JPS58158983A - Sealing type carbonic acid gas laser - Google Patents

Abstract

PURPOSE:To improve the rising characteristic after a laser is fired by forming a side branch for containing a cathode and an anode in the vicinity of both ends of a laser tube sealed with mixture gas containing at least CO2 gas, forming the cathode of catalytic cathode, providing a heater at the outer periphery of the branch surrounding the cathode, and always heating the cathode. CONSTITUTION:Reflecting mirrors 6, 6' forming an external resonator are provided through brewstar windows 5, 5 at both ends of a laser tube 1 enclosed with a coolant jacket 4 having coolant outlet and inlet 3, 3'. Further, branches 7, 7' for coupling the laser tube are mounted in the vicinity of both ends of the laser tube, a catalytic cathode 8 made of LaSrMnO3 is contained in the branch 7, and a Pd rod type anode 9 is contained in the branch 7'. Further, a combination of a heater, heat radiation means, infrared ray lamp and reflecting means enclosed with heat insulator 11, and heating means 10 made of induction heater are provided, and controlled by a temperature controller 12, and the cathode 8 is maintained at approx. 300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealed carbon dioxide laser (hereinafter referred to as a CO2 laser), and an object of the present invention is to improve the laser output rise characteristics immediately after the start of discharge.

The 002 laser usually oscillates by creating a laser gas flow in the discharge tube because of two types of phenomena: a short-term phenomenon of dissociation of 002 molecules due to electron bombardment, and a long-term phenomenon of movement of the dissociation equilibrium point due to consumption of 02 and 002 molecules. It can be said that this has led to an increase in the size and weight of the device and an increase in price, and has prevented its widespread use. The present applicant sealed a catalyst in a discharge tube and produced C, which is a dissociation product of 002 molecules.
It has been revealed that a sealed C02 laser can be constructed by recombining O and O2. It was actually observed that the dissociation of CO2 molecules occurs actively near the cathode where the temperature is high. According to experiments conducted by the inventors, it is possible to arrange a solid catalyst near the cathode, and for example, the cathode itself can be made of perovskite conductive oxide L a S r , which is a type of solid catalyst.
By constructing with MnO5, the sealed tube laser output is 55
I was able to obtain W/M. This is the upper limit of the output of the diffusion-cooled CO2 laser, and also the upper limit of the output of the sealed tube, and it is considered that dissociation of 002 molecules could be almost prevented in this discharge tube.

In addition to its catalytic effect, the electrode is an oxide, so 002 and O2 are not consumed by oxidation, as is the case with ordinary metal electrodes, and sputtering is reduced. It is the most suitable as a sealed tube CO2O laser material. Figure 1 shows the sealed C02 used by the inventors in the experiment.
The configuration of the laser tube is shown. 1 is a laser tube, and 2 is a laser gas, in which a mixed laser gas of 27% GO, 12% N2, and 81% He is sealed at 30 Torr. The inner diameter of the gas-filled region determines the resonator diameter and is selected to be 10 mφ. 3 and 3' are cooling water inlets and outlets of the water cooling jacket 4. 6 and 5' are laser tube sealing windows.
2 Zn5e Breustar window transparent to 10.6μ of laser light. This may be an internal mirror reflector.

6 and 6' are external optical systems R-60ooIII
These are two concave mirrors. 7 and D are electrode side branches of the laser tube 1, and a cathode 8 is provided inside the electrode side branch 7, and an anode 9 is provided inside the other electrode side branch 7'. The cathode 8 is a fired ceramic LaSrMnO3 electrode, and the anode 9 is a Pd rod having a diameter of 2IEl1φ. In the case of AC discharge, both the anode and the cathode are composed of catalyst electrodes, regardless of whether they are anode or cathode.

