JP2578014Y2 - Dielectric plate of laser device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser apparatus in which a gas serving as a laser medium is filled between electrodes and a laser is excited by a high-frequency discharge. The present invention relates to a dielectric plate of a laser device having high performance.

[0002]

2. Description of the Related Art Generally, in a gas laser device used for various laser processing, a pressure is 10 Torr to 200 Torr.
A laser gas of about Torr is used as a laser medium, and high-frequency discharge is applied between electrodes filled with the laser medium, thereby performing laser excitation and flowing the laser gas to suppress a rise in gas temperature due to the discharge.

FIG. 2 shows an example of a conventional gas laser device 50 suitable for this purpose. This gas laser device 50
Is a three-axis orthogonal laser device in which a discharge electric field direction, a laser gas flow direction, and a laser optical axis direction are orthogonal to each other.

[0004] As shown in the figure, a metal vacuum vessel 51 for storing a laser gas is formed by closing the start and end of a rectangular tube, and has a blower 53 and a discharge unit 5 in a tube 52.
4. The heat exchanger 55 is provided in order. Blower 53
Is provided for generating a laser gas flow, and a flow path is formed in a direction indicated by an arrow A in the figure. The heat exchanger 55
The laser gas, which is provided to absorb the gas temperature increased by the discharge and has been deprived of heat by the heat exchanger 55, is circulated again by the blower 53. The discharge unit 54 is provided for performing laser excitation by high-frequency discharge.

Conventionally, as shown in FIG. 3, a metal electrode 56 and a dielectric plate 57 are combined and provided on the discharge side 54 on the voltage side and the ground side of a high-frequency power supply 58, respectively. The metal electrode 56 and the dielectric plate 57 are provided to face each other in parallel. The dielectric plate 57 is a metal vacuum vessel 5
1, and a metal electrode 56 is attached to the outside thereof. The reason why the size of the dielectric plate 57 is larger than the size of the metal electrode 56 is to insulate the metal electrode 56 from the metal vacuum vessel 51. The dielectric plate 57 has a predetermined thickness and a sealing property, and forms a part of an outer shell of the metal vacuum vessel 51 for enclosing a laser gas.

A voltage having an oscillation frequency of about 1 MHz to 100 MHz is applied to the voltage side metal electrode 56a, and the ground side electrode 56b and the metal vacuum vessel 51 are grounded. A high-frequency current flows from the metal electrode 56 through the dielectric plate 57, and discharge is ignited in the laser gas filled in the discharge portion 54, and laser excitation is performed by the high-frequency discharge. The excited energy is extracted as laser light in a direction perpendicular to the plane of the drawing by the action of an optical resonator (not shown).

The dielectric plate 57 is electrically connected to the metal electrode 5.
6 operates in the same manner as when a capacitor is connected in series. That is, it serves to prevent local concentration of the high-frequency current and to make the discharge uniform.

[0008]

The discharge section 54 of the laser device 50 has a structure in which a dielectric plate 57 is interposed between metal electrodes. In order to discharge efficiently with respect to the applied high-frequency voltage, the dielectric constant of the dielectric plate 57 may be increased. When the dielectric constant is high, the capacitance of the dielectric plate 57 increases, the resistance decreases, and the efficiency can be increased. On the other hand, the following disadvantages are also considered. That is, when the dielectric constant of the dielectric plate 57 is increased, the metal vacuum container 51 adjacent to the dielectric plate 57 is at the ground potential, and the leakage current (arrow B) is transmitted to the metal vacuum container 51 through the dielectric plate 57 from the voltage side electrode. ) Flows. This causes a reduction in efficiency. This leakage current causes the dielectric plate 57 to generate heat. Heat generation of the dielectric plate 57 leads to damage and a decrease in efficiency due to a rise in temperature. Also, when the dielectric constant of the dielectric plate 57 is increased, the electric field formed between the electrodes is expanded, and the discharge path 59 is easily expanded in the upstream and downstream directions of the laser gas flow as shown in FIG. Gets worse. Also, the quality of the laser light is reduced.

