JPH1195177A - Image processing method using spatial optical modulation element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain a high-contrast image by using a spatial optical modulation element having an electro-optic effect and optical transmission effect. SOLUTION: While the light of a light source 1 irradiates the entire surface of a Pockels reading out optical modulation element 9 formed with transparent electrodes via insulating layers on both surfaces of an electro-optic crystal layer, voltage of several kV is simultaneously impressed on the element from a high-voltage power source 10. An image film, 5 is then mounted at the Pockels reading out optical modulation element 9 in the state of impressing the voltage of a reverse polarity thereon. When the film is irradiated with writing light 14, the image information drawn on the image film 5 is recorded in the optical modulation element 9. The reading out light 16 from the light source 15 is then cast to the Pockels reading out optical modulation element 9 to read out the recorded information. When the information is detected by a detector 13, such as a CCD, by a polarizing plate 11 and a lens 12, the detected image is the reversal image of the image recorded on the image film 5. The high-contrast image is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method using a spatial light modulator, and more particularly to an image processing method using a spatial light modulator having an electro-optic effect and a photoconductive effect.

[0002]

2. Description of the Related Art Various methods have been used for image processing, and digital image processing for converting an image into digital data and then performing processing is widely used. In digital image processing, a huge amount of two-dimensional data is processed pixel by pixel using a processing device such as a computer. Therefore, there is a problem that the processing time is long even if various image processing algorithms or dedicated processors are used. is there.

On the other hand, image processing using an optical image processing apparatus has a feature that processing at the speed of light is possible. For example, in an image processing method using a Pockels readout light modulation element using an electro-optic crystal as a light spatial modulation element, a high voltage is applied to the spatial light modulation element to form an electric field in the electro-optic crystal, Although high-speed image processing is possible, the intensity of the electric field generated in the electro-optic crystal is not sufficient, and there is a problem that the change range of the transmittance due to the electro-optic effect in the electro-optic crystal layer is narrowed.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an image processing method using a spatial light modulating element comprising an electro-optical crystal layer, wherein the spatial light modulating element has an improved transmittance variation region generated in the electro-optical crystal layer. It is an object of the present invention to provide an image processing method according to the present invention.

[0005]

According to the present invention, there is provided an image processing method using a spatial light modulator, wherein a transparent electrode is formed on both sides of an electro-optic crystal layer via an insulating layer via the transparent electrode. After applying the voltage uniformly to the entire surface, applying a voltage of opposite polarity between both electrodes, exposing the image while applying the voltage, and irradiating the reading light to form the image. This is an image processing method using the obtained spatial light modulator.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention proposes an image processing method using a Pockels readout light modulation element using an electro-optic crystal as a light spatial modulation element. The Pockels readout light modulation element uses an electro-optic crystal exhibiting the Pockels effect that causes a direct change in the refractive index due to an electric field without a mechanical change. Usable electro-optic crystals include Bi ₁₂ SiO ₂₀ , Bi ₁₂ GeO ₂₀ ,
Single crystals such as LiNbO ₃ , LiNTaO ₃ , ZnS, ZnTe, and quartz are known.

For example, a Pockels readout light modulation element using a single crystal made of Bi ₁₂ SiO ₂₀ converts the light intensity distribution of the written image information into a charge distribution in a single crystal plate and accumulates it. It converts the readout light intensity distribution using the electro-optic effect generated by the electric field.

FIG. 2 shows an example of a spatial light modulator using an electro-optic crystal. Insulating layers 22 and 23 made of glass or the like are provided on both surfaces of the electro-optic crystal layer 21, respectively. Transparent electrode layers 24 and 25 such as ITO are provided on the insulating layer, substrates 26 and 27 such as glass are provided, and the transparent electrode layers 24 and 25 are provided for connection to an external circuit. Electrode lead wires 28 and 29 are connected. A spatial light modulator using such an electro-optic crystal is disclosed in Japanese Patent Laid-Open No. 5-134.
No. 219, Japanese Patent Application Laid-Open No. 4-257822 and the like.

It is presumed that the image processing method using the Pockels readout light modulation element of the present invention is based on the following operation mechanism. (1) Voltage distribution by voltage application When voltage is applied to the Pockels readout light modulation element,
As shown in the equivalent circuit of FIG.
Are the insulating layer 22, the electro-optic crystal layer 21, and the insulating layer 2
3, the voltage is divided and distributed in inverse proportion to the capacitance ratio of C1, C2 and C3. R2 has a high resistance when light is not irradiated, and hardly causes current to flow. However, when light is irradiated, the resistance value decreases in accordance with the amount of light and current flows.

(2) Entire Irradiation of Write Light Next, when a large amount of write light is uniformly irradiated on the entire surface of the Pockels readout light modulation element, the generated photocarriers move within the electro-optic crystal to generate an electric field. The resistance R shown in
2, the voltage applied to the capacitor C2, that is, the voltage applied to the electro-optic crystal layer disappears.

