image light emission section 450 for generating the image light including a specific test pattern based on luminous flux that is emitted from the light source 410 for introducing to the lens 160, an image light detection section for detecting image light that is emitted from the lens 160, and a wavelength conversion section 42 for converting luminous flux that is emitted from the light source 410 to color light in a specific wavelength region. The wavelength conversion section 420 is provided with a plurality of filters where a transmission wavelength region is continuously set over an entire visible light region, and a filter-switching section for switching the plurality of filters. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in order to inspect a lens used in an optical apparatus, makes image light including a predetermined test pattern incident on the lens and detects light emitted from the lens for inspection. The present invention relates to a lens inspection device and a lens inspection method, which are preferably used for inspecting a projection lens used in a projector using a light modulation element such as a liquid crystal element.

[0002]

2. Description of the Related Art A projector having a light source, a light modulator for modulating a light beam emitted from the light source according to image information, and a projection lens for magnifying and projecting the light beam modulated by the light modulator. It has been known. According to such a projector, a projected image can be enlarged and projected on a screen to display a large-screen image. Therefore, a computer image can be displayed on the screen and used in a multi-presentation or the like explained by a presenter. Suitable for

For the purpose of projecting high image quality and high resolution in such a projector, for example,
There is a so-called multi-plate type projector in which a plurality of color lights such as red, green, and blue are subjected to light modulation for each color light, and the modulated color lights are combined by a prism or the like and emitted from a projection optical system. Specifically, this multi-plate type projector, for example, if it is a three-plate type projector, is equipped with a color separation optical system that separates the light flux emitted from the light source lamp into red, green, and blue color lights. An optical modulator is arranged on the optical path of, and after performing optical modulation according to image information for each color light, color synthesis is performed by a cross dichroic prism arranged at the rear stage of the optical path of each optical modulator, The color image is enlarged and projected on the screen through the projection lens.

By the way, the projection lens used in such a projector is an optical component for enlarging and projecting an image on a screen, and depending on the accuracy, chromatic aberration and distortion may occur and the image quality of the projected image may deteriorate. The inspection of the projection lens is performed by grasping the optical characteristics of the projection lens combined with the projector and determining whether or not the projection lens is compatible with the projector. The inspection of the projection lens is performed by a dedicated projection lens inspection device, and is performed for each item such as resolution inspection, flare inspection, chromatic aberration inspection, and distortion aberration.

This projection lens inspection device projects a light source for emitting an inspection reference light beam, an image light emitting portion having an inspection sheet on which a test pattern for inspection such as resolution is formed, and light emitted from a projection lens. And a screen to do. Then, the light flux emitted from the light source passes through the inspection sheet, is introduced into the projection lens as an image including a test pattern, is projected on the screen, and the optical characteristics of the projection lens are evaluated. Here, in the chromatic aberration inspection, a test pattern image is formed on the screen based on white light, red light, green light, and blue light, and the amount of chromatic aberration is obtained from each formation position. The inspection device includes a filter switching unit that switches the light flux emitted from the light source into white light, red light, green light, and blue light using a color filter.

[0006]

However, in such a projection lens inspection apparatus, the type of the color filter of the light source and the filter switching unit is usually fixed in order to keep the deviation between the inspection lenses constant. Therefore, if there is a change in the light source characteristics or the optical characteristics of the dichroic mirrors that make up the color separation optical system due to a change in the specifications of the optical equipment such as a projector that uses the projection lens, the There is a problem that the lens cannot be properly evaluated. In other words, according to the diversified types of projectors such as high brightness and miniaturization, the projection lens to be combined can be accurately adjusted to the optical characteristics such as chromatic aberration in accordance with the specifications of the optical device in which the projection lens is used. It is requested to perform an evaluation.

An object of the present invention is to provide a lens inspecting apparatus and a lens inspecting method capable of appropriately evaluating optical characteristics in relation to optical equipment.

[0008]

SUMMARY OF THE INVENTION The present invention achieves the above object by inspecting a lens by using a plurality of filters whose transmission wavelength range is continuously set over the entire visible light range. Is. Specifically, in order to inspect a lens used in an optical device, the projection lens inspection device of the present invention makes image light including a predetermined test pattern incident on the lens and detects light emitted from the lens. A lens inspection device for inspecting a light source for emitting an inspection reference light beam, and an image light including the predetermined test pattern, which is arranged in a rear stage of an optical path of the light source and is based on the light beam emitted from the light source. And an image light emission unit for generating image light, which is introduced into the lens, an image light detection unit for detecting the image light emitted from the lens, and a light beam emitted from the light source, which is disposed downstream of the optical path of the light source. A wavelength conversion unit for converting to color light in the wavelength region of, the wavelength conversion unit, the transmission wavelength region is a plurality of filters that are continuously set over the entire visible light region, and switch the plurality of filters. Characterized in that it includes a that filter switching unit.

Here, the plurality of filters can be constructed by combining a plurality of filters, for example, which divide the wavelength in the visible light region, about 400 nm to 750 nm, in units of 10 nm. Further, the range of the transmission wavelength region of each filter may be essentially continuous,
The ranges need not be even. For example, when the light introduced from the optical device to the projection lens can be roughly divided into red light, green light, and blue light as in a three-plate projector, a blue light region (range of about 455 nm to 492 nm), a green light region ( The range of about 492 nm to 577 nm), the range in the center of each region in the red light region (range of about 622 nm to 770 nm) is made fine, and in other parts, the transmission wavelength range of the filter is set to a larger range. You may.

