JPH08293637A - Laser - Google Patents

Abstract

PURPOSE: To provide a laser of a structure, wherein an optical loss and the heat generation of discharge electrodes are reduced by making improvement on the discharge electrodes and moreover, even in the case where the electrodes generate heat, various harmful influences due to the generation of the heat can be reduced. CONSTITUTION: Rail-shaped grooves are respectively formed in discharge electrode 4a and 4b and an insulator 9 made of ceramic is fitted into the grooves in such a way as to be able to slide. Moreover, the surfaces, which oppose to each other, of the electrodes 4a and 4b are molded using a material of an electric resistivity of 3×10<-8> (Ω.m) or lower and the surface roughnesses are molded in 1/2 or shorter of the wavelength of a laser beam which is generated from a laser.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device which oscillates laser light by applying a high frequency discharge electric field between discharge electrodes.

[0002]

2. Description of the Related Art As one of conventional laser devices, a schematic structure of an example of a device adopting an air cooling system as a cooling means will be described with reference to FIG. The outer wind tunnel 1 has a first dielectric 3a made of ceramics or the like attached to a notch formed in the central portion of the upper surface to keep airtightness, and an inner wind tunnel 2 made of iron or the like is installed inside thereof. Has been done. A second dielectric 3b is airtightly attached to the upper surface of the inner wind tunnel 2 as well, and a laser gas composed of CO ₂ or the like is sealed at a high pressure of about 60 torr between the outer wind tunnel 1 and the inner wind tunnel 2. A high-voltage side discharge electrode 4a is attached to the first dielectric 3a, while a low-voltage side discharge electrode 4b is attached to the second dielectric 3b, forming a pair of discharge electrodes. The high-voltage side discharge electrode 4a is connected to one terminal of the high-frequency power supply 5, and the low-voltage side discharge electrode 4b is connected to the other terminal of the high-frequency power supply 5 via a ground wire. A laser beam 6 is oscillated by applying a discharge electric field between the discharge electrodes by the high frequency power source 5 to excite the laser gas. Although the laser gas heats up and deteriorates due to the oscillation of the laser light 6, this laser gas is blown inside the wind tunnel by the blower 7 installed below the internal wind tunnel 2.
Is forcedly circulated in the direction, and is cooled and gas-exchanged by the heat exchanger 8.

[0003]

The distance between the discharge electrodes arranged facing each other, that is, the discharge gap length, affects the optical loss, quality, etc. of the oscillating laser light 6, but specifically, There was a problem.

When the discharge gap length is 5 mm or less, the discharge electrode surface acts as an optical waveguide, so that the light loss on the discharge electrode surface is large, and the discharge gap is accurate to 0.1 mm or less. If not maintained, the discharge impedance will be locally different, and there will be a part where the discharge is concentrated.

As a general problem, the insulator for supporting the discharge electrodes facing each other has a different thermal expansion coefficient from that of the discharge electrodes, so that the insulator may be destroyed by a rapid temperature change. In addition, such an insulator deteriorates due to the heat generated by the discharge, which is a cause of accelerating the deterioration of the laser gas. Furthermore, high frequency heating occurs due to the electrical resistance of the metal portion of the discharge electrode surface, and the heat generation causes power loss,
Further, this also causes thermal expansion of surrounding members.

Therefore, in the present invention, by providing an improved discharge electrode, it is possible to provide a laser device capable of reducing optical loss and heat generation, and even if heat is generated, various adverse effects due to heat generation can be reduced in advance. With the goal.

[0007]

In order to achieve the above-mentioned object, the present invention, as the invention according to claim 1, is arranged so as to face each other and is arranged with a constant space formed by an insulator. A laser device comprising two discharge electrodes and a laser gas filled between the discharge electrodes, wherein the laser gas is excited to generate laser light by high-frequency discharge between the discharge electrodes. Provided is a laser device characterized in that surface roughness of electrode surfaces facing each other is formed to be ½ or less of a wavelength of generated laser light.

According to a second aspect of the present invention, there are provided two discharge electrodes which are arranged so as to face each other and are formed with a constant gap formed by an insulator, and a laser gas filled between the discharge electrodes. A laser device for exciting the laser gas to generate laser light by high-frequency discharging between the discharge electrodes, a rail-shaped groove is formed in the discharge electrode, and the insulator is slidably fitted therein. A laser device characterized by the above is provided.

Further, as an invention according to a third aspect, two discharge electrodes which are arranged so as to face each other and which are arranged with a constant gap by an insulator, and a laser gas filled between the discharge electrodes are provided. In a laser device that excites the laser gas to generate laser light by performing high-frequency discharge between the discharge electrodes, the electrode surfaces of the discharge electrodes facing each other have an electric resistivity of 3 × 10 ⁻⁸ (Ω). -M) To provide a laser device characterized by being formed of the following materials.

Further, as the invention according to claim 4, two discharge electrodes which are arranged so as to face each other and which are arranged at a constant interval by an insulator, and a laser gas filled between the discharge electrodes are provided. A laser device for exciting the laser gas to generate laser light by high-frequency discharge between the discharge electrodes, wherein the insulator is formed of a ceramic that does not easily deteriorate under discharge. To provide a laser device.

[0011]

In the laser device thus constructed,
Since the surface roughness of the surface of the discharge electrode, which is also an optical waveguide, is 1/2 or less of the laser wavelength, the optical loss of laser light can be reduced.

Further, since the discharge electrode and the insulator having different thermal expansion coefficients can slide on each other, the thermal strain can be reduced even when they are thermally expanded, so that the thermal destruction of the insulator can be prevented.

