JPH03198390A - Gas laser oscillator - Google Patents

Abstract

PURPOSE:To make possible a high-repeat laser oscillation by a method wherein the title device is provided with a duct, by which the flow of a laser medium is made to intersect obliquely to the direction of main discharge toward the side of a cathode and the repeat period of discharge is shortented. CONSTITUTION:In the conventional case where a flow A of a laser medium and a direction B of main discharge intersect orthogonally each other, it is assumed that a sputtered substance 5 produced at the time of the main discharge reaches a point S apart by a distance X1 in the direction of the flow A from a point P1 to correspond to the top part of a cathode 12 at a point of time of the generation of the following main discharge by the flow A. In this case, a flow C is going toward the side of the cathode 12 at an angle theta to the flow A. Therefore, if it is assumed that the flow velocity of the flow C is identical with that of the flow A, the position of the substance 5 is shifted on the side of the cathode 12, but the substance 5 is moved to a point T which is positioned in the form of a circular arc with the point P1 as its center. That is, the distance between the point P1 and the point T is X1 and assuming that arc discharge centers around the center P2 in the main discharge space of a main discharge axis B, the distance between the center P2 and the point S is R1 and the distance between the center P2 and the point T is R2. As the distance R1 is shorter than the distance R2, the discharge on the path of the distance R2 is hardly generated more than that on the path of the distance R1 and the repeat period of discharge is shortened.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a horizontally pumped gas laser oscillation device.

(Prior Art) TEACO2 lasers and excimer lasers are known as horizontally pumped lasers. Conventionally, in this type of laser oscillator,
As shown in Fig. 3, the flow (A) in the discharge section of the gas laser medium circulating within the laser tube is the main flow of the main discharge electrode, which consists of a cathode (1) and an anode (2) provided opposite thereto. It is perpendicular to the discharge axis (B).

(Problem to be solved by the invention) When the discharge begins, the IEICE journal C7VOL,
J 71-C, No 12. P11183. −
As introduced in 88°12, on the so-called downstream side of the flow (A) exiting from the discharge section, there is an arc-shaped arc discharge (different from the main discharge (3) that becomes a glow discharge state).
4) occurs between the cathode (1) and the anode (2). This is because the discharge product flow (A) generated from the cathode (1) side by the main discharge (8) is flowed downstream, and conductive materials such as metal sputtered matter (5) contained in the discharge product are It is thought that this is due to the presence of substances with high levels of oxidation. In order to reduce the occurrence of the arc discharge (4), it is necessary to move the metal sputtered material (5) as far downstream as possible, increase the arc radius of the arc discharge, and increase the electrical insulation distance. To achieve this, the blower that circulates the gas laser medium must have a high output and be large enough to rotate at high speed.However, if the blower becomes large, the laser oscillation device itself must also become large, and vibrations caused by high-speed rotation must be made. There was a problem that laser oscillation became unstable due to the influence of Therefore, it has been difficult to obtain high-repetition laser oscillation because the blower cannot be made unnecessarily large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas laser oscillation device that suppresses the occurrence of arc discharge caused by sputtered metal materials without increasing the size of the device.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to solve the above problems, the present invention solves the above problems by reducing the main power generated between the optical resonance direction and the main discharge electrodes provided with the cathode and the anode facing each other. A horizontally excited type gas laser oscillation device that forms gas flows that intersect with the discharge direction, including an oblique means that directs the gas flow toward the cathode side and obliquely intersects with the main discharge direction, The discharge products move away from the center of the main discharge to locations where arc discharge is unlikely to occur.