Further, the image light detecting section projects the light flux emitted from the projection lens onto the screen, and the image is detected by the CCD.
It is preferable that the evaluation determination of the projection lens is performed by loading the image data into a computer using an image pickup device such as (Charge Coupled Device) and an image capturing device and performing image processing. Further, when the projection lens is used in a multi-plate type projector such as a three-plate type, it is preferable to dispose a dummy prism in front of the light flux incident side of the projection lens. In the case of a multi-plate type projector, it is more appropriate to evaluate the projection lens by adding the optical characteristics of this prism because the color lights are combined for each separated color light and then the color lights are combined by the cross dichroic prism. That's why.

According to the present invention, since the transmission wavelength regions of the plurality of filters are continuously set over the entire visible light region, the light source characteristics of the projector to which the lens is applied and the color separation optics. Diversification of projectors such as high brightness and miniaturization because it is possible to inspect axial chromatic aberration, lateral chromatic aberration, etc. by selecting a filter in the transmission wavelength region according to the optical characteristics of the optical elements that make up the system. Accordingly, the lens can be properly inspected.

In the above, the above-mentioned lens inspection apparatus is provided with the switching control section for outputting the control signal to the filter switching section based on the result detected by the image light detecting section to control the switching of the filter. Is preferred. According to the present invention as described above, when the inspection based on the image light detection is completed, the filters can be automatically switched, so that the lens inspection can be automated and the lens inspection can be performed more efficiently. be able to. Also, in particular, there are many filters,
This is effective when grasping the amount of chromatic aberration for all filters. Further, it becomes possible to grasp the amount of chromatic aberration deviation of the actual lens with respect to the design value of the projection lens, which can contribute to the efficiency of lens design.

Further, it is preferable that the above-mentioned switching control section selects a filter in the transmission wavelength region corresponding to the color light emitted from the main body of the optical device in which the lens to be inspected is used, among the plurality of filters, and particularly, , The optical device is a light source,
When a color separation optical system that separates the light beam emitted from the light source into a plurality of color lights is provided, it is preferable to select based on these. Here, the light beam emitted from the main body of the optical device includes a light beam directly emitted from the light source, and in the case of a multi-plate projector or the like, there is a light beam transmitted through a color separation optical element such as a dichroic mirror.

As a light source of the projector, various arc lamps such as a metal halide lamp, a halogen lamp and a high pressure mercury lamp are adopted, and the emission spectra of these lamps are different. Further, with respect to the dichroic mirror that constitutes the color separation optical system, the characteristics such as the transmission wavelength region are variously changed depending on the filtering material. Therefore, by setting the filter according to these optical components of the optical device in which the lens is used, it is possible to perform a precise inspection of the projection lens according to the type of the optical device.

In the lens inspection method of the present invention, in order to inspect a lens used in an optical device, image light including a predetermined test pattern is made incident on the lens, and the light emitted from the lens is detected to inspect it. A method for inspecting a lens, comprising: an optical characteristic acquisition procedure for acquiring design optical characteristics of a light source and / or an optical element forming the optical device body; and a transmission wavelength region corresponding to the acquired optical characteristic. A filter selection procedure for selecting a filter, an image light detection procedure for detecting image light including the test pattern by the light flux transmitted through the selected filter, and a characteristic value of the lens is calculated based on the detected image light. And a characteristic value calculation procedure for

Here, each of the above procedures can be executed by a computer that controls the above-described lens inspection apparatus, and the designed optical characteristics in the optical characteristic acquisition procedure are stored in the storage device of the computer. It can be obtained from the stored design data of the optical device. In addition, the image light in the image light detection procedure is sent to the computer by the CCD
By connecting an image pickup device such as a camera via an image capturing device such as a video capture board, it can be detected as image data. In addition, the lens inspection method of the present invention can be configured as a program for causing a computer to execute each procedure. Furthermore, the calculation of the characteristic value may be performed not only in the chromatic aberration amount as described above but also in the resolution measurement and the flare amount measurement based on the image light passed through the selected filter.

According to the present invention, since the filter selection procedure is provided, the test pattern image using the filter having the transmission wavelength region according to the design optical characteristics of the optical device is detected and the lens is detected. Since the characteristic value of can be calculated, the lens can be inspected in a state closer to the actual state as compared with the conventional inspection method in which the color filter is fixed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. (1) Structure of Projector Incorporating Projection Lens FIG. 1 shows a projector 10 incorporating a projection lens.
The structure of 0 is shown. This projector 100 is
Integrator illumination optical system 110, color separation optical system 12
0, a relay optical system 130, an electro-optical device 140, a cross dichroic prism 150 serving as a color combining optical device,
And a projection lens 160.

The integrator illumination optical system 110 comprises:
The light source device 111 including the light source lamp 111A and the reflector 111B, the first lens array 113, the second lens array 115, the reflecting mirror 117, and the superposing lens 1
19 and. The light flux emitted from the light source lamp 111A is aligned in the emission direction by the reflector 111B, is divided into a plurality of partial light fluxes by the first lens array 113, and the emission direction is 90 ° by the folding mirror.
After being bent, an image is formed in the vicinity of the second lens array 115. Each of the partial light fluxes emitted from the second lens array 115 has a central axis (chief ray) at the rear stage of the superimposing lens 11
The plurality of partial luminous fluxes that are incident perpendicularly to the incident surface of 9 and are emitted from the superimposing lens 119 are three liquid crystal panels 141R and 141 that constitute the electro-optical device 140.
G, superimposed on 141B.

