JPH1126841A - Method and device for laser oscillation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser oscillation method and a laser oscillation device which can increase its laser oscillation efficiency and laser output. SOLUTION: An oscillator 18 for oscillating an electromagnetic wave is connected to a rectangular cavity resonator 16 through a waveguide 17. A discharge tube 11 is coaxially provided within the resonator 16. The tube 11 is coaxially provided at its one end with a total reflection mirror and at the other end with a cooling discharge tube 19 of metallic material. Mounted on an outer peripheral surface of the tube 19 is a water jacket 19a for passage cooling water. An output mirror 13 is provided at the other end of the tube 19. The tube 11 is provided at its one end with an inlet pipe 14 for a laser medium gas 1. An outlet pipe 15 for the laser medium gas 1 is connected to the other end of the tube 19. As a result, the discharge excitation of the gas 1 is concentrated in an upstream direction of the gas 1. As a result, a power for the discharge excitation can be reduced to the minimum, and the laser medium gas 1 in the downstream direction of the gas flow can be efficiently cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser oscillating method and a laser oscillating device for oscillating laser light by discharging and exciting a laser medium gas by electromagnetic waves in a high frequency range.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional laser oscillating device which oscillates laser light by discharging and exciting a laser medium gas by electromagnetic waves in a high frequency range.

As shown in FIG. 4, a discharge tube 101 is provided coaxially inside a cylindrical cavity resonator 106 in which an oscillator 108 for oscillating electromagnetic waves is connected via a waveguide 107. I have. At one end of the discharge tube 101, a total reflection mirror 102 is attached. An output mirror 103 is attached to the other end of the discharge tube 101. Discharge tube 1
01 is connected to an inlet pipe 104 of the laser medium gas 1. An outlet tube 105 for the laser medium gas 1 is connected to the other end of the discharge tube 101.

In such a laser oscillation device, the inlet tube 1
When the laser medium gas 1 is supplied into the discharge tube 101 from the tube 04 and an electromagnetic wave is oscillated from the oscillator 108, the electromagnetic wave propagates through the waveguide 107 and the cavity resonator 106.
The laser medium gas 1 in the discharge tube 101 is discharge-excited by an electric field to obtain induced discharge light from the laser medium gas 1, and is reflected back and forth between the total reflection mirror 102 and the output mirror 103. The laser beam 2 is oscillated by transmitting the output mirror 103 after the amplification.

[0005]

As described above, various methods (for example, Handy and Brandeli) oscillate a laser beam 2 by exciting a laser medium gas 1 by discharge with an electromagnetic wave.
k, J. Appl. Phys. Vol. 49, p3753-3756 (1978)). However, in the laser oscillation device as described above, the discharge space is configured so that the laser medium gas 1 in the discharge tube 101 stays on the optical axis as much as possible to increase the laser output. The laser medium gas 1 must be discharge-excited over the entire length, and a large amount of power is required when the laser medium gas 1 is discharge-excited.

Further, since the discharge plasma generated by the electric field easily absorbs electric power and the temperature of the laser medium gas 1 tends to rise, it is necessary to cool the laser medium gas 1. In such a system, since a high-voltage electrode and a high-current coil are installed in the discharge tube 101, a water-cooled double-tube discharge tube 101 made of ceramics having low thermal conductivity and insulating properties must be used. In addition, the laser medium gas 1 could not be efficiently cooled.

For this reason, the laser oscillation efficiency and the laser output of the conventional laser oscillation device as described above are not good.

Accordingly, it is an object of the present invention to provide a laser oscillation method and a laser oscillation device capable of improving the laser oscillation efficiency and the laser output.

[0009]

In order to solve the above-mentioned problems, a laser oscillation method according to the present invention is a laser oscillation method in which a laser medium gas is excited by an electric field to oscillate laser light. An electric field is formed upstream of the gas flow direction to excite the laser medium gas upstream of the gas flow direction, while cooling the laser medium gas downstream of the gas flow direction of the laser medium gas. .

