JPH0445586A - Metallic vapor laser device - Google Patents

Abstract

PURPOSE:To realize effectiveness of laser oscillation by refluxing metallic vapor which is condensed at both end parts inside a laser tube from a low temperature region inside the laser tube to a high temperature region in a central part thereof for effective use. CONSTITUTION:Oscillation of a laser is generated by making discharge gas such as neon gas flow inside a laser tube, by applying a high voltage between a pair of electrodes, by generating discharge for heating to a temperature which enables adequate generation of metallic vapor and by exciting the generated metallic vapor. A temperature of the laser tube is kept at a high temperature by an insulating material, which allows metallic vapor to acquire a concentration which is necessary for laser oscillation. An inside of the laser tube which is provided with a wick is kept at a temperature which enables generation of metallic vapor, and an outside edge part of the laser tube is kept at a temperature which allows metallic vapor to condense. Vapor in a high temperature region of the laser tube diffuses to a low temperature region of an end part of the laser tube and condenses; however, it is transferred to the high temperature region side due to capillary phenomenon of the wick and circulates. The circulation eliminates reduction of laser oscillation time due to consumption of metallic vapor and enables long time operation.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a metal vapor laser device, and in particular a metal vapor laser device that can perform laser oscillation efficiently and has a long life and can operate for a long time. This invention relates to a metal vapor laser device.

(Prior Art) The configuration of a conventional metal vapor laser device will be described with reference to FIG. That is, a laser tube 2 as a heat-resistant discharge tube is housed in the center of the oscillation tube body 1. A positive electrode 3 and a negative electrode 4 are disposed facing each other at both ends of the laser tube 2, and these electrodes 3 and 4 are supported by electrode support flanges 5 and 6, respectively.
, 4, a pulsed bipolar discharge occurs in the discharge space 7 formed between the two. At the bottom of the laser tube 2, a metal vapor source 8, such as copper grains, for generating metal vapor is arranged.

Further, a heat insulating layer 9 made of a material such as alumina fiber is formed around the outer periphery of the laser tube 2, and in order to fix and protect the heat insulating layer 9 in a predetermined position, a protective tube 1 made of quartz or the like is formed.
0 is provided on the outer periphery of the heat insulating layer 9. A protection tube 10,
A vacuum heat insulating chamber 12 is formed between it and an external vacuum container 11 disposed outside. The vacuum insulation chamber 12 and the discharge space 7 within the laser tube 2 are connected to an exhaust device 13 to maintain the interior in a vacuum state.

Further, in order to insulate the positive electrode 3 and the negative electrode 4 and obtain a good discharge, a break tube 14 made of an insulating material such as ceramics or glass is interposed between the external vacuum vessel 11 and the electrode support flange 6. has been done.

To oscillate laser light, first operate the exhaust device 13 to exhaust the vacuum insulation chamber 12 and the discharge space 7, and then supply Ne into the discharge space 7 from the buffer gas supply source 15.
A buffer gas such as the following is introduced to maintain a constant internal pressure.

When the high voltage power supply 16, pulse circuit 17, and pulse drive power supply 18 are activated in this state, a pulsed high voltage is applied between the anode 3 and the cathode 4, and discharge plasma is generated in the discharge space 7. The floating metal vapor collides with the free electrons in this discharge plasma, and the metal vapor is excited.
Laser light of a predetermined wavelength is generated when the excited metal vapor transitions to a lower energy level. The laser light generated in the discharge space 7 passes through the Brewster window 19 and 20, and further passes through the output mirror 2 constituting the laser light resonator 21.
2 and the total reflection mirror 23, its amplitude increases, and the output mirror 22 oscillates.

(Problems to be Solved by the Invention) In the metal vapor laser device of the conventional structure as described above, a cylindrical tube made of ceramics is used as the laser tube 2.

However, during operation of the laser device, the metal vapor from the metal vapor source 8 disposed inside the laser tube 2 moves from the high temperature region in the center of the laser tube 2 to the low temperature regions at both ends of the laser tube 2 and condenses. There is a problem that it adversely affects laser oscillation and reduces oscillation efficiency, making it impossible to operate for a long time.

The present invention has been made to solve the above problems, and the metal vapor condensed at both ends of the laser tube is circulated from the low-temperature region in the laser tube to the high-temperature region in the center and effectively used to efficiently perform laser oscillation. The object of the present invention is to provide a long-life metal vapor laser device capable of achieving long life.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a laser tube that applies discharge energy to a metal to generate plasma as a laser medium, and a laser tube that is provided oppositely at both ends of the laser tube and that A laser tube includes a pair of electrodes for generating a pulse discharge within the laser tube, an electrode support flange that supports the pair of electrodes, and a heat insulating layer formed around the outer periphery of the laser tube to retain discharge heat within the laser tube. , characterized in that an alumina wick is provided on the low temperature region surface within the laser tube.

(Function) Laser oscillation is achieved by flowing a discharge gas such as neon gas into the laser tube, applying a high voltage between a pair of electrodes, causing a discharge, and heating the tube to a temperature at which sufficient metal vapor is generated. Produced by exciting steam. The temperature of the laser tube is maintained by insulation at a high temperature that allows the metal vapor to reach the concentration necessary for laser oscillation. The inside of the laser tube with the wick is heated to the temperature at which the metal vapor is generated, e.g. approximately 1500°C for copper, and the outer end of the laser tube is heated to the temperature at which the metal vapor solidifies, e.g. 100°C for copper.
The temperature is maintained at 85°C or higher. The vapor in the high-temperature region of the laser tube diffuses into the low-temperature region at the end of the laser tube and condenses, but is transported to the high-temperature region and circulated by the capillary action of the wick. This circulation eliminates shortening of laser oscillation time due to consumption of metal vapor, allowing long-time operation.

