JPH05110164A - Laser oscillator - Google Patents

Abstract

PURPOSE:To obtain a laser oscillator with a discharge electrode where generation of gas and fine particles from a dielectric body is suppressed by ultraviolet rays or a high-temperature laser medium which is generated due to discharge. CONSTITUTION:A title item is provided with at least a pair of discharge electrodes 1 and 1a and the discharge electrodes 1 and 1a consist of a discharge tube 15 which consists of a metal electrode 13 which is connected to a high- frequency AC power supply 17 and a first dielectric 14 which is adhered to this metal electrode 13 and is constituted so that it covers the metal electrode 13, a second dielectric 16 which exposes a side of a discharge part A of the discharge tube 15 and at the same time covers the other part of the discharge tube 15 adhesively, and a third dielectric with a high resistance against ultraviolet rays and a high temperature which is provided at one part of at least discharge part side on the surface of the second dielectric 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser oscillator,
More specifically, the present invention relates to a laser oscillator including a discharge electrode that suppresses the generation of gas and fine particles.

[0002]

2. Description of the Related Art FIG. 3 shows, for example, Japanese Patent Laid-Open No. 60-254684.
FIG. 4 is a perspective view showing an example of a conventional typical three-axis orthogonal type laser oscillator disclosed in Japanese Patent Publication No. JP-A-2003-242242, and FIG. 1, 1a is a pair of opposing discharge electrodes, 2 is a laser medium made of laser gas, for example, in the case of a gas laser, 3 is a housing for enclosing the laser medium 2, 4 is a blower for circulating the laser medium 2, and 5 is laser medium 2. Is a heat exchanger for cooling. Reference numeral 6 is a partial reflection mirror, and reference numerals 7, 8 and 9 are total reflection mirrors, which are arranged in the longitudinal direction of the housing 3 to form a resonator mirror. The total reflection mirror 8 is slightly inclined downward, and the total reflection mirror 7 is slightly inclined upward, so that the resonance optical path forms a Z shape. Reference numeral 10 is a first laser beam reflecting means including the partial reflecting mirror 6 and the total reflecting mirror 8, and 11 is a second laser beam reflecting means including the total reflecting mirror 7 and the total reflecting mirror 9. In addition, 12 is a laser beam.

Reference numeral 13 is a metal electrode, and 14 is a first electrode made of a material having a high relative dielectric constant such as glass or ceramics.
Is formed so as to adhere to and cover the metal electrode 13, and the discharge tube 15 is constituted by the metal electrode 13 and the first dielectric 14. Reference numeral 16 denotes a second dielectric body formed of a material having a good insulating property and easy to mold, such as an organic silicon resin, and exposes a part of the discharge tube 15 (first dielectric body 14) on the side of the discharge portion A. Then, the other parts are closely adhered and covered. The first dielectric 14 is made of a material having a higher relative permittivity than the second dielectric 16. The discharge electrodes 1, 1a are formed by the metal electrode 13, the first dielectric body 14, and the second dielectric body 16.
Is configured. Reference numeral 17 is a high-frequency AC power source for applying a voltage to the metal electrode 13, and reference numeral 18 is a discharge generated in the discharge part A between the opposing discharge electrodes 1 and 1a.

Next, the operation of the laser oscillator configured as described above will be described. First, when a voltage is applied between the metal electrodes 13 by the high frequency AC power supply 17, the discharge electrodes 1,
A discharge 18 is generated between 1a. At this time, since the first dielectric body 14 is made of a material having a higher relative dielectric constant than the second dielectric body 16, the first dielectric bodies 14 and 14 of the discharge electrodes 1 and 1a facing each other have a higher relative dielectric constant. The relative permittivity is increased only in the facing portion, and the discharge 18 is generated. Further, since the portion covered with the second dielectric 16 has a low dielectric constant, the discharge 18 is unlikely to occur. The reason why the portion having a high relative permittivity is likely to be discharged is that the capacitance becomes high.

The laser medium 2 is excited by the discharge 18 generated as described above, and the light generated thereby is resonated by the resonator mirror. The laser beam reflected by the total reflection mirror 9 reaches the total reflection mirror 8. Since the total reflection mirror 8 is tilted slightly downward, the laser beam reaches the total reflection mirror 7 with a slight tilt below the previous optical axis. Since the total reflection mirror 7 is tilted slightly upward, the laser beam reaches the partial reflection mirror 6 in parallel with the initial optical axis. A part of the laser beam reaching the partial reflection mirror 6 is directly output to the outside as a laser beam 12, and the remaining laser beam returns to the total reflection mirror 9 through a route opposite to the route described above. The above process is repeated, and the laser beam is amplified while traveling back and forth in the space of the discharge part A, and is output from the partial reflecting mirror 6 to the outside.

On the other hand, the laser medium 2 after excitation circulates in the direction of the heat exchanger 5 from between the discharge electrodes 1 and 1, and after being cooled here, circulates in the direction of the arrow through the blower 4.

[0007]

In the conventional laser oscillator configured as described above, gas or fine particles are emitted from the second dielectric due to ultraviolet rays generated during discharge, electrons generated, or heat generated by discharge. This gas corrodes or accelerates the deterioration of each part of the laser oscillator. In addition, the component of the laser gas that is the laser medium changes due to the gas, and the oscillation output decreases. Further, when the particles adhere to the mirror, there is a problem that the laser beam damages the mirror.

The present invention has been made to solve the above problems, and an object thereof is to obtain a laser oscillator having a discharge electrode for suppressing the generation of gas and fine particles.

