JPH0428155B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a solid-state laser oscillation device in which a laser rod is cooled by cooling water.

[Technical background of the invention and its problems]

In general, a solid-state laser oscillation device houses a laser rod and an excitation lamp facing each other inside a condensing reflector such as an elliptical cylinder, and a pair of mirrors each forming a resonator are arranged in parallel on the end face of the laser rod. It will be done. By optically exciting the laser rod with an excitation lamp, laser light is output from the mirror on the output side of the resonator. Further, since the laser rod is greatly distorted or damaged early by the heat received from the excitation lamp, the laser rod is inserted into a water pipe and cooled by water flowing through the water pipe.

By the way, conventionally, cooling water has flowed in a water pipe along the axial direction of the laser rod, and the laser rod has been optically excited by one or two excitation lamps in one direction in the circumferential direction or in two directions shifted by 180 degrees. was. Therefore, not only is the laser rod not heated uniformly in the circumferential direction by the excitation lamp, but the cooling water that flows along the axial direction in the area where the temperature has risen due to excitation by the excitation lamp in the circumferential direction is not cooled as it flows in other areas. Since the temperature rise is remarkable compared to water, the temperature difference between the laser rod and the circumferential direction is further expanded.

As described above, if a difference occurs in the temperature in the circumferential direction of the laser rod, the convex lens effect caused by the increase in temperature of the laser rod becomes non-uniform. In other words, between the first cross-sectional direction including the excitation lamp of the laser rod and the second cross-sectional direction perpendicular to the first cross-sectional direction, the focal length of the first cross-sectional direction is longer than that of the second cross-sectional direction. growing. For example, even if the cross section of the laser rod is circular, the pattern of the laser beam output will be rectangular, so when cutting with this laser beam, the processing width will differ depending on the scanning direction. , a problem arises in that precise cutting cannot be performed. Furthermore, if the convex lens effect in the circumferential direction of the laser rod is not uniform, even if the input to the excitation lamp is increased, the saturation point of the output of the laser beam will be lowered, and there will be a problem that a high-output laser beam cannot be obtained.

Regarding the flow of cooling water, please refer to Japanese Unexamined Patent Application Publication No. 1986-
A technique disclosed in Publication No. 74919 is known.
This technology is related to gas lasers rather than solid-state lasers, and a spiral rectifier plate is installed in the water jacket to flow the cooling liquid around the laser tube. It is designed to make uniform contact. However, in the case of a solid-state laser, unlike the laser tube in a gas laser, in addition to uniform contact with the cooling liquid, consideration must be given to ensure that the excitation action is not hindered.

[Purpose of the invention]

In this invention, the laser rod is cooled to a substantially uniform temperature in the circumferential direction, so that the pattern of the output laser light is uniform, and the saturation point of the laser light output relative to the input to the excitation lamp is maintained. An object of the present invention is to provide a solid-state laser oscillation device that can be made sufficiently high.

[Summary of the invention]

The laser rod, which is installed inside the condensing reflector and facing the excitation lamp, is housed in a water pipe, and the water pipe defines a flow path around the laser rod, and the water flowing through the flow path is defined by the water pipe. By providing a spiral guide body that rotates the laser rod in the circumferential direction of the laser rod, the entire circumferential direction of the laser rod is cooled with cooling water at a uniform temperature.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, reference numeral 1 denotes the main body of the oscillation device whose inner peripheral surface is formed into an elliptical shape. Openings at both axial ends of the main body 1 are closed by end plates 2. In addition, the inner peripheral surface of the main body 1 is provided with the main body 1 at locations other than both ends in the axial direction.
A condensing and reflecting mirror 3 is provided, which has an elliptical cylindrical shape similar to the inner circumferential surface of the mirror, and whose inner circumferential surface is mirror-finished. A laser rod 4 having a circular cross section, such as a YAG rod or other laser rod, is installed at one focal point of the converging reflector 3, and an excitation lamp 5 is installed at the other focal point, with their axes parallel to the axis of the main body 1. ing.

One end of a support pipe 6 is fitted to each end of the laser rod 4 in a fluid-tight manner. The other ends of these support pipes 6 are fitted into through holes 7 formed in the end plate 2 in a liquid-tight manner. At the other end opening of the support pipe 6 protruding from each end plate 2, a total reflection mirror 8 and an output mirror 9 forming a resonator are arranged parallel to and opposite to the end surface of the laser rod 4. . When the laser rod 4 is optically excited by the excitation lamp 5, a laser beam L is output from the output mirror 9. The laser rod 4 is also inserted into a water pipe 10 made of an optically transparent material. This water flow pipe 10 has a larger diameter than the laser rod 4, and defines a cooling water flow path 11 between its inner peripheral surface and the outer peripheral surface of the laser rod 4. This flow path 1
1, that is, on the outer peripheral surface of the laser rod 4, a spiral guide body 12 made of an optically transparent material and having an outer diameter approximately equal to the inner diameter of the water pipe 10 is attached.

