JP2633482B2 - Laser rod holding and cooling structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser rod holding / cooling structure for a solid-state laser oscillator, and more particularly to a laser capable of efficiently cooling a laser rod which generates laser light upon being irradiated with excitation light by a semiconductor laser. The present invention relates to a rod holding and cooling structure.

[0002]

2. Description of the Related Art When laser light for a solid-state laser oscillation device receives excitation light from around the laser rod, it absorbs the excitation light and generates heat inside. Since the thermal conductivity of the laser rod is not very high,
As a result of the thermal expansion of the laser rod due to an increase in the internal temperature, the refractive index is greatly changed and the laser output is reduced. In extreme cases, the laser rod may even be damaged by thermal stress. In order to solve this problem, it is necessary to cool the laser rod, and various laser rod cooling methods have been conventionally studied.

One of these laser rod cooling methods is disclosed in Japanese Patent Laid-Open Publication No. 63-204679 (Title of Invention: Solid State Laser Device). In this solid-state laser device, both ends of the laser rod are fixed by a support structure, and a water passage having a structure fixed to the support structure is provided on the outer periphery of the laser rod, and cooling water flows through the water passage to mount the laser rod. Cooling.

[0004]

In the laser rod cooling method described above, a pump and a pipe for circulating cooling water need to be provided outside, so that the entire solid-state laser oscillation device is increased in size and weight. There was a drawback that things could not be avoided. This drawback is particularly problematic in special operating environments, such as space environments where natural water cannot be expected due to lack of gravity.

It is therefore an object of the present invention to overcome the disadvantages of the prior art laser rod cooling method described above, which ensures a sufficient and uniform cooling of the laser rod and low mechanical stress on the laser rod. Another object of the present invention is to provide a laser rod holding / cooling structure which has a small, lightweight and simple structure while obtaining a stable laser light output and which can be used in a space environment or the like.

[0006]

According to the present invention, there is provided a laser rod holding / cooling structure comprising: a fixed holder for holding a laser rod which generates laser light by irradiation of excitation light at both ends thereof and fixing the laser rod to a pedestal; A metal sleeve that grips around an intermediate portion, a thermal coupling holder that is connected to the metal sleeve via a bellows, forms a sealed space with the metal sleeve, the bellows, and itself, and is fixed to the pedestal; A high thermal conductive fluid filled in the space.

[0007]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a laser rod holding and cooling structure according to this embodiment. 2A and 2B are structural views of the present embodiment, in which FIG. 2A is a side view, and FIG.
It is sectional drawing.

Referring to FIGS. 1 and 2, in this laser rod holding and cooling structure, a cylindrical laser rod 1 is provided.
Forms a resonator of a solid-state laser oscillator with a reflecting mirror (not shown) placed parallel to the end faces of the ends 1a and 1b and on the central axis 1d of the laser rod 1, and a semiconductor laser (FIG. (Not shown) and emits laser light in the direction of the central axis 1d. Both ends 1a and 1b of the laser rod 1 are gripped by metallic fixed holders 2A and 2B having good thermal conductivity, and the fixed holder 2A
And 2B are fixed to a pedestal 3 which is a heat sink. In addition, the end 1 to the fixed holders 2A and 2B
The gripping of a and 1b is performed by inserting the ends 1a and 1b into holes provided in the fixed holders 2A and 2B, and holding a soft and highly heat-conductive metal such as gold or indium between the two. Then, good cooling performance can be obtained. Also,
The fixing holders 2A and 2B and the pedestal 3 are fixed by screwing or the like. The fixed holders 2A and 2B and the pedestal 3
It is more preferable to fix it after taking measures to sufficiently improve the thermal conductivity, such as interposing a thermal sheet and applying silicon grease.

Here, the solid-state laser oscillator has a wavelength of 1
An oscillator such as a Nd-YAG (neodymium-yttrium-aluminum-garnet) laser that outputs a laser beam of 064 nm is used.
6 mm in diameter and 80 m in length using d-YAG as a material
m. The semiconductor laser has a wavelength of 8 when the solid-state laser oscillator is a YAG laser.
An 08 nm GaAlAs (gallium-aluminum-arsenic) laser or the like can be used. Now, in order to make the output of the laser light emitted from the laser rod 1 about 100 mJ × 50 Hz, it is necessary to irradiate the laser rod 1 with the excitation light 10 of about 60 mJ × 50 Hz × 16. By absorbing the irradiated excitation light 10, the laser rod 1 emits laser light. On the other hand, most of the excitation light 10 absorbed by the laser rod 1 is converted into heat and
Of the laser rod 1
From both ends 1a and 1b of the fixing holders 2A and 2B
Is transmitted to the pedestal 3 through the base member 3 and is radiated by the pedestal 3. However, the thermal conductivity of the laser rod 1 is not large (for example, when the laser rod 1 is Nd-YAG, the thermal conductivity is about 13 W / mK). Sufficient heat dissipation cannot be expected.

