JPS6152627A - Optical modulator - Google Patents

Abstract

PURPOSE:To cool effectively a crystal thin plate by providing a Peltier effect element group by at least two stages by combining a Peltier effect element and a plate body of oxygen free copper. CONSTITUTION:A crystal thin plate 3 having an electrochemical effect cooled to a working temperature is provided on one surface of a transparent substrate 6 in a sealed pipe body, the first plate body 21 consisting of oxygen free copper is made to about on the other surface of the substrate 6 except an effective operating area of the thin plate 3, and on the plate body 21, a Peltier element group 22A of the first stage is provided so as to surround the effective operating area of the thin plate 3. Also, the second plate body 23 consisting of oxygen free copper is made to about on the element group 22A, a Peltier effect element group 22B of the second stage is made to about on the plate body 23, and also the third plate body 24 consisting of oxygen free copper is provided on the element group 22B in the same way. As for the plate body 24, a C-shaped shell 25 for making a cooling water pass through is welded and placed in the periphery of a through-hole 24a so that the cooling water is supplied from the outside of a pipe body 1 through a feed pipe 27 and a cooling water passage 26. Accordingly, the thin plate 3 can be cooled effectively to a necessary temperature.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention utilizes the birefringence caused by an electric field of a crystal that has an electro-optical effect suitable for application to, for example, a globjector that projects a television image onto a screen. The present invention relates to an optical modulator.

[Prior art]

In a projector using an optical modulator, for example, as shown in FIG. 5, a target (2) is arranged inside a tube (1) facing a face (1f) thereof. Target (2
) is a thin crystal plate having an electro-optic effect, such as KH2PO4 (hereinafter referred to as DKDP), as shown in FIG.
Alternatively, a dielectric mirror film (for example, a multilayer film structure) having a secondary electron emission ratio of 100% and reflecting visible light may be formed on one surface of a crystal thin plate (3) made of KH2PO4 (hereinafter referred to as KDP).
4) is deposited, a transparent conductive film (5), for example, a n203 film, is deposited on the other side, and the transparent conductive film (5) side is clamped to a transparent substrate (6). Also,
The target (2) is arranged such that its transparent substrate (6 side) faces the face portion (1f).

Also, inside the tube is a mirror film (4) of the target (2).
side facing first and second grid electrodes G1 and G2;
is placed.

Then, as shown in FIG. 5, the electron beam b from the cathode K is focused and scanned on the mirror film (4) of this targut (2). (7) and (8) indicate the electromagnetic means for focusing and scanning deflection, respectively.

Then, there is a light-transmitting face plate on the front surface of the tube (1).
The light source (
9) is irradiated via a polarizer αQ, and the reflected light from the mirror film (4) is projected onto the screen (2) via an analyzer αV. On the other hand, a video signal, that is, a screen (
6) Apply the video signal to be projected onto. At this time, an electron beam from the cathode K is scanned with a constant current density Ip over the dielectric mirror film (4) of the targut (2) having a high secondary electron emission ratio δ, and is charged in accordance with the video signal.

Note that the second grid G2 is placed close to the mirror film (4) at a distance of, for example, 40 μm.

Further, the first grid G is applied with a potential of, for example, 150V, and captures floating secondary electrons generated from the mirror film (4), and the resolution is not degraded by the floating secondary electrons. This is to prevent this from occurring.

According to this configuration, depending on whether secondary electrons are emitted from the dielectric mirror film (4) or primary electrons are accumulated due to the impact of the electron beam b, that is, the incidence of primary electrons, a corresponding charge is generated. occurs in the dielectric mirror film (4), thereby applying a potential to the dielectric mirror film (4). Since the emission of secondary electrons is suppressed when this potential reaches the same potential as the second grid G2, it is balanced at this potential. That is, at each scanning position of the electron beam b, the second grid G2
4 turns of charges are generated in response to the voltage change due to the video signal applied to the crystal thin plate (3) between the mirror film (4) and the transparent conductive film (5). The pattern is given to create birefringence due to longitudinal effects depending on the video signal.

