JPS6146927A - Space optical modulating tube - Google Patents

Abstract

PURPOSE:To obtain a space optical modulating tube which can execute a coherent operation without a trouble by providing plural slots on one end face of a cylindrical spacer, sticking a crystal part to its end face, and sticking the other end face to the inside wall of an output surface of a vacuum vessel. CONSTITUTION:Plural slots 20a are provided on one end face of a cylindrical spacer 20, an electro-optical crystal 8 of LiNbO3, etc. is stuck by an epoxy compound adhesive agent, etc., and the other end face is stuck and fixed to a glass surface plate 12 of a vacuum vessel 3 for forming an output surface of a space optical modulating tube. In such a way, a ''0''-order component on a Fourier transforming surface of the time when a lens whose focal distance is 1,000mm. has been used becomes a circular spot shape, therefore, no influence is exerted on a higher order component, and a coherent optical operation is executed easily. Also, a deformation caused by a difference of coefficients of thermal expansion of the crystal 8 and the spacer 20 is absorbed by the slot part 20a, therefore, a distortion is scarcely generated in the crystal 8, and an optical operation processing is executed easily.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an electro-optic crystal that is arranged on a photocathode formed on the inner surface of a vacuum container, and emits light corresponding to the optical image formed on the photocathode. The present invention relates to a spatial light modulation tube that accumulates photoelectrons generated on the surface of the crystal, causes a change in refractive index corresponding to the accumulated charge in the crystal, and reads out the change in refractive index with a laser.

(Conventional technology) First, the basic operation of the spatial light modulation tube will be briefly explained.

FIG. 3 is a schematic cross-sectional view showing a conventional spatial light modulation tube.

An image of an incident cover turn illuminated with incoherent light is made incident on the photocathode 4 on the inner surface of the glass container 3 of the spatial light modulation tube via the lens 2.

The photocathode 4 emits photoelectrons corresponding to the incident image.

The photoelectrons are made incident on the microchannel plate 6 via the accelerating/focusing electron lens system 5, and are multiplied several thousand times.

The multiplied electrons are accumulated on the surface of an electro-optic crystal 8 such as LiNbO3, and change the refractive index of the crystal 8 in accordance with the charge image. A transparent conductive film is uniformly deposited on one surface 8a of the crystal 8.

When the crystal 8 is irradiated with laser light from the laser light source 10 via the half mirror 9, a laser light image 11 (coherent image) is obtained. This laser beam image 11 can be used to perform coherent parallel optical calculations.

Conventionally, the crystal 8 built into the above-mentioned spatial light modulation tube has been mechanically fixed directly to the output glass face plate 12 or by a spring via a ring-shaped spacer.

There is a desire to make the electro-optic crystal as thin as possible in order to improve the resolution of the spatial light modulation tube, and when the electro-optic crystal is made thinner, problems arise with the above-mentioned fixing method.

For example, if a crystal with a diameter of 25 mm and a thickness of about 300 μm is fixed using the above fixing structure, the crystal will be distorted during fixing, and further, when an operating voltage is applied, the crystal will be distorted due to electrostatic force.

As a result, the output image is distorted, making normal optical calculation difficult.

For example, when Fourier transform is performed using a lens, zero-order light is no longer focused into a spot, and cannot be separated from higher-order light.

(Object of the Invention) An object of the present invention is to provide a spatial light modulation tube that can perform coherent calculations without problems by improving the support structure of an electro-optic crystal.

(Structure of the Invention) In order to achieve the above object, the spatial light modulation tube according to the present invention includes a photocathode formed in a vacuum container and an electric current that accumulates photoelectrons emitted from the photocathode and causes an optical change. In a spatial light modulation tube including an optical crystal section, the crystal section is integrally bonded to the end face side of a cylindrical spacer provided with a plurality of slots from one end side, and the other side of the spacer is provided with a plurality of slots. By connecting the end face to the inner wall of the output surface of the container, the crystal part is configured to face the photocathode.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

The basic configuration of the spatial light modulation tube according to the invention does not differ from that previously described in FIG.

FIG. 1 is a perspective view showing an electro-optic crystal and a spacer used in a spatial light modulation tube according to the present invention.

FIG. 2 is a sectional view showing the state fixed to a vacuum container.

The electro-optic crystal 8 to be fixed is a 55° cut LINb0.
It is 3 crystals.

This electro-optic crystal 8 has a diameter of 26 mm and a thickness of 0°3 m.
m, and a transparent conductive film is formed on one surface (lower side in FIG. 1).