In the above-described laser oscillation method, the flow of the laser medium gas on the downstream side in the flow direction is disturbed.

In order to solve the above-mentioned problems, a laser oscillation device according to the present invention comprises a discharge tube to which a laser medium gas is supplied, and an electric field for exciting the laser medium gas in the discharge tube. A laser oscillating device that oscillates a laser beam, wherein the exciting unit is provided on the discharge tube upstream of the discharge medium in the flow direction of the laser medium gas, and a metal cooling discharge tube is connected to the discharge tube. And a cooling means for cooling the laser medium gas is provided in the cooling discharge tube, while being coaxially connected to the downstream side of the laser medium gas supply direction.

In the above-described laser oscillation device, a turbulence generating means for disturbing the flow of the laser medium gas is provided inside the cooling discharge tube.

[0013] In the above-mentioned laser oscillation device, the cooling means is provided on an outer peripheral surface of the cooling discharge tube, and is a cooling water flowing means for flowing cooling water.

In the above-described laser oscillation device, the cooling means is provided on an inner peripheral surface of the cooling discharge tube, and is a cooling water flowing means for flowing cooling water.

In the above-described laser oscillation device, the turbulence generating means is an annular block ring provided coaxially with the inner peripheral surface of the cooling discharge tube.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a laser oscillation method and a laser oscillation device according to the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the apparatus.

As shown in FIG. 1, a discharge tube 11 is provided coaxially inside a rectangular cavity resonator 16 in which an oscillator 18 for oscillating electromagnetic waves is connected via a waveguide 17. I have. A total reflection mirror 12 is attached to one end of the discharge tube 11. One end of a metal cooling discharge tube 19 is coaxially connected to the other end of the discharge tube 11. On the outer peripheral surface of the cooling discharge tube 19, a water jacket 19a, which is a cooling water flowing means for flowing the cooling water, is provided as a cooling means. The output mirror 13 is attached to the other end of the cooling discharge tube 19. An inlet tube 14 for the laser medium gas 1 is connected to one end of the discharge tube 11.
The outlet tube 15 for the laser medium gas 1 is connected to the other end of the cooling discharge tube 19. That is, the laser medium gas 1
The discharge tube 11, the cavity resonator 16, the waveguide 17, the oscillator 18 and the like are disposed on the upstream side in the flow direction of the laser medium, and the cooling discharge tube 19, the water jacket 19a and the like are disposed on the downstream side in the flow direction of the laser medium gas 1. It was set up. In this embodiment, the cavity resonator 16, the waveguide 17, the oscillator 18, and the like constitute an excitation unit.

Next, a laser oscillation method using such a laser oscillation device will be described. The laser medium gas 1 is supplied from the inlet tube 14 into the discharge tube 11 and the cooling discharge tube 19, and the water jacket 19 a of the cooling discharge tube 19 is provided.
When the electromagnetic wave is oscillated from the oscillator 18 while operating the electromagnetic wave, the electromagnetic wave propagates through the waveguide 17 and
6, the laser medium gas 1 in the discharge tube 11 is discharge-excited by an electric field, and the laser medium gas 1 whose temperature is increased by the discharge excitation is cooled to an appropriate temperature by the water jacket 19a of the cooling discharge tube 19. As a result, the induced discharge light is obtained from the laser medium gas 1, reciprocally reflected between the total reflection mirror 12 and the output mirror 13, amplified, and then transmitted through the output mirror 13, whereby the laser light 2 is oscillated.

That is, when the laser medium gas 1 is discharge-excited by an electric field to oscillate the laser beam 2, an electric field is formed on the upstream side in the flow direction of the gas 1 so that the vibration excitation of the gas 1 is performed on the upstream side in the flow direction. On the other hand, the gas 1 is cooled on the downstream side in the flow direction of the gas 1.

