JPH06152030A - Gas laser apparatus - Google Patents

Abstract

PURPOSE:To provide a gas laser apparatus in which a large amount of clean medium gas is not required to keep the inside of a window in a clean condition and problems such as an increase in cavity length or a leakage from a piping connecting part do not occur and a deterioration of an aperture can be prevented. CONSTITUTION:A dust filter case 9 is connected to a chamber 1 for holding main electrodes 3 and 4, and a clean medium gas filtered with a filter 13 is introduced into a secondary chamber 14 through a gas inlet passage 11 formed in the sidewall of the chamber 1. The medium gas stagnated in the secondary chamber 14 flows in the chamber 1 through a labyrinth 8 without moving the clean medium gas retained in the vicinity of the inside of a window 6. Thus, the laser medium gas in the chamber 1 containing dust is prevented from flowing toward the window 6. Also, since an aperture is mounted in the clean medium gas atmosphere between the window 6 and the labyrinth 8, a contamination or a deterioration in the aperture do not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser device,
In particular, the present invention relates to a window stain prevention mechanism provided at both ends of the discharge chamber.

[0002]

2. Description of the Related Art In a gas laser device using an active medium in a gaseous state, a gas enclosed in a chamber is caused to flow between electrodes by a fan, and gas molecules are excited by discharge to form a population inversion of the laser medium. There are CO ₂ lasers and excimer lasers that return the gas that has become high temperature to a fan after cooling it with a heat exchanger.

[0003]

In the gas laser device described above, one of the factors that hinders the extension of the laser oscillation life is contamination of the optical system. If a powdery compound or the like produced by repeating laser oscillation adheres to the window, the transmittance is lowered, and the laser output is lowered. As measures against this, Japanese Patent Publication No. 60-26312 and USP-501.
The 8161 forcibly blows the gas cleaned by the filter onto the window surface, but a large amount of purge flow rate is required to prevent the laser medium gas containing dust from being entrained. On the other hand, Japanese Examined Japanese Patent Publication Sho 58-186985
A method of cleaning the window with a clean gas by providing a purified gas inlet in the window region and providing a gas circulation path from the gas outlet of the discharge tube to the gas inlet through the electrostatic precipitator and the rest zone. However, since the gas circulation path is installed outside the discharge tube, there are problems such as an increase in the cavity length and the possibility of leakage from the pipe connecting portion. In addition, conventionally, the aperture was arranged outside the chamber, that is, on the atmosphere side, so if it is not purged, it becomes dirty.
There is a problem that the aperture reacts with the ultraviolet light and the atmospheric gas to deteriorate or generate impurities to stain the surrounding optical components. The present invention has been made in view of the above-mentioned conventional problems, and does not require a large amount of purge gas to keep the window in a clean state, and increases the cavity length and the possibility of leakage from the pipe connection portion. There is no problem,
Moreover, it is an object of the present invention to provide a gas laser device capable of preventing the deterioration of the aperture.

[0004]

In order to achieve the above object, a gas laser device according to the present invention provides a sub chamber for accommodating a labyrinth on a laser optical path inside a window, and a laser medium gas cleaned by a dust removing device is used. Introduced into the sub-chamber, returned to static pressure, and then introduced into the chamber via the labyrinth. In such a configuration, dust floating in the laser medium gas is removed by a dust remover, and the dust remover is used. The laser medium gas introduction path from the chamber to the sub chamber is built in the side wall of the chamber. Further, when the aperture for shaping the laser light is attached, it is arranged in a clean laser medium gas atmosphere near the inside of the window.

[0005]

According to the above construction, the sub chamber for accommodating the labyrinth is provided on the laser optical path inside the window, and the laser medium gas cleaned by the dust removing device is not directly introduced into the labyrinth or the inside of the window, but once the sub chamber is operated. Since it is introduced into the chamber through the labyrinth after being introduced into the chamber to recover the static pressure, a clean laser medium gas can always be retained near the inside of the window. Therefore, the laser medium gas containing dust does not reach the inner surface of the window, and the window surface can be kept clean without blowing a large amount of purge gas on the window. Further, since the gas introduction path from the dust removing device to the sub chamber is built in the side wall of the chamber, problems such as an increase in cavity length and a possibility of leakage from the pipe connecting portion do not occur. Further, when the aperture for shaping the laser light is attached, since it is arranged in a clean laser medium gas atmosphere near the window, contamination of the aperture,
It is possible to prevent problems such as contamination of surrounding optical components due to deterioration or generation of impurities.