Therefore, the present embodiment is further provided with a cooling mechanism for radiating heat from the intermediate portion 1c of the laser rod 1 to the pedestal 3. This cooling mechanism connects the sleeve 4 and the heat coupling holder 6 to each other by joining the sleeve 4 and the heat coupling holder 6 by joining or the like, as well as connecting the sleeve 4 and the heat coupling holder 6 to each other. It comprises a coupling holder 6 and a bellows 5 made of an aluminum alloy or the like, which forms a closed space by the three members, and a highly thermally conductive fluid 7 filled in the closed space.

The sleeve 4 has an annular shape with flanges 4a and 4b, and is held around the intermediate portion 1c of the laser rod 1 by the same supporting method as that of the fixed holder 2A. The heat coupling holder 6 has a heat receiving portion 6a provided with a round hole so as to be disposed around the sleeve 4, and a heat radiating portion 6b integrated with the heat receiving portion 6a. The round holes of the heat receiving portion 6 a are arranged around the sleeve 4, and the flanges 4 a and 4 b of the sleeve 4 and the heat receiving portion 6 a are connected by the bellows 5. As a result of this connection, the sleeve 4, the bellows 5, and the thermal coupling holder 6 form a closed space for filling the fluid 7, as shown in FIG. The fluid 7
Can be made of water, alcohol, mercury, etc., and after being injected and filled into the above-mentioned closed space, it is sealed in this closed space. The heat radiating portion 6b of the thermal coupling holder 6 includes the fixed holders 2A and 2A.
B is fixed to the pedestal 3 using the same means as for fixing to the pedestal. Here, since the laser rod 1 and the sleeve 4 are connected to the thermal coupling holder 6 via the flexible bellows 5 and the fluid 7, a heat is applied between the laser rod 1 and the thermal coupling holder 6. Note that almost no mechanical or mechanical stress occurs.

The heat generated in the intermediate portion 1c of the laser rod 1 due to the absorption of the excitation light 10 passes through the sleeve 4, the fluid 7 and the thermal coupling holder 6 sequentially and is transmitted to the pedestal 3 by passive conduction. The heat is dissipated from

As described above, in the laser rod holding and cooling mechanism of this embodiment, the ends 1a and 1b of the laser rod 1 are provided.
And the heat generated in the vicinity of the fixed holders 2A and 2A
In addition to the heat radiated to the pedestal 3 via B, the heat generated in the intermediate portion 1c of the laser rod 1 and its vicinity is radiated from the pedestal 3 via the thermal coupling holder 6 and the like. A large amount of heat can be sufficiently coped with, and the temperature distribution of the laser rod 1 can be made uniform.

The laser rod holding and cooling structure is
There is a feature that heat can be radiated from the intermediate portion 1c of the laser rod 1 without applying mechanical stress to the intermediate portion 1c of the laser rod 1.

Further, the laser rod holding and cooling structure is a small, lightweight and simple structure in which the heat of the laser rod 1 is mainly radiated by passive conduction and does not require the use of a cooling water circulation pump or the like. The laser rod 1 can be cooled very efficiently even in a special operation environment such as outer space.

[0017]

As described above, according to the present invention, the intermediate portion of the laser rod is gripped by the metal sleeve, and the heat coupling holder fixed to the pedestal is connected to the metal sleeve via the bellows. And a bellows and a thermal coupling holder to form a sealed space and fill this sealed space with a highly thermally conductive fluid, so that heat can be dissipated by passive conduction from the intermediate portion in addition to both ends of the laser rod. ,
The laser rod has sufficient and uniform cooling and low mechanical stress on the laser rod to obtain a stable laser light output. There is an effect that it can be used even in an operation environment.

[Brief description of the drawings]

FIG. 1 is a perspective view of a laser rod holding and cooling structure according to the present embodiment.

FIG. 2 is a structural view of the present embodiment, in which (a) is a side view,
(B) is A1-A2 sectional drawing of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser rod 1a, 1b End part 1c Intermediate part 1d Center axis 2A, 2B Fixed holder 3 Pedestal 4 Sleeve 4a, 4b Flange 5 Bellows 6 Thermal coupling holder 6a Heat receiving part 6b Heat radiation part 7 Fluid 10 Excitation light

Claims (2)

(57) [Claims] 1. A fixing holder for holding a laser rod that generates laser light by irradiation with excitation light at both ends thereof and fixing the laser rod to a pedestal, a metal sleeve for holding around an intermediate portion of the laser rod, and a bellows. A heat coupling holder connected to the metal sleeve to form a sealed space with the metal sleeve, the bellows, and itself, and fixed to the pedestal; and a high thermal conductive fluid filled in the sealed space. Characteristic laser rod holding and cooling structure. 2. The laser rod holding / cooling structure according to claim 1, wherein said pumping light is generated by a semiconductor laser device, and said highly thermally conductive fluid is water.