JPH04219987A - Gas laser oscillation apparatus - Google Patents

Abstract

PURPOSE:To prevent the deterioration of an electrode and an inside-mirror of optical resonator when impurities mixed with a laser gas adhere at a gas laser oscillation apparatus which has formed an optical resonator in which a group by a plurality of discharge tubes, a totally reflecting mirror on one side of both ends of them and a partially reflecting mirror on the other side have been arranged. CONSTITUTION:Resonator inside-mirrors on both ends of a discharge tube group constituted of a plurality of discharge tubes 1 are constituted of a totally reflecting mirror 17 whose transmissivity is small and of a partially reflecting mirror 7 as an output mirror. Electrodes 15 arranged near both ends of the discharge-tube group are used as cathodes; the cathodes 15 are grounded; electrodes 14 to the center of the discharge- tube group are used as anodes; a laser beam which is leaked slightly from the totally reflecting mirror 17 is detected by using a laser-beam detector 18. When a detected laser-beam output is lowered from a set value, an electric discharge is stopped. A laser gas which contains impurities is discharged from a laser-gas discharge port 20. A new laser gas is introduced from a laser-gas introduction port 21. Thereby, it is possible to prevent the deterioration in the electrodes and in the resonator inside- mirrors.

Description

[Detailed description of the invention]

0001

[Industrial application field]
The present invention relates to a gas laser oscillation device in which the axial direction of a discharge tube and the optical axis direction coincide.

0002

2. Description of the Related Art A conventional gas laser oscillation device is shown in FIG. In this figure, 1 is a discharge tube made of a dielectric material such as glass, and 2 and 3 are metal electrodes provided inside the discharge tube 1. 4 is a high-voltage DC power supply connected to the electrodes 2 and 3, and applies a voltage of 30 KV between the electrodes 2 and 3, for example. Reference numeral 5 denotes a discharge space within the discharge tube 1 sandwiched between the electrodes 2 and 3. 6 is a total reflection mirror, and 7 is a partial reflection mirror. The total reflection mirror 6 and the partial reflection mirror 7 are fixedly arranged at both ends of the discharge space 5, and form an optical resonator. 8 is a laser beam output from the partial reflecting mirror 7. Arrow 9 indicates the flow direction of the laser gas, which circulates within the axial flow laser device. 1
0 is a laser gas circulation tube body, 11 and 12 are heat exchangers for lowering the temperature of the laser gas whose temperature has increased due to discharge in the discharge space 5 and operation of the blower, and 13 is a blower for circulating the laser gas. This blower 13 produces a gas flow of about 100 m/sec in the discharge section 5.

The above is the configuration of a conventional axial flow type laser device, and its operation will be explained next.

First, a high voltage is applied to a pair of metal electrodes 2 and 3 from a high voltage current power source 4 to generate a glow-like discharge in a discharge space 5. The laser gas passing through the discharge space 5 is
This discharge energy is obtained and excited, and the excited laser gas enters an optical resonant state in an optical resonator formed by the total reflection mirror 6 and the partial reflection mirror 7, and a laser beam 8 is output from the partial reflection mirror 7. This laser beam 8 is used for various laser processing applications. FIG. 3 is a configuration diagram of a gas laser oscillation device having a plurality of discharge tubes. Anode 1
One cathode 4 is placed at the center of the resonator, and cathodes 15 are placed at both ends of the resonator. In this configuration, a high DC voltage is applied between one anode 14 and a plurality of cathodes 15 from the high voltage DC power supply 4, and a glow-like discharge is generated in the discharge space 5. The laser gas passing through the discharge space 5 is excited by this discharge energy and outputs a laser beam 8 similarly to the example shown in FIG. Here, the cathode 15 is not grounded and is at a high voltage in order to maintain the balance of discharge currents of a plurality of discharge tubes.

[0005]

[Problem to be Solved by the Invention] With the above configuration, when impurities such as metal oxides and organic substances are mixed into the laser gas flowing inside the discharge tube, if the discharge is continued, the impurities will adhere to the electrodes and the internal mirror of the resonator. Furthermore, there was a problem in that burn-in occurred due to discharge, which deteriorated the electrodes and the internal mirror of the resonator.

