JPH03250677A - Laser device - Google Patents

Abstract

PURPOSE:To realize stable and highly dense discharge between discharge electrodes even if a discharge gap is wide and laser gas pressure is high by a method wherein potential on a lower voltage electrode and on a higher voltage electrode is determined by stray capacitance based on wiring of a laser device and potential between the high voltage electrode and the low voltage electrode is set at ground potential. CONSTITUTION:Capacitors C8, C9 are inserted into a load circuit wherein potential on a higher voltage electrode 16a and on a lower voltage electrode 16b is determined by stray capacitance of a device. High frequency power generated on a high frequency oscillating part 20 is supplied via transformer coupling 22 to the higher voltage electrode 16a and the lower voltage electrode 16b of a discharge part. Since there is ground potential between potential Va, Vb of the higher voltage electrode 16a and the lower voltage electrode 16b, high frequency discharge 23 is generated between dielectric bodies 7a, 7b even if a discharge gap is wide or laser gas pressure is high. Therefore stable and highly dense discharge can be realized between the discharge electrodes.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention applies a high-frequency voltage between high-voltage side and low-voltage side electrodes using a high-frequency power source, and generates a high-frequency discharge across a dielectric. This invention relates to a laser device that performs.

(Conventional technology) Laser gas pressure number 10 tons used for various laser processing
FIG. 4 shows an example of a laser device that performs laser excitation by generating high-frequency discharge at about 200 torr.

Note that FIG. 4 shows a high frequency power source and a laser oscillation section. That is, the high frequency power supply 1 has an excitation section 2 and a power amplifier section 3.
The high frequency power of the frequency f (usually 13°56 HM z±2KHz) generated in the excitation part 2 is
The signal is amplified by the power amplifier section 3, and is supplied to the high-voltage side electrode 6a of the laser discharge section through a matching box 5 for impedance matching using a coaxial cable 4 having a characteristic impedance of 50 Ω. On the other hand, the low voltage side electrode 6b is grounded.

Further, the high frequency voltage supplied between the high voltage side electrode 6a and the low voltage side electrode 6b is applied to the laser gas via dielectrics 7a and 7b arranged adjacent to each electrode, generating a high frequency discharge 8. let Although not shown in the figure, in order to prevent the gas temperature from rising due to the high frequency discharge 8, the dielectric material 7a,
Laser gas is flowing between 7b. Furthermore, by arranging a reflecting mirror 9 and a partial reflecting mirror 10 with the high-frequency discharge 8 in between to form a laser resonator, laser oscillation is performed and laser light 11 is obtained. In addition,
When it is necessary to modulate the laser beam 11, the excitation unit 2
It is sufficient to send the pulse modulation signal 12 from the outside.

On the other hand, the power amplifier section 3 includes a vacuum tube 13 for amplifying high frequency signals, and a capacitor C for adjusting output impedance.
, C2 and an inductance L1, a high DC voltage is applied to the vacuum tube 13 to operate the vacuum tube 13, and a capacitor C3 is further provided to prevent this DC from passing through to the high frequency output side. It is connected. Furthermore, the matching box 5 for impedance matching is of the reverse type, and has a variable capacitor C4 and an inductance L2.
It is composed of

(Problems to be Solved by the Invention) However, in the conventional laser device having the above configuration, there were problems to be solved as described below.

That is, when the distance between the two dielectrics 7a and 7b is increased to widen the discharge gap, or when the laser gas pressure is increased, the high-frequency discharge 8 generated in the discharge section
However, there was a drawback that the discharge part was blown away in the downstream direction.

To explain this point in detail, as shown in FIG.
, 7b, and insulators 17a, 17b for fixing the respective dielectrics 7a, 7b. Here, the low voltage side electrode 6b is grounded, and its potential vb is OV. Further, this discharge section is constructed as a part of a metal laser container 18, and a laser gas flow 19 is supplied to a discharge gap sandwiched between dielectrics 7a and 7b.

In such a conventional laser device, the high voltage side electrode 6
a, high frequency voltage V is applied to the low voltage side electrode 6b.

If an attempt is made to generate a high-density high-frequency discharge 8 by applying , the high-frequency discharge 8 will occur between the dielectric 7a and the laser container 18. This is because the potential of the low-voltage side electrode 6b is the ground potential, so when a high-frequency discharge occurs, the potential of the discharge part side of the low-voltage side dielectric 7b becomes higher than the potential of the high-voltage side electrode 6a. This is because the high-frequency discharge 8 is more likely to fly toward the laser container 18, which is at ground potential. As a result, there were disadvantages in that stable discharge could not be obtained in the discharge section and the laser output was also reduced.

The present invention was proposed to eliminate the above-mentioned drawbacks of the conventional technology, and its purpose is to realize stable high-density discharge between discharge electrodes even with a wide discharge gap and high laser gas pressure. The object of the present invention is to provide a highly efficient and compact laser device.

[Structure of the Invention (Means for Solving the Problems) The present invention provides a laser device that applies a high-frequency voltage between a high-voltage side electrode and a low-voltage side electrode using a high-frequency power supply, and generates a high-frequency discharge across a dielectric. In this case, the potential of the low-voltage side electrode and the potential of the high-voltage side electrode are determined by the stray capacitance based on the wiring of the laser device, and the potential between the high-voltage side electrode and the low-voltage side electrode is set to the ground potential. It is characterized by the fact that

(Function) According to the laser device of the present invention, the ground potential is set between the high voltage side electrode and the low voltage side electrode, so that the high frequency discharge generated between the two electrodes is transferred from the discharge electrode to the laser container side which is at the ground potential. It is possible to prevent the discharge from flying to the surface, and to generate a stable, high-density discharge between the dielectric materials.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIG. Incidentally, the same members as those of the conventional type shown in FIG. 4 are given the same reference numerals, and explanations thereof will be omitted.

