JPS6232676A - Gas laser apparatus - Google Patents

Abstract

PURPOSE:To obtain a stable laser output, by setting the magnetic field intensity of a magnetic field generator, which is provided at the outer surface of the thin discharge tube part of a laser tube,at a value higher than the saturating point of the laser output. CONSTITUTION:When a magnetic field is imparted to a thin discharge tube part 3 from a permanent magnet 8, cycrotron movement owing to an electronic field and the magnetic field are generated in the thin discharge tube part 3. Electrons in a gas laser medium collide with neutral gas particles and are drifted to the wall of the tube. Thus the movement of the electrons in the axial direction of the tube is decreased. Therefore, the electron temperature in the electric field in the axial direction of the tube, i.e., within the tube, is increased. The loss in energy within the tube is increased, however, the laser output is increased more than that. The laser output is rapidly increased when the magnetic flux density exceeds 400 Gauss. The output is saturated at about 800 Gauss. Therefore the magnetic field intensity of the permanent magnet 8, which is attached to the outer surface of the thin discharge tube 3, is set at a value higher than 800 Gauss, e.g., at 860 Gauss or more. Then the laser output is not fluctuated even if the magnetic intensity is changed with the temperature of the permanent magnet 8. Thus the output is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas laser device that increases output by applying a magnetic field.

(Technical Foreword of the Invention and Problems thereof) Generally, in a gas laser device having a laser tube in which a gaseous laser medium is sealed, a magnetic field generating device is provided on the outer periphery of the laser tube, and the magnetic field generated from this device is transmitted to the gas laser device. It has been attempted to increase the laser output by adding

By the way, since the gas laser device is an ion laser, its oscillation efficiency is low, so a large power input is required, and the heat generation in the discharge capillary portion becomes extremely large.

Therefore, although the gas laser device is cooled by air cooling or water cooling, it is difficult to keep the temperature of the discharge I tube portion constant. Therefore, since the temperature of the magnetic field generator attached to the outer periphery of the laser tube is not maintained constant, the magnetic field strength of the magnetic field generator changes, causing a problem in that the laser output fluctuates.

[Purpose of the invention]

An object of the present invention is to provide a gas laser device in which the laser output does not fluctuate even if the magnetic field strength of the magnetic field generator changes with temperature.

[Summary of the invention]

This invention prevents the laser output from being affected by changes in the magnetic field strength by setting the magnetic field strength of the magnetic field generator directly above the saturation point of the laser output in the relationship between the laser output and the magnetic field strength. This is what I did.

[Embodiments of the invention]

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

The gas laser device shown in FIG. 1 includes a laser tube 1 made of, for example, a ceramic material and having a sealed structure in which a gaseous laser medium such as argon, krypton, or the like is hermetically sealed. Brewster windows 2 are installed at both ends of the laser tube 1, respectively. Further, the axially central portion of the laser IR1 is configured as a discharge mesh tube portion 3 that is thicker and has a smaller inner diameter than other portions. A first large-diameter tube section 4 is provided at one end of the discharge thin tube section 3, and a second large-diameter tube section 5 is provided at the other end.

The first large-diameter tube section 4 is provided with a cathode 6, and the second large-diameter tube section 5 is provided with one pole 7, which are connected to a discharge N source (not shown).

In addition, on the outer periphery of the discharge capillary section 3, a pair or a unit curved so that both ends thereof face each other as shown in FIG. A permanent magnet 8 as a shaped magnetic field generating device is disposed such that the discharge capillary tube portion 3 is located between the two ends, or, in the case of the pair, between opposite opposite poles. The permanent magnet 8 and the discharge capillary section 3 are forcibly cooled by an air cooling device (not shown). In this embodiment, the magnetic field is applied perpendicularly to the plane of the Brewster window 2 forming the Brewster angle.

In the above configuration, the permanent magnet 8 causes the discharge capillary 81!
When a magnetic field is applied to the discharge tube 3, cycloton motion occurs within the discharge capillary section 3 due to the electric and magnetic fields. As a result, electrons in the gaseous laser medium are lifted toward the tube wall while colliding with neutral gas particles, and electron movement in the tube axis direction is reduced. Therefore, the electric field in the tube axis direction, that is, the electron temperature inside the tube increases, and the energy loss inside the tube increases, but the laser output increases even more.

By the way, FIG. 3 shows how the laser output changes when the magnetic field strength is changed in an argon gas laser. This shows the flow as a parameter.

As can be seen from this figure, the laser output increases rapidly when the magnetic flux density exceeds 400 Gauss, and reaches a saturation state at about 800 Gauss. And even if the magnetic field strength is increased to 800 Gauss or more,
Experiments have revealed that the laser output is almost constant and its dependence is extremely small. For example, if the permanent magnet 8 is a rare earth cobalt magnet and a temperature rise of 2000° C. is expected, the amount of change in magnetic flux will be about 60 Gauss.

Therefore, if the magnetic field strength of the permanent magnet 8 attached to the outer periphery of the discharge capillary section 3 is set to 800 Gauss or more, for example, 860 Gauss or more, even if the magnetic field strength changes with the temperature of the permanent magnet 8, the As long as the magnetic field strength does not drop below 800 Gauss, the laser output will not fluctuate and the output can be stabilized.

Furthermore, at the output saturation point in FIG. 3, the laser output is about 3 to 4 times greater than when there is no magnetic field.

In this case, the oscillation efficiency is 2
It can be calculated to be about 3 times as much. Therefore, by setting the magnetic flux density to about 800 Gauss in a steady state of operation, the performance of the gas laser device can be significantly improved. In other words, by attaching the permanent magnet 8 to the discharge capillary section 3, the discharge input to obtain the same laser output can be reduced to about one-third. This not only makes it possible to downsize the device and extend its lifespan, but also to save power.

In the above embodiment, a permanent magnet is used as the magnetic field generating device, but an electromagnet may be used instead.

〔Effect of the invention〕

As described above, in the present invention, the magnetic field strength of the magnetic field generator provided on the outer periphery of the discharge capillary portion of the laser tube is set to a value equal to or higher than the saturation point of the laser output in the relationship between the laser output and the magnetic field strength. Therefore, even if the En magnetic field strength changes with the temperature of the magnetic field generator, the laser output will not fluctuate as long as the magnetic field strength does not fall below the saturation point of the laser output. In other words, it has a practically useful advantage of being able to obtain stable laser output.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and Fig. 1 is a cross-sectional view of the entire device, Fig. 2 is a cross-sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 shows the relationship between laser output and magnetic flux density. FIG. 1... Laser tube, 3... Discharge capillary section, 8... Permanent magnet (magnetic field generator) 5

Claims (3)

[Claims] (1) In a gas laser device in which a magnetic field generator is provided on the outer periphery of the discharge capillary portion of a laser tube in which a gaseous laser medium is sealed, the magnetic field strength of the magnetic field generator is determined by the relationship between the laser output and the magnetic field strength. A gas laser device characterized in that the laser output is set to a value equal to or higher than the saturation point. (2) The gas laser device according to claim 1, wherein the magnetic field generating device is a permanent magnet. (3) The gas laser device according to claim 1 or 2, wherein the magnetic field generating device applies the magnetic field from a direction intersecting the axial center of the discharge capillary portion.