JP2871218B2 - Method and apparatus for microwave excitation of gas laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for microwave excitation of a gas laser.

[0002]

2. Description of the Related Art In a conventional gas laser microwave excitation device, as shown in a front sectional view of FIG.
Is inserted and installed in a cylindrical cavity resonator 4 connected from the microwave oscillator 2 via the waveguide 3, and a total reflection mirror 5 and an output mirror 6 are installed at both ends thereof. The microwave output from the microwave oscillator 2 propagates through the waveguide 3 and is transmitted to the cylindrical cavity resonator 4 to generate a uniform TM ₀₁₀ mode microwave electric field in the axial direction thereof. The laser medium gas in 1 is discharge-excited by microwave electric field. As a result, stimulated emission light from the laser medium gas is obtained, amplified by reciprocal reflection between the total reflection mirror 5 and the output mirror 6 constituting the optical resonator, and the laser light 7 transmitted through the output mirror 6 is extracted.

However, in such a device, the electric field intensity formed in the cylindrical cavity resonator 4 is (Q
/ V) ^1/2 (Q: half width of resonance of cavity resonator / resonance frequency, V: volume of cavity resonator). However, there is a disadvantage that the Q value is reduced due to the generation of the discharge plasma and the discharge cannot be maintained. Further, when the cavity volume is reduced in anticipation of a decrease in the Q value, the capacity of the dischargeable laser medium gas is reduced, so that there is a disadvantage that the laser output is also reduced. Further, with such an electric field intensity determined by the discharge start electric field and the variation of the Q value, there is a drawback that it is not possible to achieve a population inversion distribution of an energy level suitable for laser oscillation.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of such circumstances, and can stably generate a discharge under various pressure conditions of a laser medium gas, and is suitable for laser oscillation. It is an object of the present invention to provide a method and an apparatus for microwave excitation of a gas laser capable of effectively performing discharge excitation of a laser medium gas with an increased electric field intensity and improving laser output and oscillation efficiency.

[0005]

For this purpose, the present invention introduces a microwave oscillated from a microwave oscillator to a cylindrical cavity resonator via a waveguide to form a uniform TM in the axial direction.
Microwave excitation of a gas laser that generates a ₀₁₀ mode microwave electric field and excites the laser medium gas enclosed in a discharge tube inserted axially into the cavity resonator by the electric field to obtain a laser output. In the method,
A pre-ionization member made of metal is inserted into the cavity resonator in parallel with its axis to increase the electric field strength to perform pre-ionization, and then discharge is performed by adjusting the insertion amount of the pre-ionization member made of metal. Stabilizing, a cylindrical cavity, a microwave oscillator, a waveguide for supplying microwaves to the cavity, and a laser medium inserted along the axis of the cavity. A gas laser microwave excitation device having a gas-filled discharge tube, comprising a metal preionization member inserted into the cavity resonator in parallel with its axis and with an adjustable insertion length. And are characterized.

[0006]

In the microwave excitation method for a gas laser according to the present invention, a metal pre-ionization member is inserted into a cylindrical cavity resonator in parallel with the axial direction, thereby forming an electric field in the cavity in the axial direction of the discharge tube. The intensity is increased to be equal to or higher than the electric field for starting the discharge of the laser medium gas in the discharge tube. By adjusting the insertion length of the metal preionization member so that the discharge of the laser medium gas generated by this can be maintained stably, the electric field strength required for forming the population inversion distribution of the energy level for laser oscillation Can be obtained. The same effect can be obtained by inserting the metal preionization member from one or both end surfaces of the cavity, and the same effect can be obtained by inserting the metal preionization member from the side surface of the cavity. Can be expected.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method and apparatus for microwave excitation of a gas laser according to the present invention will be described with reference to the front sectional view of FIG. 1, the same members as those in FIG. 2 are denoted by the same reference numerals, and the cylindrical cavity resonator 4 has an inner diameter of 8.6 cm and a length of 20 cm.
And a laser medium gas for carbon dioxide laser (composition C
O ₂ , H ₂ , He, pressure 40 Torr) by inserting pre-ionization metal cylinders 8 in the axial direction of the discharge tube from the end plates at both ends of the cylindrical cavity resonator 4, thereby forming the inside of the discharge tube 1. A discharge of the laser medium gas is induced. In this state, the discharge plasma is distributed only between the pre-ionization metal cylinders 8, and since a high electric field is applied to this region, the emission of the discharge plasma is unstable and the laser output is low. . When the pre-ionization metal cylinder 8 is pulled out from this state to a position where the laser output is maximized, the emission of the discharge plasma is stabilized and the laser output is improved. An experimental example in which the insertion length of the pre-ionization metal cylinder 8 was set to an optimum value in this manner showed that discharge was stable at a pressure of 40 Torr, a laser output of 85 W, an oscillation efficiency of 18%.

[0008]

In summary, according to the present invention, a microwave oscillated from a microwave oscillator is guided to a cylindrical cavity resonator via a waveguide, and a microwave electric field in a TM ₀₁₀ mode uniform in its axial direction. Generating a laser medium gas enclosed in a discharge tube axially inserted into the cavity resonator by the electric field thereof to obtain a laser output. Inserting a metal preionization member parallel to its axis into the resonator to increase the electric field strength and perform preionization, and then adjust the insertion amount of the metal preionization member to stabilize discharge. A cylindrical cavity, a microwave oscillator, a waveguide for supplying microwaves to the cavity, and a laser medium gas inserted along the axis of the cavity. With discharge tube In the microwave excitation device of the gas laser to be provided, by having a metal pre-ionization member inserted into the cavity resonator in parallel with its axis and so that the insertion length can be adjusted, various kinds of laser medium gas Discharge can be stably generated under pressure conditions, and the discharge of the laser medium gas can be effectively excited with electric field strength suitable for laser oscillation, and thus microwave of gas laser which improves laser output and oscillation efficiency The present invention is industrially very useful because it provides an excitation method and apparatus.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an embodiment of a microwave excitation device for a gas laser according to the present invention.

FIG. 2 is a front sectional view of a conventional device.

[Description of Signs] 1 Discharge tube 2 Microwave oscillator 3 Waveguide 4 Cylindrical cavity resonator 5 Total reflection mirror 6 Output mirror 7 Laser beam 8 Metal cylinder for preionization

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01S 3/0973 H01S 3/0977

Claims (2)

(57) [Claims] 1. A microwave oscillated from a microwave oscillator is guided to a cylindrical cavity resonator via a waveguide to generate a uniform _TM010 mode microwave electric field in the axial direction of the cavity. In a microwave excitation method of a gas laser in which a laser medium gas enclosed in a discharge tube inserted in an axial direction into a resonator is excited by its electric field to obtain a laser output, the shaft is inserted into the cavity resonator. A gas laser characterized in that a metal preionization member is inserted in parallel to increase the electric field strength to perform preionization, and thereafter the discharge amount is stabilized by adjusting the insertion amount of the metal preionization member. Microwave excitation method. 2. A tubular cavity resonator, a microwave oscillator, and a waveguide for supplying microwaves to the cavity resonator.
In a gas laser microwave excitation device having a discharge tube inserted along the axis of the cavity resonator and filled with a laser medium gas, the insertion length of the cavity resonator is adjusted in parallel with the axis of the cavity resonator. A microwave excitation apparatus for a gas laser, comprising a pre-ionization member made of metal which is inserted as possible.