Here, the light source lamp 11 of the light source device 111
As 1A, various ones such as a metal halide lamp, a xenon lamp, a high pressure mercury lamp, etc. are adopted according to the specifications of the projector, but the emission spectrum varies depending on the type of the light source lamp. Specifically, as shown in FIG. 2, in the case of a Dy-Nd-Cs-based metal halide lamp, the emission spectrum is as shown in graph G1, and in the case of a xenon lamp, the emission spectrum is as shown in graph G2.
The wavelengths showing the intensity peaks are different. It should be noted that the metal halide lamp is not limited to the emission spectrum as shown in the graph G1, and various emission spectra are exhibited depending on the metal halide enclosed.

The color separation optical system 120 includes two dichroic mirrors 121 and 122 and a reflection mirror 123, and a plurality of partial light fluxes emitted from the integrator illumination optical system 110 by these mirrors 121, 122 and 123. Has a function of separating light into three color lights of red, green and blue. The dichroic mirror 121 arranged in the preceding stage of the optical path has a characteristic of reflecting light having a wavelength in the red light region and transmitting light having a wavelength in the green light and blue light regions. For example, the graph G3 in FIG. As about 600nm
It has optical characteristics in which the transmittance is greatly different at front and back wavelengths. On the other hand, the dichroic mirror 122 has a characteristic of reflecting only light having a wavelength in the green light region and transmitting light having a wavelength in the blue light region, and for example, the graph G in FIG.
4 has optical characteristics in which the transmittance greatly differs at a wavelength of about 450 nm. The relay optical system 130
Includes an incident side lens 131, a relay lens 133, and reflection mirrors 135 and 137.
It has a function of guiding the color light separated by 20 such as blue light B to the liquid crystal panel 141B.

The electro-optical device 140 comprises three liquid crystal panels 141R, 141G and 141B, which are
For example, a polysilicon TFT is used as a switching element, and the respective color lights separated by the color separation optical system 120 are generated by the three liquid crystal panels 141R and 141G.
141B modulates according to image information to form an optical image. The cross dichroic prism 150 serving as the color combining optical system includes the three liquid crystal panels 141.
The image modulated for each color light emitted from R, 141G, and 141B is combined to form a color image. The color image combined by the cross dichroic prism 150 is emitted from the projection lens 160 and enlarged and projected on the screen.

(2) Structure of Projection Lens Inspection Apparatus FIG. 4 is an explanatory view showing the projection lens inspection apparatus according to the embodiment of the present invention. This device is a device for evaluating the projection lens 160 used in the projector 100 of FIG. The projection lens evaluation apparatus according to this embodiment includes a projection unit 400 on which a projection lens 160 to be inspected is mounted, a mirror 510, a screen 500, and a measurement unit 600. In this device, the projection lens 160 is removable and can be easily replaced with another projection lens.

Image light (light representing an image) emitted from the projection unit 400 is reflected by the mirror 510 and illuminates the screen 500. The screen 500 is a transmissive screen capable of observing an image from the back surface 500b side of the projection surface 500a on which the image light is projected. The measuring unit 600 is
Using the image displayed on the screen 500, various evaluation judgments such as the resolution, chromatic aberration, flare of the projection lens 160 are performed. In the following description, as shown in FIG.
The inspection device is represented by an XYZ orthogonal coordinate system having a plane parallel to the projection plane 500a of the screen 500 as an XY plane. In addition, the projection lens 160 is
It is arranged at a predetermined angle with respect to the XZ plane.
Therefore, in the following description, the projection unit 400 is represented by the STU rectangular coordinate system obtained by rotating the XYZ rectangular coordinate system about the X axis by the above-mentioned predetermined angle. The projection lens 16
The central axis n1 of 0 is parallel to the SU plane.

FIG. 5 is an explanatory view showing a state when the projection unit 400 of FIG. 4 is viewed from the + T direction. As shown in FIG. 5, the projection unit 400 includes a light source device 410 and a wavelength conversion unit 42.
0, first and second mirrors 430 and 442, an inspection sheet holding unit 440, a projection lens inspection sheet 450, a 6-axis adjusting unit 460, and a dummy prism 470. The light source device 410 is a part that emits a reference light source for inspection, and includes a light source lamp 412 and a parabolic reflector 41.
4 and. The concave surface of the parabolic reflector 414 has a paraboloidal shape of rotation. Light source lamp 412
Is arranged in the vicinity of the focal position of the concave surface of the paraboloid of revolution. With this configuration, the light emitted from the light source lamp 412 and reflected by the parabolic reflector 414 is emitted from the light source device 410 as a bundle of substantially parallel light rays.

As the light source lamp 412, a metal halide lamp, a high-pressure mercury lamp, or the like is used, but it is not possible to use a light source lamp having the same emission spectrum as that of the light source lamp of the projector using the projection lens 160 to be inspected. Since 420 is provided, it is not always necessary. Further, as the parabolic reflector 414, for example, one in which a reflective film such as a dielectric multilayer film or a metal film is formed on the concave surface of a paraboloid of revolution made of glass ceramics is used.

The wavelength conversion section 420 has a function as a wavelength range selection filter for transmitting only a light beam of a predetermined wavelength region among the light beams emitted from the light source device 410. As shown in FIG. 6, the wavelength conversion unit 420 includes a light flux transmission opening 421, a filter plate 422, and a filter switching unit 423. The light flux transmitting opening 421 allows the light flux emitted from the light source device 410 to pass through and guides the light flux to the projection lens inspection sheet 450.

