JPH06237034A - Discharge excited gas laser device - Google Patents

Abstract

PURPOSE:To lengthen the lifetime of an optical window by preventing deposition and adhesion onto the optical window of dust generated by discharge. CONSTITUTION:Negative electrodes 6 with holds, through which laser beams can pass, are installed to optical window 3 sections in a laser tube 1. Negative voltage is applied to the electrodes 6 by a negative power supply 7, and the surfaces of the optical windows 3 brought into contact with dust are charged with negative charges, thus preventing negatively charged dust from adhering by Coulomb repulsive force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge excitation gas laser device such as an excimer laser.

[0002]

2. Description of the Related Art In a discharge excitation gas laser device, a large amount of dust is generated in a laser gas from a discharge electrode or the like due to discharge. The dust adheres to the optical window and reduces the laser output, and at the same time, causes the life of the optical window to be significantly deteriorated. In the conventional discharge excitation gas laser device,
A part of the laser gas is taken out by a gas circulation pump installed outside the laser tube, the taken out laser gas is passed through a dust filter or an electrostatic precipitator, and then it is returned to the inside of the laser tube again. Are removed (for example, Japanese Patent Laid-Open No. 58-1869).
No. 85).

[0003]

However, in the conventional apparatus, it is difficult to completely remove the dust generated in the laser tube, and there is no means for avoiding the contact between the generated dust and the optical window. However, there is a drawback that dust adheres to the optical window when the laser is operated for a long time. If the optical window becomes dirty, the optical window must be cleaned or replaced, and thus the contamination of the optical window is a problem to be solved in order to facilitate maintenance and reduce running costs. The problem of dirt on the optical window due to this dust is "laser focus (Laser focus).
Focus) October 1981, pp. 65-68 ".

An object of the present invention is to provide a discharge excitation gas laser device which solves the above problems.

[0005]

DISCLOSURE OF THE INVENTION A discharge-excited gas laser device of the present invention comprises a laser tube for enclosing a laser gas, a pair of discharge electrodes for exciting the laser gas by electric discharge to cause stimulated emission of light, and the stimulated emission. In a discharge-excited gas laser device comprising at least a pair of optical windows arranged in the optical path of light, and a reflecting mirror and an output mirror forming a laser resonator, an electrode for applying a negative voltage to the optical window part in the laser tube. Is provided, and the surface of the optical window is negatively charged.

[0006]

Since fine particles such as dust tend to be negatively charged, most of the dust generated in the laser gas adsorbs electrons generated by discharge and is negatively charged. Therefore, an electrode for applying a negative voltage to the optical window is provided,
By adopting a configuration in which the surface of the optical window is charged with a negative electric charge, it is possible to suppress adhesion of dust charged with a negative electric charge to the optical window by Coulomb repulsion.

Therefore, by adopting the configuration of the present invention, it is possible to prevent the accumulation and adhesion of dust on the optical window and obtain a stable laser output for a long time. Further, since the number of times of cleaning and replacement of the optical window can be reduced, maintenance can be facilitated and the running cost can be reduced.

[0008]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and shows only a portion relating to the present invention.

In this embodiment, a plate-shaped negative voltage applying electrode 6 having a circular through hole through which a laser beam can pass and having an annular shape is installed in the optical window 3 of the laser tube 1. I am collecting. A negative voltage is applied to the electrode 6 by a negative voltage power source 7 to charge the surface of the optical window 3 in contact with dust with a negative charge, so that the dust charged with the negative charge adheres to the optical window 3. Can be suppressed by Coulomb repulsion. Therefore, it is possible to prevent the accumulation and adhesion of dust on the optical window 3 and obtain a stable laser output for a long time. Further, since the number of times of cleaning and replacement of the optical window 3 can be reduced, maintenance can be facilitated and running cost can be reduced.

The discharge electrode 2, the output mirror 4 and the reflecting mirror 5 are the same as those in the conventional discharge excitation gas laser device.

[0012]

As described above, according to the discharge-excited gas laser device of the present invention, dust generated by discharge is less deposited and adhered to the optical window, and a stable laser output can be obtained for a long time. Since the number of times of cleaning and replacement of the optical window can be reduced, maintenance can be facilitated and running cost can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing an embodiment of the present invention.

[Explanation of symbols]

 1 Laser Tube 2 Discharge Electrode 3 Optical Window 4 Output Mirror 5 Reflecting Mirror 6 Negative Voltage Applying Electrode 7 Negative Voltage Applying Power Supply 8 Laser Light

Claims (2)

[Claims] 1. A laser tube for enclosing a laser gas, a pair of discharge electrodes for exciting the laser gas by electric discharge to cause stimulated emission of light, and a pair of optical windows arranged in an optical path of the stimulated emission light. In a discharge excitation gas laser device including at least a reflecting mirror and an output mirror forming a laser resonator, an electrode for applying a negative voltage is provided in the optical window portion in the laser tube, and the surface of the optical window is charged with a negative charge. A discharge-excited gas laser device characterized by: 2. The discharge excitation according to claim 1, wherein the negative voltage applying electrode is a plate-like body having a circular laser beam passage hole, and is fixed inside the optical window. Gas laser device.