JPS5849911A - Optical surface image converting element - Google Patents

Abstract

PURPOSE:To guarantee the quality of an image over a long term by forming a transparent insulating layer on a thin plate of a crystal body having both of photocnductive and electrooptical effects and by laying a protective film on the insulating layer with a transparent electrode in-between to enhance the moisture resistance and to maintain the insulating property of the insulating layer. CONSTITUTION:The surfaces of a thin plate 21 of a single crystal body of Bi12SiO20 having body of photoconductive and electrooptical effects are photopolished, and high molecular poly-p-xylylene is vacuum-deposited to form transparent insulating layers 22 on both sides of the plate 21 or a layer 30 on one side. Transparent In2O3-base electrodes 23, 24 contg. SnO2 are formed by an ion plating method, and lead wires 25, 26 are connected to the electrodes, respectively. Protective films 27 of high molecular poly-p-xylylene are then laid on both sides, or a film is laid on one glass substrate 28. Thus, a symmetry or asymmetry type optical surface image converting element 1 is obtd. The outer protective film inhibits the absorption of moixture in the air to prevent the deterioration of the insulating layer, and the quality of an image is guaranteed.

Description

[Detailed description of the invention] The present invention relates to improvements in optical image conversion elements.

BL12SL02o has electro-optical properties and photoconductive properties as an optical image conversion element in optical information processing technology.

A device that converts an incoherent optical image into a coherent optical image using a bismuth sirenite group single crystal such as Bi12Ge 020 (D) has already been published in a publication (J, Fe1rlei
h etal, Applied optics Vo
l 11. No. 12, 1972, 2752), and according to it, it has a structure as shown in FIG. 1(a). In FIG. 1(a), 1 is an optical image quality r element, 2 is a BL
12 is a St 020 single crystal, 3.4 is an insulating layer made of polyparakylylene, 5 and 6 are transparent electrodes such as Aa, P'+ 17L20.3°S 02, etc. Furthermore, an optical image conversion element 1 having an asymmetric structure without an insulating layer 3 as shown in FIG. 1(h) has also been proposed. As shown in FIG. 2, the optical image conversion element 1 having these structures applies a voltage between the electrodes 5.6 through the power supply 7 and the switch 8, and projects image information from the image information source 9 through the lens 10. , electron-hole pairs are generated in the light-irradiated portion of the single crystal 2. These electron-hole pairs move to both poles by the applied voltage and are trapped at the interface with the insulating layer 3.4, and the potential gradient within the single crystal 2 is smaller in the light-irradiated area than in the light-irradiated area, resulting in an image. written. The image writing light 11 is 5QQr, which has a large photoconductive effect because it utilizes the wavelength dependence of the Bi 12 Si 020 single crystal 2.
Light with a short wavelength of tm or less is used. Next, when reading out an image, a long-wavelength light with a small photoconductive effect, such as Ht-Ne laser light 12, is uniformly irradiated onto the incident surface of the optical image conversion element l via a polarizer 13 and a mirror 1-7. By passing the transmitted light through an analyzer 15, an intensity-modulated coherent optical image 16 is obtained. At this time, the polarization direction of the readout light incident on the optical image conversion element 1 is 4 with respect to the crystal axis.
Set it to 5°.

Next, to describe the readout operation in detail, when a voltage is applied to the optical image conversion element 1, the crystal 2 exhibits birefringence characteristics. The refractive index for linearly polarized light in two directions (S direction and F direction) parallel to the crystal plane (100) and perpendicular to each other is different. When coherent light with an intensity I that is linearly polarized in the bisecting direction with respect to the S direction and the F direction is incident on the crystal 2, it becomes elliptically polarized light according to the double-sided threshold voltage V due to the birefringence property (Pockels effect). . Therefore, by placing an analyzer 15 perpendicular to the incident polarization direction on the output side, it is possible to extract the voltage distribution of the crystal 2 as a light intensity distribution of coherent light, and the intensity of the output light is 2. is given by the following equation.

However, λ/2 is the half-wave voltage, and Bi 12 Si
020 is 3.9 KV.

However, since the applied voltage is high in this optical image conversion element, repeated operation causes the insulating layers 3 and 4 to deteriorate, resulting in a decrease in image quality. This is mainly because the insulating layers 3 and 4 absorb moisture from the atmosphere and their insulating properties deteriorate.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an optical image conversion element in which the insulating properties of the insulating layer are improved.

