JPS62189777A - Gas laser oscillator - Google Patents

Abstract

PURPOSE:To obtain a constant oscillation mode regardless of the magnitude of laser output by a method wherein divided cathodes are arranged along the light axis direction of an optical resonator and each electrode is bent to the direction parallel to the light axis and opposite to the direction of a laser beam to have an L-shape. CONSTITUTION:A discharge exciting part 1, a heat exchanger 10 and a blower 11 are arranged in a laser duct 9 so as to circulate laser medium gas. L-shape pin type divided cathodes 2 and a plate-shape anode 3 are provided in the discharge exciting part 1 so as to face each other. Optical resonators 5a and 5b are arranged and fixed to both sides of the discharge exciting part 1. A sharp angled part 14 provided at the tip of each L-shape electrode 13 of each divided cathode 2 are oriented to the direction parallel to the light axis 8 of the optical resonators 5a and 5b and each L-shape electrode, i.e. negative glow ignition part 13 is arrange in parallel to the anode 3 and in parallel to the light axis and the laser output 8 of the optical resonators 5a and 5a and 5b. the shape of the negative glow ignition part 13 on each divided cathode has the diameter and the length sufficient to maintain the negative glow area necessary for the maximum discharge input.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a cross-flow gas laser oscillator in which the directional forces of a laser optical axis, a discharge, and a gas flow are perpendicular to each other. The present invention relates to a gas laser oscillator that can obtain a constant oscillation mode regardless of the magnitude of output.

(Prior art) Generally speaking, in a high-output cross-flow gas laser oscillator,
A blower circulates and excites the laser medium gas at high speed through a discharge excitation section consisting of a cathode and an anode.

Laser output is extracted by an optical resonator having an optical axis perpendicular to the gas flow direction of the laser medium gas. FIG. 3 shows an example of a discharge excitation part of this type of cross-flow type gas laser oscillator in which the discharge direction is orthogonal to the gas flow direction and the optical axis direction (for example, the system shown in Japanese Patent Publication No. 56-44595). Shown below. As shown in FIG. 3, the discharge excitation section ↓ consists of a pin-shaped cathode 2 divided into a plurality of parts, an integrally shaped anode 3 disposed opposite to the cathode 2, and a gas flow 4 of the laser medium gas circulating between the electrodes. It is composed of optical resonators 5a and 5b having optical axes perpendicular to the direction. Further, each divided cathode 2 is connected to a power source (not shown) via a discharge stabilizing resistor 6. It is used as a laser medium gas at a certain pressure. Further, the velocity of the gas flow 4 of the laser medium gas circulating above the discharge excitation part is about several tens of m/8 to 100 m/. During operation, a high voltage of several thousand volts or more is applied from the power supply between the cathode 2 and anode 3 to generate glow discharge 7, and the laser medium gas is excited by this discharge energy. At this time, laser oscillation occurs due to the action of the optical resonators 5a and 5b, and a laser output 8 is obtained in a direction perpendicular to the gas flow direction and discharge direction of the laser medium gas. In other words, these directions are perpendicular to the three axes.

(Problems to be Solved by the Invention) In the conventional galvanometric gas laser oscillator shown in FIG. By varying the discharge power, the ignition range of the glow discharge 7 increases or decreases primarily in the direction of the gas flow 4 of the laser medium. At this time, the direction perpendicular to the four gas flow directions of the laser medium, that is, the optical resonators 5a and 5b
In the direction parallel to the optical axis 8, the ignition range of the glow discharge 7 does not change much. Generally, the optical axis 8 of the optical resonators 5a, 5b is the one where the laser output is maximum and the spatial intensity distribution is symmetrical. Its location has been determined to be in good condition.