The filter plate 422 has a light beam transmitting opening 42.
It is a part for converting a light flux passing through 1 into a light flux in a predetermined wavelength range. The filter plate 422 is a plate-shaped body in which a plurality of interference filters are formed in a plate shape, and as shown in FIG. 6, a plurality of different transmission wavelength regions are arranged along the circumference of the substantially circular plate-shaped body. Interference filters 422A, 422B, 422
C ... are arranged. Each interference filter 422A, 42
For example, assuming that the interference filter 422A has a wavelength range of 400 nm to 410 nm, the adjacent interference filters 422B have 410 nm to 42 nm.
0 nm, and the interference filter 422C next to it is 420
nm to 430 nm, which are set continuously over the entire visible light region at intervals of 10 nm. Although not shown in FIG. 6, an opening where no interference filter is provided is formed in a part of the filter plate 422, and when this opening is arranged in the light flux transmitting opening 421, The white light of the light source device 410 is directly projected on the screen.

The filter switching section 423 is provided with a filter plate 42.
2 of the interference filters 422A, 422B, 422C, ..., Which is a part for arranging a predetermined interference filter on the light flux transmission aperture 421 to switch the filter, and includes a stepping motor which is driven according to the number of pulse steps. To be done. The filter switching unit 423 is driven based on a drive control signal from the processing unit 610 described later.

Returning to FIG. 5, the first and second mirrors 4
Reference numerals 30 and 442 have a function as a light guide unit for guiding the color light emitted from the light source device 410 and passing through the wavelength conversion unit 420 to the projection lens 160. As the first and second mirrors 430 and 442, it is possible to use mirrors or metal mirrors in which a dielectric multilayer film that reflects all color light is formed. Inspection sheet holding unit 44
0 holds the projection lens inspection sheet 450 so as not to touch the second mirror 442. In FIG. 4, the light source device 410 and the first mirror 430 shown in FIG. 5 are the same as those of the six-axis adjusting unit 460, the inspection sheet holding unit 440, and the dummy prism 4.
Since it exists in the + S direction (the direction on the back side of the paper) with respect to 70 and the projection lens 160, the illustration is omitted for convenience.

As shown in FIG. 5, the projection unit 400 is configured so that light similar to that when a projection lens is used in the projector 100 of FIG. 1 enters the projection lens 160. That is, the light source device 410 is shown in FIG.
Corresponding to the light source device 111 of the projection lens inspection sheet 45
0 corresponds to the liquid crystal panels 141R, 141G and 141B of FIG. 1, and the dummy prism 470 corresponds to the cross dichroic prism 150 of FIG. By using the inspection device including such a projection unit 400, in an environment similar to the case where a projection lens is used in a projector,
It is believed that the projection lens can be inspected.

The projection lens inspection sheet 450 introduces the luminous flux emitted from the light source lamp 412 to measure the resolution,
It has a function as an image light emitting unit that forms a test pattern image for flare measurement or the like and introduces it into the projection lens 160. In this projection lens inspection sheet 450, as shown in FIG. 7, an image area (test pattern) TP is formed on the front surface of a base material having a predetermined thickness dimension (for example, 1.1 mm) which is transparent such as glass. The base material has a predetermined vertical and horizontal dimensions (for example, 14.6 mm × 18 mm), and inside thereof a rectangular image area (test pattern) TP having a predetermined vertical and horizontal dimensions (for example, 10.8 mm × 14.4 mm). Has been formed.

As shown in the front view of FIG. 8, the test pattern TP includes a plurality of test patterns 10A for measuring resolution, and the resolution is set at a plurality of positions in a projection area based on the light emitted from the projection lens 160. It is ready to measure. Although not shown, this test pattern T
In P, a plurality of test patterns for checking other optical characteristics of the projection lens 160 are formed. Specifically, as the test patterns for examining other optical characteristics of the projection lens 160, there are a focus, an alignment adjustment test pattern, a flare and a chromatic aberration test pattern, which are respectively a test for visual inspection and a test for automatic inspection. The pattern is set.

The test pattern 10A for measuring the resolution is
As shown in FIG. 9, the vertical and horizontal dimensions are predetermined (for example, 795 μm).
It is formed in a rectangular shape (× 1074 μm) and is further divided into a resolution measurement area WA and a flare inspection area WB.
The resolution measurement area WA includes a plurality of two types of resolution measurement patterns PT1 and PT2. Pattern PT1
Are configured by arranging light-shielding regions PTV extending in the vertical direction at intervals, and light-transmitting regions PTS are formed between adjacent light-shielding regions PTV. On the other hand, the pattern PT2 is configured by arranging light-shielding regions PTH extending in the horizontal direction at intervals, and similarly to the pattern PT1, the light-transmitting regions PTS are formed between the light-shielding regions PTH.

These patterns PT1 and PT2 have dimensions corresponding to the size of the number PTN formed on the upper part thereof. The number PTN represents an index of the resolution when performing the visual inspection, and specifically represents the spatial frequency of the patterns PT1 and PT2 arranged below the index.
For example, two patterns P arranged below "20"
T1 and PT2 are patterns with a spatial frequency of 20 lines / mm, and the patterns PT1 and PT below the number "30"
No. 2 has a spatial frequency of 30 lines / mm. In the case of visually inspecting the resolution with such patterns PT1 and PT2, an inspector observes the patterns PT1 and PT2 formed on the screen 500, which are irradiated with light from the projection lens 160, and the boundary between the light shielding region and the light transmitting region is The spatial frequency of the limit that can be discriminated will be used as an index of resolution.
A case where image processing is performed using an image sensor will be described later.

The flare inspection area WB is formed in a rectangular shape having predetermined dimensions (for example, 330 μm × 340 μm) in length and width, and contains four kinds of small hole patterns PHa to PHd which are substantially circular light-transmitting areas. ing. Small hole pattern PHa ~
PHd has different diameters, for example, the small hole pattern PHa has a diameter of 26 μm, the small hole pattern PHb has a diameter of 19 μm, the small hole pattern PHc has a diameter of 10 μm, and the small hole pattern PHd. Has a diameter of 5 μm. This flare inspection region WB is used when performing automatic measurement of the projection lens inspection device, and specifies the flare amount from the difference between the hole diameter of each small hole and the image area of the transmitted light.