For this reason, the discharge excitation of the laser medium gas 1 is concentrated on the upstream side in the flow direction of the gas 1, so that the electric power at the time of discharge excitation of the laser medium gas 1 is minimized. Can be.

Even when a high-voltage electrode or a high-current coil is installed in the discharge tube 11 as in a DC discharge system or a high-frequency discharge system, the installation is performed only on the upstream side in the flow direction of the laser medium gas 1. As a result, there is no need to particularly consider insulation on the downstream side in the flow direction of the gas 1, and the cooling discharge tube 1 made of a metal material having high thermal conductivity is not required.
9 can be installed downstream of the laser medium gas 1 in the flow direction, so that the laser medium gas 1 can be efficiently cooled.

Therefore, according to such a laser oscillation method and a laser oscillation device, the laser oscillation efficiency and the laser output can be greatly improved.

In this embodiment, the water jacket 19a is used as the cooling water distribution means. However, the cooling water distribution means can be formed by winding a water cooling coil around the outer peripheral surface of the cooling discharge tube 19. .

A second embodiment of the laser oscillation method and the laser oscillation device according to the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the apparatus. However, the same members as those in the above-described first embodiment are denoted by the same reference numerals as those in the above-described first embodiment, and description thereof will be omitted.

As shown in FIG. 2, on the inner peripheral surface of the cooling discharge tube 19, a water cooling coil 29a, which is a cooling water circulating means for circulating cooling water, is provided as a cooling means.

That is, in the above-described embodiment, the laser medium gas 1 is cooled from outside the cooling discharge tube 19, but in the present embodiment, the laser medium gas 1 is cooled from inside the cooling discharge tube 19. I did it.

For this reason, the laser medium gas 1 can be cooled more efficiently than in the above-described embodiment.

Therefore, according to the present embodiment, the laser oscillation efficiency and the laser output can be further improved as compared with the above-described embodiment.

A third embodiment of the laser oscillation method and the laser oscillation device according to the present invention will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the apparatus. However, the same members as those in the first and second embodiments described above are denoted by the same reference numerals as those in the first and second embodiments, and description thereof will be omitted.

As shown in FIG. 3, the water jacket 1
On the inner peripheral surface of the cooling discharge tube 19 having the outer peripheral surface 9a, there is provided a block ring 39 serving as a turbulent flow generating means having a metal annular shape.
a are coaxially mounted at predetermined intervals along the axial direction of the cooling discharge tube 19.

That is, in the present embodiment, the block ring 39a is provided in the first embodiment described above.

In such a laser oscillation device, the flow of the laser medium gas 1 flowing in the cooling discharge tube 19 is disturbed by the block ring 39a, so that the laser medium gas 1 is mixed in the cooling discharge tube 19 and the gas is mixed. 1 and cooling discharge tube 19
The heat exchange efficiency with the substrate is greatly improved.

Therefore, according to the present embodiment, the laser oscillation efficiency and the laser output can be further improved as compared with the above-described embodiment.

[0034]

EXAMPLE In order to confirm the effects of the laser oscillation method and the laser oscillation device according to the present invention, the following confirmation experiments were performed.

[Experimental Example 1] The laser output and the laser oscillation efficiency when the laser light was oscillated using the apparatus based on the first embodiment described above were obtained. The conditions are as follows.

<Conditions> Electromagnetic wave-wavelength: 2.45 GHz Incident power: 1500 W Laser medium gas-composition: mixed gas of CO ₂ , N ₂ , He (gas for carbon dioxide laser) Pressure: 50 Torr cavity cavity -Inner diameter: 83 mm Length: 100 mm-Discharge tube-Inner diameter: 25 mm-Cooling discharge tube-Material: Aluminum Inner diameter: 30 mm Length: 300 mm <Results> The results are shown in Table 1.

[Experimental Example 2] The laser output and the laser oscillation efficiency when the laser light was oscillated using the apparatus according to the second embodiment described above were obtained. The conditions are as follows. However, the description of the same parts as in Experimental Example 1 is omitted.

<Conditions> Water-cooled coil-outer diameter: 2 mm <Results> The results are shown in Table 1.

[Experimental Example 3] The laser output and the laser oscillation efficiency when the laser light was oscillated using the apparatus based on the third embodiment described above were obtained. The conditions are as follows. However, the description of the same parts as in Experimental Examples 1 and 2 is omitted.

<Conditions> Blocking-Material: Aluminum <Results> The results are shown in Table 1.

Comparative Example For comparison, a laser output and a laser oscillation efficiency when a laser beam was oscillated using the apparatus described in the prior art were determined. The conditions are as follows. However, the description of the same parts as in Experimental Examples 1 to 3 is omitted.

<Conditions>-Discharge tube-material: quartz (without water cooling) <Results> The results are shown in Table 1.

[0043]

[Table 1]

As can be seen from Table 1, in the comparative example, the laser output was 130 W and the laser oscillation efficiency was 9%, whereas in Experimental Example 1, the laser output was 170 W and the laser oscillation efficiency was 11%. It was confirmed that the laser output and laser oscillation efficiency could be greatly improved by improving the cooling efficiency of the laser medium gas. In Experimental Example 2, the laser output was 200 W and the oscillation efficiency was 13%.
It was confirmed that the cooling efficiency could be further improved, and the laser output and laser oscillation efficiency could be further improved.
Further, in Experimental Example 3, the laser output was 250 W and the laser oscillation efficiency was 16%, and it was confirmed that the cooling efficiency was further improved as compared with Experimental Examples 1 and 2, and the laser output and laser oscillation efficiency could be further improved.

In this embodiment, a microwave having a frequency of 2.45 GHz is used as the electromagnetic wave. However, the same effect as described above can be obtained by applying a high frequency of 13.56 MHz by further measures such as insulation measures. it is conceivable that.

[0046]

The laser oscillation method according to the present invention is a laser oscillation method in which a laser medium gas is excited by an electric field to oscillate laser light, wherein an electric field is formed on the upstream side in the flow direction of the laser medium gas. While the laser medium gas is excited on the upstream side in the flow direction, while the laser medium gas is cooled on the downstream side in the flow direction of the laser medium gas, the discharge excitation of the laser medium gas is performed on the upstream side in the flow direction of the gas. As a result, the power required for the laser medium gas discharge excitation can be minimized, and high-voltage electrodes and high-current coils, such as the DC discharge method and the high-frequency discharge method, are connected to the discharge tube. Even when the laser medium gas is installed, the installation is only required on the upstream side in the laser medium gas flow direction, and it is necessary to particularly consider insulation properties on the downstream side in the laser medium gas flow direction. And the cooling discharge tube made of a metal material having high thermal conductivity can be installed downstream of the laser medium gas flow direction, so that the laser medium gas can be efficiently cooled. And the laser output can be greatly improved.

Further, since the flow of the laser medium gas on the downstream side in the flow direction is disturbed, the laser medium gas whose temperature has increased can be mixed, and the cooling efficiency of the gas can be greatly improved. Oscillation efficiency and laser output can be further improved.

The laser oscillation device according to the present invention comprises a discharge tube to which a laser medium gas is supplied and excitation means for generating an electric field to excite the laser medium gas in the discharge tube to oscillate laser light. A laser oscillation device provided, wherein the excitation means is provided upstream of the discharge tube in the flow direction of the laser medium gas, and a metal cooling discharge tube is provided in a direction in which the laser medium gas is supplied to the discharge tube. Coaxially connected to the downstream side, and the cooling means for cooling the laser medium gas is provided in the cooling discharge tube,
The discharge excitation of the laser medium gas is concentrated on the upstream side in the flow direction of the gas, so that the power required for the excitation of the discharge of the laser medium gas can be suppressed to the minimum necessary. Even when a high-voltage electrode or high-current coil is installed in the discharge tube as in the method, the installation only needs to be performed on the upstream side in the flow direction of the laser medium gas, and the insulation is performed on the downstream side in the flow direction of the laser medium gas. It is not necessary to take into account particularly, and it is possible to install a cooling discharge tube made of a metal material having high thermal conductivity on the downstream side in the flow direction of the gas, and it is possible to efficiently cool the laser medium gas. In addition, laser oscillation efficiency and laser output can be greatly improved.

Further, since the turbulence generating means for disturbing the flow of the laser medium gas is provided inside the cooling discharge tube, the laser medium gas whose temperature has increased can be mixed, and the cooling efficiency of the gas can be greatly increased. Can be improved
Laser oscillation efficiency and laser output can be further improved.

Further, if the cooling means is provided on the outer peripheral surface of the cooling discharge tube and is a cooling water flowing means for flowing cooling water, the laser medium gas can be cooled efficiently, and the laser oscillation efficiency and laser The output can be greatly improved.

Further, if the cooling means is provided on the inner peripheral surface of the cooling discharge tube and allows cooling water to flow, the laser medium gas can be cooled more efficiently, and the laser oscillation efficiency can be improved. And the laser output can be further improved.

Further, if the turbulence generating means is an annular block ring provided coaxially with the inner peripheral surface of the cooling discharge tube, the laser medium gas whose temperature has increased can be easily mixed. In addition, the cooling efficiency of the gas can be easily improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a laser oscillation device according to the present invention.

FIG. 2 is a schematic configuration diagram of a second embodiment of the laser oscillation device according to the present invention.

FIG. 3 is a schematic configuration diagram of a third embodiment of the laser oscillation device according to the present invention.

FIG. 4 is a schematic configuration diagram of an example of a conventional laser oscillation device.

DESCRIPTION OF SYMBOLS 1 Laser medium gas 2 Laser light 11 Discharge tube 12 Total reflection mirror 13 Output mirror 14 Inlet tube 15 Outlet tube 16 Cavity resonator 17 Waveguide 18 Oscillator 19 Cooling discharge tube 19a Water jacket 29a Cooling coil 39a Block ring

Claims (7)

[Claims] 1. A laser oscillation method in which a laser medium gas is excited by an electric field to oscillate laser light, wherein an electric field is formed on an upstream side in a flow direction of the laser medium gas to excite the laser medium gas. A laser oscillation method characterized in that the laser medium gas is cooled on the downstream side in the flow direction of the laser medium gas while being performed on the upstream side in the direction. 2. The laser oscillation method according to claim 1, wherein a flow of the laser medium gas in a flow direction downstream is disturbed. 3. A discharge tube supplied with a laser medium gas,
An excitation means for exciting the laser medium gas in the discharge tube by forming an electric field to oscillate a laser beam, wherein the excitation means is provided for the laser medium gas in the discharge tube. A cooling discharge tube made of metal is coaxially connected to a downstream side of the discharge tube in a direction in which the laser medium gas is supplied, and a cooling means for cooling the laser medium gas is provided on the upstream side in the flow direction. A laser oscillation device provided in a discharge tube. 4. The laser oscillation device according to claim 3, wherein turbulence generating means for disturbing the flow of the laser medium gas is provided inside the cooling discharge tube. 5. The laser oscillation device according to claim 3, wherein said cooling means is a cooling water distribution means provided on an outer peripheral surface of said cooling discharge tube for flowing cooling water. . 6. The laser oscillation device according to claim 3, wherein said cooling means is provided on an inner peripheral surface of said cooling discharge tube, and is a cooling water flowing means for flowing cooling water. apparatus. 7. The laser oscillation device according to claim 4, wherein said turbulence generating means is an annular block ring provided coaxially on an inner peripheral surface of said cooling discharge tube. Laser oscillation device.