JPH1152115A - Optical grating forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to provide a grating forming process of high flexibility, high speed and low cost by controlling a light source, a grating image forming module and position control module by a control unit. SOLUTION: The light source 1 provides the light necessary for sensitizing a photosensitive plate 4 by forming a grating image. The grating image forming module 2 is used for forming the grating image. A grating image processing module 3 receives the grating image formed by the grating image forming module 2, reduces the image to some size and further filters the noise in the image. The photosensitive plate 4 records the processed grating image. The position control module 5 holds the photosensitive plate 4 and control the position thereof. The control unit 6 provides all the control signals for the respective modules.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of reproducing a grid from an image, and has high flexibility, high speed and low cost, and uses a light spot to draw a grid on a photosensitive plate. The present invention relates to a device for generating an optical grating.

[0002]

BACKGROUND OF THE INVENTION Today, the need for the amount of grid elements is enormous in the optoelectronics industry. Gratings can be applied in various fields such as optical integrated circuits, optical systems, holographic displays and optical signal processing. In general, there are several types of methods for generating the grating, such as, for example, transmission holography, reflection holography, precision machining processes, electron beam etching processes, and laser machining processes. However, these conventional methods are disadvantageous in each operation.

[0003] Transmission holography is used in art-displayed holograms and optical signal processing. Grating elements produced by such methods have low diffraction efficiencies and cannot be used coaxially.

[0004] Reflection holography is used in the same field as transmission holography, but the diffraction efficiency of grating elements generated by reflection holography is higher than that produced by transmission holography. However, the frequency of reproduction is difficult to control and the cost is high.

[0005] Precision machining processes can produce grid elements with a certain level of quality. However, such a method can only be used to generate a linear or circular grid.

[0006] The most commonly used method is an electron beam etching process. However, such methods are not suitable for producing grating elements and diffraction-coupled optical elements with large diffraction angles. However, the laser machining process uses grating elements with large diffraction angles,
Or it is only suitable for producing a diffraction-coupled optical element.

[0007] Therefore, each of these conventional methods has its own severe limitations and therefore cannot be applied to generate various grids. Therefore, the present invention
Developed to solve the above problems.

One object of the present invention is to provide an improved optical grating generator for generating a grating on a photosensitive plate. An optical grating generator is achieved by combining a computer imaging system, an optical imaging system and a precision machine control system to provide a flexible, fast and low cost grating generation process.

It is another object of the present invention to provide an optical grating generator for reproducing a grating as a grating image on a photosensitive plate.

It is a further object of the present invention to provide an optical grid generator for generating a grid on a photosensitive plate by drawing a grid pattern directly on the photosensitive plate with concentrated light spots. It is.

[0011]

According to one aspect of the invention, an optical grating generator includes a light source module, a grating image generating module, an optical image processing module, a position control module, a photosensitive plate, and a control unit. I have. The control unit instructs the grid image generation module to generate a grid image with a specific grid pattern.
The image processing module then reduces the grid image to a certain size. The photosensitive plate held by the position control module is exposed according to the contracted grid image by the light source module.

In accordance with another aspect of the present invention, an optical grating generator further comprises a centralized light spot source such that a grating can be created by movement of a photosensitive plate held by a position control module. And the light spot acts as a pen for drawing a grid pattern on the photosensitive plate.

In accordance with a further aspect of the present invention, a grating image generation module of an optical grating generator is provided by including a grid mask of various grid patterns for creating a grid bright spot array.

In accordance with yet a further aspect of the present invention, the grating image generation module of the optical grating generator not only provides the effect of a grid bright spot arrangement, but also accommodates computer generated holograms and diffractive optical elements. And a liquid crystal display.

[0015] Other objects, advantages and novel features of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an optical grating device according to the present invention comprises a light source 1, a grating image generating module 2, an optical image processing module 3, a photosensitive plate 4, a position control module 5, and The control unit 6 is included. The light source 1 produces the grating image and provides the light necessary to sensitize the photosensitive plate 4.

The grid image generation module 2 is used to generate a grid image. Therefore, light source 1
And the grid image generation module 2 can be referred to as an “image source”. The grid image processing module 3 receives the grid image generated by the grid image generation module 2, reduces the image to a certain size, and further filters noise in the image. The photosensitive plate 4 is used for recording the processed grid image. The position control module 5 holds the photosensitive plate 4 and controls its position. A control unit, which is a computer or microprocessor, provides all control signals for each module.