With this configuration, the aforementioned laser output of 55 W/M could be obtained. Figure 2 shows how the output changes after the laser is turned on. A pulse-like output is seen immediately after lighting, but this is C
This is a transient phenomenon that corresponds to the dissociation of O2 molecules reaching equilibrium with a time constant of 1 second. Thereafter, the output that once decreased shows a gradual uniform increase and reaches a steady output value of 55 W/M after about 10 minutes. This can be explained by the fact that ion bombardment during discharge causes heating of the cathode and increases catalyst activity. That is, it can be seen that in a sealed C02 laser without external heating of the cathode as shown in FIG. 1, about 10 minutes are required for the rise time after the laser is turned on. The catalyst cathode-sealed C02 laser previously proposed by the present applicant had an output transient phenomenon as shown in FIG. 2 due to intermittent discharge, and could not intermittent the output by intermittent discharge.

For this reason, the discharge and oscillation have to continue, and the laser beam has to be intermittent using an external shutter, resulting in a lot of wasted power costs.

The present invention solves the above-mentioned drawbacks by using a catalyst cathode as the cathode and providing means for heating the cathode, thereby improving the output rise characteristics after the laser is turned on. In this case, it is possible to maintain only the cathode heating state, turn off the discharge, and allow the discharge to occur only while the laser beam is used. It has been demonstrated that the output rises with sufficient speed when the battery is discharged and blinked.

FIG. 3 shows an embodiment of the present invention. 1 to 9 in the figure are the same as the conventional one shown in FIG. 1, and only the heater 10 surrounding the catalyst cathode 8, the heat insulating material 11, and the temperature controller 12 are different. With these heating devices, the cathode 8 is always maintained at a set temperature of about 3oo'C.When laser oscillation is started at the same time as the heating device is turned on, the output shows a transient response as shown in Figure 2, but the cathode is not sufficiently heated. When the discharge was made to blink while the discharge was being carried out, the output could be intermittent without showing any transient response, as shown in FIG.

It goes without saying that the present invention can be applied as is to the case of MuC discharge and the case of internal mirrors. Note that in the case of MuC discharge, there is no distinction between an anode and a cathode, so it is necessary to heat both electrodes.

If the catalyst cathode is externally heated and the discharge is blinked as in this embodiment, the laser output can be blinked without any transient response. In an application example such as a laser scalpel, the time for actually emitting a laser beam is limited to about 10 minutes in total during one day of use. Normal gas 70-
With lasers, the laser beam can be interrupted by intermittent discharge, which can save power costs.

FIG. 5 shows a second embodiment of the invention. 9 from 1 in the same figure
is the same as the conventional one shown in FIG. 1, with the addition of a lamp 13 for heating the cathode 8 from the outside and a reflecting mirror 14 for focusing the heat rays from the lamp 13 onto the cathode 8. These heating devices keep the cathode 8 at 300°C.
The set temperature is maintained at a certain level. When laser oscillation is started at the same time as the heating device is turned on, the output shows a transient response as shown in Figure 2, but if the discharge is blinked with sufficient cathode heating, the output changes to the first response. It is possible to perform interruptions that exhibit no transient response exactly as in the example results. When heating the cathode using a heater as in the first embodiment, the laser discharge tube electrode such as the cathode generally has a
Since KVO high voltage is applied, it is necessary to ensure sufficient insulation when using a heater, but the non-contact heating method as in this example has the feature of ensuring sufficient safety. . In the case of MuC discharge, there is no distinction between an anode and a cathode, so it is necessary to heat both electrodes. Furthermore, although the case shown in FIG. 6 is for an external bell, in the case of an internal bell laser, there are only slight changes such as replacing the Brewster window shown in the same figure with a reflection firing for the resonator, and the basic principle of the present invention is It will be applied without any change.

As in this embodiment, if the catalyst cathode is externally heated with a thermal radiation source such as an infrared lamp, the catalyst is maintained at a high temperature, and then the discharge is flashed, the laser output can be intermittent without transient response.

