JPH0482280A - Metal vapor laser device - Google Patents

Abstract

PURPOSE:To prevent a laser takeout efficiency from being lowered when a metal vapor adheres to a laser takeout window by a method wherein a buffer gas is made to flow uniformly and at high speed near the introduction port and the evacuation port of the buffer gas from the circumference. CONSTITUTION:A prescribed temperature and a prescribed metal-vapor concentration are set inside a discharge tube 60. However, since a temperature is low near end-part containers 51, 52 and laser takeout windows 21, 22, a metal vapor is diffused and moved toward the windows 21, 22. At this time, a buffer gas is introduced and evacuated at high speed uniformly in the circumferential direction at the inside of the containers 51, 52 of an introduction port 11 and an evacuation port 12. Then, buffer gas streams 101, 102 and gas streams 111, 112 coming into contact with the container walls 51, 52 are generated simultaneously. Metal-vapor gas streams 121. 122 are superposed on the gas streams 111, 112 and are captured at inner circumferential walls of the containers 51, 52. Thereby, it is possible to prevent a laser output from being lowered when a vapor-source metal adheres to the laser takeout windows.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for preventing contamination of a laser extraction window of a metal vapor laser by vapor metal.

[Conventional technology]

The prior art will be explained using FIGS. 4 and 5.

In FIG. 4, the discharge tube 60 is heat shielded by a heat insulating material 80, and the electrodes 31.3 are coaxial with the discharge tube 60.
2, which are kept airtight from the outside air by a container 50 and an insulating section 40. An end container 51.52 is provided outside the electrode 31.32 and holds a laser extraction window 21.22, both of which are kept airtight from the outside air. The end containers 5] and 52 are connected to a pipe 190 for circulating gas through an insulating tube 41, and are kept airtight from the outside air. Neon gas or the like is sealed in this device as a buffer gas at a diagonal of +Torr. electrodes 31 and 32
During this period, a high voltage is applied to generate a glow discharge, the temperature of the device is raised by the discharge energy, and the vapor source metal 70 inserted into the discharge tube 60 is melted and maintained at a predetermined vapor pressure. This metal vapor is used as a laser medium and excited by glow discharge to prepare laser oscillation conditions. That is, total reflection mirror 1. When the excitation space is sandwiched between the semi-transmissive mirror 2, the laser beam is amplified and becomes stronger while being reflected back and forth between the two mirrors, and a part of it is taken out from the semi-transmissive mirror 2 and transmitted to the laser 3. used as. It may also be used as an amplifier that increases the beam intensity by passing a laser beam oscillated by another oscillator without providing the total reflection mirror 1 and the semi-transmission mirror 2.

In such a metal vapor laser, the temperature is high near the discharge tube 60 between the electrodes 31 and 32, and the metal vapor concentration is high;
The temperature near the end containers 51 and 52 and the laser extraction windows 21 and 22 is low, and the metal vapor concentration is O. There, the metal vapor diffuses from inside the discharge tube 60 toward the laser extraction window 21.22 and adheres to the laser extraction window 21.22.

As a result, the laser light is absorbed and the laser beam is extracted.

The efficiency of taking out through the windows 21, 22 is reduced.

In order to prevent this, a fan 200 is provided in the pipe 190 provided between the end containers 51 and 52 to circulate the gas, and the fan 200 in the pipe 190 is provided between the end containers 51 and 52 to circulate the buffer gas and remove the metal vapor that diffuses toward the laser extraction window. The metal vapor recovery body 210 collects the metal vapor.

Next, FIG. 5 consists of the laser extraction window 21, the end container 51, and the metal vapor adhesion prevention device 220, and from the region with high metal vapor concentration on the right side toward the laser extraction window 21,
Metal vapor diffuses.

The metal vapor adhesion prevention device 220 prevents this from adhering to the laser extraction window 21. Conventionally, the following method has been used as this metal vapor adhesion prevention device 220. These include a method using a fan, a method using a water-cooled trap, a method using an ion trap, and the like.

[Problem to be solved by the invention]

In the conventional technique shown in FIG. 4, the following two problems occur when circulating gas flows inside the discharge tube 6o.

One is that since the metal vapor is discharged outside the discharge tube 60, the wear life of the vapor source metal 70 is shortened. Another problem is that when a large amount of circulating gas flows, a cooling effect occurs, which lowers the temperature of the discharge tube 60, and in order to maintain the operating temperature, it becomes necessary to supplement the discharge force from the outside, reducing efficiency. It is. In order to avoid these problems, it is necessary to prevent the circulating gas from flowing inside the discharge tube 60 as much as possible.

