JPH0843612A - Laser device - Google Patents

Abstract

PURPOSE:To improve the thermal conduction efficiency from a mirror to a thermal cooling section without impairing the flexibility of a mirror holder. CONSTITUTION:A mirror holder is provided with flexible parts having flexibility by notches 31 to 34 between a mirror supporting part for supporting the mirror 2 and the thermal cooling section having a cooling water circulating route 36 for cooling the mirror 2. Thermal conduction members 41, 42, 45, 46 are mounted on the outer peripheries of the flexible parts and constitute a thermal conduction ring. The mirror holder 30 supports the mirror 2 always with a prescribed pressure by the flexible parts disposed between the mirror supporting part for supporting the mirror 2 and the thermal cooling section for cooling the mirror 2. Further, the heat generated from the mirror 2 is transferred from the mirror supporting part to the thermal cooling section via the thermal conduction rings mounted on the outer peripheries of the flexible parts and is cooled in the thermal cooling section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device which uses various mirrors for reflecting a laser beam in a laser oscillator or other optical systems, and more particularly to a laser device which supports a mirror by a flexible mirror holder.

[0002]

2. Description of the Related Art Many mirrors are used in laser devices. The mirror includes an optical resonator internal mirror provided inside the laser oscillator and an external optical system mirror provided outside the laser oscillator. They include total reflection mirrors and half mirrors, which are supported by a mirror holder.

In a high power laser device such as a CO ₂ gas laser, the temperature of the mirror rises during operation. When the temperature of the mirror rises, the reflecting surface is distorted. To prevent this, cooling water is circulated in the mirror holder.
At this time, the mirror holder has flexibility in order to prevent distortion of the reflecting surface due to a change in pressure from the outside such as a change in cooling water pressure. As a result, the mirror can be constantly pressed against the mirror base surface with a predetermined pressure.

In the case of a gas laser, the inside of the laser oscillator has a negative pressure. Therefore, in order to prevent the differential pressure from the atmospheric pressure from being directly applied to the internal mirror of the optical resonator, the mirror holder is made flexible, and a vacuum seal is provided between the mirror holder and the mirror base with a 0-ring or the like. Is going.

Hereinafter, in the mirror holder, a portion supporting the mirror is called a mirror supporting portion, a flexible portion is called a flexible portion, and a portion having a heat cooling mechanism is called a heat cooling portion. Figure 7
FIG. 6 is a diagram showing a configuration of a conventional mirror holder. The mirror base 1a includes a fixing portion 11a for supporting the mirror 2a.
There is. The mirror 2a is supported by being pressed against the fixed portion 11a by the mirror holder 80.
The mirror 2a is a total reflection mirror that returns the irradiated laser beam 6a.

The mirror holder 80 is fixed to the mirror base 1a with screws 51a and 52a. A circular groove is provided on the surface of the mirror holder 80 in contact with the mirror base 1a, and an O-ring is fitted therein. This O
-By the ring, the mirror holder 80 and the mirror base 1a
The airtightness between them is maintained.

The tip of the cylinder in the mirror holder 80 is a mirror support portion, and a plurality of cuts 81 to 81 are formed in the middle of the cylinder.
84 is provided. The portion where the cuts 81 to 84 are provided is a flexible portion, whereby the mirror holder 8
0 can be flexible.

On the other hand, a cooling water circulation path 86 is provided in the mirror holder 80. In the cooling water circulation path 86,
Cooling water is fed from the cooling water inlet 87, and the cooling water outlet 8
Cooling water is discharged from 8. By circulating the cooling water through the cooling water circulation path 86, the mirror 2a can be cooled. This part is the heat cooling part.

As described above, the heat generated by the mirror 2a is transferred to the mirror support portion and further transferred to the heat cooling portion via the flexible portion. As such an example, the present applicant has filed Japanese Patent Application Laid-Open No. 1-125883.

[0010]

However, since the flexible portion of the mirror holder 80 is provided with the cuts 81 to 84, the path for transmitting heat is long and the heat conductivity is very poor. Therefore, there is a problem that it is difficult for the heat generated in the mirror 2a to be transferred to the heat cooling unit.

Here, if the number of cuts is reduced to improve the heat conductivity, the spring constant of the mirror holder increases, and the pressing pressure of the mirror cannot be maintained at a predetermined pressure. Although the flexible portion may be formed of a coil spring, it still has poor heat conductivity. Therefore, it has been difficult to eliminate distortion of the mirror and obtain a high quality laser beam. In a high-power laser device having an output of 1 to 6 kw, it is particularly difficult to cool the mirror.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a laser device which improves the heat conduction efficiency from the mirror to the heat cooling section without impairing the flexibility of the mirror holder. To aim.

