JPS6026310B2 - gas laser equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a high-power pumped silent discharge gas laser device.

First, a conventional gas laser device will be explained using a horizontally excited C02 gas as an example.

Figure 1 is a diagram showing the principle of its construction, where 1 is a grounded metal electrode, 2
is a high-voltage metal electrode that constitutes a discharge electrode together with a grounded metal electrode 1, and the discharge surface is covered with a dielectric 3.

4 is a discharge space, 5 is a transformer, 6 is a high frequency power supply, 7 is a total reflection mirror, 8 is an output side reflection mirror (partially transparent), 9 is a cooling water circulation pump, 101 is a water cooler, il is ion exchange pure water It is a vessel.

In the above configuration, when an AC high voltage is applied to the high voltage metal electrode 2 by the high frequency power source 6 and the transformer 5, a stable discharge called a silent discharge occurs in the discharge space 4.

This silent discharge is an alternating current discharge that occurs between the high voltage metal electrode 2 and the ground metal electrode 1 via the dielectric 3, so it does not transition to an arc discharge, and only the electron temperature is high and the molecular temperature does not increase. Balanced discharge can be achieved stably. Although a description of the photoinduced ejaculation process by excited molecules in the discharge space 4 will be omitted, when a silent discharge occurs in the discharge space 4, a resonator formed by the total reflection mirror 7 and the output side reflection mirror 8 Laser oscillation occurs inside, and laser light is emitted from the output side reflecting mirror 8. Both the ground metal electrode 1 and the high voltage metal electrode 2 are cooled with cooling water having low electrical conductivity, and the cooling water is appropriately circulated through a water cooler 10 and an ion exchange deionizer 11 by a cooling water circulation pump 9. The ion exchange deionizer 11 is necessary to reduce the electrical conductivity of the cooling water and prevent current leakage from the high voltage metal electrode 2. Although not shown in the figure, gas in the discharge space 4 flows at high speed between the ground metal electrode 1 and the high voltage metal electrode 2 in a direction perpendicular to the laser beam and parallel to the electrode surface. Therefore, the concentration of molecules excited by the discharge is also highest a little downstream of the gas flow from the electrode center, and the laser resonance space is also a little downstream from the gas center (see Figure 2
(within the dashed circle). 2A and 2B are enlarged views of the discharge electrodes. The discharge surfaces of both the ground metal electrode 1 and the high voltage metal electrode 2 are parallel plates, and discharge occurs almost uniformly between the two metal electrodes 1 and 2.

Here, the characteristics of silent discharge will be briefly explained.

The silent discharge is an alternating current discharge that occurs through the transfer body 3, and when the voltage in the discharge space 4 increases as the power supply voltage increases and reaches the discharge start voltage, discharge occurs. When a discharge occurs, charges are deposited on the surface of the dielectric 3, the voltage in the discharge space 4 decreases, and the discharge disappears. Due to the rise in power supply voltage, the discharge space 4
When the voltage reaches the discharge start voltage, a discharge occurs, and the discharge is repeated several times during a half cycle of the AC power supply. Further, in the next half cycle, the discharge with the opposite polarity is repeated in the same way, and the discharge starting voltage is approximately proportional to the interval between the discharge electrodes. Lateral excitation type C as a secondary gas laser device
Although the 02 laser has been described above, in such a laser,
In order to increase the output of the laser beam, it is possible to increase the discharge power input into the discharge space 4, but at that time, the mirror diameter of the resonator must also be increased so that the laser beam density on the mirror surface does not become too large, otherwise total reflection will occur. Mirror 7 and output side reflecting mirror 8 are damaged.

However, when the mirror diameter is increased, the optical path diameter of the discharge space 4 is also increased, and therefore the interval between the discharge electrodes is also increased. therefore,
The discharge starting voltage becomes high, causing problems with the insulation of power sources such as the high frequency power source 6. Further, as the power supply voltage increases, the dielectric strength of the dielectric 3 also becomes a problem, and the reliability of stable operation as a whole is significantly reduced. The present invention has been made in view of the above points, and an object of the present invention is to provide a gas laser device in which the power supply voltage can be lowered even when the optical path diameter is increased by improving the electrode structure.

An embodiment of the present invention will be described below with reference to the drawings.

Figures 3A and 3B show discharge electrodes. In this figure, 21・
, 212 are two high voltage metal electrodes cooled by cooling water, each covered with a dielectric material 22, 222 . Further, high voltage is equally applied to the two high voltage metal electrodes 21, 212. A grounded metal electrode 23 is located between the two high voltage metal electrodes 21, 212 and on the upstream side of the gas flow, is cooled with cooling water, and has a circular cross section.

In the discharge electrode configured as described above, high voltage is equally applied to the high voltage metal electrodes 21, 212, so that symmetrical discharge spaces 24, 242 with the ground metal electrode 23 are formed.

Furthermore, since the high voltage metal electrodes 21, 212 are covered with dielectrics 22, 222, respectively, the discharge spaces 24, 212 are covered with dielectrics 22, 222, respectively.
242 is uniformly distributed on the high voltage side, and does not become a concentrated discharge like an arc discharge, but maintains a discharge that is convenient for excitation of the gas dielectric. And discharge space 24,
The excited molecules generated in can be caused. Further, in the discharge electrode, the discharge starting voltage is between the ground metal electrode 23 and the high voltage metal electrode 21.
, 212 is the discharge starting voltage for each electrode spacing. Therefore, the firing voltage in this case is approximately 1/2 of the firing voltage corresponding to the apparent discharge space interval (the interval between the high voltage metal electrodes 21 and 212). Therefore, according to such a gas laser device, it is possible to create a silent discharge space where the discharge starting voltage is substantially halved, so even if the optical path diameter is increased, the power supply voltage can be lowered, and the laser resonance with a large optical path diameter can be achieved. The practical effects are significant in realizing this.

Note that the ground metal electrode 23 should not significantly disturb the gas flow and discharge should not be excessively concentrated on the ground metal electrode 23 side, and for simplicity, a circular cross-section is adopted, but elliptical, rectangular, A plate-shaped one is also acceptable.

Furthermore, the effects of the present invention can be better exhibited if the discharge on the ground metal electrode 23 side is also more uniformly dispersed.

Therefore, the entire circumference of the ground metal electrode 23 may be thinly covered with the exposed body. As detailed above, according to the present invention, it is possible to provide a gas laser equipment having very great effects.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of construction of a horizontally pumped C02 laser as a conventional gas laser device, Fig. 2 is an enlarged view of the discharge electrode of the laser, A is a longitudinal sectional view, B is a transverse sectional view, and Fig. 2 is an enlarged view of the discharge electrode of the laser. The figures are diagrams for explaining one embodiment of the gas laser device according to the invention, in which A is a longitudinal cross-sectional view and B is a cross-sectional view. 21,,212...High voltage metal electrode, 22,,
222...Dielectric, 23...Grounded metal electrode, 24, 242...Discharge space. Note that the same reference numerals in the figures indicate the same or corresponding parts. 1st
Figure 2 Figure 3

Claims (1)

[Claims] 1. A horizontally excited silent discharge gas laser device, which has two electrodes covered with a dielectric material and having the same potential, and a metal electrode placed between them, and a high voltage is applied between the two electrodes. A gas laser device characterized in that a discharge portion is formed by applying a . 2. The gas laser device according to claim 1, wherein the metal electrode placed in the middle is covered with a dielectric material.