JPS6326559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the mechanism of a gas laser device such as a carbon dioxide laser.

For high power lasers such as CO ₂ laser,
The amount of heat generated by the discharge tube is large, causing expansion and bending of the discharge tube, which causes fluctuations in the oscillation mode and decreases the oscillation output. A conventionally known CO ₂ laser tube has a so-called double glass tube structure in which the outer periphery of the discharge tube is covered with a water-cooled tube. However, the problem is how to connect this double glass tube to the resonant mirror holder. In the simplest laser resonator known so far, mirror holders are glued to both ends of this double glass tube. However, such a structure cannot sufficiently stabilize the laser output and mode. That is, the double glass tube is
Even if it is supported at one or three points, it will bend due to thermal expansion and contraction and vibration, and the oscillation output and mode will fluctuate. Additionally, tap water for cooling is not always at a constant temperature, and the outer walls of the water cooling pipes are affected by the temperature, causing the double pipes to expand and contract. moreover,
This is because the adhesive of the mirror holder is highly elastic and tends to change over time, making the bonded area susceptible to fluctuations.

An alternative conventional laser device employs a method in which the holding of the double glass tube and the supporting of the resonant mirror holder are separated. That is, a pair of resonator support plates located at both ends of the discharge tube are connected by a material having an extremely small coefficient of thermal expansion, such as an Invar rod or a quartz tube (usually three pieces). On the other hand, the discharge tube made of a double glass tube is fixed to each resonator support plate at both ends so that its axis coincides with the optical axis of the resonant mirror. This method significantly improves the laser power and mode stability. However, the disadvantages of this method are that the connecting rods that connect the resonator support plates are located outside the outer diameter of the double glass tube, which increases the external dimensions of the resonator support plates, and that the connecting rods have a low coefficient of thermal expansion. It is expensive because it is made of special material.

Furthermore, the disadvantages of conventional glass double tube discharge tubes are:
The following points apply.

First of all, an electrode glass tube and a gas distribution glass tube are inserted from the outside into the cathode and anode holder that supports the internal discharge tube that generates heat, perpendicular to the axial direction of the discharge tube. Since the glass tube is fixed to the outer water-cooled glass cylinder, the discharge tube, which thermally expands in the tube axis direction, bends in the radial direction, causing mode and output fluctuations.

Second, double glass tubes containing such electrodes tend to have a complicated structure, which not only requires high processing costs but also requires precise glass processing (straightness, tolerance, and deviation of the inner diameter of the discharge tube relative to the outer tube). (Corness is important) is difficult to obtain as it requires reliance on the few skilled glass craftsmen.

The present invention was proposed to solve the above problems, and the laser oscillation tube is supported in a discharge tube holder fixed to a pair of resonator support plates via ball bearings, and the laser oscillation tube is radially moved. By fixing one of the pair of resonator support plates on the substrate of the gas laser device and placing the other on the substrate via casters, thermal expansion and contraction in the tube axis direction of the laser oscillation tube can be prevented. The aim is to allow this and suppress its bending, thereby improving the stability of the laser oscillation output and oscillation mode.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically showing a gas laser device according to the present invention, and FIGS. 2 and 3 are partially enlarged views showing essential parts of the present invention.

First, to explain the entire gas laser device, the gas laser device according to the present invention includes a laser oscillation tube 1 and a first water layer 27 formed between the laser oscillation tube 1 and the first water layer 27 for passing cooling water at a constant temperature. an inner cylinder 23 made of alumina that surrounds the laser oscillation tube;
A second pipe for flowing constant temperature cooling water between the inner cylinder 23 and the inner cylinder 23 is provided.
An outer cylinder 61 that surrounds the inner cylinder 23 to form a water layer 63, a pair of resonator support plates 3 that support the laser oscillation tube 1 at both ends, and a pair of resonator support plates 3 disposed on one side of the resonator support plates 3. A resonant mirror 18 inside the
It consists of a mirror holder 17 that stores 19,
The laser oscillation tube 1 is composed of an anode holder 4 located in the center of an inner cylinder 23, cathode holders 5 at both ends, and an alumina discharge tube 6 connecting the two. Laser light is oscillated by flowing active gas and causing a discharge phenomenon between the anode and cathode, and the laser light is irradiated from the above-mentioned resonant mirror to the affected area via the manipulator, and each fitting part is airtight and insulated. It is fused with glass frit to ensure its properties.