As shown in FIG. 4, when the peak position of the ignition range of glow discharge changes mainly in the gas flow direction 4 of the laser medium gas with the discharge power, the optimum optical axis position 8 of the optical resonators 5a and 5b is determined. Also changes mainly in the gas flow direction of the laser medium gas. However, the optical resonator 5a shown in FIG.
Since the optical resonators 5b are fixedly arranged on both sides of the discharge excitation section, the optical axes of the optical resonators 5a and 5b are at fixed positions. For this reason, a problem has arisen in that the relay laser oscillation efficiency, in which the laser oscillation mode changes from the vicinity of the laser output O to the maximum laser output range, decreases. In particular, during so-called pulse operation in which the discharge power is changed over time to obtain a pulsed laser output, the above-mentioned problem occurs during one pulse period.

There was a problem with the stability of the oscillation mode of the laser output.

Furthermore, when the laser oscillation mode changes, the optical resonator, 5a
, 5b changes, the laser beam may deviate from a predetermined direction and the stability of the optical resonators 5a, 5b may deteriorate.

Therefore, the present invention does not depend on the magnitude of the laser output.

The purpose of this invention is to provide a galvanometric gas laser oscillator that can oscillate in a stable mode.

[Structure of the invention]

(Means for solving the problem) In order to achieve the above object, the present invention provides an optical resonator 5a,
5b The cathode 2 divided in the optical axis direction is provided with a negative glow ignition part made of an L-shaped electrode bent parallel to the optical axis 8 and in a direction opposite to the laser beam direction.

(Function) By configuring the discharge excitation section as described above, the direction of change in the discharge excitation range that changes with discharge power can be made parallel to the optical axis direction of the tip shaker.

Even when the emitted flfr1 force is changed, the discharge excitation distribution in the direction perpendicular to the optical axis of the light valve oscillator does not change, so the laser oscillation mode remains constant regardless of the magnitude of the laser output.

〔Example〕

(Configuration of Example) The present invention will be explained below using an example shown in the drawings.

FIG. 1 is a perspective view showing a schematic configuration of a cross-flow type gas laser oscillator, which is an embodiment of the present invention. In the laser wind tunnel 9, a discharge excitation section, a heat exchanger 10, and a blower 11 are arranged so that the laser medium gas is circulated. Inside the discharge excitation section, an L-shaped bottle-shaped divided cathode 2 and a plate-shaped anode 3 are arranged facing each other, and each divided cathode 2 is connected to a power source (not shown) via a discharge stabilizing resistor 6. are connected to each other. The optical resonators 5 and 5b are fixedly arranged on both sides of the radiator 1i@Oibe Kei. To explain the discharge excitation part in detail using FIG. 2, the cathode 2 is a pin-shaped cathode with a diameter of several meters, made of molybdenum with excellent heat resistance and sputtering resistance.
It is made of a material such as tungsten and is attached to an insulating plate 12. Further, the acute angle portion 14 provided at the end of the L-shaped electrode 13 of the cathode 2 is oriented in a direction parallel to the optical axis 8 of the optical resonators 5a, 5b. The L-shaped electrode part or negative glow ignition part 13 is arranged parallel to the anode 3 and parallel to the optical axes of the optical resonators 5a, 5b and the laser output 8.

The shape of the negative glow ignition part 13 on the cathode is set to a diameter and length that can ensure the necessary negative glow area at the time of maximum discharge input. The negative glow area is a function of the discharge current value, but even at the same current value it changes depending on the gas component and gas pressure.

Since the cathode shape is affected by gas flow rate, etc., various discharge parameter conditions are taken into consideration when determining the cathode shape.

(Operation of the embodiment) Next, the operation of the structure of the embodiment shown in FIGS. 1 and 2 will be described.

