JP2014146691A - Gas laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas laser oscillator in which breakage of a ceramic electrode hardly causes a failure of other devices.SOLUTION: An opening is formed on each of wall faces facing each other in a discharge chamber. A pair of ceramic electrodes blocks the openings, respectively, and faces each other. A gas supply system supplies laser gas in a discharge region between the pair of ceramic electrodes. An air inflow suppressing structure is prepared, the air inflow suppressing structure being configured for suppressing air from flowing into the discharge region through the openings when the ceramic electrode is broken.

Description

  The present invention relates to a gas laser oscillator having a ceramic electrode.

    A ceramic electrode in which a metal electrode is coated with ceramic is used as a discharge electrode of a gas laser oscillator. Patent Document 1 discloses a gas laser oscillator in which a ceramic electrode is part of a laser container. The metal electrode is accommodated in a recess formed on the outer surface of the ceramic member. That is, the metal electrode is separated from the space in the laser container and opened to the atmosphere. When the metal electrode is disposed inside the laser container, the entire surface of the electrode must be insulated from the discharge region. When the metal electrode is disposed outside the laser container, the insulating portion of the metal electrode can be reduced.

JP 2001-237475 A

  Since ceramic is more brittle than metal or the like, a slight crack is likely to lead to cracking of the ceramic. In the case where the ceramic electrode constitutes a part of the laser container, when the ceramic electrode is cracked, the pressure in the laser container is rapidly increased. A blower or power supply may break down due to a sudden rise in pressure.

  An object of the present invention is to provide a gas laser oscillator in which breakage of a ceramic electrode is unlikely to cause failure of other equipment.

According to one aspect of the invention,
A discharge chamber in which openings are formed on the walls facing each other;
A pair of ceramic electrodes that close the opening and oppose each other;
A gas supply system for supplying a laser gas to a discharge region between the pair of ceramic electrodes;
There is provided a gas laser oscillator having an air inflow suppressing structure configured to suppress air from flowing into the discharge region through the opening when the ceramic electrode is broken.

  When the ceramic electrode is damaged, the inflow of air into the discharge region is suppressed, so that it is possible to prevent a failure due to a rapid increase in the pressure in the discharge region.

1 is a cross-sectional view of a gas laser oscillator according to a first embodiment. FIG. 2 is a cross-sectional view of the discharge chamber and the ceramic electrode of the gas laser oscillator according to the first embodiment. FIG. 3 is a graph showing the time change of the pressure in the laser container when the ceramic electrode is broken in the gas laser oscillator according to the first embodiment. FIG. 4 is a cross-sectional view of a discharge chamber and a ceramic electrode of the gas laser oscillator according to the second embodiment. FIG. 5 is a graph showing the time change of the pressure in the laser container when the ceramic electrode is broken in the gas laser oscillator according to the second embodiment.

[Example 1]
FIG. 1 is a sectional view of a gas laser oscillator according to the first embodiment. The laser container 10 of the gas laser oscillator according to the first embodiment includes a discharge chamber 20, a blower chamber 30, and a gas circulation path 40. The discharge chamber 20, the gas circulation path 40, and the blower chamber 30 form a closed gas circulation path. The laser container 10 is filled with a laser gas, for example, a mixed gas of carbon dioxide gas, helium gas, and nitrogen gas. The chambers are airtightly connected to each other, and the airtightness in the laser container 10 is ensured.

  A blower 31 is attached in the blower chamber 30. Laser gas is circulated through the blower chamber 30, the discharge chamber 20, and the gas circulation path 40 in this order by the blower 31.

  Openings 21 are formed in the wall surfaces of the discharge chamber 20 facing each other. A pair of ceramic electrodes 22 each block the opening 21. A discharge region 23 is defined between the pair of ceramic electrodes 22. The discharge region 23 has a long shape in a direction orthogonal to the direction of the laser gas flow. The direction of laser gas flow, the direction in which discharge occurs, and the direction in which laser light propagates are orthogonal to each other. A power source 25 supplies AC power to the ceramic electrode 22.

  A heat exchanger 41 is disposed in a part of the gas circulation path 40. The heat exchanger 41 cools the laser gas. The pressure sensor 43 measures the pressure in the laser container 10. The pressure measurement result is input to the control device 50. The control device 50 controls on / off of the power supply 25 and the blower 31 based on the measurement result of the pressure.

  The gas circulation path 40, the blower chamber 30, and the blower 31 constitute a gas supply system that supplies laser gas to the discharge region 23.

