JP2980381B2 - Laser equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device which excites a laser medium by discharge heating to oscillate laser light.

[0003]

2. Description of the Related Art FIG. 3 shows a conventional laser device 41. In the figure, a laser device 41 includes a vacuum vessel 3, a pair of cylindrical electrodes 5 and 7 disposed in the vacuum vessel 3, and a cylindrical discharge tube 9 disposed between the electrodes 5 and 7. And a power supply 13 for applying a voltage between the pair of electrodes 5 and 7, and resonator mirrors 15 and 17 disposed outside the vacuum vessel 3 for extracting laser light.

The vacuum vessel 3 has a cylindrical shape, has windows 19 at both ends, and has a laser gas inlet 21 and an exhaust port 23 near both ends. A laser gas is supplied from a laser gas inlet 21 into the vacuum vessel 3 by a laser gas supply unit (not shown), and a vacuum vessel 3 is supplied from an exhaust port 23.
Unnecessary gas inside is exhausted.

The electrodes 5 and 7 are arranged in the vacuum vessel 3 such that both ends thereof face the window 19, respectively.
3 applies a voltage. By applying a voltage to these electrodes 5 and 7, discharge is performed in the laser gas sealed in the vacuum vessel 3.

In the laser apparatus 41 having the above-described structure, the vacuum vessel 3 is evacuated from the exhaust port 23 to evacuate the inside of the vacuum vessel 3, and then a laser gas is introduced from the laser gas inlet 21 to form a cylindrical electrode. A voltage is applied by the power supply 13 between 5 and 7 to discharge in the discharge tube 9. As a result, the laser medium in the laser gas in the discharge tube 9 is excited, and laser light is extracted.

However, in the above-mentioned conventional laser device 41, the temperature near the central axis of the discharge tube 9, that is, near the optical axis of the laser beam, is increased by the heat generated by the discharge as compared with the surrounding temperature. Since the cooling of the laser gas is mainly performed by heat conduction from the discharge tube 9, the temperature of the laser gas around the central axis of the discharge tube 9 becomes higher than that of the surroundings.

In order to efficiently perform laser oscillation, it is important to efficiently excite the laser medium to the upper level of laser light oscillation or to efficiently remove the lower level.

However, the energy level of the level is 2
When a relatively low laser medium of 3 ev or less is used, the laser medium is easily thermally excited to a lower level due to a rise in the temperature of the laser gas. For this reason, the density of the lower level near the center axis increases, the oscillation intensity at the center decreases, and oscillation at the center does not occur. In addition, the oscillation output and oscillation efficiency of the laser beam also decrease.

[0010] Such a tendency becomes more remarkable as the size of the laser device becomes larger and the output becomes larger.

[0011]

As described above, in the conventional laser device, the temperature near the optical axis of the generated laser light becomes higher than the surrounding temperature, so that the density of the lower level near the optical axis is increased. And the oscillation intensity at the center decreases, and oscillation at the center hardly occurs.

An object of the present invention is to provide a laser device in which the oscillation intensity near the optical axis of laser light does not decrease.

[Structure of the Invention]

[0014]

In order to achieve the above object, according to the first aspect of the present invention, near the optical axis of laser light,
Along this optical axis, the circumference of the laser gas near the optical axis
A cooling means for suppressing a rise in temperature with respect to the temperature of the surrounding laser gas is provided.

According to a second aspect of the present invention, the cooling means according to the first aspect is characterized in that the cooling means is an electrically insulating pipe disposed near the optical axis and through which a refrigerant passes. According to the third aspect of the present invention, the cooling means of the first aspect includes:
It is disposed near the optical axis and has thermal conductivity.

[0016]

According to the first aspect of the present invention, the optical axis portion is cooled by the cooling means arranged near the optical axis of the laser beam, and the temperature rise is suppressed.

As a result, the laser medium is less likely to be excited to the lower level, and an increase in the lower level density near the central axis is suppressed. As a result, the oscillation intensity at the center does not decrease.
Oscillation output and efficiency of laser light increase.

According to the second aspect of the present invention, since the pipeline through which the refrigerant passes is provided along the central axis and near the central axis, heat of the central axis is released to the refrigerant by the refrigerant. The temperature rise of the central shaft is suppressed.

Further, by adjusting the flow rate of the refrigerant passing through the pipeline by the flow rate adjusting means, the temperature of the center axis can be adjusted to an arbitrary temperature, thereby making it possible to adjust the operation suitable for laser light oscillation. Temperature can be controlled.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a laser device according to the present invention will be described below with reference to the drawings. Note that the same components as those of the laser device 41 shown in FIG. 3 are denoted by the same reference numerals in the drawings, and redundant description will be omitted.

First Embodiment FIG. 1 shows a laser device 1. The laser device 1 has a structure in which a cooling tube 11 is inserted through the discharge tube 9 and the electrodes 5 and 7. This cooling pipe 11
Is made of ceramic, through which a cooling gas supplied by a cooling gas supply means (not shown), particularly a cooling gas having good thermal conductivity such as helium, passes. The cooling gas absorbs heat near the central axis of the vacuum vessel 3, that is, near the optical axis, and cools the vicinity of the optical axis of the laser beam L.