[0013]

According to the present invention, in order to solve the above problems, in a laser device using various mirrors for reflecting a laser beam in a laser oscillator or other optical systems, a mirror support for supporting the mirrors is provided. And a heat cooling unit for cooling the mirror, a flexible unit having flexibility is provided, and the heat of the mirror support unit is transferred to the heat cooling unit on the outer periphery of the flexible unit. There is provided a laser device having a mirror holder to which a heat conduction ring is attached.

[0014]

The mirror holder always supports the mirror at a predetermined pressure by the flexible portion provided between the mirror support portion supporting the mirror and the heat cooling portion for cooling the mirror.
Further, the heat generated from the mirror is transferred from the mirror support portion to the heat cooling portion via the heat conducting ring mounted on the outer circumference of the flexible portion, and is cooled in the heat cooling portion.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a structure of a mirror holder of a laser device of the present invention. The mirror base 1 has a fixing portion 11 for supporting the mirror 2. The mirror 2 is pressed by the mirror holder 30 so that the fixed portion 11
Supported by. The mirror 2 is a total reflection mirror that returns the irradiated laser beam 6.

The mirror holder 30 is fixed to the mirror base 1 with screws 51 and 52. A circular groove is provided on the surface of the mirror holder 30 that contacts the mirror base 1, and an O-ring is fitted therein. The O-ring maintains the airtightness between the mirror holder 30 and the mirror base 1. The mirror holder 30 is made of aluminum alloy. As an aluminum alloy, for example, A
5056 (Al-Mg alloy) is used.

On the other hand, a cooling water circulation path 36 is provided in the mirror holder 30. In the cooling water circulation path 36,
Cooling water is sent from the cooling water inlet 37, and the cooling water outlet 3
Cooling water is discharged from 8. By circulating the cooling water through the cooling water circulation path 36, the mirror 2 can be cooled. That is, the portion of the cooling water circulation path 36 is the thermal cooling section.

The cylindrical tip of the mirror holder 30 is a mirror support portion, and a plurality of cuts 3 are formed in the middle of the cylinder.
1-34 are provided. The portions of the cuts 31 to 34 are flexible portions, which allows the mirror holder 30 to have flexibility.

The flexible portion has a smaller radius than the other portions and has a groove 35 on the periphery. In this groove 35, the O-ring 4
The heat conduction members 41, 42, 45, 46 supported by 0 are attached. The shape of the heat conduction members 41, 42, 45, 46 is an arc shape along the outer circumference of the flexible portion. Although not shown, there are two more heat conducting members having the same shape as the heat conducting members 41 and 42, and the four heat conducting members added thereto form a heat conducting ring on the heat cooling unit side. Similarly, although not shown, there are two more heat conducting members having the same shape as the heat conducting members 45 and 46, and these four heat conducting members form a heat conducting ring on the mirror 2 side. For these heat conducting rings, those coated with nickel on copper are used.

The heat conducting ring on the heat cooling portion side is in close contact with the surface of the groove 35 on the heat cooling portion side and the outer peripheral surface of the flexible portion. The heat conducting ring on the heat cooling section side has a conical surface on the outer circumference. The heat conducting ring on the side of the mirror 2 is in close contact with the surface of the groove 35 on the side of the mirror 2 and also has a conical surface with the same inclination angle as the heat conducting ring on the side of the heat cooling unit on the inner circumference. The conical surface is in close contact with the heat conducting ring on the heat cooling section side.
Low vapor pressure grease is applied to these contact surfaces. The low vapor pressure grease serves to improve heat conduction.

Further, the heat conducting ring on the side of the mirror 2 has a conical surface provided on the outer periphery so as to face the conical surface of the heat conducting ring on the side of the heat cooling unit. Therefore, a V-shaped valley is formed on the outer circumference by the two heat conducting rings. An O-ring is attached to this valley.

The heat generated when the laser beam 6 is reflected by the mirror 2 thus mounted is
The heat is transmitted to the heat conducting ring on the side of the mirror 2 through the portion of the mirror holder 30 that is in contact with the mirror 2. The heat is further transmitted to the heat conduction ring on the heat cooling unit side, and the mirror holder 30
It is transmitted to the cooling water circulation path 36 inside. Then, it is cooled by the cooling water circulating in the cooling water circulation path 36.