  FIG. 2 shows a cross-sectional view of the discharge chamber 20 and the ceramic electrode 22. Openings 21 are formed in the wall surfaces of the discharge chamber 20 facing each other. A pair of ceramic electrodes 22 block the pair of openings 21. A discharge region 23 is defined between the pair of ceramic electrodes 22. A sealing member 60, for example, an O-ring is inserted between the wall surface of the discharge chamber 20 and the ceramic electrode 22, and the airtightness of the discharge region 23 is ensured.

  Each ceramic electrode 22 includes a ceramic member 26 and a conductive member 27. A ceramic member 26 closes the opening 21. On the surface of the ceramic member 26 facing the discharge region 23, a convex portion 28 is formed extending in a direction perpendicular to the gas flow direction (a direction perpendicular to the paper surface in FIG. 2).

  A recess 29 is formed on the outer surface of the ceramic member 26. The concave portion 29 is disposed at a position corresponding to the convex portion 28. A conductive member 27 is accommodated in the recess 29. A resin film 65 is formed on the outer surface of the ceramic electrode 22. An opening for exposing a part of the conductive member 27 is formed in the resin film 65. A connecting conductor 61 is disposed in the opening. AC power is supplied from the power source 25 (FIG. 1) to the conductive member 27 through the connection conductor 61.

The resin film 65 is less brittle than the ceramic member 26. Even if a crack occurs in the ceramic member 26, the resin film 65 closes the portion of the crack, so that the airtightness is not easily destroyed.

  With reference to FIG. 3, the control method of the control apparatus 50 when the ceramic electrode 22 is damaged is demonstrated. The horizontal axis in FIG. 3 represents the elapsed time, and the vertical axis represents the pressure in the laser container 10. The pressure in the laser container 10 (FIG. 1) in a normal operating state is represented by Pn. The pressure Pn is lower than the atmospheric pressure Pat. Assume that a crack occurs in the ceramic electrode 22 (FIG. 2) at time t0. Even if the ceramic electrode 22 is cracked, the resin film 65 blocks the crack, so that there is little leakage through the crack. For this reason, the pressure in the laser container 10 gradually increases according to the amount of leakage as shown by the solid line in FIG. At time t1, the pressure in the laser container 10 reaches the threshold value Pth. The control device 50 (FIG. 1) stops the blower 31 and the power source 25 (FIG. 1) when detecting that the pressure in the laser container 10 exceeds the threshold value.

  In the case where the resin film 65 is not formed, if the ceramic electrode 22 is cracked, the ceramic electrode 22 may be immediately divided into a plurality of fragments due to the brittleness of the ceramic. When the ceramic electrode 22 is destroyed, as shown by a broken line in FIG. 3, the pressure in the laser container 10 rapidly increases and reaches the atmospheric pressure Pat. For this reason, before the blower 31 and the power supply 25 stop, it operate | moves on the conditions of atmospheric pressure. Since the blower 31 and the power supply 25 operate under conditions that are significantly different from normal conditions, failures are likely to occur.

  In the first embodiment, when the ceramic electrode 22 is cracked, the pressure in the laser container 10 gradually increases. Therefore, the blower 31 and the power supply 25 can be stopped before a failure occurs. The resin film 65 plays a role as an air inflow suppressing structure that suppresses air from flowing into the discharge region 23 through the opening 21 when the ceramic member 26 is damaged.

  In the first embodiment, the resin film 65 is used as the air inflow suppressing structure. However, instead of the resin film 65, a film made of a flexible material that is less brittle than ceramic may be used.

[Example 2]
FIG. 4 is a cross-sectional view of the discharge chamber 20 and the ceramic electrode 22 of the gas laser device according to the second embodiment. Hereinafter, differences from the first embodiment will be described, and description of the same configuration will be omitted. In the first embodiment, the resin film 65 (FIG. 2) is used as the air inflow suppressing structure. However, in the second embodiment, the resin film 65 is not formed on the ceramic electrode 22.

  A pair of sealing plates 66 are attached to the outside of the discharge chamber 20. The pair of sealing plates 66 each block the pair of openings 21 and form an airtight space 69 between the ceramic electrodes 22. For the sealing plate 66, a material that is less brittle than the ceramic member 26, such as a metal, is used. A sealing member 67, for example, an O-ring is disposed between the sealing plate 66 and the wall surface of the discharge chamber 20, and the airtightness of the airtight space 69 is ensured.