[0006] The present invention solves the above problems.
It is an object of the present invention to provide a highly reliable gas laser oscillation device that can prevent deterioration of electrodes and resonator internal mirrors by detecting impurities mixed into the laser gas, stopping the discharge, and replacing the laser gas with new laser gas. purpose.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a plurality of discharge tubes made of an insulator, metal electrodes provided at both ends of each discharge tube, and a plurality of discharge tubes made of an insulator. A high-voltage DC power supply that applies high voltage to each electrode pair, and a total reflection mirror with a slight transmittance placed at both ends of a discharge tube group formed by multiple discharge tubes.One part is a total reflection mirror with a slight transmittance, and the other part is an output mirror. In a gas laser oscillation device comprising a resonator internal mirror which is a reflecting mirror, a blower for flowing laser gas in the axial direction of the discharge tube group, and a circulation tube body forming a gas circulation path together with the discharge tube group, Electrodes placed near the internal mirrors of the resonator at both ends of the tube group are used as cathodes, and the cathodes are grounded. Multiple electrodes near the center of the discharge tube group are used as anodes, and an insulating tube body is connected between these anodes. Connecting. Furthermore, there is a laser beam detector that detects a part of the laser beam output from the total reflection mirror with a slight transmittance, an outlet for the laser gas containing impurities, an inlet for the new laser gas, and a laser beam output that is set to the set value. The device is equipped with a control circuit that controls to stop oscillation when the temperature drops further, exhaust the laser gas containing impurities, and introduce new gas.

[0008]

[Operation] According to the above means, a part of the laser beam output from the total reflection mirror side is detected, and the laser beam detector detects that the discharge current is reduced due to impurities in the laser gas and the laser beam output is reduced. However, since the laser discharge is stopped and the impurity-containing laser gas is replaced with new laser gas, deterioration of the electrodes of the gas laser oscillator and the internal mirror of the resonator can be prevented.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment of a gas laser oscillation device according to the present invention. The same parts as in FIGS. 2 and 3 showing the conventional example are given the same numbers, detailed explanations are omitted, and different parts will be explained.

In FIG. 1, 7 is a partial reflection mirror as an output mirror of the resonator, 17 is a total reflection mirror with a slight transmittance for detecting the laser beam output, and 18 is a laser beam from the total reflection mirror 17. a laser beam detector that detects a part of the output; 19 a control circuit that stops the discharge when detecting a decrease in the laser beam output and controls replacement of impurity-containing laser gas with new laser gas; 20 a laser gas exhaust port; 21 is the laser gas inlet. Furthermore, total reflection mirror 1
A grounded cathode 15 is provided near the resonator 7, and a plurality of anodes 14 are provided near the center of the resonator, and each anode 14 is connected by an insulating tube 16.

In the gas laser oscillation device constructed as described above, when impurities are generated in the laser gas during discharge, the discharge is disturbed and a discharge current flows in the insulating tube between the plurality of anodes 14. Since this discharge state is close to an arc, it does not contribute to laser oscillation. Therefore, the discharge current flowing through the normal discharge section decreases, and the laser beam output decreases, so that the actual laser beam output detected by the laser beam detector 18 is lower than the set laser beam output. Therefore, in this state, the control circuit 19 stops the discharge, exhausts the laser gas containing impurities from the laser gas outlet 20, and introduces new laser gas from the laser gas inlet 21, thereby preventing deterioration of the electrodes and the resonator internal mirror. .

0012

As is clear from the above description, according to the present invention, the incorporation of impurities into the laser gas is detected as a decrease in laser beam output, the discharge is stopped, and the laser gas containing the impurities is discharged. By replacing the laser gas with a new one, the discharge will continue with the laser gas still mixed with impurities, and the electrodes and resonator internal mirror will not deteriorate, making it possible to realize a gas laser oscillation device that can perform highly reliable and stable processing. can.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a gas laser oscillation device of the present invention.

[Figure 2] A configuration diagram showing a conventional example of a gas laser oscillation device with one discharge tube.

[Figure 3] A configuration diagram showing a conventional example of a gas laser oscillation device with multiple discharge tubes.

[Explanation of symbols] 1 Discharge tube 4 High voltage DC power supply 7 Partial reflector 8 Laser beam 10 Circulation pipe body 13　Blower 14 Anode 15 Cathode 16 Insulating tube body 17 Total reflection mirror 18 Laser beam detector 19 Control circuit 20 Laser gas exhaust port 21 Laser gas inlet

Claims (1)

[Claims] Claim 1: A plurality of discharge tubes made of an insulator, metal electrodes provided at both ends of each discharge tube, a high voltage DC power supply that applies a high voltage to each pair of electrodes, and a plurality of resonator internal mirrors, one of which is a total reflection mirror with a slight transmittance and the other is a partial reflection mirror serving as an output mirror, disposed at both ends of the discharge tube group formed by the discharge tube group; A blower for flowing laser gas in the axial direction, a circulation tube body that forms a gas circulation path together with the discharge tube group, an insulating tube body that connects a plurality of anodes near the center of the discharge tube group, and a laser beam. a laser beam detector for detecting the output of the laser beam, a laser gas exhaust port for discharging laser gas containing impurities, a laser gas inlet for introducing new laser gas, and a laser beam output detected by the laser beam detector that is initially set. It consists of a control circuit that controls the discharge to be stopped and the laser gas to be replaced by a signal that is lower than the output value of the laser beam. Furthermore, the gas laser oscillation device has its cathode grounded.