JPS5841672B2 - Sealed carbon dioxide laser oscillator - Google Patents

Description

Detailed Description of the Invention The present invention relates to a sealed-forming acid gas (hereinafter referred to as CO2) laser oscillator, and prevents the dissociation of CO2 molecules generated after the start of discharge for laser excitation in a sealed CO2 laser oscillator. The purpose of this is to increase the laser output.

CO2, which is the main molecule in the CO2 laser gas, has a dissociation energy of 3.75 eV and a weak binding force, and about 70% of the enclosed amount will dissociate about 1 second after the start of discharge, so the output will decrease accordingly. Resulting in.

For this reason, in conventional CO2 lasers, the interior of the discharge tube is constantly supplied with fresh gas from a gas cylinder, while the gas that has passed through the diffuser tube is exhausted by an exhaust device such as an oil rotary pump.

In this case, a decrease in output can be avoided, but there are disadvantages in the size, shape, weight, cost, and operation and maintenance of the laser device, which has hindered the development of the CO2 laser application field.

Sealed CO containing a catalyst that prevents the dissociation of CO2 molecules
2 Attempts to develop a laser oscillator have been announced using both solid catalysts and gas catalysts, but no one that simultaneously satisfies various aspects such as catalyst performance, laser output, and encapsulation time has yet to be developed. .

Gaseous catalysts are suitable for sealed lasers because they operate at room temperature and have nonlocal action.
H2 or H2O reported by an is well known (
Phys, Lett, 26A, 454.

(1968), but there is a limit to its catalytic ability, and these gases sealed as catalysts disappear due to adsorption, etc., which puts an upper limit on the charging time (usually 1000
There is a drawback that (about time).

On the other hand, solid catalysts have excellent catalytic ability, but their activity usually increases at a fairly high temperature of about 300°C, and CO
2.As shown in Fig. 1, the catalytic furnace has been conventionally installed in the laser tube as shown in Fig. 1. It was used by forcing laser gas to circulate between a gas regeneration device that was installed outside and included a laser tube and a catalytic furnace (Norio Karube et al., Machinery and Tools, November 1977 issue).

In FIG. 1, 1 is a laser tube, 2 and 3 are reflecting mirrors constituting a resonator, and 4 is an excitation power source, the operating principles of which are known.

Reference numeral 5 denotes a gas regeneration device including a catalyst furnace, a gas circulation pump, and various filters, and gas circulation is performed between the laser tube 1 and the gas regeneration device 5.

A gas cylinder 6 is a gas source when the laser tube 1 is filled.

7 and 8 are gas system paths, 9 is a gas to be discharged, and 10 is a laser beam.

This method has sufficient catalytic ability and the laser output is the same as a gas flow laser (Norio Karube et al., Machinery Tools, November 1977 issue), but the gas regeneration device 5 is large and requires maintenance because it includes moving parts. Also, the gas filling time is the longest i
It has the disadvantage that it is limited to about 1 hour.

In the present invention, a solid catalyst is adopted from the viewpoint of catalytic ability, and in order to overcome the drawback of its local action, a catalyst layer is provided on the entire inner wall of the laser tube. An electroless deposition method that uses room temperature operation due to the effect of gas atoms adsorbed on a metal catalyst supported on a metal support moving onto an oxide support, and enables mass production of laser tubes as a method for manufacturing the catalyst layer. chemical treatment methods such as ion exchange and ion exchange methods are used.

As a result, the catalyst is built into the sealed CO2 laser tube, eliminating the need for an external gas regeneration device, which greatly simplifies the device. Not only can the required power be greatly improved, but the sealing time of the laser tube can also be greatly increased, so it is expected that the field of application of CO2 lasers will be further expanded.

FIG. 2 shows an example of the configuration of a sealed CO2 laser device according to the present invention.

11 is a sealed CO2 laser tube, 12 and 13 are reflecting mirrors that constitute a resonator, and in this actual case, both the output coupling mirror 12 and the total reflection mirror 13 are internal mirrors installed directly at the end of the laser tube 11. However, this may also be an external mirror system in which both ends of the laser tube are sealed with optical windows.

14 and 14' are cooling water inlet and outlet ports of the water cooling pipe 15.

16 is a discharge tube, and 17 is a catalyst provided in layers on its inner wall.

18 is a negative electrode, and 19 is a positive electrode, to which a high voltage is applied from a laser excitation power source 20.

21 indicates a laser beam. As is well known, in a CO2 laser, it is necessary to cool the discharge gas, and as shown in the figure, the discharge tube 16 has a water-cooled double tube structure, so the inner wall of the discharge tube 16 is at almost the same temperature as the cooling water. It has become.

Therefore, the co-located catalyst layer usually does not exhibit any catalytic activity.

The gist of the present invention is to use a catalyst layer that exhibits high activity at room temperature and is easily mass-produced, and the manufacturing method thereof will be described below.

The catalyst layer for room temperature operation is one in which an oxide such as MnO2 is formed as a catalyst carrier on the inner wall of the discharge tube, and then platinum is supported on the surface of the oxide by ion exchange.