The light projected from the light source 1 is used as a backlight for a grid image generating module 2 for generating a grid image. The grating image is sent to an optical image processing module 3 for optical image processing. The processed image is then shaped on the photosensitive plate 4 and the photosensitive plate 4 is exposed. By such a method, several hundred μ
An m square grid image can be recorded at a time on the photosensitive plate 4. The position of the photosensitive plate 4 is controlled by a position control module 5.

Therefore, various grating images, each having an area of several hundred μm, can be integrated and arranged to form a grating in large size. The light source 1, the grating image generation module 2 and the position control module 5 are controlled by a control unit 6.

The wavelength of light from the light source 1 shown in FIG. In addition, the time and brightness at which the light enters the optical image processing module 3 must be controllable to ensure proper exposure. Therefore, the light source can consist of a mercury lamp or a laser. A shutter (not shown) can be added directly to it to control the exposure time. The light source 1 is preferably an LED or a semiconductor laser whose light time and brightness can be controlled directly by the control unit 6 without using a shutter.

The photosensitive plate 4 is made by covering a substrate with a photosensitive material in order to record light energy and brightness. Commonly used photosensitive materials include silver halides, photopolymers and photoresists. The substrate can be made from glass, metal, or other materials. The position control module 5 is used to hold the photosensitive plate 4, and can move the photosensitive plate 4 in various directions in a stepwise or continuous manner. The position control module 5 controls the interferometer measurement method (inte
Rferometry) operation or a dislocation stage used in integrated circuit fabrication operations. If the grid is produced by reproduction from a grid image generated by the grid image generation module 2, it is necessary to control the transition on the X axis and the transition on the Y axis. On the other hand, if the grating is produced directly on the photosensitive plate 4 by spotting, it is preferable to control the transition on the X axis, the transition on the Y axis and the rotation on the Z axis, and in this case Preferably, the movement is a continuous method.

The image processing module 3 is an optical reduction means that uses various lenses to form a reduced grid image from the grid image generated by the grid image generating module 2 before the position control module 5. Can consist of Now, if the photosensitive plate 4 is placed on the position control module 5, a reduced grid image is recorded on the photosensitive material 4. Optical image processing module 3
Can consist of a simple single reduction lens 3a, as shown in FIG. 2, or another type of lens, or a lens combination that reduces the image to a certain size.

For example, referring to FIG. 3, the optical image processing module 3 includes a collimating lens 3b and a focusing lens 3c. Each lens can consist of a single lens or a lens combination. The collimating lens 3b was sent out by the grating image generation module 2 as parallel light while the focusing lens 3c was used to collect the parallel light at one point and concentrate this concentrated light on the photosensitive plate 4. It is used to deform diffuse spherical light emitted from any bright spot light source. Because of the process described above, the clarity of the focal points on the photosensitive plate 4 depends on the quality of their lenses.

Since the light sent between the collimating lens 3b and the focusing lens 3c is parallel, these lenses 3b, 3c
The distance between c is independent of the quality of the image formed on the photosensitive plate 4.

However, the quality of the image is degraded by the rough surface of the photosensitive plate 4, or by vibrations of the system. As shown in FIG. 8, it is preferable to add an automatic focusing unit to the optical image processing module 3. The automatic focus adjustment means includes a laser diode 70, two sensors 71 and 72, and a mirror 73 arranged on an optical path between the collimating lens 3b and the focusing lens 3c. The laser beam is emitted from the laser diode 70, is reflected by the mirror 73 and reaches the photosensitive plate 4, and the return laser beam returns along the same path and is received by the two sensors 71 and 72.

The two sensors 71, 72 determine whether the focus adjustment on the photosensitive plate 4 is clear according to the laser beam received. If the answer is no, then the position of the focusing lens 3c is adjusted to achieve a clear focus adjustment. Since autofocus is conventional, a detailed description of it is omitted here.

There are various methods for realizing the grid image generation module 2. For example, FIG. 4 shows an embodiment of a grid image generation module 2 adapted to generate a "grid array" used in a hologram display. This "grating arrangement" consists of various linear gratings of different directions and different pitches. In practice, creating such a grid array requires dozens of grid angles and several grid pitches. The image generation module 2 of FIG. 4 includes a light diffusion plate 2a, grating masks 2b, 2c, and 2d having different grating pitches,
And an area control mask 2e. The light diffusing plate 2a is used to diffuse incoming light and create a more uniform light intensity distribution.