(3) Application of reverse voltage Next, when a voltage -V having an opposite polarity is applied to the Pockels readout light modulation element, voltage distribution is again applied to the insulating layer, electro-optic crystal, and insulation layer inside the Pockels readout light modulation element. However, as shown in FIG.
2, the applied voltage −V having the opposite polarity,
Since the voltage applied to C1 and C2 is applied in series by the application of the first voltage, a voltage larger than the voltage applied to C2 by the application of the first voltage is applied. As a result, the electric field strength in the electro-optic crystal becomes larger than the electric field strength when a voltage is applied before light irradiation.

Therefore, the electro-optic effect caused by the electric field intensity is also increased as compared with the first voltage application, so that the transmittance is also improved. Higher-contrast modulation can be performed as compared with the case where writing is performed.

FIG. 1 is a view for explaining an example of an apparatus used for the image processing method of the present invention. Light from the light source 1 such as a xenon lamp is transmitted as a writing light 14 through the electromagnetic shutter 2 and the monochromatic filter 3 to be converted into monochromatic light with high intensity, and transmitted through the lens 4 to form an image film 5 on which an input image is drawn. Is removed, the image information is transmitted through the lens 6, the half mirror 7, and the polarizing plate 8 to irradiate the entire surface of the Pockels readout light modulation element 9 while a voltage of several kV is applied from the high voltage power supply 10 at the same time. You.

Next, the Pockels readout light modulation element 9
When an image film 5 is attached, a magnetic shutter is opened, and writing light is irradiated in a state where a voltage having a reverse polarity is applied to, image information drawn on the image
The light passes through the half mirror 7 and the polarizing plate 8 and reaches the Pockels readout light modulation element 9 where image information is recorded. Next, the reading light 16 from the light source 15 is
Electromagnetic shutter 17, monochromatic filter 18, lens 19
And the direction is changed by the half mirror 7,
When the recording information is read out by irradiating the Pockels readout light modulating element 9 through the polarizing plate 8 and detected by the detecting device 13 such as a CCD by the polarizing plate 11 and the lens 12, the detected image is recorded on the image film 5. An inverted image of the image obtained was obtained with high contrast.

In the above description, an example in which an image film is used for inputting an image has been described. However, the input of an image after irradiating the entire surface of the Pockels readout light modulation element can be performed by an input device such as an image scanner without depending on the image film. Alternatively, the input can be made by an arbitrary method such as input means by drawing a laser beam.

[0016]

The present invention will be described below with reference to examples. Example 1 A xenon lamp (manufactured by Hamamatsu Photonics, Ltd.) was applied to the Pockels readout light modulation element (ITI-PROM manufactured by Nippon Insulators) with a voltage of 5 kV applied by the apparatus illustrated in FIG.
L2274) and a monochromatic filter (glass filter KT-60 made by Toshiba Glass Co., Ltd.)
Irradiation with uniform reading light having a m and a half value width of 12 nm was performed. As a result, 4% of the reading light was transmitted and detected by the CCD detector. The electromagnetic shutter is opened for 10 seconds while a voltage is applied to the Pockels readout light modulation element, and a xenon lamp (L2274 manufactured by Hamamatsu Photonics) and a monochromatic filter (glass filter KT-5 manufactured by Toshiba Glass) are used.
0), the entire surface was uniformly irradiated with writing light monochromatized with a center wavelength of 500 nm and a half-value width of 10 nm after removing the image film.

Next, readout light was irradiated while maintaining the voltage, and it was confirmed that the transmittance of the Pockels readout light modulation element became 0%. When a voltage of −5 kV was applied to the Pockels readout light modulation element in a state where the readout light was irradiated, it was confirmed that 9% of the readout light was transmitted in 3 seconds. This was twice or more the transmittance when the entire surface was uniformly exposed and no reverse polarity voltage was applied. In addition, with the voltage applied continuously, the image film was attached, the electromagnetic shutter was opened for 10 seconds, and the writing light having the center wavelength of 500 nm and the half-value width of 10 nm previously used was irradiated. To obtain an inverted image.

[0018]

The transmissivity can be increased by the spatial light modulator using the electro-optic crystal, so that a high-contrast image can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an apparatus used for an image processing method using a spatial light modulator according to the present invention.

FIG. 2 is a diagram illustrating a spatial modulation element.

FIG. 3 is an equivalent circuit for explaining the spatial light modulator of the present invention.

[Explanation of symbols]

1: light source, 2: electromagnetic shutter, 3: monochromatic filter,
4 lens, 5 image film, 6 lens, 7 half mirror, 8 polarizing plate, 9 Pockels readout light modulator, 10 high voltage power supply, 11 polarizing plate, 12 lens, 13 detecting device , 14 ... writing light, 15 ... light source,
Reference numeral 16: reading light, 17: electromagnetic shutter, 18: monochromatic filter, 19: lens, 21: electro-optic crystal layer, 2
2, 23 ... insulating layer, 24, 25 ... transparent electrode layer, 26, 2
7 ... substrate, 28, 29 ... electrode lead wire

Claims (1)

[Claims] In an image processing method using a light modulation element, a spatial modulation element having transparent electrodes formed on both sides of an electro-optic crystal layer via an insulating layer with a voltage applied between the transparent electrodes is applied to the entire surface. Spatial light modulation characterized by applying a voltage of opposite polarity between both electrodes after uniform exposure, exposing the image with the voltage applied, and irradiating with reading light to obtain an image An image processing method using an element.