On the other hand, the O-ring 40 holds the heat conducting ring lightly. Therefore, the provision of the heat conduction ring does not affect the flexibility of the mirror holder 30. That is, the change in spring constant is so small that it can be ignored. Further, since the O-ring 40 is attached to the valley formed on the outer periphery of the heat conducting ring, the heat conducting ring on the side of the mirror 2 is on the surface on the side of the mirror 2 and the heat conducting ring on the side of the heat cooling unit is the heat conducting ring. It can always be pressed against the surface on the cooling unit side.

FIG. 2 is a view showing the heat conducting ring on the heat cooling section side. FIG. 7A is a plan view of a heat conduction ring on the heat cooling unit side. This heat conduction ring includes four heat conduction members 41 to 4
It is divided into four. The shape of each of the heat conducting members 41 to 44 is an arc, and the inner diameter is equal to the outer diameter of the flexible portion.

(B) is a sectional view taken along line XX of (A). The heat conducting members 41, 4 constituting the heat conducting ring on the heat cooling section side.
The inner peripheral surfaces 41a and 42a of 2 are surfaces contacting the outer periphery of the flexible portion, and the side surfaces 41b and 42b of the heat conducting members 41 and 42.
Is a surface in contact with the surface of the mirror holder 30 in the groove 35 on the side of the thermal cooling unit. Further, the outer peripheral surfaces 41c, 42c of the heat conducting members 41, 42 are conical and are surfaces that contact the heat conducting ring on the mirror side.

FIG. 3 is a view showing the heat conducting ring on the mirror side. (C) is a plan view of the heat conducting ring on the mirror side. This heat conducting ring includes four heat conducting members 45 to 48.
Is divided into The heat conducting members 45 to 48 have a circular arc shape, and the inner diameter is equal to the outer diameter of the flexible portion.

(D) is a sectional view taken along line YY of (C). Heat conduction member 4 which constitutes a heat conduction ring on the cooling water circulation path side
The inner peripheral surfaces 45a and 46a of the reference numerals 5 and 46 have a conical shape, and are surfaces in contact with the outer peripheral surface of the heat conducting ring on the heat cooling unit side. The side surfaces 45b and 46b of the heat conducting members 45 and 46 are surfaces that contact the surface of the groove 35 of the mirror holder 30 on the mirror 2 side.

As shown in FIGS. 2 and 3, the heat conducting ring on the heat conducting portion side and the heat conducting ring on the mirror side are each composed of four heat conducting members. Accordingly, even if an error occurs in the diameter of the surface where the cutout portion of the mirror holder 30 and the heat conducting ring are in contact with each other due to thermal expansion or the like, it is possible to secure the adhesion and maintain good heat conducting efficiency. This also prevents deterioration of the heat conduction efficiency due to dimensional errors during manufacturing of the heat conduction ring.

FIG. 4 is a diagram showing a laser beam output system of a gas laser device for carrying out the present invention. Laser gas circulates inside the discharge tubes 3a and 3b in the laser oscillator 3, and the laser gas is excited when a high frequency voltage is applied from the excitation power source. A rear mirror supported by a mirror holder 30c and a folding mirror supported by a mirror holder 30a are provided at both ends of the discharge tube 3b. An output mirror supported by the mirror holder 30d and a folding mirror supported by the mirror holder 30 are provided at both ends of the discharge tube 3a. The laser beam 6 output from the laser oscillator 3 is guided to an arbitrary location by the external mirror supported by the mirror holder 30d.

The mirror holders 30, 30a, 30b, 30c and 30d used in this gas laser device have a heat conducting ring in the flexible portion, and the cooling water circulates inside. Then, in each mirror, heat generated by reflecting the laser beam is generated by the mirror holder 30,
Heat is efficiently dissipated by 30a, 30b, 30c and 30d.

FIG. 5 is a diagram showing the relationship between the elapsed time after the start of laser beam output and the temperature change of the mirror. In the figure, the horizontal axis represents the elapsed time from the start of laser beam output, and the vertical axis represents the temperature rise from the temperature at the start of laser beam output. A solid line 71 in the figure is a case where the mirror is cooled by using the embodiment shown in FIG. 1 of the present invention, and a broken line 7
2 is the case where the mirror is cooled by the conventional method.

As described above, when the present invention is used, the temperature rises immediately after the start of laser beam output, but thereafter a constant temperature is maintained. This temperature is almost the same as the temperature of the cooling water. This is because the heat conduction ring between the mirror and the cooling water circulation path is improved by providing the heat conduction ring on the mirror holder.