The respective pitch of the grating masks 2b, 2c, 2d is set according to the required grating pitch and the reduction multiple of the image. The grating masks 2b, 2c, 2d are mounted on a dislocation stage (not shown), and the corresponding grating mask can be moved towards the optical axis X in order to select a suitable pitch. Each grating mask 2b, 2c, 2d can be rotated by means such as a motor (not shown) to obtain the required grating angle. The number of grating masks can be increased or decreased as needed. The transposition stage and the motor are controlled by the control unit 6 (FIG. 1). Area control mask 2e
Is used to control the size of the exposure area of the reduced grid image. The diffusion plate 2a and the area control mask 2e are arranged on the optical axis X, and the object distances (the object distance) of the grating masks 2b, 2c, 2d.
tances) must be chosen correctly.

FIG. 5 shows another embodiment of the grid image generation module 2. In the figure, the liquid crystal projection surface 2
The liquid crystal display as f is the lattice mask 2 shown in FIG.
Used in place of b, 2c, 2d. Liquid crystal projection surface 2f
Is controlled by the control unit 6 to generate any requested image. In this case, the region control mask 2e can be eliminated.

Referring to FIG. 6, the optical image processing module 3 can be realized by using an optical Fourier transform. In this embodiment, the optical image processing module 3 includes a Fourier transform lens 3
d, an inverse Fourier transform lens 3e, and a filtering mask 3f. Each lens 3d, 3e
Can consist of a single lens or a lens combination. When the optical image processing module 3 of this embodiment is used in conjunction with the grating image generation module 2 shown in FIG. 4 or FIG. 5, the diffusion plate 2a must be eliminated and the light source 1 Must produce parallel coherent light with the appropriate wavelength and controllable exposure.

The grid image generated by the grid image generating module 2 is illuminated by parallel coherent light, and further deformed by the Fourier transform lens 3d. The filter mask 3f is arranged at the position of the Fourier transform plane of the Fourier transform lens 3d in order to filter the spectral signal of the deformed lattice image. The filtered grating image is then transformed by the inverse Fourier transform lens 3e, and the final grating image is obtained at the back focal plane of the inverse Fourier transform lens 3e. Therefore, a photosensitive plate 4 is placed at the back focal plane for recording the final grid image. The final lattice image is arranged by following the relative relationship of the focal length between the Fourier transform lens 3d and the inverse Fourier transform lens 3e.
It can be reduced or enlarged. In the arrangement of FIG. 6, the auto-focusing module shown in FIG. 8 can be added.

Further, a set of one or more lenses including a Fourier transform lens and an inverse Fourier transform lens can be used. The distance between all two lens sets should be equal to the sum of the back focal length of the inverse Fourier transform lens (front set) and the front focal length of the Fourier transform lens (back set). Is preferred. A Fourier transform surface is in each set. The filter mask 3f can be arranged on any Fourier transform plane.

Image processing using the Fourier transform can be adapted to simply reproduce a grid from a grid image.

Returning to FIGS. 1, 2 and 3, the light source 1 and the optical image processing module 2 can be replaced by a bright spot light source (not shown). That is, the "image source" is the light spot for it. The light of the bright spot light source is collected by the optical image processing module 3 to form a very fine light spot on the photosensitive plate 4. The fine light spots change the position relative to each other, hold the photosensitive plate 4 to control the brightness of the light of the light spot light source, and move the photosensitive plate 4 with respect to the light spot. By the position control module 5, it can be used as a pen for drawing arbitrary patterns of the grid on the photosensitive plate 4.

There are various ways to generate a bright spot light source. For example, an ideal bright spot light source can be obtained by focusing the laser beam or filtering the laser beam with a pinhole. An LED or laser diode can be used directly as a bright spot light source. Alternatively, the bright spot light source is obtained by concentrating the light of a common lamp light source or filtering the light with a pinhole on the focal plane. Any of the selected light sources must have the appropriate wavelength to be sensed by the photosensitive plate 4, and the brightness and exposure of that spot must be controllable.

In practice, calibration is required for an optical grating generator. Therefore, it is preferable to add a monitoring function to the system. Referring to FIG. 7, a monitoring module 6 that can utilize the principles of microscope monitoring is added to the system. The monitoring module 6 includes a beam splitter 61, a CCD (Charge Coupled Device) image receiver 62, and a monitor 63. When the grating image is projected onto the photosensitive plate 4, diffused light from the surface of the photosensitive plate 4 returns along the same path and is reflected by the beam splitter 61 to the CCD image receiver 62. Then, the CCD image receiver 62
Converts the received optical signal into an electric signal. The quality of the grid image can be observed on the monitor 63 and can be checked by further analyzing the electrical signal. Instead of a CCD, eye monitoring can also be used according to the principle of microscopic monitoring.