[0006]

Embodiments of the gas laser device according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the structure of the excimer laser device, and FIG. 2 is P of FIG.
FIG. In these figures, 1 is a chamber for enclosing a predetermined gas, 2 is a fan, 3 and 4 are main electrodes, 5
Is a fan driving motor, 6 is a window, 7 is a window holder, and 8 is a labyrinth. A dust filter case 9 is connected to the chamber 1, and the chamber 1 and the dust filter case 9 are provided in a dust filter inlet 10 provided substantially at the center in the optical axis direction and inside wall surfaces of both ends of the chamber 1. The gas introduction path 11 and the dust filter outlets 12 provided at both ends of the dust filter case 9 communicate with each other. Inside the dust filter case 9, filters 13 for the front window and the rear window are arranged.

The laser medium gas flows between the main electrodes 3 and 4 by driving the fan 2, blows off the gas between the main electrodes 3 and 4, and then is cooled by a heat exchanger (not shown) and is again fan 2.
Return to. The pressure difference generated by the fan 2 is used to generate a flow in the dust filter case 9, and the laser medium gas enters the dust filter case 9 from the dust filter inlet 10 and is filtered by passing through the filter 13. . The clean gas that has exited the dust filter outlet 12 passes through the gas introduction passage 11 in the chamber wall surface, as shown in FIG.
As shown in, the sub-chamber 14 for accommodating the labyrinth 8 is entered.
The sub-chamber 14 is provided on the laser optical path and forms a buffer region B for stabilizing the flow of the inflowing gas. Here, the gas that has returned to the static pressure does not move the clean gas that remains in the statically determinable region A near the inner surface of the window 6,
It flows through the labyrinth 8 toward the discharge region C in the chamber 1, that is, in the direction of the main electrodes 3 and 4. Therefore, the gas in the discharge region C containing dust is prevented from flowing toward the window 6.

FIG. 3 is a cross-sectional view of the vicinity of the window of the gas laser device according to claim 3 in which the aperture is attached. The aperture 15 is the bottom of the stepped hole of the window holder 7,
That is, it is attached to the boundary surface between the statically determined area A and the buffer area B. Therefore, since the aperture 15 is always in a clean laser medium gas atmosphere, problems such as contamination and deterioration do not occur by selecting the material. For example, in an excimer laser device in which fluorine is used as a laser medium gas, good results can be obtained by using an aperture of Ni plated on aluminum. Further, the aperture 15 also has a function as a partition that separates the static determination area A and the buffer area B, and the area A can be kept more stable.

[0009]

As described above, according to the present invention, the following effects can be obtained. (1) A sub-chamber for accommodating the labyrinth is provided on the laser optical path inside the window, and the laser medium gas cleaned by the dust removing device is introduced into the sub-chamber and allowed to settle, and then introduced into the chamber through the labyrinth. Therefore, the clean laser medium gas can always stay in the vicinity of the inside of the window. Therefore, the laser medium gas containing dust floating in the discharge region does not reach the inner surface of the window, and the window surface can always be kept clean without blowing a large amount of purge gas on the window. (2) Since the laser medium gas introduction path from the dust remover to the sub chamber is built in the side wall of the chamber, the cavity length increases,
Problems such as the possibility of leaks from the pipe connections do not occur. (3) When the aperture for shaping the laser beam is attached, since it is arranged in a clean laser medium gas atmosphere near the inside of the window, the surrounding optical parts due to contamination, deterioration of the aperture or generation of impurities. It is possible to prevent the occurrence of problems such as stains and the like, and there is no need for a purge mechanism dedicated to the aperture. Further, since the atmosphere laser medium gas in which the aperture is placed is completely dry and the only gas that may cause a chemical reaction is halogen, selection of the material of the aperture becomes easy. Further, by attaching the aperture to the boundary surface between the statically-determining region A and the buffer region B, the clean medium gas in the statically-determining region can be kept more stable, so that the effect of preventing the window from becoming dirty is increased. To do.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the structure of a gas laser device.

FIG. 2 is an enlarged view of a P part in FIG.

FIG. 3 is a cross-sectional view near a window of a gas laser device having an aperture attached.

[Explanation of symbols]

 1 Chamber 6 Window 8 Labyrinth 9 Dust Filter Case 11 Gas Inlet 13 Filter 14 Sub-chamber 15 Aperture

Claims (3)

[Claims] 1. In a gas laser device, a sub-chamber for accommodating a labyrinth is provided on a laser optical path inside a window, and a laser medium gas cleaned by a dust remover is introduced into the sub-chamber to return to a static pressure. A gas laser device characterized by being introduced into a chamber through the labyrinth. 2. The gas laser according to claim 1, wherein dust floating in the laser medium gas is removed by a dust remover, and a laser medium gas introduction path from the dust remover to the sub chamber is built in a side wall of the chamber. apparatus. 3. The gas laser device according to claim 1, wherein the aperture for shaping the laser beam is arranged in a clean laser medium gas atmosphere near the inside of the window.