FIG. 6 shows a third embodiment of the present invention. Since the structure is the same as the conventional one shown in FIG. 1 except for the structure of the side branch 7, the same parts are given the same reference numerals and the explanation will be omitted. A catalyst electrode 8 made of a conductive oxide is sealed inside the side branch 7 . It is well known that a high frequency coil 15 for dielectric heating is provided outside the side branch 7, and that the high frequency current in the coil 15 induces an induced current in the electrode 8, and the Joule heat directly heats the electrode/catalyst 8. Since this is an application of the same technology, it will not be described in detail here. The feature of this embodiment is that in addition to being able to prevent the transient phenomenon shown in FIG. 2, the wall of the side branch 7 is not directly heated, so it does not become high temperature, which prevents gas release from the wall of the side branch 7 and He gas permeation. The seal life is not shortened due to changes in the seal gas composition.

FIG. 7 shows a fourth embodiment of the present invention using dielectric heating.

In this case as well, the catalyst has low electrical conductivity and induction heating is difficult. Since it is the same as FIG. 1 except for the side branch 7, the explanation will be omitted. A catalyst electrode 8 with low electrical conductivity is installed inside the side branch 7 .

Further, a dielectric heating flat plate electrode 16 is provided outside the side branch 7 . The action and effect of the heated catalyst are exactly the same as in the previous box 3 embodiment.

In addition, although the above-mentioned embodiment described the case where the electrode is located inside the side chamber, the present invention is not limited to this, and is similarly applicable even if the electrode is located inside the laser tube.

As described above, the present invention uses at least one of the discharge electrodes of a sealed carbon dioxide laser as a catalyst electrode, and is provided with a heating means for heating this catalyst electrode.In the present invention, the catalyst is constantly heated and is sufficiently activated. When the laser output was controlled by intermittent discharge, the output transient response of about 10 minutes as shown in FIG. 2 disappeared, and the output started to rise at a sufficient speed. As a result, the electric power for discharge and the electric power for the cooler can be significantly reduced. Furthermore, since it is no longer necessary to maintain a discharge state for a long time, the life of the sealed tube laser can be significantly extended. Furthermore, by starting cathode heating prior to use of the laser beam, it is possible to start up laser oscillation quickly.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the configuration of a conventional sealed CO2 laser using a catalyst electrode, Figure 2 is a diagram showing the output rise characteristics of the conventional laser, and Figure 3 is a sealed CO2 laser of the present invention. 4 is a cross-sectional view showing the first embodiment of the laser, FIG. 4 is a diagram showing the output response characteristics of the laser of the present invention to intermittent discharge, and FIGS. 5, 6, and 7 are the sealed type C02 of the present invention. FIG. 7 is a cross-sectional view showing another embodiment of the laser. 1... Laser tube, 2... Filled gas, 3
...Cooling water inlet/outlet, 4...Cooling water jacket, 61g...Breestar window, e,
e...Reflector 7, 7' constituting the external resonator
... Side branch for electrode, 8 ... Catalyst negative electrode,
9... Anode, 1o... Heater for cathode heating, 11... Heat insulating coating for heater, 12...
... Temperature controller, 13 ... Lamp, 14
・River...Reflector. 16... High frequency coil, 16... Flat plate electrode for dielectric heating. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure I3 Figure 4 Figure 1 Hour Figure 5

Claims (1)

[Scope of Claims] (1) A laser tube sealed with a mixed gas containing at least carbon dioxide, and two or more electrodes provided inside or outside the laser tube, and at least one of the electrodes is A sealed carbon dioxide laser comprising a catalyst electrode, and at least the catalyst electrode is provided with heating means. (b) The sealed carbon dioxide laser according to claim 1, wherein the heating means is a heater. (3) The sealed carbon dioxide laser according to claim 1, wherein the heating means is a thermal radiation device. G4) The sealed carbon dioxide laser according to claim 3, wherein the thermal radiation device is a combination of an infrared lamp and a reflecting means. (5) The sealed carbon dioxide laser according to claim 1, wherein the heating means is an induction heating device. (6) The sealed carbon dioxide laser according to claim 1, wherein the heating means is a dielectric heating device.