The inner cylinder 23 is fitted from the outside with a metal cooling jacket 10 made of stainless steel or the like, and a heat insulating cylinder 60, and both ends of the cooling jacket 10 are arranged so that the laser oscillation tube 1 is connected in its radial direction. It is fixed to the resonator support plate 3 via a flange member to support the resonator. The constant-temperature cooling water flowing through the first water layer 27 flows into the first water layer 27 through the joint 12 fixed to one end of the outer cylinder 61 and exits through the through hole 14 formed in the anode holder 4. Tube 6
The liquid flows out to the outside through a joint 15 fixed to the other end of 1.

Note that the joints 12 and 15 are the cooling jacket 1.
The lid 37 is fixed at zero and sealed from the first water layer 27 by an O-ring 38, and is screwed together with a pipe screw 39. The constant temperature cooling water circulating in the first water layer 27 has the function of cooling the laser oscillation tube 1, which generates a large amount of heat, to a substantially constant temperature, increasing the laser output, and stabilizing the output and mode. If the constituent material of the laser oscillation tube 1 is alumina, which has a higher thermal conductivity than glass, the cooling effect will be better.

Further, the constant temperature cooling water flowing through the second water layer 63 is transferred to the second water layer from a joint 64 provided at one end of the outer cylinder 63.
The water flows into the water layer, flows through the water layer, and flows out from the joint 65 provided at the other end of the outer cylinder 63. Therefore, the cooling jacket 10 is always maintained at a constant temperature by the constant temperature cooling water flowing through the second water layer 63 without being directly exposed to the atmosphere.

The reason why the cooling jacket 10 is controlled at a constant temperature in this way is that the cooling jacket 10 not only supports the laser oscillation tube 1 in its radial direction, but also maintains the resonator spacing parallel and constant, and controls the laser output and mode. This is for stabilization.

Note that the temperature in the first water layer 27 for heat dissipation cooling of the laser oscillation tube 1 varies depending on the output level of the laser and the length of the oscillation time, even though constant temperature water is circulated. In order to keep the jacket 10 at a constant temperature for a longer period of time, the heat insulating tube 60 is made of synthetic resin with a large heat insulating effect, and the heat insulating tube 6
By providing a thin air layer between the cooling jacket 10 and the cooling jacket 10, it is possible to further improve the heat insulation effect.

The mirror holder 17 maintains a vacuum via the resonator support plate 3 and the bellows 16, and resonant mirrors 18 and 19 are installed inside the mirror holder 17, forming a laser resonator together with the laser oscillation tube 1. The laser oscillation tube 1 is supported by each resonator support plate 3 so that its axis coincides with the optical axis of the resonant mirrors 18 and 19.

The gas laser device is mounted on a substrate 20, and the lower surface of the right resonator support plate 3 is connected with several screws 2.
A caster 22 is attached to the lower surface of the left resonator support plate and placed on the substrate 20.

Next, an embodiment of the anode section, the cathode section, and the support section of the discharge tube will be described in detail based on FIG. 2.

First, the structure of the anode section will be described.

As mentioned earlier, the anode holder 4 is arranged at the center of the inner cylinder 23, and a rod-shaped gas joint 9 is provided in the central axis direction of the anode holder 4.
A through hole is bored through which the open ends of the discharge tube 6 face, and one end of an alumina discharge tube 6 is fitted and fused to the openings at both ends of the through hole to maintain airtightness.

Further, the inner circumferential surface of the inner cylinder 23 is fused and fitted to the stepped portions at both ends of the outer circumferential surface of the anode holder 4 .

