JPS61159780A - Silent discharge type gas laser device - Google Patents

Abstract

PURPOSE:To lower breakdown voltage, to eliminate the dispersion of breakdown even on a plurality of discharge tubes, to control main discharge power easily while lengthening the life of a trigger electrode and to control even trigger discharge power by fitting a pair of dielectric electrodes near a discharging section in the discharge tube. CONSTITUTION:A pair of dielectric electrodes 17a, 17b are mounted to a gas flow contraction nozzle 15 avoiding the oscillating optical path of laser beams on the gas-flow upstream side of a discharging section, and the electrodes 17a, 17b function as trigger electrodes. The power of trigger discharge can be controlled by controlling the electrostatic capacitance of the dielectric. When voltage is applied from a high-frequency power supply 4, trigger discharge is started in a section A first. Main discharge is started from a gas downstream end B by the effect of charged particles generated by trigger discharge. Breakdown voltage Vs at that time is made smaller than a time when there is no trigger discharge, and no dispersion is generated. When the electrostatic capacitance of the dielectric electrodes 17a, 17b is reduced to approximately one tenth of that of a main discharge section, a laser output is not affected, and the titled device functions as a trigger.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a silent discharge type gas laser device in which the axial direction of the discharge tube and the optical axis direction are aligned, and in particular, the invention relates to a silent discharge type gas laser device in which the axial direction of the discharge tube and the optical axis direction are coincident, and in particular, it is made easy to start the discharge. Related to Gas Laser Apparatus [Prior Art] Conventionally, as this type of trickle type gas laser apparatus, the one shown in FIG. 7 has rarely been used. In this figure, (1) is a discharge tube made of a dielectric material.

(21, +31 are metal electrodes provided in close contact with the outer peripheral surface of the discharge tube (1). (4) is the electrode (2).

(3) Both electrodes (2) are connected to the high frequency power supply.
(3) A high frequency voltage is applied between them. (5) The electrode <21. (The discharge space in the discharge tube (1) sandwiched between )teeth.

They are fixedly arranged at both ends of the discharge space (5) to form an optical resonator. (8) is a laser beam outputted by the partial reflecting mirror (7). Arrow (9) indicates the direction in which the laser gas flows.

As shown in FIG. 7, the gas is circulated within the gas laser vcrlt. +1 (l is the air pipe, aυ, a3 & is a heat exchanger for lowering the temperature of the laser gas, which has risen in temperature due to the discharge and blower 0, in the discharge space (5) before construction.

In order to circulate the laser gas, the blower U3 is required to obtain a gas flow rate of 100 yl/sec or more in the discharge space (5).

In order to reduce pressure loss, the discharge section is equipped with a gas expansion nozzle 1. A contraction nozzle αS is provided.

The above is a description of the configuration of a conventional axial flow type gas laser device and its operation traps.

First, a pair of metal electrodes (2), (31) and a high frequency power source (4
), a high frequency and high voltage is applied to the discharge space (5) to generate a stable glow-like discharge known as a silent discharge. The laser gas passing through the discharge space (5) is excited by obtaining the energy of this silent discharge, and the light generated from the excited gas is formed by the total reflection mirror (6) and the partial reflection mirror (7). The optical resonator enters a resonant state.

A laser beam (81) is emitted from the partially reflecting mirror (7). This laser beam (8) will be used for purposes such as laser processing.

[Problem that the invention seeks to solve]

In conventional gas laser equipment like the one mentioned above.

A picture frequency high voltage is applied to the metal electrode +21.13).

When obtaining the laser beam (8), the electrode +21. (31
The discharge force changes as shown in FIG. 8 in response to changes in the voltage applied between them. As shown in Figure 8, the voltage at the start of the discharge is not always the same, and the discharge force is
Variations occur as shown in (a), (b), and (C) of the figure.

In FIG. 1, vs indicates the average value of the discharge starting voltage.

To solve the above problem, in order to reduce the pressure loss to 1%, the discharge section should be divided into two parts (or four parts) as shown in Figure 7.
In the case of the structure, it is very difficult to discharge multiple discharges at the same time. Make it.

As a means to suppress this variation at the start of discharge, the ninth
As shown in the figure, it is often used to provide a trigger discharge section using a metal piece tte.

When the metal piece we is connected to a power source, a trigger discharge occurs as the applied voltage increases.

The voltage is lower than the discharge starting voltage v3 shown in FIG. 8, and is stable.

However, this trigger discharge disturbs the uniformity of the discharge density distribution within the discharge tube, resulting in an unstable discharge, so it has been found that as the trigger discharge force increases, the laser excitation efficiency decreases. In conventional devices, it is impossible to appropriately control the trigger discharge force, and the trigger discharge force becomes larger than the main discharge force, resulting in a significant decrease in laser efficiency.

Furthermore, since a metal piece is used as the trigger electrode, sputtering caused by charged particles can occur.

Problems that caused metal pieces to wear out and gas deterioration were also encountered.

This invention was made to solve the above-mentioned problems, and it is possible to reduce the discharge starting voltage, eliminate variations in discharge starting even in the case of multiple discharge tubes, and control the main discharge force. It is an object of the present invention to provide a silent discharge type gas laser device that facilitates the operation, extends the life of a trigger electrode, and also enables trigger discharge power control.