On the other hand, the polarizer and the analyzer αη are used to detect the light incident on the target (2) from the light source (9) and the light reflected from the light source (9) without applying any potential turns to the crystal thin plate (3). and are arranged so that their optical axis directions are perpendicular to each other.

According to this configuration, the linearly polarized light that enters the target (2) through the polarizer αQ is reflected by the dielectric mirror film (4) and passes back and forth through the thin crystal plate (3), thereby becoming amplified. The light is modulated by the birefringence generated in response to the video signal at the analyzer α, and this causes the light passing through the analyzer α to have shading, resulting in an optical image being projected onto the screen (2).

In this way, a projector can be configured by using an optical modulator, and this type of projector
Various proposals have been made. One example is Japanese Patent Publication No. 43-29086.

[Problem that the invention seeks to solve]

The above-described modulator is used while being maintained at an operating temperature slightly higher than the Curie point of its crystal thin film. The Curie temperature of this crystal thin plate varies somewhat depending on the composition of the crystal thin plate, but for example, if the degree of substitution of heavy water is 9.
In the case of 596 DKDP, one cucumber is approximately -51℃
When using this type of crystal thin plate,
For example, it is used after being cooled to -50°C. However, as mentioned above, when this modulator is used under electron beam scanning, it must be held in a sealed tube maintained at a high degree of vacuum; Cooling means also need to be placed within the sealed tube. Therefore, in this case, care must be taken to ensure that the degree of vacuum is not impaired by this cooling means, that is, to prevent inconveniences such as unstable gas release from the cooling means itself and a decrease in the degree of vacuum inside the tube. required to do so.

In the present invention, when the above-mentioned modulator is used in, for example, a projector, etc., even when the modulator is used under electron beam scanning, the crystal of the modulator can be reliably maintained without disturbing the degree of vacuum inside the tube. The present invention provides a modulator in which a thin plate can be cooled and maintained at a predetermined low temperature, for example, -50°C.

[Means for solving problems]

In the present invention, in contrast to a transparent substrate holding a crystal thin plate having an electro-optical effect, such as DKDP or KDP, on one surface, which is cooled to an operating temperature of, for example, -50°C, other parts of the transparent substrate are used. A first plate made of oxygen-free copper is provided on the surface of the crystal thin plate, which is in contact with a portion other than the effective operating area of the crystal thin plate. In addition to the effective operating area of the thin crystal plate mentioned above in contact with this first plate,
A first stage Peltier effect element group is provided in which a plurality of Bertier effect elements are arranged so as to surround this effective operating area.

A second plate made of oxygen-free copper is similarly placed in contact with each Vertier effect element of the first stage Peltier effect element group. Furthermore, in a region other than the effective operating area of the above-mentioned crystal thin plate in contact with the second plate, a second stage Peltier effect element group is provided in which a plurality of Bertier effect elements are similarly arranged so as to surround this effective operating area. will be established. Then, a third plate made of oxygen-free copper is placed in contact with each of the Vertier effect elements of the second stage Peltier effect element group.

The transparent substrate having these crystal thin plates, the first to third plates, and the first and second stage Peltier effect element groups disposed between them are, for example, mechanically integrated with each other and are placed in a vacuum. Disposed within a sealed tube.

A cooling means, such as a cooling pipe through which cooling water flows, is provided in close thermal contact with the third plate, thereby cooling the third plate from outside the vacuum-sealed tube.

[For production]

As described above, in the present invention, at least the first to third oxygen-free copper plates are provided, and the Peltier effect element group is provided between them. Therefore, its thermal conductivity is high and unnecessary gas release is avoided, but this is not possible, and together with the use of the Beltier effect element, it is an inconvenience that the degree of vacuum inside the vacuum-sealed tube decreases. It was confirmed that it was possible to avoid this and maintain a vacuum degree of about 10 Torr.

Further, according to the present invention, the above-mentioned oxygen-free steel with high thermal conductivity is used and at least two groups of Peltier effect elements are used.
By providing steps and by cooling the third plate made of oxygen-free steel from outside the tube by means of a cooling means, it was possible to reliably cool the crystal thin plate to about 50° C. below its operating temperature.

〔Example〕

An example of an optical modulator according to the present invention will be explained with reference to FIG. (1) shows the optical modulator according to the present invention as a whole.

