Gas laser device

Details Gas laser device Gas laser device

1980-02-06

1982-05-25

Miller, Jr., Stanley D.

Coherent light generators

Particular resonant cavity

372 61, 372 98, H01S 308

Patent

active

043319394

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a gas laser device in which the structure of an electrode on the upper stream side of a gas flow is improved.


BACKGROUND ART

In general, a gas laser device is such that gas molecules are excited by causing the glow discharge in a tube which is filled with a gas, that a beam which repeats reflections between a pair of reflectors disposed as resonators at both the end parts of the tube is amplified by the stimulated emission action so as to reach oscillation, and that the oscillation output is derived from one of the reflectors. As the gas to be contained in the discharge tube, there is employed helium (He), neon (Ne), carbon dioxide (CO.sub.2), nitrogen (N.sub.2), argon (Ar), or the like. In order to electrically excite the gas molecules, the discharge tube is provided with an anode and a cathode along the tube, and they are connected to an appropriate power supply. As described in, for example, Japanese Patent Application Publication No. 46-20465, in an axial flow type laser device, the axis of a gas flow and the axis of a laser beam within the discharge tube are coincident, and hence, the anode and the cathode are in the shape of a cylinder or a disc having a gas circulating hole in its central part. The gas which is fed from a gas pressure feed device such as blower and pump flows into the discharge tube and flows out of the discharge tube by passing through a gas passage in the central parts of the cylindrical or disc-shaped anode and cathode. While the gas flows across both the electrodes, the discharge is performed and the glow is formed. When, owing to the flow discharge, the gas molecules have been raised to a specified energy level at a sufficiently high rate and have reached an inverted population state, the laser beam is generated.
In case of using the electrodes in this kind of shape, the glow generated across the anode and the cathode is pushed against the inner wall surface of the discharge tube by the gas stream flowing at high speed, and a space in which the glow is not formed appears immediately downstream of the gas circulating hole of the electrode on the upper stream side within the discharge tube. This space occupies 20-30% of the volume of the whole glow discharge portion. For this reason, the laser beam taken out has a concave intensity profile in which the intensity is low in the central part of the discharge tube and high in the peripheral part thereof, and it does not become the Gaussian distribution which is deemed a desirable intensity profile. Accordingly, there is the disadvantage that a laser output of high power and high efficiency is difficult to obtain. As the speed of the gas flow is higher, the glow discharge becomes more stable and the laser output becomes higher. This makes it a trend to set the gas flow speed of the axial flow type laser device at a large value, and the speed mounts up to 200-300 m/sec. In consequence, the disadvantage as above stated is aggravated.


DISCLOSURE OF THE INVENTION

An object of this invention is to provide a gas laser device which exhibits a high laser generation efficiency.
A feature of this invention consists in that, on the outer peripheral side of a gas circulating hole for discharge provided in the central part of an upper gas stream side electrode, a plurality of gas circulating apertures are further provided, a glow discharge portion within a discharge tube being fined towards the center in the radial direction of the tube by a gas passing through the gas circulating apertures on the outer peripheral side.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an axial flow type gas laser device to which this invention is applied.
FIG. 2 is a sectional view showing the outline of the fundamental structure of the gas laser device shown in FIG. 1.
FIG. 3 is a sectional view showing a state in which the glow discharge is being performed in the interior of a discharge tube between an anode and a cathode.
FIG. 4 is a sectional view along IV--IV of the cathode shown in FIG

REFERENCES:
patent: 4287487 (1981-09-01), Kuwabara et al.

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