FIG. 6 is a diagram showing the change of the mode of the laser beam with the lapse of time from the start of the laser beam output.
The upper part of the figure shows the case where the mirror holder shown in FIG. 7 is used, and the lower part shows the case where the mirror holder shown in FIG. 1 is used.

As can be seen from the figure, by mounting the heat transfer ring on the mirror holder, it is possible to prevent distortion of the mirror. Therefore, even after several minutes or more, immediately after the laser beam output is started. You can get almost the same mode as. As described above, the fact that the mode does not change with time means that it is possible to perform processing from the start point to the end point of the laser processing under the same conditions, and high quality processing is possible.

Since the heat conducting ring is attached to the flexible portion of the mirror holder as described above, the heat conductivity can be improved while the flexibility of the mirror holder is ensured. Therefore, the distortion of the mirror can be suppressed to a minimum, and the processing can be performed in a high-power laser device while maintaining a good mode pattern.

In the above description, the two heat conducting rings are contacted by the conical surface, but they may be contacted by the cylindrical surface. Further, the example of the mirror holder that supports the mirror of the total reflection mirror has been described, but the present invention can be similarly applied to a partial reflection mirror (anti-reflection mirror).

[0037]

As described above, according to the present invention, since the heat conducting ring is attached to the flexible portion of the mirror holder, the heat conduction from the mirror to the heat cooling portion can be performed without impairing the flexibility of the mirror holder of the mirror. The efficiency can be improved, and the distortion generated in the mirror can be minimized even in a high-power laser device.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a mirror holder of a laser device of the present invention.

FIG. 2 is a diagram showing a heat conduction ring on a heat cooling unit side.
(A) is a plan view of the heat conduction ring on the heat cooling unit side,
(B) is an XX sectional view of (A).

FIG. 3 is a diagram showing a heat conducting ring on a mirror side.
(C) is a plan view of the heat conducting ring on the mirror side,
(D) is a YY sectional view of (C).

FIG. 4 is a diagram showing a laser beam output system of a gas laser device for carrying out the present invention.

FIG. 5 is a diagram showing the relationship between the elapsed time after the start of laser beam output and the temperature change of the mirror.

FIG. 6 is a diagram showing a change in mode of a laser beam with the lapse of time from the start of laser beam output.

FIG. 7 is a diagram showing a configuration of a conventional mirror holder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mirror base 2 Mirror 30 Mirror holder 31, 32, 33, 34 Notch 36 Cooling water circulation path 40 O-ring 41, 42, 45, 46 Heat conduction member

Claims (10)

[Claims] 1. A laser device using various mirrors for reflecting a laser beam in a laser oscillator or other optical system, wherein a mirror support part for supporting the mirror and a heat cooling part for cooling the mirror are provided. A mirror holder provided with a flexible portion having flexibility, and a heat conduction ring for transmitting heat of the mirror support portion to the heat cooling portion is attached to an outer periphery of the flexible portion, Laser device. 2. The heat conducting ring is composed of a first heat conducting ring and a second heat conducting ring that is in contact with the first heat conducting ring. Laser device. 3. The heat conducting ring has a first heat conducting ring having a conical surface on the outer circumference, and a second heat conducting ring having a conical surface on the inner circumference which is in contact with the conical surface of the first heat conducting ring. A ring and a ring.
The laser device described. 4. The heat conducting ring has a first heat conducting ring having a cylindrical surface on the outer circumference, and a second heat conducting ring having a cylindrical surface on the inner circumference that is in contact with the cylindrical surface of the first heat conducting ring. A ring and a ring.
The laser device described. 5. The heat conducting ring has a first heat conducting ring having a conical surface on the outer periphery and a conical surface contacting the conical surface of the first heat conducting ring on the inner periphery,
2. The laser device according to claim 1, further comprising a second heat conducting ring which has a conical surface which is opposed to the conical surface of the first heat conducting ring and forms a valley on the outer circumference. 6. The laser device according to claim 1, wherein the heat conducting ring is divided into a plurality of arc-shaped heat conducting members. 7. The heat conducting ring is supported by an O-ring mounted on the outer periphery of the heat conducting ring.
The laser device described. 8. The laser device according to claim 1, wherein the heat conducting ring is supported by a ring-shaped coil spring mounted on the outer periphery. 9. The laser device according to claim 1, wherein the heat conducting ring has a low vapor pressure conductive grease applied to a contact surface for conducting heat. 10. The thermal cooling unit cools by circulating cooling water inside.
The laser device described.