As a result, the temperature rise of the laser gas near the center axis of the vacuum vessel 3 is suppressed, the laser medium is hardly excited to the lower level, the oscillation intensity at the center does not decrease, and the oscillation output of laser light and Efficiency increases. This is particularly effective for a large laser device. Furthermore, the flow rate of the cooling gas flowing through the inside of the vacuum vessel 3 can be adjusted, and the temperature near the center axis of the laser gas is maintained at a predetermined temperature, so that the laser gas can be operated at an operating temperature suitable for laser oscillation. Oscillation output and oscillation efficiency can be obtained. In particular, high oscillation output and oscillation efficiency can be obtained when the device is enlarged, enlarged in diameter, and increased in output.

Also, the flow rate can be adjusted by monitoring the laser output and the oscillation pattern and feeding back the results.

In the above-described embodiment, an example in which ceramic is used as the cooling pipe 11 through which gas flows is shown. However, the present invention is not limited to this. A pipe having a heat pipe structure may be inserted into the electrode 5 or the heat conductive pipe may be used. A good rod may be inserted into the electrodes 5 and 7. The refrigerant may be a liquid other than a gas.

Second Embodiment Next, a laser device 31 according to a second embodiment will be described with reference to FIG. The laser device 31 of the present embodiment is a case of a metal vapor laser device using metal vapor as a laser medium. In the laser device 31 of the present embodiment, a heat insulating material 33 is wound around a discharge tube 9 disposed between the electrodes 5 and 7, and a flow regulating device 3 that regulates the flow rate of the refrigerant in the middle of the cooling tube 11.
5 are arranged. The laser medium metal 8 is provided on the discharge tube 9.

According to the present embodiment, the electrodes 5 and 7 are driven by the power source 13 while the laser gas is sealed in the vacuum vessel 3.
When a voltage is applied in between, discharge occurs in the laser gas, and the laser medium metal 8 in the discharge tube 9 is heated and vaporized, and metal vapor is generated. Further, the metal vapor is excited by the discharge, and laser light oscillates.

At this time, gas flows in the cooling pipe 11 and
Although the vicinity of the central axis of the discharge tube 9 is cooled, the heat insulating material 33 is arranged around the discharge tube 9 and the discharge tube 9 is kept warm, so that the temperature rise of the laser gas near the central axis is suppressed, The laser medium is less likely to be excited to a lower level, the oscillation intensity at the center does not decrease, and the oscillation output and oscillation efficiency of the laser increase. In addition, by adjusting the flow rate of the gas flowing inside the tube and adjusting the flow rate so that the temperature near the central axis of the laser gas is almost equal to the wall temperature of the discharge tube, it operates at an operating temperature suitable for laser oscillation. And higher oscillation efficiency and oscillation output can be obtained.
Instead of inserting a ceramic tube in which gas has flowed into the center of the discharge tube, a tube having a heat pipe structure may be inserted, or a rod having good heat conduction characteristics may be inserted.
In this case, it is particularly effective when the size, diameter, and output of the apparatus are increased.

The present invention provides a metal ion laser, a carbon dioxide laser,
The present invention can also be applied to a laser device such as a fluorine laser device using a laser medium whose energy level of the lower level is relatively low. Further, as a means for cooling the laser gas near the central axis of the discharge tube, a method other than the above embodiments can be applied.

In each of the above embodiments, the cooling pipe 11 is arranged in parallel with the optical axis of the laser light. However, the present invention is not limited to this, and cooling means other than the cooling pipe 11 may be arranged along the optical axis of the laser light. Alternatively, the cooling pipe 11 may be bent. Further, the cooling pipe 11 may be spirally arranged near the optical axis of the laser beam.

[0030]

As described above, according to the present invention, the oscillation intensity near the optical axis of the laser beam does not decrease,
The effect is obtained that a laser device having a large output and good oscillation efficiency can be provided.

[Brief description of the drawings]

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

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

FIG. 3 is a configuration diagram showing a conventional laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 31 Laser apparatus 3 Vacuum container 5, 7 electrode 9 Discharge tube 11 Cooling tube 13 Power supply 15, 17 Resonator mirror 33 Insulation material

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ikuo Watanabe 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Research Institute Co., Ltd. (56) References JP-A-56-80190 (JP, A) JP-A Sho 49-9198 (JP, A) JP-A-49-64390 (JP, A) JP-A-1-286475 (JP, A) JP-A-56-131985 (JP, A) JP-A-49-64392 (JP, A) A) (58) Field surveyed (Int.Cl. ⁶ , DB name) H01S 3/041 H01S 3/03

Claims (3)

(57) [Claims] 1. A laser device which discharges in a laser gas containing a metal vapor to excite a laser medium and oscillate laser light , wherein a laser near an optical axis of the laser light is provided.
Temperature rise of the gas relative to the temperature of the laser gas around it
Cooling means for suppressing the vicinity of the optical axis of the laser light.
And a laser device arranged along the optical axis . 2. The laser apparatus according to claim 1, wherein said cooling means is a conduit disposed near said optical axis and having electrical insulation and through which a refrigerant passes. 3. The laser device according to claim 1, wherein said cooling means is disposed near said optical axis and has thermal conductivity.