Further, by inserting the insulator into the rail shape, it is possible to support the distance between both electrodes with an accuracy of 0.1 mm or less even if the discharge gap changes due to the weight of the discharge electrode. Become.

The surfaces of both discharge electrodes facing each other are gold,
Since it is formed of a low resistance material such as silver, it is possible to reduce Joule heat loss due to high frequency heating applied to the electrode surface.

Further, since the insulator is formed of ceramics such as quartz glass which is not easily deteriorated by discharge, it is possible to reduce contamination and deterioration of the laser gas caused by the deterioration of the insulator.

[0016]

Embodiments of the present invention will be described below with reference to FIG. 1 showing an example of a discharge electrode portion of a laser device. The high-voltage side discharge electrode 4a and the low-voltage side discharge electrode 4b are arranged to face each other, and a laser gas containing carbon dioxide gas, carbon monoxide gas or the like as a main component is filled between the electrodes. The surface roughness of the electrode surfaces facing each other is ½ or less of the laser wavelength of the laser light to be oscillated. As a concrete numerical value, in the case of a carbon dioxide gas laser device, the surface roughness is required to be 5.3 × 10 ⁻⁶ (m) or less, and in the case of a carbon monoxide gas laser device, it is 2.8 ×. It is necessary that the surface roughness be 10 ⁻⁶ (m) or less. A high-frequency AC power source 5 is connected to each of the discharge electrodes, and an AC electric field is applied between the electrodes to excite the laser gas and generate laser light. Such laser light is emitted after it has been given directionality (beam property) by being reflected multiple times by the resonator mirror 13.

In the laser device having such a structure, since the surface roughness of the surface of the discharge electrode, which is also an optical waveguide, is 1/2 or less of the lasing wavelength, it is difficult for the laser light to be absorbed by the electrode surface. Light loss can be reduced.

Further, in this embodiment, rail-shaped grooves are formed in both discharge electrodes, and an insulator 9 is slidably fitted in the grooves, so that both discharge electrodes are supported while forming a predetermined gap. are doing.

In the laser device having such a structure, the discharge electrodes 4a and 4b and the insulator 9 having different thermal expansion coefficients are used.
Even if the and are thermally expanded, they can slide with respect to each other, so that the thermal strain can be reduced, so that the thermal breakdown of the insulator 9 can be prevented. Further, by inserting the insulator 9 as in the present embodiment, it is possible to support the distance between both electrodes with an accuracy of 0.1 mm or less even if the discharge gap changes due to the weight of the discharge electrode. Becomes

Further, in this embodiment, the surfaces of both discharge electrodes facing each other are formed of a material having an electric resistivity of 3 × 10 ⁻⁸ (Ω · m) or less. By molding the electrode surface with such a low resistance material, it becomes possible to reduce Joule heat loss due to high frequency heating applied to the electrode surface. Specifically, the electrode is formed of gold, silver, copper, aluminum, platinum, or an alloy thereof, or is formed by plating or coating the surface of the electrode.

Further, in this embodiment, the insulator 9 is formed of ceramics which is not easily deteriorated by electric discharge. Specifically, ceramics mainly containing quartz glass, alumina, silicon nitride, aluminum nitride and the like are applicable. In the insulator 9 having such a configuration, it is possible to reduce the contamination of the laser gas caused by the alteration of the insulator 9 under discharge. The present invention can be applied not only to the carbon dioxide gas laser device and the carbon monoxide gas laser device, but also to an excimer laser device and the like.

[0022]

As described above, according to the present invention, even if the distance between the discharge electrodes is shortened, the light loss is reduced, and the heat generation is reduced. By reducing the above, it becomes possible to dramatically improve the characteristics of the laser device.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an example of a discharge electrode portion of a laser device of the present invention.

FIG. 2 is a cross-sectional view showing an overall schematic configuration of an example of a conventional laser device that employs an air-cooling system as a cooling means.

[Explanation of symbols]

4a ... High-voltage side discharge electrode, 4b ... Low-voltage side discharge electrode, 5 ... High frequency power source, 9 ... Insulator

Claims (4)

[Claims] 1. A discharge gas between the discharge electrodes, comprising: two discharge electrodes arranged to face each other and arranged at a constant interval by an insulator; and a laser gas filled between the discharge electrodes. In a laser device that excites the laser gas to generate laser light by high-frequency discharge, the surface roughness of the electrode surfaces of the discharge electrodes that face each other is formed at 1/2 or less of the wavelength of the generated laser light. Laser device characterized by being provided. 2. A discharge gas is provided between two discharge electrodes, which are arranged to face each other and are arranged with a constant gap formed by an insulator, and a laser gas filled between the discharge electrodes. A laser device that excites the laser gas to generate laser light by high-frequency discharge of, in which a rail-shaped groove is formed in the discharge electrode, and the insulator is slidably fitted therein. Laser device. 3. Discharge electrodes are provided between two discharge electrodes, which are arranged to face each other and are arranged at a constant interval by an insulator, and a laser gas filled between the discharge electrodes. In a laser device that excites the laser gas to generate laser light by high-frequency discharge, the electrode surfaces of the discharge electrodes facing each other have an electric resistivity of 3 ×
A laser device characterized by being formed of a material of 10 ⁻⁸ (Ω · m) or less. 4. A discharge gas is provided between two discharge electrodes, which are opposed to each other and are arranged with a constant gap formed by an insulator, and a laser gas filled between the discharge electrodes. A laser device that excites the laser gas to generate a laser beam by high-frequency discharge, wherein the insulator is formed of ceramics that does not easily deteriorate under discharge.