Further, both ends of the water pipe 10 are liquid-tightly connected to a first flow path 14 and a second flow path 15 each having a circular cross section and partitioned by partition walls 13 at both ends of the main body 1 in the axial direction. It is connected to the. Therefore, inside the main body 1, the water pipe 10 and the pair of partition walls 13 form an upper chamber 16 on the radially upper side in which the laser rod 4 is housed, and a lower chamber 17 on the lower side in which the excitation lamp 5 is housed. It is segregated. Further, the main body 1 includes a supply pipe 18 communicating with the first flow path 14 and the first flow path 1 of the lower chamber 17.
A discharge pipe 19 is connected to one end corresponding to the discharge pipe 4 . In addition, the partition wall 13 forming the second flow path 15 has a space between the second flow path 15 and the lower chamber 1.
A through hole 20 communicating with 7 is bored. Cooling water is supplied from the supply pipe 18 . Therefore, the cooling water flowing into the first flow path 14 from the supply pipe 18 flows through the water flow pipe 1 as shown by the arrow in FIG.
0, second flow path 15, through hole 20 and lower chamber 17
The water passes through the drain pipe 19 and flows out from the discharge pipe 19.

In the laser oscillation device configured in this way, when outputting the laser beam L, the supply pipe 18
When the laser rod 4 is optically excited by supplying cooling water from the pump and excitation lamp 5, laser light L is output from the output mirror 9 forming a resonator. On the other hand, the cooling water supplied from the supply pipe 18 to the first flow path 14 flows into the flow path 1 on the outer periphery of the laser rod 4.
When the water flows into the water pipe 10 formed with the water flow passage 11, it flows along the spiral guide body 12 provided in the flow passage 11 while swirling around the outer peripheral surface of the laser rod 4. Therefore, the entire circumferential direction of the laser rod 4 is cooled with cooling water at the same temperature.
Even if the laser rod 4 is optically excited by the excitation lamp 5 from only one direction in the circumferential direction, the circumferential direction of the laser rod 4 is cooled to a substantially uniform temperature by cooling water of the same temperature. Therefore, the convex lens action of the laser rod 4 is almost the same in the radial direction in which it is optically excited by the excitation lamp 5 and in the direction orthogonal to this radial direction, so that the pattern of the laser beam L output from the output mirror 9 is The shape is circular, which is equal to the end face shape of the laser rod 4. Then, the laser beam L has the same circular cross-sectional shape as the laser rod 4.
When this laser beam L is output, when cutting is performed using this laser beam L, the cutting width is constant even if the scanning direction is different, so that the cutting can be performed precisely. Furthermore, when the convex lens action of the laser rod 4 is made uniform in the circumferential direction, the output of the laser beam L changes almost proportionally to the input to the excitation lamp 5, so the saturation point of the output of the laser beam L increases. do. In other words, high-power laser light L can be obtained.

Furthermore, since the water pipe 10 that accommodates the laser rod 4 and the guide body 12 provided on the outer peripheral surface of the laser rod 4 are both made of optically transparent material, they block the light from the excitation lamp 5. However, there is no possibility that the laser rod 4 will not be optically excited efficiently.

Note that this invention is not limited to the above embodiment,
For example, the laser oscillation device may be one in which two excitation lamps are provided at positions 180 degrees apart in the circumferential direction of the laser rod. In addition, the guide body may be attached to a partition wall, etc., not on the outer circumference of the laser rod, but on the inner circumference of the water pipe, or at the upstream and downstream parts of the water flow.In short, the guide body may be fixed to the flow path formed by the water flow pipe. It suffices if it is set up accordingly.

〔Effect of the invention〕

As described above, the present invention accommodates the laser rod, which is provided inside a condensing reflector and faces an excitation lamp, in a water pipe, and defines a flow path on the outer periphery of the laser rod by the water pipe. Since a spiral guide body is provided in the flow path to circulate the cooling water in the circumferential direction of the laser rod, even if the laser rod is optically excited unevenly in the circumferential direction by the excitation lamp, the cooling water can be rotated in the circumferential direction of the laser rod. The water makes the temperature distribution of the laser rod substantially uniform in the circumferential direction. Therefore, since the convex lens effect of the laser rod is almost uniform in the circumferential direction, it is possible to obtain a laser beam with the same pattern as the cross-sectional shape of the laser rod, making it possible to perform cutting without changing the cutting width depending on the scanning direction. This method not only can be performed with high precision, but also has the advantage of being able to obtain a high-output laser beam with a high saturation point in proportion to the input to the excitation lamp.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, with FIG. 1 being a vertical cross-sectional view showing a schematic configuration, and FIG.
It is a sectional view along a line. 3... Concentrating reflector, 4... Laser rod, 5...
...Excitation lamp, 10...Water pipe, 11...Flow path, 12...Guide body.

Claims (1)

[Claims] 1. A condensing reflector, a laser rod and an excitation lamp that are provided inside the condensing reflector to face each other, and a flowing water that accommodates the laser rod inside and defines a cooling water flow path on the outer periphery of the laser rod. A solid-state laser oscillation device characterized by comprising a pipe and a spiral guide body provided in the flow path and configured to swirl cooling water flowing through the flow path in the circumferential direction of the laser rod.