In FIG. 5, the inspection sheet holding section 440 is provided.
Is fixed to the 6-axis adjusting unit 460,
By controlling 60, the inspection sheet holding unit 440
The placement of is adjusted. The 6-axis adjusting unit 460 includes parallel movements in the S direction, T direction, and U direction in the drawing, and S axis, T axis,
It is a combination of six movable stages that can rotate about the U axis. By controlling the 6-axis adjusting unit 460, the spatial arrangement of the projection lens inspection sheet 450 held by the inspection sheet holding unit 440 can be adjusted. In other words, the spatial arrangement of the test pattern TP is adjusted by the control of the 6-axis adjusting unit 460.

As described above, the dummy prism 470 is provided to simulate the cross dichroic prism 150 of the projector 100 of FIG. Figure 4
In the cross dichroic prism 150 shown in (1), an “X” -shaped thin film is provided inside in order to combine the light emitted from the three liquid crystal panels 141R, 141G, and 141B. However, since this thin film is not necessary in the present inspection apparatus, a cubic glass body having the same antireflection coating as the cross dichroic prism 150 is used as the dummy prism 470. The projection lens 160, which is the measurement target, is sequentially replaced and mounted in the evaluation device.

With the configuration of the projection unit 400 described above, the light emitted from the light source device 410 (FIG. 5) is converted into the wavelength conversion unit 42.
The light is converted into a predetermined color light by 0 and reflected by the first and second mirrors 430 and 442. The light reflected by the second mirror 442 passes through the projection lens inspection sheet 450 and is emitted as image light representing an image in the image area TP. This image light passes through the dummy prism 470.
After passing through, the image is projected by the projection lens 160.

By the way, as shown in FIG. 4, in the projection unit 400 of the present embodiment, the central axis n1 of the projection lens 160,
A normal line n2 passing through the center of the projection lens inspection sheet 450 is deviated by a predetermined distance. This is for simulating the state of "agitated projection" in the projector.
The projection lens 160 is designed to project and display an image without distortion in such a tilted projection state. It should be noted that the projection in which the central axis n1 of the projection lens 160 and the normal line n2 passing through the center of the projection lens inspection sheet 450 do not coincide with each other is usually referred to as “orientation projection”.

The measuring section 600 (see FIG. 4) is the processing section 61.
0, four adjustment CCD cameras 620a to 620d arranged near the four corners of the screen 500, and one measurement CCD camera 640. FIG. 10 is an adjustment CCD when the screen 500 is viewed from the + Z direction.
It is explanatory drawing which shows arrangement | positioning of cameras 620a-620d and CCD camera 640 for a measurement. 4 as shown
The adjustment CCD cameras 620a to 620d are provided at the four corners of the screen 500, respectively, and can be moved in the XY plane by a moving mechanism (not shown).

The measuring CCD camera 640 is provided near the center of the screen 500 and can be moved in the XY plane by a moving mechanism (not shown). However, as shown in FIG. 4, the measurement CCD camera 640 is
Since the adjustment CCD cameras 620a to 620d are displaced in the + Z direction, they can be moved without interfering with the adjustment CCD cameras 620a to 620d. Then, these adjustment CCD cameras 620
a to 620d and the measurement CCD camera 640 are electrically connected to the processing unit 610 via an image capturing device such as a video capture board, and the captured image data is
It is converted into an image signal such as an RGB signal suitable for a computer by the image capturing device and processed by the processing unit 610.

The processing unit 610, as shown in FIG. 11, is a processing unit 610A and a hard disk 610.
Although not shown, the processing unit 610 is connected to an input device such as a keyboard and a mouse, and an output device such as a display and a printer. The processing unit 610 includes an image processing unit 611, a lens characteristic value calculation unit 612, and a CCD camera control unit 61.
A three- and six-axis adjusting unit control means 614, a filter switching control means 615, and a database management means 616 are provided, and each means 611 to 616 is developed on an OS (Operating System) that controls the operation of the arithmetic processing device 610A. Configured as a program. In addition, the hard disk 610
In B, a design data storage unit 617 and an actual measurement data storage unit 618 are secured.

The image processing means 611 is a CCD camera 620a to 620d, 6 captured by an image capturing device.
The CCD camera 620a is a part that performs image processing based on the image signal from the CCD 40, and based on the image processing result.
To 620d and 640, images displayed on a display device such as a display, or the lens characteristic value calculation means 61
The lens characteristic value in 2 is calculated. Incidentally, as a method of image processing by the image processing means 611, a pattern matching process based on imaged image data is mainly adopted. The lens characteristic value calculating unit 612 is a unit that calculates the characteristic value of the projection lens 160 from the imaged image data based on the image processing result by the image processing unit 611. Specific lens characteristic values include resolution, flare amount, chromatic aberration, distortion and the like, and each item is calculated as follows.

First, the resolution MTF is calculated by the image processing means 61.
1 is performed based on the image of the resolution measurement area WA of the test pattern 10A, and the luminance value Io of the background portion without the resolution measurement patterns PT1 and PT2 and the resolution measurement patterns PT1 and PT2. Based on the maximum luminance value Imax and the minimum luminance value Imin in the above, it is calculated by the following equation (1).

