JPS63231313A - Acoustooptic element - Google Patents

Abstract

PURPOSE:To maintain the specified temp. of an acoustooptic medium by providing temp. control elements by bringing said elements into contact with the two side face parts, except optical faces through which a light beam passes, of the acoustooptic medium as well as the surface to be mounted with an input transducer or reflection face. CONSTITUTION:The temp. control elements 7a-7c are brought into all of the faces, except the optical faces through which the light beam passes, of the acoustooptic medium 6, i.e., the two side face parts 5, the surface 2 to be mounted with the input transducer and the ultrasonic reflection face 1. The face 1 and the two faces 5 contact the element 7a through a good heat conductive material. The face 2a likewise contacts the element 7b. The output of a thermistor 9 (temp. control sensor 8) is compared with a prescribed reference voltage by a differential amplifier 11 and the differential output is inputted via a voltage amplifier 12 and a power amplifier 14 to an electronic cold heat element 15 (temp. control elements 7a-7c), by which the temp. over the entire part of the acoustooptic medium is maintained uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an acousto-optic device having a temperature control element.

[Conventional technology].

Conventional acousto-optic elements have a structure in which the acousto-optic medium is directly fixed to a container or housing with an adhesive or the like, or is placed on a movable member and the movable member is attached to the container or housing. Therefore, the temperature of the acousto-optic medium was not actively controlled.

[Problems to be Solved by the Invention] Since the conventional acousto-optic device has the above-described configuration, when the acousto-optic device is driven, electromechanical transduction vibration of the piezoelectric body of the input transducer is generated. heat generated by electrical resistance during power supply to the input transducer,
Another problem is that the diffraction angle and intensity of transmitted light fluctuate due to heat generated from ultrasonic vibrations of the acousto-optic medium itself.

[Means for Solving the Problem] The present invention has been made to solve the above-mentioned problem. The present invention provides an acousto-optic element characterized in that a temperature control element is provided in contact with or in the vicinity of at least either the mounting surface of the input transducer or the ultrasonic reflecting surface.

[Function] In the present invention, a temperature control element is provided on two side surfaces of the acousto-optic medium excluding the optical surface through which the light beam passes, or on at least one of the input transducer mounting surface and the ultrasonic reflecting surface. By bringing it into contact with or providing it nearby, the temperature of the acousto-optic medium is kept constant and no temperature gradient or temperature fluctuation occurs within the acousto-optic medium. Therefore,
Fluctuations in the diffraction angle and intensity of the light beam can be suppressed.

[Example] An example of the present invention is shown in FIGS. 1 and 2. Figure 1(a)
shows a plan view of the acousto-optic element, (b) shows a side sectional view taken along line AA', and (C) shows a front view. FIG. 2 shows a block diagram of the temperature control circuit.

Temperature control elements 7a are provided on all surfaces of the acousto-optic medium 6 except for the optical surface 3 through which the light beam passes, that is, the two side surfaces 5, the input transducer mounting surface 2, and the ultrasonic reflecting surface 1.
~7c is in contact. The ultrasonic reflecting surface 1 and the two side surfaces 5 are in contact with the temperature control element 7a via a material with good thermal conductivity. The input transducer mounting surface 2 is
It is in contact with the temperature control element 7b via an insulating and highly thermally conductive material. The acousto-optic device shown in this example is a multi-acousto-optic device that simultaneously modulates ten laser beams. Therefore, in this embodiment, the optical surface 3 through which ten laser beams pass has a larger width and area than the conventional optical surface through which one laser beam passes.
Although zero laser beams are modulated, the number of laser beams to be modulated is not limited to ten. Temperature control element 7a
~7c are attached to a portion of the heat dissipation structural members 4, 4'. Aluminum with a black alumite surface treatment is used as the material for the heat dissipation structural members 4 and 4', but a metal material with good thermal conductivity such as brass or a polymer compound material with good thermal conductivity should also be used. You can also do it. Heat dissipation structure material 4
is a rectangular parallelepiped material whose volume is larger than that of the acousto-optic medium 6,
A groove having a sloped bottom similar to the ultrasonic reflecting surface 1 of the acousto-optic element is provided, and an acousto-optic medium 6 is fitted into the line groove, and the ultrasonic reflecting surface of the acousto-optic medium 6 of the heat dissipation structure material 4 is provided. 1
and a temperature control element 7a at a position corresponding to the two side surfaces 5.
, 7c is provided. The heat dissipation structure material 4 is not limited to a rectangular parallelepiped material, and materials such as a quadrangular pyramidal or conical material can also be used. Further, the temperature control elements 7a and 7c have the same shape and area as the ultrasonic reflecting surface 1 and the two side surfaces 5, but the area may be increased or decreased, and the acousto-optic medium It is preferable to be able to efficiently control the temperature with a minimum area according to the amount of heat generated in step 6.Also, it is effective to use the same or similar shapes, but it is thought that uniform temperature control can be achieved by using a lattice shape, etc. .

One surface of the rectangular parallelepiped material of the heat dissipation structure 4' is in contact with the input transducer 2' so as to cover the entire surface thereof, and a temperature control element 7b is provided at a position corresponding to the input transducer 2'. The temperature control element 7b has the same shape and area as the input transducer 2', but
The area can be increased or decreased,
It is preferable that the temperature can be controlled efficiently with a minimum area according to the amount of heat generated by the input transducer 2' and the acousto-optic medium 6.Also, it is effective to use the same or similar shapes, but it is preferable to use a grid-like or similar shape. It is thought that the temperature can also be controlled uniformly. The heat dissipation structure material 4' is a temperature control element 7
Any solid body can be used as long as it has one surface that can cover the outer periphery of b. It is effective to dissipate heat by providing a cavity in the heat dissipating structural members 4, 4' and injecting a liquid such as water into the cavity, or by circulating the liquid such as water through a pipe to the outside. Furthermore, it is believed that the heat radiation efficiency can be further improved if the surfaces of the heat radiation structural members 4, 4' are processed into a corrugated shape to increase the surface area.