It is known that M n 02 has CO oxidation catalytic ability at room temperature, but by further supporting platinum, P
t MnO2 becomes a spillover catalyst, and the catalyst activity at room temperature increases further.

The M n 02 layer was formed on the inner wall of the glass discharge tube by electroless deposition.

Persulfate ion (S208 metal ion Mn++ in one solution is Mn+++ 2H20+ 820B-9MnO2+ 4
Mn 02 is deposited on the inner wall of the discharge tube by the electrolytic reaction of IP+2804- (1).

The chemical used was manganese acetate (Mn(CH3COO)2).
), ammonium acetate (CH3COONH4), ammonium persulfate ((NH4) 2820g, silver nitrate (Ag
NO3) and acetic acid (CH3COOH).

These chemicals were used as a manganese acetate Mn++ ion source, ammonium acetate as a supporting electrolyte, ammonium persulfate as an oxidizing agent, silver nitrate as a catalyst for starting the oxidation reaction, and acetic acid as a pH adjusting agent.

To prepare a Pt layer on MnO2, tetraammineplatinum chloride ((pt (NH
3) 4]cz2) This was carried out by injecting an aqueous solution and leaving it to stand.

Mn:OH2 is generated on the surface of MnO2 by hydration.

In this case, the electron pair of the oxygen atom in the water molecule is considerably Mn'
As a result of being attracted to +, the hydrogen atom becomes H+ and becomes easily dissociated.

As a result, ion exchange takes place between H+ and (P t (NH3)4)'', and Pt is fixed on the surface of MnO2 in the form of an ammonium complex.

NH3 is removed by heat treatment below 300°C and finally P
t is supported on Mn 02.

The catalyst layer on the inner wall of the discharge tube manufactured by the method described above is produced by filling the discharge tube with a mixed gas of CO2:N2:He=11:27:62 up to various pressures of 1O-30Torr.
The rate of dissociation of CO2 molecules was measured by gas flow mass spectrometry after discharging at a discharge current of 30 mA.
It was confirmed that the dissociation of 2 was well prevented by operating the catalyst at room temperature.

After the start of discharge, CO2 molecules are dissociated at various locations around the anode and near the anode and cathode.

On the other hand, the operating area of the catalyst is near the inner wall of the discharge tube, but since the inner diameter of the discharge tube is 6 mm, the C0 molecules can reach the tube wall by moving 1.5 mm on average, and the catalyst can be approximately The operating region extends over the entire discharge region and may be considered to overlap with the location where CO2 dissociation occurs.

Therefore, even if the gas is stirred, the dissociation of CO2 is sufficiently suppressed, and an enclosed CO2 laser tube can be constructed.

Therefore, the output per unit length of the sealed CO2 laser can be set to 50 W/m, which is about the same as that of a gas flow CO2 laser, and a high output of the sealed CO2 laser can be achieved.

In addition, as a spillover catalyst, the above-mentioned PiM n O
In addition to 2, Pt PbO2, Pt 5io2. Pt5
n02 y Pd MnO2t P d P b0
2 , P dS io 2 , P dS n O
2nd class can also be used in the same way.

As described above, the present invention supports an oxide layer catalyst carrier such as MnO2 and a platinum catalyst on the inner wall of an encapsulated CO2 laser tube by chemical treatments such as electroless deposition and ion exchange, respectively. The spillover medium effect of the CO2 oxidation reaction activates the CO oxidation reaction at room temperature, thereby enabling sealed tube operation of the CO2 laser.

According to the present invention, dissociation of CO2 molecules generated by discharge for laser excitation can be prevented, and the unit length output of a sealed CO2 laser can be made to a value comparable to that of a gas flow type laser.

Furthermore, since the structure of the sealing tube can be simplified and the number of vacuum seals can be reduced, the life of the seal can be greatly extended.

Furthermore, since an external gas regeneration device is not required, the dimensions, weight, price, and power requirements of the laser oscillation device are greatly reduced, and operability and maintenance are also greatly simplified.

In addition, it brings about a number of excellent features, such as eliminating the need to bring large and heavy gas cylinders to the place where the laser is used.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a conventional CO2 laser oscillator using an external gas regeneration device, and FIG. 2 is a sectional view showing the configuration of a sealed CO2 laser oscillator in an example of the present invention. 11... Laser tube, 12... Output coupling mirror, 13... Total reflection mirror, 14, 14'...
... Cooling water inlet/outlet, 15... Double pipe for cooling water,
16...discharge area, 17...catalyst layer,
18... cathode, 19... anode, 20...
...Laser excitation power supply, 21...Laser beam.

Claims (1)

[Claims] 1. In a sealed acid gas laser oscillator in which a laser active medium is sealed in a laser tube, on the inner wall of the laser tube,
A sealed layered laser oscillator characterized by comprising an oxide catalyst carrier having catalytic ability at room temperature and a platinum catalyst layer covering the oxide catalyst carrier.