JPH0413871B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser oscillator. In recent years, a stable laser oscillator with high output characteristics and little output fluctuation has been desired as a laser oscillator.
An example of a resonator of a conventional gas flow type laser oscillator is shown in FIG.

In the figure, 1 is a laser tube, 2 is a total reflection mirror, and 3
constitutes an optical resonator with an output coupling mirror. Reference numeral 4 denotes an outer tube of the gas introduction section, and 40 an inner tube, which constitute a double tube. Reference numeral 5 indicates a gap between the end face of the inner tube 40 and the end face of the laser tube 1, and 50 indicates a cavity for improving gas inflow. Reference numeral 6 denotes an electrode, which is cylindrical or rod-shaped (pin-shaped). 7 is an opposing electrode.
8 and 9 indicate the direction of flow of the medium gas. 10 is the laser output.

In this example, the medium gas flows from both ends of the resonator in the direction of arrow 8, flows along the inner tube 40, is introduced into the laser tube 1 through the gap 5, and is introduced from the center of the resonator in the direction of arrow 9. is discharged. The discharge is at electrode 6
and electrode 7.

FIG. 2 is an enlarged perspective view of the gas introduction portion in this configuration example, and FIG. 3 is an enlarged cross-sectional view.

In the conventional method shown in Figs. 2 and 3, the gap 5
is formed by two cylinders, the inner tube 40 and the end face of the laser tube 1, so gas uniformly flows into the laser tube 1 from the outer periphery of the double tube inner tube 40, so that the gas flows into the center of the laser tube 1. The gas flow is concentrated and a uniform flow velocity distribution cannot be obtained. For this reason, the discharge points are concentrated in one point, and the temperature of the electrode 6 often becomes high, and the discharge volume is small, making it impossible to obtain a sufficient output.
Furthermore, since this discharge point moves around irregularly, the output fluctuates each time, and sometimes the discharge may stop. For this reason, it was not possible to increase the gas pressure or the input power, and it had the disadvantage that it had to be operated at a low output value in order to obtain stable output.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a laser oscillator with high output and high output stability.

FIG. 4 shows a structure of a resonator of a laser oscillator in an embodiment of the present invention. Although this embodiment shows a case where gas is introduced from both ends of the resonator, the present invention is not limited to this. It should be noted that this method is applicable regardless of the gas flow direction.

In FIG. 4, the same parts as in the conventional example shown in FIG. 1 are given the same numbers, and detailed explanations are omitted. The feature of this embodiment is that the inner pipe 40 constitutes a double pipe in the gas introduction section.
1 has an electrode function, a plurality of coupling passages 55 are provided on the laser tube 1 side of the inner tube 401, and a medium gas is introduced into the laser tube 1 through the coupling passages 55.

An enlarged perspective view of the gas introduction portion of this embodiment is shown in FIG. 5, and an enlarged sectional view is shown in FIG. 6.

As shown in FIGS. 5 and 6, in this embodiment,
The outer tube 4 and the inner tube 401 that also serve as electrodes constitute a double structure, and a total reflection mirror 2 is provided at one end of the inner tube 401 that also serves as an electrode, and a plurality of mirrors are provided at the other end of the inner tube 401 that also serves as an electrode. A coupling passage 55 is provided. At this time, the material of the inner tube 401 which also serves as an electrode is preferably copper, titanium, or the like.

The medium gas introduced between the outer tube 4 and the inner tube 401 that also serves as an electrode is forcibly ejected into the laser tube 1 from a plurality of coupling passages 55 provided in a part of the inner tube 401 that also serves as an electrode. In the laser tube 1, a turbulent flow is formed due to the pressure difference between the coupling passage 55 part and the part without the coupling passage 55 and the collision of the ejected gases, and the flow velocity distribution of the medium gas in the tube axis direction in the laser tube 1 is uniform. become. This turbulent flow prevents the concentration of the discharge point and the discharge volume is uniformly expanded within the laser tube through which the laser beam passes, which greatly contributes to an increase in output. Due to this turbulent flow effect and the cooling effect of the gas and electrode due to adiabatic expansion based on the introduction of gas from the narrow coupling passage 55 into the large diameter laser tube 1, it becomes possible to input more power and prevent discharge. Since output fluctuations caused by stability can be greatly reduced, a large output can be stably obtained.