The temperature control elements 7a, 7c of the heat dissipation structure 4, the two side surfaces 5 of the acousto-optic medium 6, and the ultrasonic reflecting surface l are in contact with each other via heat conductive silicone grease.

Further, the mounting surface 2 of the input transducer and the temperature control element 7b of the heat dissipating structure member 4' are in contact with each other via an insulating heat conductive silicone sheet. Since an insulating heat conductive silicone sheet is used, if the temperature control element 7b of the heat dissipation structure 4' is made of a metal material, it will not come into contact with the electrode part of the piezoelectric body and cause a short circuit, and the piezoelectric body will not be damaged during operation. It is also effective as a cushion that absorbs vibrations.

It is considered that the heat dissipation structural members 4, 4' and the temperature control elements 7a to 7C attached to each of them have a considerable effect even if only one of them is provided. In order to reduce costs, only one of them may be provided.

The temperature control sensor 8 includes temperature control elements 7a to 7c in the heat dissipation structure 4, 4', near the ultrasonic reflecting surface 1, the two side surfaces 5, and the input transducer 2' of the acousto-optic medium 8, respectively. Provided so that it does not touch.

In this example, the temperature control elements 7a to 7c are connected to the ultrasonic reflecting surface 1 of the acousto-optic medium 8 via the two side surfaces 5 and thermally conductive silicone grease, and to the input transducer 2' via an insulating thermally conductive silicone grease. Although they are in contact with each other through a sheet, they are provided in the heat dissipation structure material 4.4' so that they do not come in direct contact with each other.
Temperature can also be controlled indirectly.

FIG. 2 is a block diagram of the temperature control circuit. A certain resistance value corresponding to the set temperature of the acousto-optic element is selected by the temperature setting resistor 10, and a reference voltage determined by the resistance value is inputted to the non-inverting terminal (+) of the differential amplifier 11. The thermistor 9 is the temperature control sensor 8 in FIG.
The input voltage to changes. Therefore, when the input voltage at the inverting terminal (-) of the differential amplifier 11 becomes smaller than the reference voltage at the non-inverting terminal (+), the differential amplifier 11 outputs a positive voltage equal to the voltage difference between the reference voltage and the input voltage. and the non-inverting terminal (+
) When the input voltage at the inverting terminal (-) becomes larger than the reference voltage of the differential amplifier 11, the differential amplifier 11 outputs a negative voltage equal to the voltage difference between the reference voltage and the input voltage. When the differential amplifier 11 outputs a certain voltage value, the voltage amplification amplifier 12 further amplifies the output voltage value. The PID feedback circuit 13 is
This prevents the voltage amplification amplifier 12 from oscillating. The PID feedback circuit 13 also has the purpose of preventing oscillation of the entire temperature control circuit system due to temperature changes in the acousto-optic medium. The output of the voltage amplification amplifier 12 is amplified in both current and voltage by the voltage amplification amplifier 14 and input to the electronic cooling element 15 . Is the electronic cooling element 15 the temperature control element shown in Fig. 1? a~7c
The electronic cooling element 15, which corresponds to , is a Peltier effect element, and absorbs or generates heat in proportion to the input current value.
It may be one that generates heat, as long as it acts so that the entire acousto-optic medium has a uniform temperature distribution and can reduce fluctuations in the diffraction angle and intensity of each party beam due to non-uniform temperature distribution. Therefore, in this case, a resistance heating element or the like can be used instead of the Peltier effect element. The temperature control circuit is not limited to this embodiment, and may be configured separately as appropriate.

[Effects of the Invention] By having the above-described structure, the present invention controls the temperature of the acousto-optic medium within ±0.1°C with respect to the set temperature. An excellent effect in that the diffraction angle of the transmitted light fluctuates and spreads into a fan shape when the 10 parallel laser beams pass through the acousto-optic medium, and the fluctuations in the intensity of the transmitted light are improved. shows.

According to the present invention, the angle of spread of transmitted light at both ends is 0.0.
The variation in the intensity of transmitted light was improved to 5 mrad or less, and the variation in the intensity of transmitted light was improved to 1% or less.

[Brief explanation of drawings]

1 and 2 show diagrams of an embodiment of the present invention, FIG. 1(a) is a plan view of the acousto-optic element, (b,) is a side sectional view taken along the line AA', and (C) is a plan view of the acousto-optic element. The front view, FIG. 2, shows a block diagram of the temperature control circuit. 1...Ultrasonic reflecting surface, 2...Input transducer mounting surface, 2'...
・Input transducer, 3... Optical surface, 4, 4'... Heat dissipation structure material, 5.
... Side part, 8... Acousto-optic media 7a to 7C...
・Temperature control element, 8...Temperature control sensor, 8...Thermistor, lO...Temperature setting resistor, 1
1...Differential amplifier, 12...Voltage amplification amplifier, 1
3...PIDID feedback, 14...Power amplification amplifier, 15...Electronic cooling element

Claims (1)

[Claims] Temperature control elements are provided on two side surfaces of the acousto-optic medium excluding the optical surface through which the light beam passes, and at least on either the input transducer mounting surface or the ultrasonic reflecting surface. An acousto-optic element characterized by being placed in contact with or in the vicinity.