Furthermore, the rod-shaped anode connector 7 with the anode wire 24 fused to its axis passes through the outer cylinder 61, the cooling jacket 10, the heat insulating cylinder 60, and the anode holder 4, and its lower end faces the through hole of the anode holder 4. The anode connector 7 and the lid 27 are bonded together, and the lid 27 is fixed to the outer cylinder 61 with screws.

Note that O-rings 26 and 28 are provided between the anode connector 7, the outer cylinder 61, and the cooling jacket 10 to prevent water leakage from the second water layer 63.
Between the lower end of the anode connector 7 and the through hole of the anode holder 4, there is an O to prevent leakage of active gas.
A ring 25 is attached, and the anode connector 7 is penetrated through the O-ring so that the outer cylinder 61, the cooling jacket 10, and the anode holder 4 are allowed to expand and contract in the axial direction.

Next, the structure of the cathode section will be described.

The alumina cathode holder 5 located at both ends of the inner cylinder 23 consists of a large diameter part and a small diameter part.The small diameter part is inserted into the inner cylinder 23, and the large diameter part is fitted into the heat insulating cylinder 60. An end portion of the inner cylinder 23 is fused and fitted into a stepped portion provided on the shoulder portion of the cathode holder 5 . Further, a through hole is bored at one end of the small diameter portion to connect with a bored hole passing through the large diameter portion and the small diameter portion, and the end of the alumina discharge tube 6 is fused and fitted into the through hole by a glass frit. It is in contact with a cylindrical cathode 29 loaded into a bore hole in the small diameter portion. Further, a hollow ring 30 is bonded to the cylindrical cathode 29, with the open end of the gas jet 9 facing the hollow part, and a lid 3 is attached to the hollow part of the hollow ring 30.
2. The lower end of a rod-shaped cathode connector 8 passes through the large diameter portion of the outer tube holder 33, cooling jacket 10, heat insulating tube 60, and cathode holder 5, and the cathode wire 31 is fused to the center of the cathode connector 8. The tip is screwed to the hollow ring 30.

The lid body 32 is fixed to the outer cylinder holder 33 with screws, and the cathode connector 5 is connected to the O-ring similar to the anode connector 4 in order to prevent water leakage from the second water layer 63 and leakage of active gas flowing out from the gas joint 9. Rings 34, 35, and 36 are attached and penetrate through the O-rings 34, 35, and 36 to allow expansion and contraction of the outer cylinder 61, cooling jacket 10, and cathode holder 5 in the axial direction.

Next, a method of supporting both ends of the laser oscillator will be explained. One end of a cylindrical body 40 is screwed into the bored hole in the large diameter part of the cathode holder 5 so as to abut the hollow ring 30 from the outside. It is supported through a ball bearing 43 with a certain clearance in the tube axis direction, and is
The ring 42 maintains the airtightness of the cathode section. Furthermore, the discharge tube holder 2 is equipped with an O-ring 44.
It is fixed to the resonator support plate 3 via.

The method of attaching the cooling jacket 10 and the outer cylinder 61 to the resonator support plate 3 is that a flange member 45 is screwed to the end of the cooling jacket 10, and this flange member 45 is attached to the flange 11 attached to the resonator support plate 3. It is fixed with screws.

Also, the outer cylinder holder 3 fixed to the flange 11
3 holds the outer cylinder 61, but the O-ring 4
6 and 47 seal the space between the outer cylinder 61 and the second water layer 63, and the clip 48 prevents the outer cylinder 61 from falling off.

Furthermore, although FIG. 3 shows the mounting structure of the gas joint 9, the mounting structure of the gas joint 9 is also similar to that of the cathode connector 8 and the anode connector 7, and the gas joint 9
A lid 49 is fitted and adhered to the upper part of the housing, and the lid 49 is screwed onto the outer cylinder or the outer cylinder holder 33. The O-ring 50 seals the active gas, and the O-rings 51 and 5
2 ensures the sealing of the second water layer 63, and the gas joint 9 allows the laser oscillator, the inner tube 23, the outer tube 61 of the cooling jacket 10, etc. to expand and contract in the axial direction.

