JPH03230587A - Waveguide type gas laser oscillator - Google Patents

Abstract

PURPOSE:To obtain a comparatively high output laser without generating an abnormal nonuniformity in an exciting intensity by providing a discharge thin tube portion with a plurality of projections formed on the inner wall of the thin tube portion and directed toward the axis of the thin tube portion. CONSTITUTION:A plurality projections 21 are integrally formed on the inner wall surface of a laser tube 20 made of a dielectric with equal angles toward the axis of the laser tube 20 and in radial directions. The inside of the laser tube 20 wherein the projections 21 are formed constitutes a discharge thin tube path 22. The area of the inner wall surface of the discharge thin tube path 22 increases and a discharge portion with an increased discharge section corresponding to the longest distances between the tips of the projections 21 and the inner wall surface is formed by forming such a plurality of the projections 21. Thus, a comparatively uniform laser intensity can be obtained and a laser output can be increased.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a waveguide type gas laser oscillator.

(Prior Art) Taking an excimer laser as an example, the prior art will be explained with reference to FIG. (1) is a laser tube filled with excimer gas, and an output mirror (2) is attached to one end and a high reflection mirror (3) is airtightly attached to the other end, and these mirrors constitute an optical resonator. ing.

The laser tube (1) is a vacuum pump (3) that creates a high vacuum inside.
And it is connected to a gas supply source (4) that supplies excimer gas after the high vacuum. (5) and (6) are discharge electrodes with an arcuate cross section provided on the outside of the laser tube (1), (7) is a high frequency power source, and (8) is a trigger circuit that is powered by the high frequency power source (6). It is connected to the discharge circuit via a capacitor (9). The laser tube (1) is made of a dielectric material such as quartz or ceramics, and has a narrow discharge tube path (10) formed therein.

(Problem to be Solved by the Invention) When excited by high-frequency discharge, a high excitation density is achieved only near the tube wall of the discharge capillary (10), and the excitation density decreases as the distance from the tube wall increases, achieving laser oscillation. It will no longer be done. For example, when the tube diameter of the discharge capillary path (10) is made relatively large, the maximum value of the excitation intensity distribution occurs at point D, which is slightly away from the tube wall, as shown in FIG. Therefore, as shown in FIG. 6, the laser output distribution becomes a so-called donut-shaped distribution (15) with high power at the periphery and low power at the center.

Therefore, the narrow discharge tube (lO) is limited to a small diameter, and the effective discharge volume is small, and only a relatively low output laser can be obtained. Furthermore, if the human energy is intentionally increased in an attempt to increase the output, the excitation intensity near the tube wall becomes abnormally strong, which causes the stability of the discharge to be lost and, in extreme cases, the oscillation to stop.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a laser oscillation device that can generate a relatively high output laser without causing abnormal non-uniformity in the excitation intensity within the discharge capillary (10).

[Structure of the Invention] (Means and Effects for Solving the Problems) In a waveguide type gas laser oscillator that oscillates a laser by applying a high frequency voltage to a discharge capillary portion formed of a dielectric material and having both ends as optical resonators, the above-described method is provided. The discharge capillary section has a plurality of protrusions formed on its inner wall toward the center of the tube, making it difficult for energy to concentrate within the discharge capillary path (10).

(Example) EMBODIMENT OF THE INVENTION Hereinafter, this invention will be explained based on drawing which shows an Example.

FIG. 1 shows an embodiment of the present invention, showing a cross section of a laser tube (20). That is, a plurality of protrusions (21) extend along the radial direction and at equal angles toward the axial center line of the laser tube (20) made of a dielectric material on the inner wall portion. It is integrally formed. The inside of the laser tube (20) in which these protrusions (21) are formed is a narrow discharge tube path (22). Furthermore, grooves (23) are formed on the outer side of the laser tube (20) in portions corresponding to the protrusions (21) and extending in the direction of the axis center line. A segmented cathode (24a) branched from the cathode body (24) and a segmented anode (25a) branched from the anode body (25) are symmetrically inserted into these grooves (23).

Next, the operation of the above configuration will be explained. By forming a plurality of protrusions (21), the area of the inner wall surface of the discharge narrow channel (22) increases, and the discharge for the longest distance (r) from the tip of the protrusion (21) to the inner wall surface increases. A discharge portion with an increased cross-sectional area is formed. In addition, in the protrusion (21), discharge occurs at multiple locations between the cathode (24a) and the anode (25a), so as shown in Fig. Provides strength.

Please note that the laser tube (2
0) may have a configuration in which discharge electrodes are provided at both ends. In this case, since preliminary ionization is performed by "exo electrons" emitted from the tube wall, a large effective discharge cross section can be obtained.

E Effects of the Invention] From the excitation intensity results shown in FIG. 2, a relatively flat laser intensity as shown in FIG. 3 was obtained, and the laser output could be increased.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the tube diameter and excitation intensity in the present invention, FIG. 3 is also a distribution diagram of energy intensity, and FIG. 4 is a conventional diagram. A sectional view showing an example, FIG. 5 is a diagram showing the relationship between the tube diameter and excitation intensity in the conventional example, and FIG. 6 is a distribution diagram of energy intensity. (1) ・Laser tube (2)...Protruding body! Flash and R-Mui) No trouble

Claims (1)

[Claims] In a waveguide type gas laser oscillator that applies a high frequency voltage to a discharge capillary section formed of a dielectric material and whose ends become optical resonators to oscillate a laser, the discharge capillary section is formed on its inner wall toward the center of the tube. A waveguide type gas laser oscillator characterized by having a plurality of protruding bodies.