[0046]

[Equation 1]   MTF = (Imax-Imin) / (Io * 2-Imax-Imin) (1)

The flare amount is calculated based on the image of the light transmitted through each of the small hole patterns PHa to PHd in the flare inspection region WB of the test pattern 10A acquired by the image processing means 611, and each small hole is calculated. The flare amount is calculated by taking the difference with the area of. The amount of chromatic aberration is red light,
The test pattern 10A image based on green light and blue light is C
It is obtained by capturing an image using the CD camera 640 and calculating the amount of displacement of the image position of each color light by pattern matching processing. The amount of distortion aberration is the frame portion of the test pattern TP projected on the screen 500 (see FIG. 8).
The CCD camera 640 for measurement is moved along the
The distortion aberration amount is calculated by acquiring a plurality of coordinates on the screen of the frame portion imaged by the CD camera 640.

The CCD camera control means 613 controls the CCD cameras 620a-620 acquired by the image processing means 611.
Image data 0d and 640, lens characteristic value calculation means 61
A control signal is generated based on the result of the lens characteristic value acquired in No. 2 to adjust CCD cameras 620a to 620.
d, a part for outputting a control signal to the measuring CCD camera 640. CCD cameras 620a to 620d, 640
The control signals for the CCD cameras 620a to 620a ...
There are control signals relating to zoom / focus control and light amount diaphragm control in addition to those for controlling movement of 620d and 640 along the screen 500.

The 6-axis adjusting section control means 614 controls the adjustment CCD cameras 620a to 620a acquired by the image processing means 611.
A control signal is generated based on the image data of 20d, and 6
This is a part that outputs a control signal to the axis adjusting section 460. Specifically, the 6-axis adjusting section 460 outputs a control signal for adjusting the position of the projection lens inspection sheet 450 at the back focus position of the projection lens 160 to be inspected. Output to. The filter switching control unit 615 as a switching control unit is a unit that outputs a control signal to the filter switching unit 423 on condition that the lens characteristic value calculation unit 612 acquires the lens characteristic value. Specifically, the filter switching control means 615 is configured so that the filter 42 in a predetermined transmission wavelength range is used.
When the lens characteristic value in the state of using 2A is calculated, the control signal for switching to the filter 422C or the like in the different transmission wavelength region is output to the filter switching unit 423.

The database management means 616 searches the information stored in the design data storage section 617 described later, and records and stores the lens characteristic value calculated by the lens characteristic value calculation section 612 in the measured data storage section 618. It is the part to do. The design data storage unit 617 is configured by the projection lens 16
In addition to the design information of 0, the design information of the optical device using the projection lens is stored. Specifically, the design data storage unit 617 uses the model number of the projection lens 160 as an index, and the optical characteristics of the lenses forming the projection lens, as well as the light source lamp 111 of the optical device using this.
A wavelength range showing the designed peak intensity in the emission spectrum of A, and dichroic mirrors 121 and 12 for color separation.
It is configured as a table-structured database in which the two cutoff wavelength regions in the design are recorded as one record.

The measured data storage section 618 is a section for storing characteristic values such as resolution, flare amount, chromatic aberration amount, and distortion amount calculated by the lens characteristic value calculation means 612. The serial number of the projection lens 160 to be inspected is used as an index, and a database having a table structure in which these characteristic values are used as one record is configured.

(3) Projection Lens Inspection Method Next, the projection lens inspection method by the above-described lens inspection apparatus will be described with reference to the flowchart shown in FIG. (3-1) When the lens inspection device is activated and the operator specifies the model of the projection lens 160 to be inspected, the database management means 616 uses this as a trigger to perform a search in the design data storage unit 617 to determine the model. The design data of the projection lens 160 corresponding to the above is called on the arithmetic processing device 610A (process S1: optical characteristic acquisition procedure). Projection lens 1
The design data of 60 includes, in addition to the design information of the projection lens 160 itself, a wavelength range in which the intensity peak in the emission spectrum of the light source lamp 111A constituting the projector 100 in which the projection lens 160 is used and the dichroic mirrors 121 and 122 are cut. There is an off wavelength range.

(3-2) When the design data is called, C
The CD camera control means 613 outputs a control signal to move the adjustment CCD cameras 620a to 620d, and arranges the adjustment CCD cameras 620a to 620d at positions where images of the four corners of the projection lens inspection sheet 450 can be acquired ( Process S2). At this stage, the light flux transmitting opening 42
An opening is provided at 1 where no interference filter is provided.

(3-3) The image processing means 611 uses the adjustment C
Based on the image data acquired from the CD cameras 620a to 620d, the in-focus state of the image at the four corners is determined, and the result is output to the 6-axis adjusting unit control means 614.
The 6-axis adjusting unit control means 614 outputs a control signal according to the determination result of the image processing means 611 to output the 6-axis adjusting unit 460.
Is operated to adjust the focus / alignment position of the projection lens inspection sheet 450 so that all the images at the four corners of the projection lens inspection sheet 450 are in focus (step S3). (3-4) When the focus / alignment position of the projection lens inspection sheet 450 is adjusted, the CCD camera control means 613 outputs a control signal to the measurement CCD camera 64.
0 is moved to one of the test patterns 10A of FIG. 8 (process S4).

(3-5) When the measurement CCD camera 640 is arranged on the predetermined test pattern 10A, the measurement CCD
Image pickup by the camera 640 is started, and image processing means 611 is started.
Converts the image signal including the test pattern on the screen input through the image capturing device into image data (process S
5: Image light detection procedure). (3-6) The image processing means 611 performs pattern matching processing based on the detected image data (processing S
6), based on this result, the lens characteristic value calculation means 61
2 calculates the resolution (process S7).