As shown in FIG. 1, the laser device of this embodiment is composed of a self-excited high frequency power source and a laser oscillation section. That is, the high-frequency oscillation section 20 of the high-frequency power supply is composed of a Colpitts circuit that easily extracts high frequencies to the discharge load side by transformer coupling, and includes a vacuum tube (triode) 2 for oscillating high frequencies.
1. It is composed of capacitors C5 and C6 that determine the oscillation frequency f, and an inductance L3 that also serves as a coupling transformer with the load. Further, a high DC voltage is applied to the vacuum tube 21 to operate the vacuum tube, and a capacitor C is also applied to prevent this DC component from passing through to the high frequency output side.
7 is installed.

In addition, at this time, the oscillation frequency f generated in the high frequency oscillator 20 is f=1/2πJ]/L3・(1/C+, + 1/C
2)...(1), the oscillation frequency changes with fluctuations in the discharge load, and has the effect of softening the reflected power due to the mismatch state. Further, in the case of this embodiment, when pulse modulating the laser beam 11, it is sufficient to send the pulse modulation signal 12 to the grid of the vacuum tube 21 from the outside.

Furthermore, capacitors C8 and C9 are inserted in the load side circuit, and these capacitors C8°C9
The potential of the high voltage side electrode 16a and the low voltage side electrode 16b is
The configuration is determined by the stray capacitance of the device.

Further, the high frequency power of the frequency f (±10% in terms of frequency fluctuation range) generated in the high frequency oscillator 20 is transmitted to the transformer coupling 2
2 to the high voltage side electrode 16a and low voltage side electrode 16b of the laser discharge section. Here, under a certain discharge input condition, the transformer coupling 22 (
For example, the turn ratio of the primary side and the secondary side is adjusted so that the output impedance of the high frequency oscillation section 20 and the impedance of the laser discharge section can be matched.

The operation of the laser device of this embodiment having such a configuration will be described below.

That is, in the laser device of this embodiment, the potential Va of the high voltage side electrode 16a and the low voltage side electrode 1.6b.

Since there is a ground potential between vb (va-vb-Vo),
Even when the discharge gap is wider than before or when the laser gas pressure is higher, the high frequency discharge 23 is generated between the dielectrics 7a and 7b as shown in FIG. 3. this is,
This is because, unlike in the case of the conventional type shown in FIG. 2, where the high-frequency discharge was more likely to fly toward the laser container 18, which is at ground potential, it is more likely to occur between the dielectrics 7a and 7b due to the potential. .

In this way, according to this embodiment, by setting the ground potential between the high-voltage side electrode and the low-voltage side electrode, the discharge can be maintained even under conditions of a wide discharge gap interval and high laser gas pressure. A stable high-density discharge can be realized between the electrodes, and a highly efficient and compact laser device can be obtained.

Note that the present invention is not limited to the embodiments described above, and although fixed capacitors are used as the capacitors C8 and C7 disposed in the laser oscillation section, at least one of them may be a variable capacitor. Alternatively, the secondary side may be floated relative to the negative side at the position of the transformer coupling 22 shown in FIG. 1 without using the capacitors C8 and C9.

[Effects of the Invention] As described above, according to the present invention, the potential of the low-voltage side electrode and the potential of the high-voltage side electrode are determined by the stray capacitance based on the wiring of the laser device, and the high-voltage side By setting the ground potential between the electrode and the low-voltage side electrode, stable high-density discharge can be achieved between the discharge electrodes even with a wide discharge gap or high laser gas pressure, and it is highly efficient and compact. It is possible to provide a laser device with a wide range of functions.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the laser device of the present invention;
FIG. 2 is an enlarged sectional view showing the discharge state near the discharge section of the conventional example, FIG. 3 is an enlarged sectional view showing the discharge state near the discharge section of this embodiment, and FIG. 4 is an example of the conventional laser device. FIG. DESCRIPTION OF SYMBOLS 1... High frequency power supply, 2... Excitation part, 3... Power amplifier part, 4... Coaxial cable, 5... Matching box, 6
a...High voltage side electrode, 6b...Low voltage side electrode, 7a
, 7b... dielectric, 8... high frequency discharge, 9... reflecting mirror, 10... partial reflecting mirror, 11... laser light, 1
2...Pulse modulation signal, 13...Vacuum tube, 16a.
...High voltage side electrode, 16b...Low voltage side electrode, 20.
...High frequency oscillation section, 21... Vacuum tube, 22... Transformer coupling, 23... High frequency discharge. Figure 2

Claims (1)

[Scope of Claims] A laser device in which a high frequency voltage is applied between a high voltage side electrode and a low voltage side electrode by a high frequency power supply to generate a high frequency discharge across a dielectric, the potential of the low voltage side electrode and the high voltage A laser device characterized in that the potential of the side electrode is determined by a stray capacitance based on wiring of the laser device, and the potential between the high voltage side electrode and the low voltage side electrode is set to a ground potential.