  A wiring 68 connecting the conductive member 27 and the power source 25 (FIG. 1) intersects the sealing plate 66 and is drawn out of the airtight space 69. Airtightness is also maintained at the intersection between the sealing plate 66 and the wiring 68. Each volume of the airtight space 69 is sufficiently smaller than the volume of the laser container 10 (FIG. 1).

Next, a preferable volume of the airtight space 69 will be described. The volume of the airtight space 69 is represented by VS, and the pressure in the airtight space 69 in the normal state is represented by PS. The pressure PS is atmospheric pressure. The volume of the laser container 10 is represented by VL, and the pressure in the laser container 10 during operation is represented by PL. The maximum operable pressure of the blower 31 is represented by Pmax. At this time, the inequality VS <((Pmax−PL) / (PS−Pmax)) × VL
It is preferable to set the volume VS of the airtight space 69 so as to satisfy the above. Where PL <
Assume that Pmax <PS holds. When this inequality is satisfied, even if one ceramic electrode 22 is broken, damage to the blower 31 can be prevented.

  In the second embodiment, when the ceramic electrode 22 is damaged, the atmosphere in the hermetic space 69 flows into the laser container 10 (FIG. 1). However, since the volume of the airtight space 69 is sufficiently smaller than the volume of the laser container 10, the pressure in the laser container 10 does not rise above the maximum operable pressure of the blower 31.

  With reference to FIG. 5, the control method of the control apparatus 50 (FIG. 1) when the ceramic electrode 22 is damaged will be described. The horizontal axis in FIG. 5 represents the elapsed time, and the vertical axis represents the pressure in the laser container 10. The pressure in the laser container 10 (FIG. 1) in a normal operating state is represented by Pn. It is assumed that a crack occurs in the ceramic electrode 22 (FIG. 4) at time t0. Since the air in the airtight space 69 (FIG. 4) flows into the laser container 10 (FIG. 1), as shown by the solid line in FIG. 5, the pressure in the airtight space 69 and the pressure in the laser container 10 become equal. The pressure in the laser container 10 increases. Since the volume of the airtight space 69 is sufficiently smaller than the volume of the laser container 10, the pressure increase in the laser container 10 is slight.

  The threshold value Pth is set to a value lower than the pressure after the rise in the laser container 10. After the ceramic electrode 22 is damaged, the pressure in the laser container 10 reaches the threshold value Pth at time t1. When detecting that the pressure in the laser container 10 has reached the threshold value Pth, the control device 50 (FIG. 1) stops the blower 31 and the power source 25 as in the case of the first embodiment.

  Also in the second embodiment, since the blower 31 and the power source 25 can be stopped before the pressure in the laser container 10 increases excessively, it is possible to prevent device failure due to breakage of the ceramic electrode 22.

  After the blower 31 and the power supply 25 are stopped, the atmosphere may flow into the laser container 10. Therefore, a slight leak may occur between the sealing plate 66 and the discharge chamber 20.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Laser container 20 Discharge chamber 21 Opening 22 Ceramic electrode 23 Discharge area | region 25 Power supply 26 Ceramic member 27 Conductive member 28 Convex part 29 Concave part 30 Blower chamber 31 Blower 40 Gas circulation path 41 Heat exchanger 43 Pressure sensor 50 Control apparatus 60 Seal member 61 Connecting conductor 65 Resin film 66 Sealing plate 67 Sealing member 68 Wiring 69 Airtight space

Claims (4)

A discharge chamber in which openings are formed on the walls facing each other;
A pair of ceramic electrodes that close the opening and oppose each other;
A gas supply system for supplying a laser gas to a discharge region between the pair of ceramic electrodes;
A gas laser oscillator having an air inflow suppressing structure configured to suppress air from flowing into the discharge region through the opening when the ceramic electrode is damaged.   The gas laser oscillator according to claim 1, wherein the air inflow suppressing structure includes a resin film formed on an outer surface of the ceramic electrode.   2. The gas laser oscillator according to claim 1, wherein the air inflow suppression structure includes a sealing plate that is attached to the outside of the discharge region, closes the opening, and forms an airtight space between the ceramic electrode. The gas supply system includes a gas circulation path having the discharge region in the path;
A blower for circulating laser gas in the gas circulation path,
further,
A power source for supplying AC power to the ceramic electrode;
A pressure sensor for measuring the pressure inside the gas circuit;
The gas laser oscillator according to any one of claims 1 to 3, further comprising a control device that stops the blower and the power source based on a measurement result of the pressure sensor.

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