(Example) An example of a metal vapor laser device according to the present invention will be described with reference to FIGS. 1 and 2.

In Fig. 1, an alumina laser tube 2 as a heat-resistant discharge tube is located in the center of the oscillator tube body designated by the reference numeral 1.
is accommodated. Positive electrodes 3 are attached to both ends of the laser tube 2.
and a negative electrode 4 are arranged to face each other, and these electrodes 3.
4 are supported by electrode support flanges 5 and 6, respectively, and a pulsed bipolar discharge occurs in a discharge space 7 formed between the electrodes 3 and 4. At the bottom of the laser tube 2 is a metal vapor source 8, such as copper grains, which generates metal vapor.
is placed. Short tubular wicks 24 and 25 made of high-purity alumina are provided near the electrodes 3 and 4, that is, in the low temperature region.

Further, a heat insulating layer 9 made of a material such as alumina fiber is formed around the outer periphery of the laser tube 2, and in order to fix and protect the heat insulating layer 9 in a predetermined position, a protective tube 1 made of quartz or the like is formed.
G is provided on the outer periphery of the heat insulating layer 9. A protection tube 10,
A vacuum heat insulating chamber 12 is formed between it and an external vacuum container 11 disposed outside. The vacuum insulation chamber 12 and the discharge space 7 within the laser tube 2 are connected to an exhaust device 13 to maintain the interior in a vacuum state.

Further, in order to insulate the positive electrode 3 and the negative electrode 4 and obtain a good discharge, a break tube 14 made of an insulating material such as ceramics or glass is inserted between the external vacuum vessel 11 and the electrode support flange 6. has been done.

The high-purity alumina wick 24, 25 must have a crystalline structure that allows the liquefied metal to be transported by capillarity. Therefore, as shown in FIG. 2, which is an enlarged schematic diagram of the crystal structure of the alumina particles, high purity alumina particles 26 with particle diameters of 20 to 30 microns are combined to form pores 27 of 10 to 20 microns. Use alumina ceramics or alumina wool formed into a short tube shape.

Therefore, in order to oscillate a laser beam, first, the exhaust device 13 is operated to exhaust the inside of the vacuum insulation chamber 12 and the discharge space 7, and then a buffer gas such as Ne is supplied from the buffer gas supply source 15 into the discharge space 7. is introduced to maintain a constant internal pressure.

When the high voltage power supply 16, pulse circuit 17, and pulse drive power supply 18 are activated in this state, a pulsed high voltage is applied between the anode 3 and the cathode 4, and discharge plasma is generated in the discharge space 7. The floating metal vapor collides with the free electrons in this discharge plasma, and the metal vapor is excited.
Laser light of a predetermined wavelength is generated when the excited metal vapor transitions to a lower energy level. The laser light generated in the discharge space 7 passes through the Brewster window 19 and 20, and further passes through the output mirror 2 constituting the laser light resonator 21.
2 and the total reflection mirror 23, its amplitude increases, and the output mirror 22 oscillates. Due to this oscillation, the temperature of the laser tube 2 is maintained by the heat insulating material 9 at a high temperature at which the concentration of metal vapor necessary for laser oscillation can be obtained.

The vapor in the high temperature area in the laser tube 2 diffuses into the low temperature area at the end and condenses, but is transferred to the high temperature area in the center and circulated by the capillary action of the -wicks 24, 25. This circulation prevents the laser oscillation time from being shortened due to consumption of metal vapor, allowing long-term operation.

Here, if the material of the wicks 24 and 25 is made of metal, it is not preferable because metal oxides are emitted due to the high temperature and reduce the laser oscillation output. Therefore, it is necessary to use high-purity alumina, which is the same material as the laser tube 2. Wick made of high-purity alumina does not generate impurities.
Since laser oscillation output is obtained, a metal vapor laser device with high laser oscillation efficiency and long life can be obtained.

As the material for the wicks 24 and 25, foamed alumina, which is made by foaming a high-purity alumina material 28 to form a large number of pores 29, can also be used, as shown in FIG. The metal liquefied within the laser tube 2 is transported by capillary action due to the holes 29 and flows back within the wick.

[Effects of the Invention] According to the present invention, it is possible to provide a long-life metal vapor laser device that has improved laser oscillation efficiency and can be operated for a long time.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a metal vapor laser device according to the present invention, and FIGS. 2 and 3 are partially enlarged reproductions of the crystal structure of the wick in FIG. 1. 4 are cross-sectional views showing a conventional metal vapor laser device. 1... Oscillator tube body 2... Laser tube 3.4... Electrode 5.6... Electrode support flange 7... Discharge space 8... Metal vapor source 9... Heat insulating layer O. ...Protection tube 1...External vacuum container 2...Vacuum insulation chamber 3...Exhaust device 4...Break tube 5...Buffer gas supply source 6...High voltage power supply 7...Pulse Circuit failure...Pulse drive power supply 9.20...Brewster window 21...Laser resonator 22...Output mirror 23...Total reflection mirror 24, 25...Wick 26...Alumina particles 27 ...Vacancy 28...High-purity alumina material 29...Vacancy 222 ~ Fig. 000\Foot convexity

Claims (1)

[Claims] (1) A laser tube that applies discharge energy to metal to generate plasma that serves as a laser medium; a pair of electrodes that are provided oppositely at both ends of the laser tube and that generate a pulse discharge within the laser tube; an electrode support flange for supporting an electrode; and a heat insulating layer formed around the outer periphery of the laser tube to retain discharge heat within the laser tube, and an alumina wick is provided in a low temperature region within the laser tube. A metal vapor laser device characterized by: