JP2871217B2 - Microwave pumped gas 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 microwave-excited gas laser device.

[0002]

2. Description of the Related Art In a conventional microwave-excited gas laser 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 passes through the coupling portion 8 having the size of the waveguide 3 shown in the side view of FIG. The transmitted laser medium gas in the discharge tube 1 is discharged and excited by the electric field of the microwave. 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,
Since a large number of standing waves of microwaves that can be formed in the cylindrical cavity resonator 4 are mixed as known as TM or TE mode, the waveguide 3 and the cylindrical cavity resonator 4 When the opening of the cavity in the coupling portion 8 is the same as the size of the waveguide 3, as shown in the schematic diagram of FIG. The wave electric field intensity is not constant in the discharge tube axis direction. Therefore, the laser medium gas in the entire discharge tube 1 cannot be excited by discharge, and the electric field of the discharge is concentrated in a local space in the discharge tube 1, so that the temperature of the generated discharge plasma increases, thereby contributing to laser oscillation. Since the inversion distribution of the energy level is hardly established, there are disadvantages such as low laser output and oscillation efficiency. In addition, since the load as a microwave circuit fluctuates greatly due to the generation of discharge plasma, there is a disadvantage that the discharge becomes unstable.

[0004]

[0008] The present invention has been proposed in view of such circumstances, TM ₀₁₀ suitable for laser oscillation from a variety of microwave electromagnetic field mode in the cylindrical cavity resonator An object of the present invention is to provide a microwave-excited gas laser device capable of uniformly exciting a laser medium gas in a discharge tube by only a mode and improving laser output and oscillation efficiency.

[0005]

For this purpose, the present invention provides a cylindrical cavity resonator, a microwave oscillator, a waveguide for propagating microwaves oscillated by the microwave oscillator, and a waveguide. An optical resonator comprising a coaxial tube connected to a tube for introducing microwaves into the cavity resonator, a discharge tube axially inserted into the cavity resonator, and mirrors disposed at both ends of the discharge tube; And a rotatable loop antenna in which the outer conductor of the coaxial tube is connected to the cavity resonator, and the inner conductor and the outer conductor of the coaxial tube are connected to each other. And a cylindrical cavity resonator, a microwave oscillator, a waveguide for propagating microwaves oscillated by the microwave oscillator, and a microwave connected to the waveguide, Coaxial tube introduced into cavity resonator A microwave-excited gas laser device comprising a discharge tube inserted axially into the cavity resonator and optical resonators comprising mirrors arranged at both ends of the discharge tube; A conductor is connected to the cavity resonator, and an inner conductor of the coaxial waveguide is formed in a probe-like antenna whose insertion amount can be adjusted into the cavity resonator.

[0006]

In the microwave-excited gas laser apparatus according to the present invention, a coaxial tube is installed at the joint between the waveguide and the cylindrical cavity resonator, and a loop-shaped or probe-shaped antenna is inserted into the cavity resonator. The microwave is efficiently transmitted through the cavity by adjusting the angle between the loop surface and the cavity in the axial direction or the length of the probe inserted into the cavity. As a result, by specifying the electromagnetic field mode of the microwave formed inside the cavity and facilitating the formation of the _TM010 mode, the discharge is generated by the uniform microwave electric field in the axial direction of the cavity. A uniform discharge can be generated in the tube axis direction, and the entire laser medium gas in the discharge tube can be excited by discharge. By performing the above adjustment, the transmitted microwave power to the inside of the cavity resonator can be controlled, so that the load fluctuation due to the fluctuation of the plasma density in the discharge tube can be suppressed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the microwave-excited gas laser apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view of a first embodiment in which a loop antenna is formed, and FIG. 2 is a cylindrical cavity resonator in the same. FIG. 3 is a schematic view of a microwave electromagnetic field mode in the above, and FIG. 4 is a side view of a cylindrical cavity resonator in a second embodiment in which a probe-like antenna is formed.

In FIGS. 1 and 2 of the first embodiment, FIG.
6, the same members as those in FIG. 6 are denoted by the same reference numerals, and the outer conductor of the coaxial tube 10 attached to the coupling portion 8 between the waveguide 3 and the cylindrical cavity resonator 4 (inner diameter 8.6 cm, length 20 cm). A part of the inner conductor 10b is brought into contact with the inner conductor 10b by a conductor to form a loop antenna 11 inserted into the cylindrical cavity resonator 4, and the loop surface of the loop antenna 11 and the cylindrical cavity resonator 4 are formed. An experiment was performed using the angle in the axial direction as a parameter shown in Table 1.

[Table 1]

The loop surface angle of the loop antenna 11 is 5
In the case of °, the electromagnetic field strength in the cylindrical cavity resonator 4 is constant in the axial direction of the discharge tube 1 as can be seen from the electric field vector 9 shown in FIG. Discharge tube 1
The whole discharges uniformly. At this loop plane angle, the reflection of the microwave to the microwave oscillator 2 is almost zero with respect to the cylindrical cavity resonator 4, and the microwave is efficiently transmitted into the cylindrical cavity resonator 4. Recognize. Table 1 shows the laser output and oscillation efficiency obtained at various loop plane angles for the carbon dioxide laser medium gas.

