JPH0223684A - High frequency laser oscillator - Google Patents

Abstract

PURPOSE:To realize an electron density distribution of axial symmetry which is high at the axis and to acquire a high quality laser beam mode by changing a shape and a position of a slit of an insulator which is provided inside a counter electrode. CONSTITUTION:When a high frequency voltage is applied to opposed electrodes 2, 3 from a high frequency power source 4, high frequency discharge generates inside a discharge tube 1 and excites an excitation medium. Since insulators 24, 25 are provided inside the opposed electrodes 2, 3 through the discharge tube 1, discharge is carried out only between slits 26, 27. As the discharge proceeds centering the tube shaft through the slits 26, 27 in direction of tube shaft center, the discharge direction changes between both side edge positions of the opposed electrodes 2, 3. Therefore, an electron density distribution in x- and y-directions which is averaged in shaft center direction of the discharge tube 1 is high at a radial center which is a shaft center section of the discharge tube 1 and enables production of a high quality laser beam mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency laser oscillator that performs high-frequency discharge excitation for industrial or medical use.

BACKGROUND OF THE INVENTION FIGS. 5(a) to 5(d) outline the general structure of a conventional high-frequency laser oscillator that performs high-frequency discharge excitation.

FIG. 5(a) is a schematic front view of a conventional high-frequency laser oscillator, FIG. 5(b) is a cross-sectional view taken along line A-A in FIG. 5(a), and FIG. 5(e) is the tube axis of the discharge tube. Discharge state diagram in the direction, Figure 5 (d
) to (r) are diagrams explaining the x and y directions perpendicular to the tube axis in the discharge tube, and x when averaged in the tube axis direction,
FIG. 3 is a distribution characteristic diagram of electron density in the y direction.

In Figure 5 (&), 1 is a tubular discharge tube made of a dielectric material, 2.8 is a discharge tube which is placed in close contact with the outer wall of the discharge tube, and is placed opposite to each other with the axis of the discharge tube 1 as the center. counter electrode,
4 is a high frequency power source, which is connected to the counter electrode 2.8.

5 is a total reflection mirror, and 6 is a partially transparent output mirror, which are installed opposite to each other at both ends of the discharge tube 1 in the longitudinal direction, and from the output mirror 6,
Laser light is oscillated in the direction indicated by the arrow ]. This discharge tube] has a blower 9 and a heat exchanger 1o inside.
It is connected to the air supply pipes 7 and 8 equipped with the air supply pipes 7 and 8 for circulatory communication. Co2. It is filled with a mixed gas such as N, Ha, etc. In this discharge tube, when a voltage is applied to the counter electrode 2.8 from the high frequency power source 4,
A discharge occurs within the discharge tube 1, and as a result, 002 molecules are excited, and laser oscillation occurs within an optical resonator composed of a total reflection mirror 5 and a partially transmitting output mirror 6. Part of the laser beam is shown by the arrow】
As shown at 1, the light is output to the outside through a partially transparent output mirror 6. As the gas temperature rises due to discharge, the laser output decreases, so the gas is circulated by a blower 9 and cooled by a heat exchanger 0. In this structure, the discharge direction within the discharge tube is limited to a certain direction as shown in Figure 5 ((1)), and the X and Y coordinates are set as shown in Figure 5 (d). ] is averaged in the direction of the tube axis, as shown in Figure 5 (
11) The electron density distribution is shown in (r).

Problems to be Solved by the Invention As mentioned above, in conventional high-frequency laser oscillators that perform high-frequency discharge excitation, the direction of discharge is limited to a certain direction,
In particular, there is a problem that the electron density distribution within the discharge tube is not axially symmetrical, making it difficult to obtain a high-quality laser beam mode.

The present invention solves the above-mentioned problems, and the discharge direction is not limited to a certain direction, and a higher electron density distribution can be formed at least in the axial center of the discharge tube than in the peripheral part, and a high-quality laser beam mode can be obtained. The purpose of this invention is to provide a high frequency laser oscillator that can be used.