The present invention will be described below by way of examples with reference to the drawings.

An embodiment of the present invention is shown in FIG. In Figure 3, 21 is Bz
It is a thin plate of 12 St 020 or B'12 Ge 020 single crystal, and both end surfaces thereof are optically polished to a surface precision of /10 or more. On the entire surface of this crystal 210 including both end faces, a polymer film of polyparaxylylene was vacuum-deposited to a thickness of 5μ to form an insulating layer 22, and on both end faces of the insulating layer 22, Iyc203 containing a small amount of 5rLo2 was formed. The element body is constructed by sequentially forming very transparent electrodes 23 and 24 by the ion blating method. After that, lead wires 25.26 for applying voltage to the electrodes 23.24 are connected to the electrodes 23.24, and a polymer film of polyparaxylylene is vacuum-deposited on the outer surface of the element body to a thickness of about 20 μm. A transparent protective film 27 is formed.

According to this embodiment, since the protective film 27 is formed on the element body, the protective film 27 can prevent the insulating layer 22 from absorbing moisture in the atmosphere, thereby improving the durability of the insulating layer 22.

FIG. 4 shows another embodiment of the invention. Bi12 Si
020 or Bt Ge 02Q single crystal thin plate 21 has both end faces. It has been optically polished to a surface precision of above. First, one side of this thin plate 21 is optically polished and a transparent electrode 23 containing a small amount of 5rLO2 in nO2 is formed by vacuum evaporation, and then fixed on a glass substrate 28 with a transparent optical adhesive 29, and a lead wire 25 is attached. The electrode 23 is drawn out through the hole 28α of the glass substrate 28. Next, the other surface of the thin plate 21 is optically polished so that the thickness of the thin plate 21 is about 100 μm.

On the optically polished surface of this thin plate 21, a polymer film of polyparaxylylene is vacuum-deposited to a thickness of 5 μm to form an insulating layer 30, and then an I? A transparent electrode 24 containing a small amount of 5rLO2 is formed on 1203 by the ion-blating method, a lead wire 26 is bonded to the electrode 24, and a polymer film of polyparaxylylene is vacuum-deposited on the electrode 24 to a thickness of about 20 μm. A protective film 31 is then formed.

According to this embodiment, since the thin plate 21 is bonded to the glass substrate 28 and then polished, the thin plate 21 can be made thinner to a desired thickness, improving resolution. This can suppress absorption of atmospheric moisture by the insulating layer 30 and improve its durability.

As described above, according to the present invention, since a protective film is provided on the electrode on the insulating layer in the optical image conversion element, the protective film can prevent the insulating layer from absorbing moisture in the atmosphere. It is possible to suppress the deterioration of the insulating layer and suppress the deterioration of image quality.

[Brief explanation of the drawing]

1 and 2 are front views showing each side of a conventional optical image conversion element, FIG. 3 is a model diagram showing an example of an optical image recording and reproducing device, and FIGS. 4 and 5 are each side of a conventional optical image conversion element. It is a sectional view showing an example. 21...Crystal, 22.30...Insulating layer, 23.2
4 electrodes, 27.31...protective film. Procedural amendment book type) % type % 1 Indication of the case 1982 Patent Application No. 64711 2 Name of the invention Optical image conversion device 3 Person making the amendment Relationship to the case Appointment of patent applicant
Location 1-3-6 Nakamagome, Ota-ku, Tokyo Name (
674) Rico Co., Ltd.-4 Agent〒゛156 Address 2-6-28-6 Sakuragaoka, Setagaya-ku, Tokyo
Subject of amendment: “Brief explanation of drawings” column 7 of the specification
Contents of the amendment (1) The sentences from page 6, line 17 to the last line of the same page of the specification are corrected as follows. 1 (al, (bl) is a front view showing each side of a conventional optical image conversion element, FIG. 2 is a model diagram showing an example of an optical image recording and reproducing device, and FIGS. 6 and 4 are in accordance with the present invention. It is a sectional view showing each example of.

Claims (1)

[Claims] A crystal body that has both a photoconductive effect and an electro-optical effect, a transparent insulating layer provided at one end or both ends of this crystal body, and a transparent insulating layer provided at both ends of the crystal body through this insulating layer. An optical image conversion element having an electrode, characterized in that a protective film is provided on the insulating layer via the electrode.