JPH10107360A - Laser oscillation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize laser output by constituting a laser oscillation device with a laser head that is set, so that a light axis is directed vertically and a cover for shutting off the laser head from external air, and controlling a temperature so that the temperature inside the cover becomes higher at an upper part than at a lower part. SOLUTION: Laser beams are taken extracted out of a vertically installed laser head 11 vea, for example, mirrors 12 and 13, focusing lenses 14a and 14b, and a spectroscope 15a. A laser oscillation tube of the laser head 11 is covered with a water-cooling pipe and is arranged in a cover 18, thus preventing the effects due to external temperature fluctuations. Also, heaters 19a and 19b are installed near the upper and lower edges of the laser head 11, and the convection of air is suppressed by setting the temperature at an upper side to be higher than that at the lower side, thus stabilizing the temperature in the cover 18 and hence reducing the temperature fluctuations around the laser head 11, preventing distance fluctuation between resonator mirrors, and stabilizing the output for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a laser oscillation device having a stable gas laser output and good environmental resistance.

[0002]

2. Description of the Related Art When performing fine processing such as fusion splicing of an optical fiber using a gas laser, it is important to stabilize the output of the gas laser. As shown in FIG. 4, for example, a laser oscillation device using a conventional gas laser includes an air-cooled or water-cooled laser head 1, a plurality of lenses 2a to 2c for condensing laser light, and a laser light for turning on / off the laser light. The shutter 3 includes a laser head 1 and a cover 4 that covers an optical system and is provided to prevent leakage of laser light and to ensure safety. In addition, a power sensor for measuring laser output and an output variable device are attached as required. In a laser oscillation device using a gas laser, when the temperature of the laser gas increases, the oscillation efficiency decreases. Therefore, a laser oscillation tube (not shown) constituting the laser head 1 is cooled by air or water cooling, and the electrodes are discharged. The electrodes are cooled because they generate heat and the heat tends to cause unstable discharge. Further, in order to stabilize the output of the gas laser, a laser oscillation device is installed in a constant temperature chamber so that the ambient temperature is kept constant.

[0003]

However, even if the laser head 1 is installed in a constant temperature chamber as described above, there is a limit in stabilizing the output of the gas laser, and it is necessary to control the output to be sufficiently constant for a long time. There was a problem that was difficult. In addition, there is a problem in that the use place of the laser oscillation device is limited because the laser oscillation device is installed in the constant temperature room, and that it is expensive to install facilities in the constant temperature room.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a laser head installed so that an optical axis is vertically oriented, and a cover for shielding the laser head from the outside air. The laser oscillation device is characterized in that the temperature inside the cover is controlled so that the temperature in the upper portion is higher than that in the lower portion.

As a result of diligent studies, the present inventor has found that variations in the distance between the resonator mirrors provided at both ends of the laser oscillation tube constituting the laser head, distortion of each resonator mirror, and deviation of the angle with respect to the optical axis. The inventors have found that this is a major cause of unstable gas laser output, and have reached the present invention. That is, in the laser oscillation device having the above-described configuration, the resonator mirror at the upper end of the laser oscillation tube constituting the vertical laser head is controlled to have a higher temperature than the resonator mirror at the lower end by the heater or the cooling device. Therefore, an upward airflow of air is generated along the laser head. Further, since the laser head is shielded from the outside air by the cover, the temperature inside the laser head can be controlled at a constant temperature, and the flow of the surrounding air is a stable natural convection, forming a rising laminar flow.
Here, the meaning of “the cover that shields the laser head from the outside air” means that the air outside the cover does not affect the temperature around the inside laser head 11 and the flow of air. Need not be completely airtight. It should be noted that this cover has a function of ensuring safety as in the related art. Therefore, according to the present invention, since the resonator mirrors provided at both ends of the laser head are located in an atmosphere at a stable temperature, the distance fluctuation between the resonator mirrors and the distortion of each resonator mirror,
The deviation of the angle with respect to the optical axis can be prevented, and the output is stabilized. Further, conventionally, the laser oscillation device is installed in a large and costly constant temperature room. However, according to the present invention, it is not necessary to use such a constant temperature room.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram of one embodiment of a laser oscillation device according to the present invention. In FIG. 1, laser light oscillated upward from a vertically installed laser head 11 is reflected by mirrors 12 and 13 respectively.
By changing the direction of 0 °, the condenser lenses 14a and 14b, the spectroscope 15a, the output variable device 16, the shutter 17, the lens 14
Through c, it is taken out downward. In addition, 15b is a power measurement sensor. The laser head 11 has a structure shown in FIG. 2, and resonator mirrors 21 a and 21 b are attached to both ends of a laser oscillation tube 20. The laser oscillation tube 20 is a water cooling cooling tube 2 for cooling the discharge electrode 22.
Covered with 3.