A spacer 20 that supports this crystal 8 has an outer diameter of 25 mm.
, a glass cylinder with an inner diameter of 21 mm and a height of 5 mm is used. A plurality of slots 20a...2 are formed from one end surface of this cylinder.
0a is provided.

In this embodiment, eight slots were provided, but in the case of this size, it is appropriate to provide 8 to 16 slots evenly distributed at angles.

An electro-optic crystal 8 is placed on the end face where the slot 20a is provided.
The side on which the transparent conductive film is provided is adhered with an epoxy adhesive or a polyimide adhesive.

This bonded and integrated structure is bonded and fixed to the glass face plate 12, which is the output surface of the vacuum container 3, using a spacer 20.

Conventionally, the spatial light modulation tube equipped with the electro-optic crystal 8 as described above has a focal length of ! When a 1000 mm lens is used, the 0-fire component on the Fourier transform surface is shaped like an oblong or triangular shape, but it becomes a small circular spot.

As a result, it does not affect higher-order components, making it easier to perform coherent light calculations.

Next, a plurality of slots 20 formed in the spacer 20
Explain the technical meaning of a.

The spatial light modulation tube is baked at a high temperature of 200° C. or higher for degassing or for creating a photocathode.

The thermal expansion coefficients of normal glass and electro-optic crystal are different as follows.

Glass・・・・・・50X10-7/degree LiNbO3
55° cut plate X-axis...120xlO-7/degree y-axis...
......30 x 10-7/degree It is thought that this difference in thermal expansion coefficient caused problems such as cracking of the crystals and peeling of the bonded portion when bonding in the past.

In the present invention, the difference in the amount of deformation due to the difference in thermal expansion coefficients is absorbed by the plurality of slits, and the conventional problem is completely solved.

- (Modifications) Various modifications can be made to the embodiments described in detail above within the scope of the present invention.

In the embodiment described above, the spacer 20 was fixed by adhering to the glass face plate 12 which is the output surface of the vacuum container 3, but this may be fixed mechanically.

Further, although a glass cylinder is shown as an example of the spacer 20, a ceramic cylinder or a cylinder having a similar shape may also be used.

Electro-optic crystals are not limited to LiNbO3, but also LiT
aO3, B i+z S l 020 (BSO), etc. can be used.

(Effects of the Invention) As explained above in detail, in the spatial light modulation tube according to the present invention, the crystal portion is formed on the end face side of the cylindrical spacer provided with the plurality of slots from one end side, where the slots are provided. The spacer is bonded together and the other end surface of the spacer is connected to the inner wall of the output surface of the container, so that the crystal part faces the photocathode.

However, deformation due to the difference in thermal expansion coefficients is absorbed by the slits, and the thin electro-optic crystal can be supported in a state where distortion is less likely to occur, resulting in spatial light modulation suitable for optical arithmetic processing. Can you provide tubes?

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an electro-optic crystal and a spacer used in a spatial light modulation tube according to the present invention. FIG. 2 is a sectional view showing the state fixed to a vacuum container. FIG. 3 is a sectional view showing the basic configuration of the spatial light modulation tube. 1...Enter cover turn 2...Lens 3.
...Glass container 4...Incidence surface 5...
Focusing lens system 6...Micro channel plate 7...Mesh electrode 8...Electro-optic crystal 9...Half mirror 10...Ray f light fi11.
...Output pattern 12...Output surface 20...
・Spacer 20a... Sliding patent applicant: Hamamatsu Photonics Co., Ltd. Agent Patent attorney: Inoro Dokuga Figure 1 Figure 2

Claims (4)

[Claims] (1) In a spatial light modulation tube consisting of a photocathode formed in a vacuum container and an electro-optic crystal part that accumulates photoelectrons emitted from the photocathode and produces an optical change, the crystal part has a plurality of crystal parts starting from one end. is integrally adhered to the end surface side of a cylindrical spacer provided with the slot, where the slot is provided;
The spatial light modulation tube is configured such that the other end surface of the spacer is connected to the inner wall of the output surface of the container so that the crystal portion faces the photocathode. (2) The electro-optic crystal is made of LiNbO_3, LiTa
The spatial light modulation tube according to claim 1, which is any one of O_3, Bi_1_2SiO_2_0 crystal. (3) The spatial light modulation tube according to claim 1, wherein the electro-optic crystal is a 55° cut crystal of LiNbO_3. (4) The spatial light modulation tube according to claim 1, wherein the output surface of the vacuum container is made of glass, and the spacer is made of glass.