A typical laser oscillation operation is shown in FIG. 3, which is a conventional example. Also, 7) 2Iii1 like 1, cathode 2゜19 pole, 4 U number 1
A high voltage of 000V or more is applied to generate glow discharge 7, and the laser medium gas is excited by this discharge energy. At this time, laser oscillation occurs due to the action of the optical resonators 5a and 5b, and a laser output 8 is obtained in a direction perpendicular to the gas flow direction and discharge direction of the laser medium gas. In addition, the laser medium gas is cooled by the heat exchanger 10 and further circulated at high speed by the action of the blower 11, so that the glow discharge 7
The gas temperature rise between the cathode 2 and anode 3 due to the discharge energy is suppressed to about 100° C., and laser oscillation is performed efficiently.

In this embodiment, when a high voltage is applied between the cathode 2 and the anode 3, each divided cathode 2
A glow discharge 7 occurs each time. At discharge power around the laser oscillation threshold, the discharge current value per cathode is small. Therefore, the negative glow area for supplying charged particles to the glow discharge section is small and ignition occurs only on a portion of the negative glow ignition section 13 shown in FIG. 2. In FIG. 2, the unsupported side end 14 of each cathode 2 is machined to have an acute angle in one place, so that the electric field strength at this part is greater than that on the other cathodes, and a negative glow is ignited only at the cathode tip. However, if a plurality of locations are formed with acute angles, the stability of the negative glow decreases. As shown in FIG. 1, the glow discharge area has a shape that expands in the downstream direction of the gas flow due to the action of the gas flow 4. At the time of maximum laser output oscillation, the discharge power is increased and the discharge current value per cathode is also large (b4), so the negative glow area on the cathode 2 is also large. In this case, the negative glow ignition range 13 shown in FIG. A negative glow ignites over the entire surface. The glow discharge area has a shape that expands in the downstream direction of the gas flow due to the action of the gas flow 4, but as shown in FIG. Since the upper part increases in the direction parallel to the optical axis 8, the discharge density in the direction parallel to the optical axis 8 increases.

The discharge distribution in the direction perpendicular to the optical axis 8, that is, the discharge distribution of the gas flow 4, does not change. Therefore, the discharge excitation distribution in the direction perpendicular to the optical axis 8 of the optical resonators 5a, 5b does not change. In this embodiment, the cathode 2
Because the area is divided and arranged, the negative glow area follows the temporal changes in the current value well, and the development described above can be observed even during pulse operation where the discharge power changes rapidly over time. There is.

〔Effect of the invention〕

As described above, in the present invention, when the discharge power is changed, the ignition range of the glow discharge changes in a direction parallel to the optical axis of the optical resonator. The spatial gain distribution of the laser oscillation is constant, and a constant oscillation mode can be obtained regardless of the magnitude of the laser output. Furthermore, it is possible to provide a cross-flow type gas laser oscillator that has a good oscillation mode during pulse operation.

3 is a perspective view of the main part of the conventional device, FIG. 4 is an enlarged explanatory view of the cathode part of FIG. 3, and FIG. 5 is an enlarged explanatory view of the cathode part of FIG. 1.

1: Discharge excitation part, 2: Cathode, 3: Anode, 4: Gas flow, 5a, 5b: Optical resonator, 6: Discharge stabilizing resistor, 7: Glow discharge,
8: Laser output.

13: Negative glow ignition part, 14: Acute angle part.

Agent: Patent Attorney Noriyuki Chika Same as Hirofumi Mitsumata Figure 1 Figure 2 Figure 3 4th tl￥I Figure 5

Claims (3)

[Claims] (1) In a cross-flow gas laser excavator in which an electrode array consisting of an anode and a plurality of cathodes is arranged parallel to the laser optical axis, and gas is caused to flow between the anode and the cathode in a direction perpendicular thereto, the cathode The gas laser oscillator is characterized in that it includes a negative glow ignition part parallel to the laser optical axis. (2) The gas laser oscillator according to claim 1, wherein the negative glow ignition part is an L-shaped electrode bent in a direction opposite to the direction of the laser beam. (3) The gas laser excavator according to claim 2, wherein the tip of the L-shaped electrode is formed at an acute angle with an internal angle of 90 degrees or less.