As shown in FIG. 1, the laser head 11 and the mirror 12 are covered with a cover 18 for ensuring safety. The cover 18 blocks the outside air so that the temperature fluctuation on the outside does not affect the laser head 11. Accordingly, the degree of sealing of the cover 18 may be such that air does not easily enter from the outside, and it is not necessary to make the cover 18 completely airtight. It is more preferable that the cover 18 be made of a heat insulating material. In the present embodiment, the optical system is bent in a U-shape, but by doing so, the entire device can be downsized.

Heaters 19a and 19b are provided near the upper and lower ends of the laser head 11, respectively. The heaters 19a and 19b are sheet-shaped and are attached to the inner wall of the cover 18. The heaters 19a and 19b are connected to temperature control means (not shown), and the periphery of the resonator mirrors 21a and 21b is
a is lower than the temperature of the lower resonator mirror 21b by 2 to 3.
The heating is performed at a constant temperature set to be higher by about 5 ° C., for example, 35 ° C. to 40 ° C. Fans 24 are attached to the inside of the cover 18 vertically. These fans 24 are used when the temperature distribution of the heat generated from the heaters 19a and 19b inside the cover 18 is uneven.

As described above, the resonator mirrors 21a, 21b
By actively heating the surrounding area to a constant temperature,
Since the fluctuation of the ambient temperature around the resonator mirrors 21a and 21b can be extremely reduced, the fluctuation of the distance between the resonator mirrors 21a and 21b and the deformation of the resonator mirrors 21a and 21b, which are the major factors of the laser output fluctuation, can be reduced. Can be prevented. In addition, since the laser head 11 is of a vertical type and the temperature at the upper end is kept higher than the temperature at the lower end, convection of air does not occur, and a stable distribution such that the temperature inside the cover 18 increases as it goes upward. I do.

According to the present embodiment, the output of 0.12 W can be suppressed within the fluctuation range of +/− 3 mW.

The present invention is not limited to the above embodiment. 1) The set temperature around the resonator mirrors 21a and 21b is:
The temperature is not particularly limited as long as it is higher than the maximum temperature of the outside air and does not impair the devices and components inside the cover 18. By setting such a temperature, the influence of the outside air temperature can be avoided. 2) The number of heaters is not limited to two, but may be more than two. 3) The heaters 19a and 19b are not limited to the above-mentioned sheet-shaped heaters. For example, if two or more ring-shaped heaters are arranged as shown in FIG. Thus, a symmetrical temperature distribution can be realized. 3) The heaters 19a and 19b set the temperature inside the cover 18 higher than the outside air temperature to realize a stable temperature distribution. However, instead of the heaters 19a and 19b, a cooling device is used to The temperature may be set lower than the outside air temperature to realize a stable temperature distribution. For example, refrigerant tubes are arranged around both ends of the laser head 11. 4) The optical system does not need to have a U-shape, but may be linear or bent if necessary. 5) The cooling method of the laser head 11 is not limited to water cooling, but may be air cooling or oil cooling. 6) The fan 24 is not always necessary.

[0012]

As described above, according to the present invention, since the resonator mirrors provided at both ends of the laser head are located in an atmosphere having a stable temperature, the distance between the resonator mirrors can be changed. In addition, distortion of each resonator mirror and deviation of the angle with respect to the optical axis can be prevented, and there is an excellent effect that the output is stabilized. Further, conventionally, the laser oscillation device is installed in a large and costly constant temperature room. However, according to the present invention, it is not necessary to use such a constant temperature room.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a laser oscillation device according to the present invention.

FIG. 2 is an explanatory diagram of a laser head used in the embodiment.

FIG. 3 is a partial explanatory view of another embodiment of the laser oscillation device according to the present invention.

FIG. 4 is an explanatory diagram of a conventional laser oscillation device.

[Explanation of symbols]

 Reference Signs List 11 laser head 12, 13 mirror 14a, 14b, 14c lens 15a spectroscope 15b power measurement sensor 16 output variable device 17 shutter 18 cover 19a, 19b heater 20 laser oscillation tube 21a, 21b resonator mirror 22 electrode 23 cooling tube 24 fan

Claims (1)

[Claims] 1. A temperature control system comprising: a laser head provided so that an optical axis thereof is arranged in a vertical direction; and a cover for shielding the laser head from the outside air, wherein the temperature in the cover is higher at the upper portion than at the lower portion. A laser oscillation device characterized by being performed.