Next, in FIG. 4 of the second embodiment, in this case, only the inner conductor 10b of the coaxial tube 10 is inserted into the cavity from the end face of the cylindrical cavity resonator 4, and the probe antenna 12 is inserted.
When an experiment was performed using the probe insertion length as a parameter shown in Table 1, the probe insertion length was 5 mm.
The result with the best performance was obtained.

On the other hand, the laser output and the oscillation efficiency in the conventional case where no antenna is provided at the coupling portion 8 between the waveguide 3 and the cylindrical cavity resonator 4 are shown in Table 1 for reference. The electric field is not constant in the direction, the discharge becomes non-uniform, and the laser output and the oscillation efficiency are low.

Thus, according to such a device, a uniform discharge of the laser medium gas can be generated in the axial direction of the discharge tube provided in the cylindrical cavity resonator 4, and the laser in the discharge tube 1 can be generated. Discharge excitation of the medium gas can be effectively performed.

[0013]

In summary, according to the present invention, a cylindrical cavity resonator, a microwave oscillator, a waveguide for propagating microwaves oscillated by the microwave oscillator, and a connection to the waveguide A coaxial tube for introducing microwaves into the cavity resonator, a discharge tube axially inserted into the cavity resonator, and an optical resonator including mirrors disposed at both ends of the discharge tube. In the microwave pumped gas laser device provided, the outer conductor of the coaxial tube is connected to the cavity resonator, and the inner conductor and the outer conductor of the coaxial tube are connected to form a rotatable loop antenna. That a cylindrical cavity resonator, a microwave oscillator, a waveguide for propagating microwaves oscillated by the microwave oscillator, and a microwave connected to the waveguide and transmitting the microwave to the cavity resonator. Coaxial tube to be introduced into the In a microwave-excited gas laser device comprising a discharge tube inserted into a resonator in an axial direction and optical resonators including mirrors arranged at both ends of the discharge tube, an outer conductor of the coaxial tube has an empty space. By connecting the inner conductor of the coaxial tube to the probe-shaped antenna which can be inserted into the cavity resonator and connected to the cavity resonator, various micro-cavities can be formed in the cylindrical cavity resonator. A microwave-excited gas laser device that can uniformly excite and excite the laser medium gas in the discharge tube in only the _TM010 mode suitable for laser oscillation from the wave electromagnetic field mode and improve laser output and oscillation efficiency, The invention is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a first embodiment in which a loop antenna of a microwave-excited gas laser device of the present invention is formed.

FIG. 2 is a side view of the cylindrical cavity resonator in the above.

FIG. 3 is a schematic diagram of a microwave electromagnetic field mode in the above.

FIG. 4 is a side view of a cylindrical cavity resonator according to a second embodiment in which a probe antenna is formed.

FIG. 5 is a front sectional view of a conventional microwave-excited gas laser device.

FIG. 6 is a side view of the cylindrical cavity resonator in the above.

FIG. 7 is a schematic diagram of a microwave electromagnetic field mode in the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge tube 2 Microwave oscillator 3 Waveguide 4 Cylindrical cavity resonator 5 Total reflection mirror 6 Output mirror 7 Laser light 8 Coupling part 9 Electric field vector 10 Coaxial tube 10a Outer conductor 10b Inner conductor 11 Loop antenna 12 Probe Antenna

(Equation 1)

Claims (2)

(57) [Claims] 1. A cylindrical cavity resonator, a microwave oscillator, a waveguide for propagating a microwave oscillated by the microwave oscillator, and a microwave connected to the waveguide and transmitting the microwave to the cavity. A microwave-excited gas laser comprising a coaxial tube to be introduced into a resonator, a discharge tube axially inserted into the cavity resonator, and an optical resonator including mirrors disposed at both ends of the discharge tube. In the device, the outer conductor of the coaxial waveguide is connected to the cavity resonator, and the inner conductor and the outer conductor of the coaxial waveguide are connected to each other to form a rotatable loop antenna. Wave-excited gas laser device. 2. A cylindrical cavity resonator, a microwave oscillator, a waveguide for transmitting microwaves oscillated by the microwave oscillator, and a microwave connected to the waveguide and transmitting the microwave to the cavity. A microwave-excited gas laser comprising a coaxial tube to be introduced into a resonator, a discharge tube axially inserted into the cavity resonator, and an optical resonator including mirrors disposed at both ends of the discharge tube. In the apparatus, an outer conductor of the coaxial waveguide is connected to the cavity resonator, and an inner conductor of the coaxial waveguide is formed in a probe-like antenna whose insertion amount can be adjusted into the cavity resonator. A microwave-excited gas laser device.