[Means for solving problems]

The silent discharge type gas laser device according to the present invention has a pair of dielectric electrodes provided in the vicinity of the discharge portion within the discharge tube.

[For production]

Since the trigger discharge section in this invention is composed of a pair of dielectric electrodes, the trigger discharge force can be controlled by the capacitance of this dielectric, and it does not affect the laser output and also serves as a trigger. .

〔Example〕

FIGS. 1(a) and 1(b) are cross-sectional views showing the main parts of a silent discharge type gas laser device according to an embodiment of the present invention.

In FIG. 1, parts given the same reference numerals as those in FIG. 7 indicate the same or equivalent parts. (17J1) (17b) is a gas condensation nozzle (
A pair of dielectric electrodes provided at is, which serve as trigger electrodes. The power of the trigger discharge can be controlled by controlling the capacitance of this dielectric.

A typical example of the structure of this trigger electrode made of dielectric material is shown in the second example.
As shown in the figure. In the figure, α11 is a glass tube (19 is a metal power supply part).

In FIG. 1, when a voltage is applied from a high frequency power source (4), a trigger discharge starts at the λ portion. Next, due to the influence of the charged particles generated by the trigger discharge, the main discharge starts from the gas downstream end B as shown in FIG. The discharge starting voltage v3 in this case is smaller than in the case without trigger discharge, and there is no variation at all, and the relationship between the applied voltage and the main discharge power is K as shown in Figure 4, indicating that the effect of the trigger electrode is achieved. I understand. Further, it goes without saying that even in a discharge tube having a number of a, there is no variation in the start of discharge. In addition, it has been revealed that by setting the vj dielectric electrode capacitance to 1/10@f degrees of the capacitance of the main discharge part, it does not affect the laser output and can function as a trigger. Ta. Furthermore, by using a dielectric as the trigger electrode, as shown in Figure 6, there was less decrease in output compared to a metal piece, and it was confirmed that gas deterioration and the life of the trigger electrode were extended.

In the above embodiment, both of the pair of dielectric electrodes Uη were connected to the same power source as the metal electrode, but as shown in FIG.
Even if one side is grounded, the same effects as in the above embodiment can be achieved.

〔Effect of the invention〕

As described above, according to this invention, since a pair of electrostatic poles are provided near the discharge part in the discharge tube, the discharge starting voltage can be lowered, and the main discharge force and trigger discharge force can be controlled. can be easily carried out, and furthermore, it has the extremely excellent effect of suppressing the deterioration of gas caused by the following electric current.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a cross-sectional view and a longitudinal sectional view showing the main parts of a silent discharge gas laser device according to an embodiment of the present invention, respectively, and FIG. 3 is a cross-sectional view showing the main parts of a silent discharge gas laser device according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view showing the applied voltage in a silent discharge gas laser device according to an embodiment of the present invention. FIG. 5 is a characteristic diagram comparing the laser output of a silent discharge type gas laser device according to an embodiment of the present invention with that of a conventional device;
FIG. 6 is a sectional view showing the main parts of a silent discharge gas laser device according to another embodiment of the present invention, FIG. 7 is a configuration diagram showing a conventional silent discharge gas laser device, and FIG. 8 is a conventional silent discharge gas laser device. FIG. 9 is a characteristic diagram showing the relationship between applied voltage and main discharge force in a gas laser device, and is a sectional view showing the main parts of an improved conventional silent discharge type gas laser device. In the figure, (1) is a discharge tube, and +21 (3) is a metal electrode. (4) is a power source, (5) is a discharge space, and (8) is a laser beam. (9) indicates the gas flow direction, (171 indicates the dielectric electrode. In the 2 figures, the same symbols indicate the same - or equivalent parts. (α) 1 figure +79 4: hidden s: fiNt, party jump' f Near 7" person 5 round square 1 turtle, /7b: fusuma body body Kangyoku 2nd section Figure 3 Figure 4 Figure 5yA Figure 6vA Figure S Figure '?

Claims (6)

[Claims] (1) A laser gas is caused to flow in the axial direction of a discharge tube made of a dielectric material with a plurality of metal electrodes arranged on the outer circumferential surface, and a high frequency voltage is applied between the electrodes to generate a silent discharge within the discharge tube. A silent discharge gas laser device that emits a laser beam in the axial direction of a discharge tube, characterized in that a pair of dielectric electrodes are provided near a discharge portion within the discharge tube. (2) The silent discharge type gas laser device according to claim 1, wherein the capacitance of the pair of dielectric electrodes is set to 1/10 or less of the capacitance of the discharge portion. (3) The silent discharge type gas laser device according to claim 1 or 2, characterized in that a pair of dielectric electrodes is provided on the gas flow upstream side of the discharge portion. (4) Claims 1 to 3, characterized in that a voltage is applied to the dielectric electrode from the same power source as the metal electrode.
The silent discharge gas laser device according to any one of paragraphs. (5) A silent discharge gas laser device according to any one of claims 1 to 4, characterized in that the pair of dielectric electrodes is provided outside the oscillation optical path of the laser beam. (6) Laser gas is 100m/sec in the axial direction of the discharge tube
A silent discharge type gas laser device according to any one of claims 1 to 5, characterized in that the laser beam is emitted at a high speed of at least 100%.