JPH05226742A - Laser oscillator - Google Patents

Abstract

PURPOSE:To prevent a reduction in a laser oscillation efficiency caused by high frequency power differences which are produced by impedance differences in a discharge tube and which are injected in the discharge tube in the case where a high frequency power source through a matching circuit is combined with a laser oscillator to discharge. CONSTITUTION:A variable capacitor 15 is provided in the vicinity of at least an electrode 6, whereby fine impedance differences in a plurality of discharge tubes are corrected so that a high frequency power derived from a high frequency power source part 14 can uniformly be injected to each of the discharge tubes through a matching circuit 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial laser oscillator that cuts, welds, heat-treats metal or the like by utilizing generated laser light.

[0002]

2. Description of the Related Art In recent years, as the demand for industrial gas laser devices as metal working machines has increased, improvements have been desired.

A conventional laser oscillator will be described below with reference to the drawings. As shown in FIG. 2, the gas laser oscillator, which is called a high-speed axial flow type, includes an output mirror 1, an output mirror holder 2, a main flange 3, an assembly block 4, a discharge tube 5, an electrode 6, a folding block 7, and a terminal mirror holder. 8,
It is composed of a terminal mirror 9, a heat exchanger 10, a gas pipe 11, and a blower 12.

With respect to the laser oscillator having the above components, the relationship and operation of each component will be described below. First, the laser medium gas is filled in a vacuum container composed of the main flange 3, the assembly block 4, the discharge tube 5, the heat exchanger 10, the gas pipe 11, and the blower 12, and the blower 12 is held at a constant pressure. To circulate the laser medium gas. High-frequency power is injected into the circulated laser medium gas from the external high-frequency power source through the electrode 6 into the discharge tube 5 to discharge the laser medium gas and generate laser light. The generated laser light is amplified by an optical resonator composed of the output mirror 1, the folding block 7, and the terminal mirror 9, and a part of the laser light is taken out from the output mirror 1 and used for processing. At this time, in order to remove the heat generated in the discharge tube 5 and cool the laser medium gas, the heat exchanger 10 is provided in the middle of the gas pipe 11.
Is provided. Further, in order to form the optical resonator, the output mirror 1 and the terminal mirror 9 need to be maintained in parallel via the folding block 7, and therefore the output mirror holder 2
And the end mirror holder 8 are used for fine adjustment. Further, the main flange 3 and the assembly block 4 are structurally strong, and have sufficient strength so that the angle between the output mirror 1 and the terminal mirror 9 does not change due to thermal expansion or external force.

Next, as shown in FIG. 4, in a general connection method of the conventional high frequency power supply unit 14 and the laser oscillator, the matching circuit 13 is provided between the high frequency power supply unit 14 and the electrode 6 and Is generally output by a coaxial cable 17 having an output impedance of 50 ohms and is connected to the matching circuit 13. The matching circuit 13 is connected in parallel to the electrode 6 provided for each discharge tube 5 with a copper plate 18 or the like, and high frequency power is transmitted.

[0006]

However, in the above-mentioned conventional structure, when the high frequency power supply is actually connected to the electrodes of the discharge tube constituting the laser oscillator through the matching circuit, a slight difference in impedance between the electrodes of the discharge tube is caused. There is a problem that high frequency power is not evenly injected into each discharge tube electrode and the oscillation efficiency is reduced.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a laser oscillator in which the impedance difference between a plurality of discharge tube electrodes is corrected and a decrease in oscillation efficiency is prevented.

[0008]

To achieve the above object, the laser oscillator of the present invention corrects a delicate impedance difference between discharge tube electrodes by finely adjusting a variable capacitor provided in the vicinity of at least one electrode. The high frequency power is evenly injected into each discharge tube electrode.