(Example) Hereinafter, the present invention will be explained based on drawings showing examples. That is, in FIG. 1, there is provided a laser tube (11) in which a gas laser medium is sealed at a predetermined pressure, and a discharge means and a gas laser medium circulation means are provided inside. The discharge means includes a cathode (12) serving as a main discharge electrode and an anode (1
3) are supported in an electrically conductive state by the support plates (14a) and (14b), and the support plate (14a) is connected to the high voltage side and the ground side of the power source (15) that supplies high voltage and large current pulses, respectively. ) and (14b). Support plate (1) on the cathode (12) side
4a) is a peaking capacitor (
The upper pin electrode (17) connected to the main discharge space (
18) are provided at a predetermined pitch on both sides of the cathode (12) along the optical axis. Further, lower pin electrodes (19) are provided on the support plate (14b) to face each of the upper pin electrodes (17), and these upper and lower pin electrodes are used to pre-circulate the main discharge space (18). l! It constitutes a pre-ionization electrode that separates the ions. On the other hand, gas laser medium circulation is carried out by a fan (20) that circulates within the laser tube (11) and supplies it to the main discharge space (18), and a heat exchanger (21) provided on the upstream side of the flow of the gas laser medium. , and a filter (22) which is also provided on the downstream side and which adsorbs discharge products. By the way, on the upstream side, the heat exchanger (2
1) and one pre-ionization electrode, a duct (25) is provided as an oblique means for directing the gas flow toward the cathode and obliquely intersecting the main discharge direction. The blowing angle of this duct (25) is directed towards the cathode (12),
The flow of the blown gas laser medium (C) is along the main discharge axis (B
) is set at an obtuse angle.

Next, the operation of the above structure will be explained with reference to FIG. 2, which shows an enlarged view of the main discharge section in FIG. 1. That is, in the conventional case where the flow (^) of the gas laser medium and the main discharge direction (B) are perpendicular to each other, the sputtered matter (5) generated during the main discharge is deposited on the top of the cathode (12) by the flow (A). At the time when the next main discharge occurs from the corresponding point (pi),
(S) separated by a distance (xl) in the flow (^) direction
Assuming that the point is reached, in the configuration of the present invention, the flow (C)
is toward the cathode (12) at an angle θ with respect to the flow (A), so if the flow velocity is the same as the flow (A), the position will shift toward the cathode (12), but the point (Pl) Move to point (T) located in an arc with . That is, the point (
The distance between point PI) and point (T) is (xi). The arc discharge occurs at the midpoint (p) of the main discharge axis (B) in the main discharge space.
2), the distance to point (S) is (R1), and the distance to point (T) is (R2).

Here, if the flow velocity of flow (A) (flow (B)) is V and the oscillation frequency is f, then distance (Xl) - V・1 /' f
is required.

Also, X2−xLψ cos θ・・・・・・・・・・・・
......(1) Y2-Yl+Xls in
θ・・・・・・・・・・・・・・・(2) R2−(X2
) 2 + (Y2) 2 ・・・・・・・・・(4
)(1) to (4), (R2) ” −(R1) ” −(X2)2 + (Y2)2− (Xi)2− (
Yl)2=(XI)2cos 2θ+(Yl)2
+ 2 (Xi) (Yl) sin θ+(XI)2s
in' θ(Xi) 2- (Yl)
2 = (Xi)2 (cos 2 θ+sin 2
θ)+(Yl)2+ 2 (XI)(Yl)s i
n θ-(XI)2-(Yl)2 , ::, 4
', CO52θ+5in2θ-1, so -2(XI)(Yl)s in θ> 0---
------- (5) From the above equation (5), the radius of the arc of the arc discharge was increased by changing the direction of the flow velocity.

[Effects of the Invention] As detailed above, since distance (R1) < distance (R2), arc discharge (4b) is outside of arc discharge (4a), and is less likely to occur compared to arc discharge (4a). As a result, the discharge repetition period can be shortened and high-repetition laser oscillation can be achieved without increasing the size of the blower that circulates the gas laser medium, compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged view showing the discharge action in the main discharge space, and FIG. 3 is a sectional view showing a conventional example. (11)・ Fist laser tube (12)... Cathode (13)... Anode (25)... Duct (oblique means)

Claims (1)

[Claims] In a horizontally pumped gas laser oscillation device that forms gas flows that intersect the optical resonance direction and the main discharge direction generated between main discharge electrodes with a cathode and an anode facing each other,
A gas laser oscillation device comprising oblique means for directing the gas flow toward the cathode and obliquely intersecting the main discharge direction.