It is also possible to combine this gas joint 9 with the cathode connector 8 or anode connector 7. To do this, the tip of the gas joint 9 is branched into two, one of which is used as a gas inlet, and the other branch pipe is connected to the other branch pipe. The cathode wire 31 may be fused.

By the way, in the above explanation, cooling jacket 10
Although a metal material such as stainless steel is used for this purpose, if a higher degree of output stability is expected, quartz or invar material may be used, and the area around the resonator mirror may also be cooled with constant temperature water.

In addition, the discharge tube 6 and the outer cylinder 23 may be made of Pyrex glass instead of alumina material, but in this case, a combination of an O-ring and a tube screw may be used to connect the cathode and anode holder. Can be adopted.

In this way, the gas laser device of this embodiment has the following features: First, the cooling jacket whose outer periphery is cooled to a constant temperature functions as a connecting rod for the resonator support plate, and the spacing between the cooling jackets is always kept constant. In addition to significantly improving the laser output and mode stability, it is also possible to manufacture a compact laser device with a small cross-sectional area of the laser resonator, and it is also possible to create a simple mechanism that does not use expensive invars for connecting rods. Therefore, it is possible to reduce the cost of the device.

Second, both ends of the laser oscillation tube are restrained and suspended only in the radial direction by ball bearings, and protruding members such as the gas tube, electrode connector, and water cooling joint are connected to the outer tube 61 and the cooling jacket 1.
0 through an O-ring to allow expansion and contraction in the axial direction, and one side of the resonator support plate 3 is placed on the substrate through a caster. Therefore, the laser oscillation tube has a structure that allows thermal expansion and contraction in the tube axis direction, while being constrained in the radial direction to ensure the optical axis, so that the laser output and mode stability are significantly improved.

Third, because the cathode holder, anode holder, and the discharge tube and inner cylinder that connect them are fused together using glass frit, the laser oscillation tube itself requires precise and complicated glass processing technology. It is easy to manufacture in-house and is relatively inexpensive.

Fourth, as a method of supporting both ends of the discharge tube, a method that allows thermal expansion and contraction in the tube axis direction is adopted, which prevents bending of the discharge tube due to thermal factors, and thus reduces fluctuations in oscillation output and mode. Can be suppressed.

As described above, according to the present invention, thermal expansion and contraction in the tube axis direction of the laser oscillation tube can be allowed and bending thereof can be suppressed, so that the stability of the laser oscillation output and the oscillation mode can be improved.

Note that the present invention can also be applied to gas laser devices other than U-shaped multiple folded high-power lasers and CO ₂ lasers.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the entire gas laser device according to the present invention. FIG. 2 is a partially enlarged view showing an embodiment of a method for supporting an anode section, a cathode section, and a discharge tube. FIG. 3 is a sectional view showing how to attach the gas joint. 1: Laser oscillation tube, 2: Discharge tube holder,
3: Resonator support plate, 4: Anode holder, 5:
Cathode holder, 6: Discharge tube, 10: Cooling jacket, 11: Flange, 29: Cathode, 1
8, 19: Resonant mirror, 20: Substrate, 22: Caster, 43: Ball bearing.

Claims (1)

[Claims] 1. A discharge tube, a water-cooled tube, and a water-cooled tube constituting a laser oscillation tube.
and a gas laser device configured by coaxially arranging the outer cylinder, the laser oscillation tube is supported via a ball bearing in a discharge tube holder fixed to a pair of resonator support plates, and the laser oscillation tube is radially arranged. one of the pair of resonator support plates is fixed on the substrate of the gas laser device, and the other is placed on the substrate via casters, and the tube of the laser oscillation tube is A gas laser device characterized by allowing thermal expansion and contraction in the axial direction, suppressing bending thereof, and improving the stability of laser oscillation output and oscillation mode.