Means for Solving the Problems In order to solve the above-mentioned problems, the high frequency laser oscillator of the present invention includes a discharge tube made of a dielectric material, a counter electrode having an arcuate cross section and an insulator, which face each other about the tube axis of the discharge tube. a body along its length with the insulator inside;
A slit is formed in each of the insulators at a symmetrical position with respect to the tube axis, displaced across both side edges of the opposing electrode, and extending in the tube axis direction.

Furthermore, in the high frequency laser oscillator of the present invention, a discharge tube made of a dielectric material is provided with a plurality of counter electrodes and an insulator having an arcuate cross section and facing each other with the tube axis of the discharge tube as the center, with the insulator inside. A slit is provided along the length direction of the discharge tube, and a slit is formed in each of the insulators at a symmetrical position with respect to the tube axis and displaced between both side edges of the opposing electrode and extending in the tube axis direction, The positions of the pairs of opposing electrodes adjacent in the tube axis direction in the circumferential direction of the discharge tube are displaced from each other.

Effect With the above configuration, when a voltage is applied to the opposing electrode by an external high-frequency power source, a discharge occurs only between the slits of the insulator installed corresponding to the inside of the opposing electrode, and moreover, across both sides of the opposing electrode. Because it has a slit structure made of insulating material that can be displaced, it is possible to change the discharge direction, and at least form a higher electron density distribution in the narrow part of the discharge tube than in the peripheral part, making it possible to produce a high-quality laser beam mode. Obtainable.

Furthermore, the electron density distribution within the discharge tube can be made axially symmetrical, and a higher electron density distribution can be formed in the axial center than in the peripheral part, making it possible to obtain a higher quality laser beam mode.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1(a) is a schematic front view of a high-frequency laser oscillator showing a first embodiment of the present invention, and FIG. 1(b) is a perspective view of a main part of a discharge section of the same high-frequency laser oscillator. Figure 1 (a), (
In b), reference numeral 1 denotes a discharge tube made of a dielectric material, and a counter electrode 2.8 having an arcuate cross section facing the tube axis of the discharge tube 1 is provided on the outer peripheral surface of the discharge tube. A pair of insulators 24. made of alumina (AlaO3) having the same shape as the counter electrodes 2.8 are provided on the inner peripheral surface of the discharge tube 1 along the length direction, corresponding to the counter electrodes 2.8. 25, each of the insulators 24 and 25 is disposed symmetrically with respect to the tube axis as shown in FIG. Wave-shaped slits 26, 27 extending in the axial direction are formed.

With the above configuration, when a high frequency voltage is applied to the counter electrode 2.8 by the high frequency power source 4, a high frequency discharge occurs within the discharge tube, thereby exciting the excitation medium.

At this time, since the insulators 24.25 are provided inside the counter electrode 2.8 via the discharge tube 1, the insulators 24.25.
The discharge occurs only between the slits 26 and 27 of the slits 25 and 25, and the discharge direction is as shown in FIG. 1(d).
6.27, the position changes between the positions of both side edges of the opposing electrodes 2 and 8 as the center moves in the direction of the tube axis. Therefore, the electron density distribution in the x and y directions averaged in the tube axis direction of the discharge tube l is as shown in Fig. 1 (r), (g
), a high electron density distribution is formed at the radial center, which is the axial center of the discharge tube 1, making it possible to produce a high-quality laser beam mode. In this case, Figure 1 (
f), (Like gl, the electron density distribution is not axially symmetrical with respect to the x and y directions of the discharge tube 1, but it has a high electron density distribution in the center, so it has better quality than the conventional one. A laser beam mode can be obtained.