That is, compared to the flow path resistance of the discharge tube 60, the gas circulation piping 1
A necessary condition is that the flow path resistance of 90 is small. The inner diameter and length of the discharge tube 60 are directly related to the output of the laser, and are therefore device-specific values. Also, since it is a laser generator, it is a straight cylindrical tube. Therefore, the gas circulation plumber 90 is longer than the discharge tube 60. As a result, the inner diameter of the gas circulation pipe 190 needs to be larger than the inner diameter of the discharge tube 60. The disadvantage is that the device is very large.

Further, in the conventional technology shown in FIG. 5, any method requires high voltage insulated power charging equipment on the high voltage side. or,
Since it is used in areas subject to high temperatures and heat radiation, it requires the use of structural materials with good heat resistance, which has the disadvantage of requiring large equipment and being expensive in terms of heat resistance.

An object of the present invention is to prevent metal vapor from adhering to the laser extraction window and reducing laser extraction efficiency.

[Means to solve the problem]

In order to achieve the above object, before the metal vapor in the discharge tube 60 scatters toward the laser extraction window 21 by concentration diffusion and adheres to the laser extraction window 21, a buffer gas is introduced;
By flowing the buffer gas uniformly from the surrounding area near the exhaust port at high speed, it is collected on the end container wall.

[Effect]

Metal vapor lasers operate at high temperatures to melt and vaporize the metal. As a result, the structural materials deteriorate and impurity gases are emitted. This impurity gas is circulated and regenerated or replaced with the buffer gas in order to prevent a decrease in laser output due to unrestricted-excitation 2 population inversion reduction due to instability of discharge. This buffer gas is uniformly introduced and exhausted in the circumferential direction inside the device at the inlet and the outlet at a high speed to generate a gas flow that contacts the end container wall. The metal vapor generated in the discharge tube and diffused to the laser extraction window is brought into contact with the end container wall by this gas flow and collected, thereby protecting the laser extraction window from contamination and removing the laser beam. It is possible to prevent a decrease in output.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, the discharge section includes electrodes 31, 32 and a discharge tube 60.
．． Insulation material 80. It is composed of a container 50 and a discharge tube 6.
0 is heat shielded with a heat insulating material 80, and a pair of electrodes 31 and 32 are provided at both ends of the discharge tube coaxially with the discharge tube. The outer periphery connecting the electrodes is covered with a container 50 and an insulating cylinder 40 that electrically insulates the electrodes, maintaining airtightness from the outside air. The axially inverting discharge tube 60 side of the electrode 31.32 is provided with an end container 51.52, at each end of which a laser extraction window 21.22 is held. Except for the gas inlet 91 and the outlet 92, the airtightness is maintained substantially from the outside air. Buffer gas 11 is fed into the device through an inlet 91, and buffer gas 11 is fed into the device through an outlet 92.
2 is emitted, and the temperature within the discharge tube ranges from several Torr to several tens of T.
It has become orr.

A high voltage is applied between the electrodes 31 and 32 to generate a glow discharge, the temperature of the device is raised by the discharge energy, and the vapor source metal 70 inserted into the discharge tube 60 is melted and maintained at a predetermined vapor pressure. . This metal vapor is used as a laser medium and excited by glow discharge to prepare laser oscillation conditions. That is, total reflection mirror 1. When the excitation space is sandwiched between the semi-transmissive mirror 2, the laser beam is amplified and becomes stronger while being reflected back and forth between the two mirrors, and a part of it is taken out from the semi-transmissive mirror 2 and is emitted by the laser 3. used as. It may also be used as an amplifier to strengthen the beam intensity by passing a laser beam oscillated by another oscillator without providing the total reflection mirror 1 and the half-transmission mirror 2.

In this metal vapor laser, the inside of the discharge tube 60 is at a predetermined temperature and a predetermined metal vapor concentration.
The temperature near the laser extraction windows 21 and 22 is low, and the concentration of metal vapor is O. There, metal vapor flows into the discharge tube 60.
The laser beam diffuses and moves toward the laser extraction windows 21 and 22. When the buffer gas is uniformly introduced and exhausted in the circumferential direction at a high speed inside the end containers 51 and 52 of the buffer gas inlet 11 and exhaust port 12, the buffer gas 1 flows into the discharge tube.
01 and a buffer gas flow 102 from inside the discharge tube toward the gas outlet 92, gas flows 111, 112 are generated which contact the end vessel walls 51, 52.