(3-7) When the measurement of the resolution is completed, the lens characteristic value calculating means 612 outputs a signal to that effect to the filter switching control means 615, and based on this, the filter switching control means 615 performs designing. The interference filters 422A, 422B, 422C, ... Used for the chromatic aberration inspection are selected from the data (process S8: filter selection procedure). The optical characteristic of the projector 100 obtained in the optical characteristic acquisition step S1 is
For example, if the emission spectrum of the light source lamp 111A is given in FIG. 2, the selection is performed in consideration of the peak intensity near 440 nm and the peak intensity near 550 nm.
Two interference filters in the transmission wavelength region including these are selected, and one in the transmission wavelength region including the median value is selected between red wavelength regions 622 nm to 770 nm with no particular peak, and a total of three interference filters are selected. It is done by doing.

(3-8) The filter switching control means 615 is
Selected interference filters 422A, 422B, 422C
Any one of the ... Is set in the light flux transmitting opening 421 (process S9). The image processing unit 611 includes the interference filter 4
22A, 422B, 422C, ... Perform pattern matching processing on the test pattern image (processing S1
0), and the lens characteristic value calculation means 612 calculates the chromatic aberration amount based on this (process S11: characteristic value calculation procedure).

(3-9) When the chromatic aberration amount is calculated, the lens characteristic value calculating means 612 outputs a signal to that effect to the filter switching control means 615, and the filter switching control means 615.
Performs switching control of the interference filters 422A, 422B, 422C, ... And all the selected interference filters 42.
The processes S9 to S11 are repeated until the chromatic aberration amount can be calculated for 2A, 422B, 422C, ... (Process S1.
2). (3-10) When all the chromatic aberration amounts have been calculated, based on the image of the flare inspection area WB of the test pattern 10A acquired by the image processing means 611, the lens characteristic value calculating means 6
12 calculates the flare amount (processing S13).

(3-11) When the above is completed, the lens characteristic value calculation means 612 associates the obtained lens characteristic value with the serial number of the projection lens 160 and stores it in the measured data storage section 618 via the database management means 616. The data is recorded and stored, and a signal to that effect is output to the CCD camera control means 613 and the filter switching control means 615. The filter switching control unit 615 returns the filter plate 422 to the default position so that the image light becomes white light, and C
Based on this, the CD camera control means 613 moves the measurement CCD camera 640 to the next test pattern,
Lens characteristic values are acquired for all the test patterns 10A shown in FIG. 8 (process S14).

(3-12) When the characteristic values of the resolution, flare amount, and chromatic aberration amount of all test patterns 10A are acquired,
The filter switching control unit 615 includes a filter switching unit 423.
Output a control signal to the interference filters 422A, 422
B, 422C ... is returned to the initial opening only state,
The CCD camera 640 for measurement is moved along the frame portion of the test pattern TP to calculate the amount of distortion (process S1).
5).

(4) Effects of the Embodiment According to this embodiment as described above, there are the following effects. (4-1) Multiple interference filters 422A, 422B, 42
The transmission wavelength region of 2C ... is in the visible light region (400 nm to 75 nm).
0 nm), the projector 100 to which the projection lens 160 is applied is set continuously.
Light source lamp 111A, dichroic mirror 121,
The interference filter 42 in the transmission wavelength region according to the characteristics of 122.
2A, 422B, 422C ... to select longitudinal chromatic aberration,
Since it is possible to inspect chromatic aberration of magnification and the like, it is possible to appropriately inspect the projection lens 160 in response to diversification of the projector 100 such as higher brightness and smaller size.

(4-2) In calculating lens characteristic values such as the resolution of the projection lens 160, the interference filter 4 is automatically controlled by the filter switching control means 615 of the processing unit 610.
Since 22A, 422B, 422C ... Are switched, the lens inspection can be automated, and the lens inspection can be performed more efficiently. Further, in particular, there are many interference filters 422A, 422B, 422C, ... And it is effective when the evaluation determination is performed for all the filters. (4-3) Projector 1 in which the projection lens 160 is used
00 light source lamp 111A, dichroic mirror 12
Since the interference filters 422A, 422B, 422C, ... Are selected according to the optical characteristics of the optical components 1, 122, etc., it is possible to accurately evaluate the projection lens 160 according to the type of the projector 100.

(4-4) Since the filter selection procedure S8 is provided, the interference filter 422A having a transmission wavelength region according to the designed optical characteristics of the projector 100,
Since it is possible to calculate the chromatic aberration of the lens by detecting the test pattern image using 422B, 422C, ..., As compared with the conventional inspection method in which the color filter is fixed, the lens inspection can be performed in a state closer to the actual condition. It can be carried out. (4-5) Since the lens inspection method can be automatically performed by causing the processing unit 610 to execute the series of procedures shown in the flowchart of FIG. 12, the inspection accuracy is improved without causing the inspection complexity. Can be achieved.

(4-6) Interference filters 422A and 422
B, 422C ... are in the visible light region (400 nm to 750 n
m) can be continuously switched, so that, for example, as shown in Table 1, the axial chromatic aberration is continuously measured over the entire visible light region to show the axial chromatic aberration of the projection lens 160. The measurement can be performed as shown in 13, and the design value can be confirmed and evaluated, which can contribute to the efficiency of the lens design.

[0065]

[Table 1]

(5) Modification of Embodiments The present invention is not limited to the above-mentioned embodiments, but includes the following modifications. In the above-described embodiment, the interference filters 422A and 422 are equally divided into the visible light region of 400 nm to 750 nm.
Although the transmission wavelength region of B, 422C ... Is set, the present invention is not limited to this. That is, in short, if each interference filter is combined, it suffices that the transmission wavelength region is continuous over the entire visible light region, and for example, the red light, the green light, and the vicinity of the peak of the blue light wavelength region are finely divided. However, the transmission wavelength region of each interference filter may be set so as to largely divide the other portions.