Conversely, if the dielectric constant of the dielectric plate 57 is lowered, the above-mentioned disadvantage can be solved, but the discharge efficiency is not good. This is because the higher the dielectric constant is, the higher the dielectric plate 5 is.
This is because the resistance of No. 7 is small. As described above, the dielectric plate 57 forms a part of the outer shell of the metal vacuum vessel 51 and requires high strength. Generally, a dielectric material having a low structural strength is used. In many cases, there is a problem in strength as compared with metal parts.

Next, a dielectric plate having a low dielectric constant and a dielectric plate having a high dielectric constant are combined to form, for example, a dielectric plate having a high dielectric constant just below a metal electrode, and a dielectric plate having a low dielectric constant is disposed above and below the metal electrode. Think about configuring. With this configuration, the leakage current is reduced, and the electric field formed between the electrodes is shaped. However, in this case, since the joining portion between the dielectric plates increases, a problem occurs in the sealing property.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a dielectric plate of a laser device which can reduce heat generation, shape a discharge shape, and have a high sealing property.

[0012]

In order to achieve the above object, the present invention provides a discharge section in which a pair of dielectric plates having metal electrodes on a voltage side and a ground side are opposed to each other on both sides of a laser gas flow path. In a laser device that excites a laser gas by applying a high frequency between electrodes, the dielectric plate includes a laser gas.
Outside the laser gas flow path
Provide a high-permittivity material facing the side
A metal electrode from outside the laser gas flow path
Of the laser gas flow.
Road facing, immediately upstream and downstream of this part
The inner surface of the laser gas flow path is made of a material having a low dielectric constant .

[0013]

According to the above construction, the leakage current to the metal vacuum vessel is reduced, so that the heat generation of the dielectric plate is reduced. In addition, the discharge between the electrodes is relatively efficient.

Also, the electric field between the electrodes becomes relatively linear, and the discharge shape is shaped.

Further, since the dielectric plate constituting the outside of the discharge portion can be made of a material having a high dielectric constant, the strength is increased, and at the same time, the joint between the dielectrics is not exposed outside the laser gas flow path. Good sealing properties.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a discharge unit 1 according to the present invention. The metal vacuum vessel 51 and a portion (not shown) connected to the metal vacuum vessel 51 are the same as those of the laser apparatus of FIG. 2 described in the conventional example, and include a blower 53, a heat exchanger 55, a high-frequency power supply 58, and the like. As shown in FIG.
Is provided with a dielectric plate 2 opposed thereto. The dielectric plate 2 forms a part of the outer shell of the metal vacuum vessel 51 and is fixed integrally with the metal vacuum vessel 51 continuously. The laser gas flow path 3 is formed between the metal vacuum vessel 51 and the dielectric plate 2. The laser gas flow flows in the direction of arrow A.

Each of the two dielectric plates 2 is provided with a concave portion 4 having a uniform depth on the outside. The concave portion 4 is located near the upstream of the laser gas flow of the dielectric plate 2,
The distance from the recess 4 to the metal vacuum vessel 51 is formed to be short on the upstream side and long on the downstream side. A metal electrode 5 serving as a voltage-side or ground-side electrode is fitted in each recess 4. One metal electrode 5 is connected to a high frequency power supply 58 to form a voltage side metal electrode 5a, and the other ground side electrode 5b is grounded.

The two dielectric plates 2 have different structures.

First, one dielectric plate is connected to the voltage side electrode 5a.
The outer surface of the laser gas flow path 3 and the portions directly below and on both sides of the voltage side electrode 5a along the recess 4 are made of a material having a relatively high dielectric constant such as alumina. ing. The portion 3a immediately below the high dielectric constant voltage side electrode 5a faces the laser gas flow path 3. The inner surfaces 3c, 3c of the laser gas flow path 3 upstream and downstream of the portion 3a directly below
d is made of a material having a relatively low dielectric constant such as glass.