FIGS. 2(a) and 2(b) are a schematic front view of a high-frequency laser oscillator and a perspective view of a main part of its discharge section, showing a second embodiment of the present invention. As shown in FIGS. 2(a) and 2(b), on the outer circumferential surface of the discharge tube, there are alumina (AJ203) molasses 84. are provided in pairs along the length of the discharge tube 1, and counter electrodes 2.3 of the same shape are provided on the outside of the insulators 84, 85. The insulators 84 and 85 also have slits 86 that have the same shape as the slits in the embodiment of No.
．． 87 is formed. With this configuration as well, the same effects as in the first embodiment can be obtained, as shown in FIGS. 2(d) to 2(g).

In Example 1.2, regarding the laser beam mode,
Although a mode with better quality than the conventional one can be obtained, Fig. 1 (f
The electron density distributions shown in Figures 1, (g), Figure 2 (r), and '(g) are not axially symmetrical with respect to the x and y directions of the discharge tube. As an example for improving this and obtaining an even better quality laser beam mode, Example 3.4 will be shown below.

FIG. 8(a) is a perspective view of a main part of a discharge section of a high frequency laser oscillator showing an eighth embodiment of the present invention. In this eighth embodiment, a plurality of pairs of counter electrodes and insulators having a structure similar to that of the first embodiment are provided on the outer peripheral surface and inner peripheral surface of the discharge tube in the tube axis direction. Each pair of opposing electrodes 2, 8.12°] 8 and a wave-shaped slit 4 adjacent to the
Insulator 44.45.54 with 6.47.56.57
．． 55 in the circumferential direction of the discharge tube are arranged so as to be displaced by 90 degrees from each other, as shown in Fig. 8(b), ((+)
It is shown in the figure below.

Also with this configuration, the counter electrode 2.8 in the discharge tube 1
．． ] 2, 18 and the insulators 44.45.54.55, the same effects as in the first and second embodiments are obtained, and the discharge state is as shown in FIG. 8 (dl, (
6), and the averaged X in the longitudinal direction of the discharge tube 1
, the electron density distribution in seven directions is shown in Figure 8(g).

As shown in Φ), a high electron density distribution is formed at the radial center of the discharge tube 1, and when averaged in the tube axis direction, the electron density distribution in the x and y directions becomes axially symmetrical, and the -layer A high quality laser beam mode can be obtained.

FIG. 4 (1 is a perspective view of a main part of a discharge section of a high-frequency laser oscillator showing a fourth embodiment of the present invention. In this fourth embodiment, an opposite A plurality of pairs of electrodes and insulators are provided on the outer peripheral surface of the discharge tube in the tube axis direction, and each pair of opposing electrodes 2, 8 .
12.18 and wave-shaped slits 66, 67, 76,
The positions of the insulators 64, 65, 74, and 77 in the circumferential direction of the discharge tube are displaced by 90 degrees from each other, as shown in FIGS. 4(b) and (6).

With this configuration as well, the same effects as in the eighth embodiment as shown in FIGS. 4(d) to (h) f can be obtained, and a high-quality laser beam mode can be obtained.

Here, as shown in FIG. 8(i), the intersection angle of the discharge direction at both side edge positions of the opposing electrodes 2 and 8 is set to θ. 8 if
By installing pairs of opposing electrodes in the number of 60°/2θ in the discharge tube 1, shifted by θ from each other, the entire area within the discharge tube can be covered as a discharge range, and it is possible to cover the entire discharge range in only 1.7 directions. Instead, the electron density is all axially symmetrical within the circular plane of the discharge tube, making it possible to obtain a laser beam mode of even better quality.

In this example, alumina (Al*Os) was explained as an example of an insulator, but silica (SiO□
).

A similar effect can be obtained by using an insulator such as barium titanate or titanium oxide.