Further, in the above embodiment, the interference filters 422A, 42A are exclusively based on the characteristics of the light source lamp 111A.
2B, 422C ... Are selected, but not limited to this, the interference filters 422A, 422 are further considered in consideration of the cutoff frequencies of the dichroic mirrors 121, 122.
B, 422C ... may be selected.

Further, in the above embodiment, the switching of the interference filters 422A, 422B, 422C, ... Is used only for the chromatic aberration measurement, but the image light using the interference filter is also used for other resolution inspection and flare inspection. You can go. Further, in the above-described embodiment, the projection lens used in the projector using the liquid crystal panel as the light modulation device is inspected, but the present invention is not limited to this, and the lens used in the projector by another modulation method or another optical device is used. The present invention may be employed to perform the inspection of. In addition, the specific structure, shape, and the like when implementing the present invention may be other structures and the like as long as the object of the present invention can be achieved.

[0069]

According to the present invention as described above, since the transmission wavelength regions of the plurality of filters are continuously set over the entire visible light region, the light source characteristics of the projector to which the lens is applied, Since it is possible to inspect axial chromatic aberration, lateral chromatic aberration, etc. by selecting a filter in the transmission wavelength region according to the optical characteristics of the optical elements that make up the color separation optical system, a projector with high brightness, compact size, etc. It is possible to properly inspect the lens in response to the diversification of.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a structure of a projector including a projection lens to be inspected according to an embodiment of the present invention.

FIG. 2 is a graph showing a light source characteristic of the projector in the embodiment.

FIG. 3 is a graph showing characteristics of a dichroic mirror that constitutes the projector according to the exemplary embodiment.

FIG. 4 is a schematic diagram showing a structure of a lens evaluation device in the embodiment.

FIG. 5 is a schematic diagram showing a structure of a lens evaluation device in the embodiment.

FIG. 6 is a schematic diagram showing a structure of a wavelength conversion section in the embodiment.

FIG. 7 is a side view showing an inspection sheet in the embodiment.

FIG. 8 is a front view showing an inspection sheet in the embodiment.

FIG. 9 is a front view showing a pattern for resolution and flare measurement included in the inspection sheet in the embodiment.

FIG. 10 is a front view showing the arrangement of image pickup devices on the screen in the embodiment.

FIG. 11 is a schematic diagram showing a structure of a processing unit in the embodiment.

FIG. 12 is a flow chart for explaining the lens inspection method in the embodiment.

FIG. 13 is a graph showing the characteristics of axial chromatic aberration of the projection lens that is the inspection target in the embodiment.

[Explanation of symbols]

100 Projector (optical equipment) 160 Projection lens (lens) 10A Test pattern 410 Light source device (light source) 450 Inspection sheet (image light emission part) 420 Wavelength conversion parts 422A, 422B, 422C ... Interference filter (filter) 423 Filter switching part 111A Light source lamp (light source of optical equipment) G1 Emission spectrum of light source (characteristic of light source of optical equipment) G3, G4 Characteristics of dichroic mirror (characteristic of optical element of optical equipment) S1 Optical characteristic acquisition procedure S5 Image light detection procedure S8 Filter selection Procedure S11 Characteristic value calculation procedure

Claims (5)

[Claims] 1. A lens inspecting apparatus for inspecting a lens used in an optical instrument, wherein image light including a predetermined test pattern is incident on the lens, and light emitted from the lens is detected to perform the inspection. A light source that emits an inspection reference light beam, and an image light including the predetermined test pattern is generated based on the light beam emitted from the light source, the image light being disposed in the latter stage of the optical path of the light source and introduced into the lens. An image light emitting unit, an image light detecting unit that detects the image light emitted from the lens, and a wavelength that is arranged downstream of the optical path of the light source and that converts a light beam emitted from the light source into color light in a predetermined wavelength range. A plurality of filters having a transmission wavelength region continuously set over the entire visible light region, and a filter switching unit that switches the plurality of filters. Lens inspection apparatus characterized by there. 2. The lens inspection apparatus according to claim 1, wherein a switching control unit outputs a control signal to the filter switching unit based on a result detected by the image light detection unit to control switching of the filter. A lens inspection device comprising a control unit. 3. The lens inspection apparatus according to claim 2, wherein the switching control unit has a transmission wavelength corresponding to a color light emitted from an optical device body in which a lens to be inspected is used among the plurality of filters. A lens inspection device characterized by selecting a filter of a region. 4. The lens inspection apparatus according to claim 3, wherein the optical device includes a light source and a color separation optical system that separates a light beam emitted from the light source into a plurality of color lights, and the switching control unit includes: A lens inspection apparatus, characterized in that a filter in a transmission wavelength region is selected according to a characteristic of the light source and / or a characteristic of an optical element forming the color separation optical system. 5. A lens inspection method for inspecting a lens used in an optical device, which comprises injecting image light including a predetermined test pattern into the lens and detecting light emitted from the lens to perform inspection. And an optical characteristic acquisition procedure for acquiring design optical characteristics of a light source and / or an optical element constituting the optical device body, and a filter selection procedure for selecting a filter having a transmission wavelength region according to the acquired optical characteristics. And an image light detection procedure for detecting image light including the test pattern by the light flux transmitted through the selected filter, and a characteristic value calculation procedure for calculating a characteristic value of the lens based on the detected image light. A lens inspection method characterized by being provided.