[0009]

A laser oscillator according to the present invention comprises at least a pair of discharge electrodes, the discharge electrodes being in close contact with a metal electrode connected to a high frequency AC power supply and covering the metal electrode. And a second dielectric body that exposes the discharge portion side of the discharge tube and closely covers the other portion of the discharge tube. The third dielectric is provided on the surface of the dielectric and has high resistance to ultraviolet rays and high temperature.

[0010]

The ultraviolet rays and electrons of the discharge and the heat generated by the discharge are blocked by the third dielectric stable to the heat and the ultraviolet, and do not directly impinge on the second dielectric. Therefore, gas or fine particles are not generated from the second dielectric.

[0011]

EXAMPLE 1 FIG. 1 is a vertical sectional view showing a first example of the present invention. In addition, the same or corresponding parts as those of the conventional example shown in FIG. Reference numeral 19 denotes a third dielectric provided so as to cover only the surface portion of the second dielectric 16 located on the discharge part A side, that is, only the discharge surface side B.

The third dielectric 19 is a dielectric having resistance to ultraviolet rays and high temperatures, and as a material thereof, for example, ceramics is suitable, and recently, alumina ceramics and the like are available at low cost. In this case, when the discharge electrodes 1 and 1a are long in the direction perpendicular to the paper surface shown in FIG. 1, they may be arranged separately. This is because it is difficult and expensive to manufacture a ceramic plate having a size of several 100 mm or more. Although the first dielectric 14 and the third dielectric 19 are in close contact with each other in FIG. 1, a gap may be formed between them without close contact. Similarly, when a plurality of third dielectrics 19 are used, there may be voids between the third dielectrics 19 or another insulating substance may be interposed.

By the way, the second dielectric 16 is the metal electrode 1
Discharge tube 1 constituted by 3 and the first dielectric 14
5 must be in close contact with the gap 5 without any gap, and must absorb the thermal expansion of the discharge tube 15 due to heat, so it must be an elastic material. Therefore, the organic material is suitable, but the organic material is generally liable to be unstable due to ultraviolet rays or temperature. On the other hand, the third dielectric 19
Must be a material that is stable to ultraviolet light and temperature, so it is difficult for the second dielectric 16 to also serve as the third dielectric 19.

Next, the operation of the first embodiment constructed as above will be described. The operation of the laser oscillator is shown in FIG.
The description is omitted because it is the same as the case shown in FIG. The operation of the discharge electrodes 1 and 1a is as shown below. As shown in FIG. 1, the laser medium 2 passes through the space on the side of the discharge part A and is excited therein, but the laser medium 2 is in a considerably high temperature state. In particular, the temperature becomes higher on the downstream side (left side in FIG. 1) with respect to the flow direction of the laser medium 2. The first dielectric 14 forming the discharge tube 15 is made of a material that is stable even at high temperatures, such as glass and ceramics, but the second dielectric 16 insulating the discharge tube 15 is, for example, Since it is an organic silicon resin, it becomes unstable at high temperatures. However, since the third dielectric 19 is provided on the second dielectric 16 facing the discharge part A side, the second dielectric 16 is not directly heated. Thus, the third dielectric 19 minimizes gas release, reduces laser output degradation, and extends the life of the mirror.

Further, in the discharge part A, in the case of the carbon dioxide laser, a large amount of ultraviolet rays are emitted. This ultraviolet ray is the second dielectric 16
When it hits, it decomposes to generate fine particles or gas. However, since the second dielectric 16 is protected by the third dielectric 19, it is sufficiently protected from ultraviolet rays.

Embodiment 2 FIG. 2 is a vertical sectional view showing a second embodiment of the present invention. 1
Reference numeral 9a is a third dielectric made of, for example, ceramics, which covers the entire surface portion of the second dielectric 16. According to the second embodiment, the generation of gas or fine particles can be suppressed more effectively than in the first embodiment.

Third Embodiment In the third embodiment, a third dielectric made of, for example, ceramics covers only the downstream (left side in FIG. 1) surface of the second dielectric 16. According to the third embodiment,
It is sufficient that the third dielectric protects the second dielectric 16 from the high temperature properties of the laser medium 2.

Fourth Embodiment In the fourth embodiment, a third dielectric made of, for example, ceramics is molded at the same time as the second dielectric 16. According to the fourth embodiment, the assembling workability is improved.

Fifth Embodiment In the fifth embodiment, a third dielectric made of, for example, ceramics is embedded in the second dielectric 16.

[0020]

As is apparent from the above description, according to the present invention, at least the discharge part side of the second dielectric is covered with the third dielectric having high resistance to ultraviolet rays and high temperature, and therefore gas and fine particles are not formed. It is possible to obtain a laser oscillator with high safety without emitting any of the above.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a second embodiment of the present invention.

FIG. 3 is a perspective view showing an example of a conventional laser oscillator.

4 is a vertical cross-sectional view of FIG.

[Explanation of symbols]

 1, 1a Discharge electrode 2 Laser medium 6 Partial reflection mirror 7, 8, 9 Total reflection mirror 13 Metal electrode 14 First dielectric 15 Discharge tube 16 Second dielectric 17 High frequency AC power supply 19, 19a Third dielectric A discharge part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Kurosawa 5-1-14, Yanda Minami, Higashi-ku, Nagoya City Mitsubishi Electric Corporation Nagoya Works

Claims (1)

[Claims] 1. A metal electrode connected to a high-frequency AC power source, and a first dielectric body configured to be in close contact with and cover the metal electrode, the discharge electrode comprising at least a pair of discharge electrodes. And a second dielectric body that exposes the discharge part side of the discharge tube and closely covers the other part of the discharge tube, and at least the discharge part side of the second dielectric surface. A laser oscillator comprising a third dielectric having high resistance to ultraviolet rays and high temperature, which is partially provided.