In FIG. 1, parts corresponding to those in FIG. 5 are given the same reference numerals. In this example, a sealed tube (within one tube, e.g.
A transparent substrate (6) made of aFZ is coated with D in the same manner as described above.
A KDP region or an assembly having a thin crystal plate (3) made of KDP is placed. Although not shown, the transparent conductive film explained in FIG. 5 above is formed on the transparent substrate side of the crystal thin plate (3) or on the crystal thin plate side of the transparent substrate.
Although not shown, the dielectric mirror film explained in FIG. 5 is similarly deposited on the side opposite to the transparent substrate (6) of 3). Then, facing this crystal thin plate (3), a second grid electrode G2 and a first grid electrode G are sequentially arranged, and an electron beam emitting device (not shown in the figure) provided on the neck side of the tube body (1) is provided. A monocrystalline thin plate (3) is arranged to face the source, that is, the cathode.The transparent substrate (6) is
A first plate e1 made of oxygen-free copper is disposed in contact with the opposite side to the side where the crystal thin plate (3) is disposed, that is, the front surface. This first plate (b) K has a thin crystal plate (3
), a through hole (21 m) with an inner shape is bored along the periphery of the effective operating area, and this first
The plate body (c) is brought into contact with the transparent substrate (6) except in the operating region where nine turns of potential are formed in accordance with the projected image of the crystal thin plate (3) disposed on the transparent substrate (6).

Then, as shown in FIG. 2, a through hole (21m) of the first plate e1 is formed on the surface of the first plate e21 opposite to the side that comes into contact with the transparent substrate (6). For example, a total of 8 Bertier effect elements (2
) to form the first stage Peltier effect element group (22A
) will be established. The Bertier effect elements of this element group (22A) are electrically connected to each other in series, but thermally arranged in parallel, with each cooling (endothermic) side facing the first plate. 9 with vacuum grease to make a thermally tight bond. Furthermore, these first stage Peltier effect element groups (2
A second plate plate made of oxygen-free copper is similarly brought into contact with the heat generating side of each of the Bertier effect elements in 2A). In this case as well, there is a through hole (23a) in the center of the second plate (good) facing the effective operating area of the crystal thin plate (3) and having an inner shape corresponding to the outline of this operating area. The second plate (material) is located around the effective operating area of the crystal thin plate (3) and is arranged in contact with each element plate of the Bertier effect element group (22A). Vacuum grease is also interposed between the second plate and each of the Bertier effect elements (a), so that the two are tightly coupled thermally. Furthermore, the first stage of the Bertier effect elements of this second plate 4 (
As shown in FIG. 3, a second stage Bertier effect element group (22B) consisting of a plurality of Bertier effect elements (22B) is similarly arranged on the side opposite to the side on which the Bertier effect elements 22A) are arranged.

For each Bertier effect element of this Bertier effect element group (22B), for example, a 2WA Bertier effect element) is arranged on each short side of the through hole (23a) in the second plate, and each Three Bertier effect elements (goods) are arranged for each long side, and one Bertier effect element is arranged corresponding to each corner between each side, resulting in a total of 14 Bertier effect elements (A). can be placed. Also in this second-stage Bertier effect element group (22B), each Bertier effect element (A) is electrically connected in series and thermally arranged in parallel with each other, so that each Bertier effect element The heat-absorbing side of (A) is trapped in such a way that it is tightly thermally adhered to the second plate (A) with vacuum grease. In addition, these first and second stages
The Vertier effect element groups (22A) and (22B) in the tiers are, for example, connected to each other in series, and two common terminals are led out of the tube body (1). Furthermore, a third plate (C) made of oxygen-free steel is arranged on the second-stage Bertier effect element group (22B). In this third plate (c) as well, a through hole (24m) having an inner shape corresponding to the outline of the thin crystal plate (3) is bored in a portion facing the effective operating area of the thin crystal plate (3). In this third plate (c), the heat generating sides of each of the Bertier effect elements of the second-stage Bertier effect element group (22B) are thermally tightly coupled with vacuum grease.