While numerous features and advantages of the invention have been set forth in the foregoing description, together with structural details and features of the invention, the specification is illustrative only and is not to be considered within the scope of the principles of the invention. It is to be understood that there may be variations in details, particularly in matters relating to shape, size and arrangement of elements, to the extent indicated by the generic term for the words recited in the claims.

[0038]

【The invention's effect】

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an arrangement of an optical grating generation device according to the present invention.

FIG. 2 shows an example of an optical image processing module of the optical grating generation device according to the present invention.

FIG. 3 shows another example of the optical image processing module of the optical grating generation device according to the present invention.

FIG. 4 shows an example of a grating image generation module of the optical grating generation device according to the present invention.

FIG. 5 shows another example of the grating image generation module of the optical grating generation device according to the present invention.

FIG. 6 shows an example of an optical image processing module based on a Fourier transform.

FIG. 7 shows an embodiment including a monitoring module of the optical grating generation device according to the present invention.

FIG. 8 shows an automatic focusing unit module of the optical grating generation apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Lattice image generation module 2b, 2c, 2d ... Lattice mask 2e ... Area control mask 2f ... Liquid crystal projection surface 3 ... Optical image processing module 3a ... Reduction lens 3b ... Parallelizing lens 3c ... Focusing lens 3d ... Fourier transform lens 3e Inverse Fourier transform lens 3f Filtering mask 4 Photosensitive plate 5 Position control module 6 Control unit 61 Beam splitter 62 CCD image receiver 63 Monitor 70 Laser diodes 71 and 72 Sensor 73 mirror

Claims (24)

[Claims] 1. An image source for providing an image, an optical image processing module for performing processing for controlling a dimension of the image, and a photosensitive plate for recording a processed image formed thereon. And a position control module for supporting and controlling the position of the photosensitive plate, and a control unit for controlling the image source, the optical image processing module and the position control module. An optical grating generator. 2. An image source, comprising: a grid image generating module for generating a grid image; and a light source for providing light required to generate the grid image and exposing a photosensitive plate. The optical grating generation device according to claim 1, comprising: 3. The light source includes a light emitting diode (LE).
3. The optical grating generator according to claim 2, wherein D). 4. The optical grating generator according to claim 2, wherein said light source is a semiconductor laser. 5. A grid image generating module, comprising: a diffusion plate for diffusing light; at least one controllable rotatable grid mask; and a grid image formed on the photosensitive plate via the grid mask. 3. The optical grating generation device according to claim 2, further comprising: an area control mask for controlling the area. 6. The optical grating generating apparatus according to claim 5, wherein said grating image generating module includes a plurality of grating masks having various grating patterns having different pitches. 7. An optical grating generator according to claim 6, wherein an appropriate one of said grating masks is selected by a control unit to form a grating image on a photosensitive plate. 8. The liquid crystal display according to claim 2, wherein the grid image generating module includes a light diffusing plate for diffusing light, and a liquid crystal display.
An optical grating generator according to any of the preceding claims. 9. The optical grid generator according to claim 1, wherein the image source is a bright spot light source for drawing a grid image on a photosensitive plate at the light spot. 10. The bright spot light source draws a grid image on the photosensitive plate by a control unit that controls a position control module supporting the photosensitive plate to change the position of the photosensitive plate. The optical grating generator according to claim 9. 11. The optical grating generator according to claim 9, wherein the bright spot light source is an LED (Light Emitting Diode). 12. The optical grating generator according to claim 9, wherein said bright spot light source is a semiconductor laser. 13. The optical grating generation apparatus according to claim 2, wherein the optical image processing module includes a Fourier transform lens, an inverse Fourier transform lens, and a filter mask. 14. The optical grating generation device according to claim 13, wherein each lens is a lens combination. 15. The optical grating generator according to claim 13, wherein the filter mask is disposed between a Fourier transform lens and an inverse Fourier transform lens. 16. The apparatus according to claim 1, wherein the optical image processing module is a reduction lens. 17. The optical grid generation device according to claim 16, wherein the lens is a lens combination. 18. The optical grating generator according to claim 1, wherein the optical image processing module includes a collimating lens for converting the diffused light into parallel light, and a focusing lens. 19. The optical grating generator according to claim 18, wherein each lens is a lens combination. 20. The position control module,
An optical grating generator according to claim 1, characterized in that it is a controllable transition stage that can be made into a program. 21. The optical grating generator according to claim 1, wherein the control unit is a computer. 22. The apparatus according to claim 1, wherein the control unit is a microprocessor. 23. The apparatus of claim 1, further comprising an autofocus module for automatically inspecting and adjusting the focus of the image formed on the photosensitive plate. 24. The apparatus of claim 1, further comprising a monitoring module for monitoring image quality.