[0009]

According to the present invention, in the above structure, when the high frequency power source is connected to the laser oscillator through the matching circuit, if there is a slight impedance difference between the plurality of discharge tube electrodes, the high frequency power is applied to each discharge tube electrode. Since it is not injected evenly, a matching circuit is provided to match the output impedance of the power supply with the impedance of all discharge tube electrodes. If there is a pressure difference in the laser medium gas, the impedance difference between the plurality of discharge tubes is ignored, and a difference occurs in the high frequency power injected into each discharge tube. The difference in the high frequency power injected into each discharge tube electrode causes a temperature difference in the laser medium gas passing through the discharge tube. Since the oscillation efficiency of the laser decreases remarkably when the temperature exceeds a certain temperature, the presence of even one discharge tube exceeding the limit temperature affects the overall laser oscillation efficiency. Therefore, at least one variable capacitor is provided in the vicinity of each discharge tube to correct a slight impedance difference between the discharge tubes, and high-frequency power can be evenly injected into each discharge tube.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The configuration of the laser oscillator itself is the same as that shown in FIG. 2 described in the conventional example, and the description thereof is omitted. In particular, the connection peripheral of the discharge tube and the high frequency power source will be described. As shown in FIG. 1, the discharge tube electrode 6 of the laser oscillator of the present embodiment includes a high frequency power supply unit 14, a variable capacitor 15,
They are connected by a circuit composed of a fixed capacitor 16 and a matching circuit 13.

With respect to the electrode circuit of the laser oscillator including the above components, the relationship and operation of the components will be described with reference to FIGS. 1 and 2. First, the matching circuit 13 matches the output impedance of the high frequency power supply unit 14 as viewed from the electrode 6 of the discharge tube 5 and the impedance of all the electrodes 6, and in this embodiment, the capacitor component is set to a value slightly lower than the matching point. Actually, the impedance of the electrode 6 is matched with the solid capacitor 16. The value of the solid capacitor 16 is set to the same value as the center value of the variable range of the variable capacitor 15. Therefore, when there is a difference in the impedance of the electrodes 6 among the plurality of discharge tubes due to the pressure difference of the laser medium gas, etc., the value of the variable capacitor 15 provided on the remaining electrodes is adjusted and injected into each electrode 6. Make sure there is no difference in high frequency power. When the difference in the high frequency power injected into each discharge tube is reduced, the difference in the temperature of the laser medium gas passing through the discharge tube is reduced, and the overall laser oscillation efficiency can be maintained at a high level.

[0012]

As is apparent from the above embodiments, according to the present invention, it is possible to reduce the difference in the high frequency power applied to each electrode even if there are large variations in the impedance between the plurality of discharge tube electrodes. As shown in the comparison of the measured values between the case of the circuit of FIG. 4 described in FIG. 3 of the related art and the case of the circuit of FIG. 1 described in the present embodiment, the variation width of the complex impedance of the discharge tube electrode On the other hand, it can be seen that the variation of the high frequency power injected into the discharge tube electrode is improved by several% according to the present embodiment. As a result of the above, an excellent laser oscillator with high oscillation efficiency can be realized.

[Brief description of drawings]

FIG. 1 is a power supply circuit diagram of a laser oscillator according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of a gas laser oscillator.

FIG. 3 is an impedance characteristic diagram of electric power injected into a discharge tube electrode.

FIG. 4 is a power supply circuit diagram of a conventional laser oscillator.

[Explanation of symbols]

 1 Output Mirror 5 Discharge Tube 6 Electrode 9 Terminal Mirror 11 Gas Pipe 12 Blower 13 Matching Circuit 14 High Frequency Power Supply 15 Variable Capacitor

Claims (1)

[Claims] 1. A plurality of discharge tubes, a laser resonator having output mirrors and terminal mirrors at both ends thereof, and a gas pipe connected to each of the discharge tubes is provided with an air blower to circulate gas in the gas pipes.
Laser light is generated by transmitting and discharging high-frequency power from an external high-frequency power source through electrodes arranged substantially parallel to the outside of each discharge tube, and a matching circuit is provided between the high-frequency power source and the electrodes. A laser oscillator provided with a variable capacitor disposed in the vicinity of at least one of the electrodes.