Further, a cooling means is disposed on the opposite side of the third plate (c) from where the second-stage Bertier effect element group (22B) is arranged, that is, on the front surface. This cooling means is, for example, by welding a C-shaped shell through which cooling water flows around the through hole (24a) of the third plate body (goods), and connecting this shell (2) and the third plate body. 041, a C-shaped cooling water channel (1) is formed. A cooling water supply pipe (b) and a cooling water outlet pipe (to) (not shown) are led out of the tube body (1) from both ends of the cooling water channel (a), respectively.

Needless to say, the passages of the cooling water supply pipe (to) and the takeoff pipe (to) through the pipe body (1) are hermetically sealed.

On the other hand, a terminal lead-out portion is provided in a part of the tube body (1). This terminal lead-out part is made by sealing a glass tube, for example, which communicates with the tube body (1), and a plurality of terminal pins 01) are insulated from each other and planted at the outer end of the glass tube (1). The stems 0* arranged in the same manner are sealed. For example, the terminal pins 0ρ are lower than each hermetically sealed metal capillary tube, and although not shown, two terminal pins G selected from among these are
The aforementioned Bertier effect element groups (22A) and (22B)
are connected to each other.

Although not shown, for example, the transparent substrate (6) K is provided with a thermistor or thermocouple as a temperature detection element, and each terminal thereof, for example, the end of each metal wire of the thermocouple made of copper-constantan (N1-Cu alloy) It is led out of the tube body by another terminal pin 01) of the terminal lead-out section 1.

In such a configuration, the first-stage Beltier effect element group (22A) for the current applied to the Peltier effect element
FIG. 4 shows the results of measuring the cooling effect of the cooling effect alone and the cooling effect of the first-stage and second-stage Bertier effect element groups (22A) and (22B).

The white line @(a) in the same figure indicates the applied voltage of the Beltier effect element (a), and the curve (a) and (a) in the same figure indicate the cooling water temperature of 2, respectively.
First-stage Bertier effect element group (2
2A) is a measurement curve in which the temperature of a crystal thin plate cooled only by a thermocouple is detected. This figure shows the respective cooling temperatures when using the first and second-stage Bertier effect element groups.As is clear from this, the temperature of about -50°C is lowered to both Peltier effect element groups (22A).
and (22B).

〔Effect of the invention〕

As described above, according to the present invention, by providing at least two stages of Peltier effect elements by combining the Bertier effect element and the oxygen-free copper plate, the thin crystal plate can be effectively cooled to a required temperature, e.g. It was possible to cool down to -50°C.

Further, according to the present invention, the degree of vacuum inside the tube body (1) could be maintained at a high degree of vacuum of about 10 Torr despite the provision of a cooling means.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view of the essential parts of an example of an optical modulator according to the present invention, FIG. 2 is a diagram showing the arrangement of the first stage of Peltier effect elements, and FIG. FIG. 4 is a measurement curve diagram for explaining the present invention; FIG. 5 is a configuration diagram of an example of a conventional optical modulator; FIG.
The figure shows the route layout of the main parts. (1)... tube body, (7)... optical modulator, G1...
First grid electrode, G2... second grid electrode,
(3)...Crystal thin plate, (6)...Transparent substrate,
...first plate body, ■...second plate body, (c)...third plate body, (22A)...first stage Peltier effect element group N (22B). ...Second stage Peltier effect element color (2)...Bertier effect element. Figure 3 Figure 4 Electrical: L I (A)

Claims (1)

[Claims] A transparent substrate holding a crystal thin plate having an electro-optic effect that is cooled to an operating temperature on one side, and an oxygen-free copper plate that is in contact with the other side of the transparent substrate except for the effective operating area of the crystal thin plate. a first plate consisting of a plurality of Peltier effect elements that are in contact with the first plate and are arranged so as to surround the effective operating area of the crystal thin plate; and a plurality of Peltier effect elements that are in contact with each of the Peltier effect elements; a second plate made of oxygen-free copper, a plurality of Peltier effect elements arranged in contact with the second plate so as to surround the effective operating area of the thin crystal plate, and each of the Peltier effect elements. A third plate member made of oxygen-free copper that is in contact with the optical modulator is disposed within a vacuum-sealed tube, and the third plate member is cooled from outside the tube body.