FIG. 7 is an enlarged perspective view of a second embodiment of the gas introduction portion of the laser oscillator of the present invention. The same parts as in FIG.
This is an example in which it is provided at a position slightly away from the side end face.
In this case as well, the same effects as in the first embodiment can be obtained. The coupling passage 55 may be installed in the vicinity of the end face of the inner tube 401 which also serves as an electrode.

The shape of the coupling passage 55 is preferably a slit-like hole extending in the axial direction of the laser tube 1, as shown in both embodiments. In the above embodiment, the case where the electrode-doubling inner tube 401 is entirely made of electrode material has been explained, but the electrode material portion is connected to the coupling passage 55.
If it exists at least in the vicinity of , it can play a sufficient role.

Figure 8 shows a comparison of the output characteristics of the laser oscillator of the first embodiment shown in Figure 5 and a conventional oscillator. The output fluctuation (particularly the large spike-like output fluctuation that occurs when the position of the discharge point changes) becomes large, and eventually the discharge is cut off and no more output can be extracted.In contrast, with this method, as shown by the solid line, It is possible to obtain high output while keeping output fluctuations low. In the above explanation, it is assumed that the inner tube 401 also serves as an electrode, but the laser output can be similarly increased and stabilized by the coupling passage 55 even if the inner tube 401 is provided separately without serving as an electrode. .

As described above, the present invention provides a gas flow type oscillator in which the gas introduction section into the laser tube has a double tube structure, in which a plurality of gas coupling paths are provided on the laser tube side of the inner tube that can also serve as electrodes. By ejecting the medium gas from this narrow coupling passage, the flow velocity of the medium gas in the radial direction within the laser tube is made uniform, preventing the concentration of discharge in the center of the tube and achieving high output. At the same time, discharge can be stabilized and output fluctuations can be reduced.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the structure of the resonator section of a conventional gas flow type laser oscillator, Figure 2 is an enlarged perspective view of the gas introduction part in Figure 1, and Figure 3 is an enlarged perspective view of the gas introduction part in Figure 1. FIG. 4 is an enlarged sectional view showing the structure of the resonator section of a laser oscillator according to an embodiment of the present invention. FIG. 5 is an enlarged perspective view of the gas introduction part of the oscillator, and FIG. Enlarged cross-sectional view of the part,
FIG. 7 is an enlarged perspective view of another embodiment of the gas introduction part for laser oscillation of the present invention, and FIG. 8 is a diagram showing a comparison of laser output characteristics of the present invention and a conventional example. 1... Laser tube, 2... Total reflection mirror, 3... Output coupling mirror, 4... Outer tube of gas introduction section, 40... Inner tube of gas introduction section, 5... Gap made by cylindrical end surface ,
50... Vacancy, 6, 7... Electrode, 8, 9... Gas flow direction, 55... Connection passage, 401... Inner tube also used as electrode.

Claims (1)

[Scope of Claims] 1. The medium gas introduction part of the laser tube has a double tube structure including an outer tube and an inner tube, and an elongated hole is formed in the axial direction of the laser tube near the end surface of the inner tube on the laser tube side. A laser oscillator characterized in that a plurality of slit-shaped coupling passages are provided, and a medium gas is introduced into the laser tube from a region surrounded by the outer tube and the inner tube through the coupling passage to generate turbulent flow. 2. The laser oscillator according to claim 1, wherein at least the vicinity of the coupling passage of the inner tube is formed of an electrode material.