As described above, according to the present invention, by changing the shape and position of the slit of the insulator provided inside the counter electrode, the direction of discharge is not limited to a fixed direction, and the axial center of the discharge tube A high-quality laser beam mode can be obtained by freely creating an electron density distribution state in which the electron density is high, and by creating an axially symmetrical electron density distribution with a high electron density particularly at the axial center.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic front view of a high-frequency laser oscillator showing a first embodiment of the present invention, FIG. 1(b) is a perspective view of a main part of a discharge section of the same high-frequency laser oscillator, and FIG. ) is shown in Figure 1 (
BB sectional view of a), Figure 1 (d3 is a diagram of the discharge state in the tube axis direction of the discharge tube, Figure 1 (61 ~ (gl is the x, y direction perpendicular to the tube axis of the discharge tube) An explanatory diagram, a distribution characteristic diagram of the electron density in the X and seven directions when averaged in the tube axis direction, and FIG. 2(a) is a schematic front view of a high-frequency laser oscillator showing a second embodiment of the present invention. , FIG. 2(b) is a perspective view of the main part of the discharge section of the same high-frequency laser oscillator, FIG. 2(c) is a sectional view taken along line C-C in FIG. 2(IL), and FIG. Discharge state diagram in the tube axis direction, Figures 2(e) to (d) are diagrams explaining the x and y directions perpendicular to the tube axis in the discharge tube, and 1.7 when averaged in the tube axis direction. FIG. 8(a) is a distribution characteristic diagram of the electron density in the direction, and FIG.
cl is shown in Figure 8 (D-D and E-E sectional views of a3,
Figures (d) and (e) are diagrams of the discharge state in the tube axis direction of the discharge tube, and Figures 8 (f) to (11) are diagrams explaining the X and 7 directions perpendicular to the tube axis in the discharge tube, and the tube Figure 8 (i) is a diagram of the electron density distribution in the x and y directions when averaged in the axial direction; Figure 8 (i) is a schematic cross-sectional diagram illustrating the installation conditions of multiple pairs of opposing electrodes and insulators; Figure 4 (a) FIG. 4(b) is an overview diagram of a discharge section of a high frequency laser oscillator showing a fourth embodiment of the present invention.
1) is the FF and G-C sectional view of Fig. 4(a),
Figures (d) and (e) are diagrams of the discharge state in the tube axis direction of the discharge tube,
Figure 4 (fl~(g)) is a diagram explaining the XIF direction perpendicular to the tube axis in the discharge tube and a characteristic diagram of the electron density distribution in the x and y directions when averaged in the tube axis direction. Figure (a
) is a schematic front view showing a conventional high-frequency laser oscillator;
Figure (b) is a sectional view taken along line A-A in Figure 5 (&), Figure 5 (e)
are discharge state diagrams in the tube axis direction of the discharge tube, Fig. 5(d) to (
f) is a diagram explaining the x and y directions perpendicular to the tube axis in the discharge tube, and when averaged in the tube axis direction! , is an electron density distribution characteristic diagram in seven directions. 1...Discharge tube, 2.8.12.38...Counter electrode,
24°25, 84.85.44.45.54.55.6
4.65.74.75...Insulator, 26.27.86
．． 87.46.47.56.57.66゜67, 76,
77...slit.

Claims (1)

[Claims] 1. A discharge tube made of a dielectric material is provided with a counter electrode having an arcuate cross section and an insulator that face each other about the axis of the discharge tube in the longitudinal direction of the discharge tube, with the insulator inside. A high-frequency laser oscillator, wherein a slit is formed in each insulator along the tube axis, the slit being disposed symmetrically with respect to the tube axis, extending between both side edges of the opposing electrode, and extending in the tube axis direction. 2. A discharge tube made of a dielectric material is provided with a plurality of pairs of counter electrodes and insulators having an arcuate cross section and facing each other with the tube axis of the discharge tube as the center, with the insulators on the inside, along the length direction of the discharge tube. , forming a slit in each of the insulators at a symmetrical position with respect to the tube axis, displaced between both side edges of the opposing electrode, and extending in the tube axis direction;
A high-frequency laser oscillator in which the positions of each pair of opposing electrodes adjacent in the tube axis direction in the discharge tube circumferential direction are displaced from each other.