The metal vapor gas streams 121, 122 are superimposed on the gas streams 111, 112 in contact with this end vessel wall, and the end vessels 51,52
collected on the inner wall of the

In FIG. 2, the gas exhaust port 92 in FIG.
32 and the discharge tube 60, and is disposed so as to be discharged from the portions located at both ends of the heat insulating material 80. A pressure difference is provided between the introduced gases 11 and 12', and on the higher pressure side,
The introduced gas flow 11 is divided within the end container 51 into a gas flow 101 that is introduced into the discharge tube 60 and a gas flow 111 that flows so as to collect the metal vapor gas flow 121 on the inner peripheral wall of the end container 51. Furthermore, the gas flow 101 toward the discharge tube 60 is combined with the gas flow 130 flowing inside the discharge tube 60, the electrode 31, and the discharge tube 6.
It separates into a gas flow 151 which is discharged to the outside from an exhaust port 141 through a gap of 0.0 mm.

On the low gas pressure side, the inlet gas stream 12' flows in the end vessel 52 in such a way that the gas stream 102' and the metal vapor gas stream 122, which are introduced into the discharge tube 60, are collected on the inner circumferential wall of the end vessel 52. The gas flow 102' directed into the discharge tube 60 merges with the gas flow 1.30 flowing inside the discharge tube 60, and flows from the gap between the electrode 32 and the discharge tube 60 to the exhaust port 142.
The gas flow 152 is discharged to the outside through the gas flow.

In this way, the structure and functions are exactly the same as in FIG. 1, except for the gas introduction and exhaust port positions.

FIG. 3 shows the structure of the banfa gas introduction and exhaust section.

(a) shows the case where the gas introduction and exhaust portions are formed in the inner periphery of the end container 51 in the form of --shaped slits 170. (
b) is a case where the gas introduction and exhaust portions are formed in 180 rows of small holes on the inner periphery of the end container 51.

〔Effect of the invention〕

According to the present invention, the vapor source metal diffused from inside the discharge tube is absorbed by the gas flow that is introduced into or exhausted from the inside and outside of the laser main body at the introduction section and the exhaust section, and is brought into contact with the end container wall. Since it can be collected on the end container wall, it can be prevented from adhering to the laser extraction window and reducing the laser output.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a metal vapor laser device showing an embodiment of the present invention, Fig. 2 is a cross-sectional view showing an application example of the present invention, and Fig. 3 is a gas introduction/exhaust diagram of Fig. 1 and Fig. 2. FIG. 4 is a sectional view of a conventional metal vapor laser, and FIG. 5 is an explanatory view of an end portion of a conventional metal vapor laser. 11.12'...Introduction gas flow, 12...Exhaust gas flow, 21.22.Laser extraction window, 31.32.
Electrode, 51.52 End container, 60 Discharge tube, 70
・Steam source metal, 91.92 ・Scrap intake and exhaust pipe, 17
0den 1 figure 5 figure

Claims (1)

[Scope of Claims] 1. A cylindrical ceramic discharge tube inside a container, a heat insulating material around the discharge tube, and a pair of cylinders substantially coaxial with the discharge tube provided at both ends of the discharge tube. a laser extraction window at both ends of the pair of electrodes so as to become part of the container, a buffer gas introduction and exhaust port in the container wall between the window and the electrode, and an inside of the discharge tube; In a vapor laser device in which a metal serving as a laser medium is provided and a gas containing a metal vapor in which a part of the metal evaporates and becomes gaseous is excited by electric discharge, the A metal vapor laser device characterized in that slits are provided in both walls of the container in the circumferential direction of the container, one of which serves as an inlet for the buffer gas, and the other serves as an exhaust port. 2. In claim 1, the space between the electrode and the laser extraction window is substantially sealed except for the buffer gas introduction/exhaust port, and communicates with a space provided with a heat insulating material. The vapor laser device is provided with an exhaust port that can exhaust air from both axial ends of the heat insulating material part, and a circumferential slit between the electrode and the laser extraction window is used only for introducing the buffer gas. 3. The metal vapor laser device according to claim 1 or 2, wherein a plurality of rows of holes are provided in place of the slits in the intake and exhaust ports for the buffer gas provided between the electrodes and the laser extraction window.