On the other hand, the dielectric plate 2b provided with the ground side electrode 5b is made of only high dielectric constant alumina or the like.

Next, the operation of the embodiment will be described.

The portion 3a immediately below the voltage side electrode 5a is formed with a high dielectric constant, and the inner surface 3a of the laser gas flow path on both sides thereof is formed.
Since c and 3d are formed with a low dielectric constant, the current from the voltage-side electrode 5a easily flows directly below. Also,
From the voltage side electrode 5a toward the metal vacuum vessel 51 on the upstream and downstream sides, the cross section of the high dielectric constant portion of the dielectric plate 2a is small, and it becomes difficult for current to flow. Therefore, when a high voltage is applied between the voltage side electrode 5a and the ground side electrode 5b from the high frequency power supply 58, most of the current flows from the voltage side electrode 5a directly downward (arrow 6). The current flowing through the dielectric plate 2a to the metal vacuum vessel 51 is reduced, and the dielectric plate 2
The heat generation of a is reduced.

In the laser gas flow path 3, the path of the discharge current is concentrated in a narrow area immediately below the voltage side electrode 5a.
That is, the path of the discharge current becomes relatively straight, and the discharge shape is shaped.

Dielectric plate 2b provided with ground side electrode 5b
Is made of only alumina having relatively high strength and has few joints, so that it has sufficient strength and good sealing properties.

On the other hand, the dielectric plate 2a on which the voltage side electrode 5a is provided is made of alumina or the like having relatively high strength on the outside, and the inside surfaces 3c and 3d of the laser gas flow path made of glass or the like are covered with this. I have. With this combination structure, the strength of the dielectric plate 2a is increased. Since the joint between the dielectrics of the inner surfaces 3c and 3d of the laser gas flow passage and the portion 3a immediately below the voltage-side electrode 5a is not exposed outside the laser gas flow passage 3, the sealing property is good.

As described above, since the dielectric plate 2 has a high dielectric constant and high strength outside the laser gas flow path 3 and has a low dielectric constant inside, the heat generation in the dielectric plate 2 is small, and the discharge is reduced. A dielectric plate whose shape is shaped and which has a high sealing property is realized.

In this embodiment, the voltage-side dielectric plate 2a
Although only the inside is covered with a low dielectric constant dielectric, it goes without saying that the inside of the ground-side dielectric plate 2b may also be covered with a low dielectric constant dielectric.

[0029]

[Effects of the Invention] The present invention exhibits the following excellent effects.

(1) Since the heat generation of the dielectric plate is suppressed,
A decrease in laser emission efficiency due to a rise in temperature can be prevented.

(2) Since the shape of the discharge is shaped, the quality of the laser beam is improved.

[Brief description of the drawings]

FIG. 1 is a structural view of an electrode part of a laser device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a laser device.

FIG. 3 is a structural view of an electrode portion of a laser device showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge part 2, 2a, 2b Dielectric plate 3 Laser gas flow path 5, 5a, 5b Metal electrode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-8381 (JP, A) JP-A-3-208383 (JP, A) JP-A-60-262479 (JP, A) JP-A-60- 217675 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01S 3/038

Claims (1)

(57) [Scope of request for utility model registration] 1. A laser device in which a discharge section is provided on both sides of a laser gas flow path with a pair of dielectric plates having metal electrodes on a voltage side and a ground side facing each other, and a high frequency is applied between the electrodes to excite the laser gas. In the above, the dielectric plate is a laser
Connect the laser gas flow path to the metal
Provide a high-permittivity material facing outward, and use this high-permittivity material.
A metal electrode is fitted to the material from outside the laser gas flow path.
And a portion directly below the metal electrode is formed by laser gas.
So that it faces the flow path, and
A dielectric plate for a laser device, wherein an inner surface of a flow laser gas flow path is made of a material having a low dielectric constant .