JPH0374040B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a carbon dioxide laser oscillation method and its apparatus. (Prior Art) Carbon dioxide lasers are gas lasers that can stably produce high-power laser light, and are widely used for various purposes such as medical purposes and mechanical processing. This carbon dioxide laser has a
Devices in which CO ₂ , N ₂ , and He are introduced at a predetermined partial pressure and discharge is performed in this mixed gas atmosphere to generate laser oscillation are widely used. However, such a carbon dioxide laser requires a high-pressure cylinder and gas piping, resulting in a large-scale apparatus and high cost. Particularly in the case of continuously oscillating a high-output laser beam, a large amount of mixed gas is required, which increases the storage volume of the gas cylinder, which poses the problem of making the entire device large-scale. (Objective of the Invention) An object of the present invention is to provide a carbon dioxide laser oscillation method and its apparatus that are inexpensive and can be miniaturized. (Structure of the Invention) The carbon dioxide laser oscillation method of the present invention is characterized in that discharge is performed in an atmosphere consisting of air and organic compound vapor. Furthermore, the carbon dioxide laser oscillation device of the present invention includes:
It is characterized by comprising a discharge tube, means for supplying a mixed gas of air and organic compound vapor from one end of the discharge tube, and an exhaust pump connected to the other end of the discharge tube. The present invention decomposes organic compounds in the air by performing electric discharge in a mixed atmosphere of air and organic compound vapor to generate CO ₂ etc., thereby emitting oscillation of carbon dioxide laser light. Therefore, a high pressure cylinder and gas piping are not required, so the device can be made small and inexpensive. In the present invention, an organic compound is one that is composed of at least carbon and hydrogen and is liquid at approximately room temperature. However, it is more preferable that the organic compound satisfies the following requirements. (1) Contains no atoms other than hydrogen, carbon, oxygen, or nitrogen. (2) It has an appropriate vapor pressure so that it can completely react with oxygen in the air. (3) The number of hydrogen atoms is relatively small compared to the number of other constituent atoms and does not produce a large amount of H ₂ O. Aromatic compounds such as toluene C ₆ H ₅ CH ₃ , ethylbenzene C ₆ H ₅ CH ₅ , xylene C ₆ H ₄ (CH ₃ ) ₂ , and styrene C ₆ H ₅ CH=CH ₂ meet these requirements. Hydrocarbons, alcohols such as ethanol C ₂ H ₅ OH, methanol CH ₃ OH, formaldehyde
Aldehydes such as HCHO, acetaldehyde CH ₃ CHO, ketones such as acetone CH ₃ COCH ₃ , formic acid
Carboxylic acids such as HCOOH, acetic acid CH ₃ COOH, acetic anhydride (CH ₃ CO) ₂ O, ethyl acetate
Esters and ethers such as CH ₃ COOC ₂ H ₅ C ₂ H ₅
-O- _C2H5 can _be mentioned. Incidentally, combustion-type gas dynamic lasers are known in which cyanogen (C ₂ N ₂ ) or carbon monoxide is mixed with air as a fuel, combusted in a burner, and then adiabatically expanded from a nozzle to emit laser oscillation. The combustion type gas dynamic laser differs from the carbon dioxide laser of the present invention in that it does not generate electric discharge, requires a large amount of combustion gas, and has a large-scale device. Hereinafter, the present invention will be explained using the drawings. FIG. 1 is a schematic illustration of the method and apparatus of the present invention. Cylindrical discharge tube 1 similar to conventional gas laser equipment
Brewster windows 1a and 1b are provided at both ends of the discharge tube 1, which are inclined in the axial direction of the discharge tube 1. discharge tube 1
Along the axial direction, a total reflection mirror 2a is arranged on one side, and a semi-transmission mirror 2b is arranged on the other side. A liquid reservoir 3 is connected to one end of the discharge tube 1 via a conduit 3a. The inside of the liquid reservoir 3 is filled with an organic compound liquid, and an air introduction pipe 3b is extended into the organic compound liquid. An exhaust pump 4 is connected to the other end of the discharge tube 1. Electrodes 5a and 5b for discharging are provided at both ends of the discharge tube 1, and each is connected to a power source 6. When the exhaust pump 4 is operated, the inside of the discharge tube 1 is exhausted, and the pressure in the liquid reservoir 3 is lowered. As a result, external air is introduced from the air introduction tube 3b, and organic compound vapor and air are A mixed gas of is introduced into the discharge tube 1. After the gas mixture of organic compound vapor and air is filled in the discharge tube 1, the electrodes 5a,
When a voltage is applied between 5b and 5b by the power supply 6 to generate a discharge in a mixed atmosphere consisting of organic compound vapor and air, the organic compound is decomposed and this decomposed product reacts with oxygen in the air, producing CO2. ₂ , _H2O is produced. Furthermore, when the generated CO ₂ , H ₂ O, and N ₂ in the air are excited by discharge, laser oscillation is started and laser light 7 is emitted.
H ₂ O formed by the discharge and N ₂ contained in the air serve to increase the intensity of laser oscillation. The exhaust pump 4 is constantly operated to exhaust the laser gas and keep the pressure at an appropriate level. The results of experiments conducted using the above-described apparatus are listed in the table below. Xylene as an organic compound
_C6H4 ( _{CH3 ) 2 , tolueneC6H5CH3} , _benzene
C6H6 , _{ethanolC2H5OH , methanol
CH3OH} , acetone _{CH3COCH3 was} used. The purity of these organic compounds was 99.5% or more. Furthermore, confirmation that the carbon dioxide laser light was being oscillated was performed using a spectrum analyzer for carbon dioxide lasers. For comparison, the results obtained when a conventional CO ₂ mixed gas was used are also shown.

[Table] In the above table, the products are calculated. Stability was evaluated as ○ if laser oscillation was performed for 30 minutes or more; × if less than 30 minutes. Laser output of several watts was obtained at the beginning of discharge with all the organic compounds used, but when acetone and benzene were used, oscillation stopped within 20 minutes after discharge stopped. This is because the vapor pressure of acetone and benzene is relatively high, so the amount of O ₂ is insufficient, causing incomplete combustion of organic compounds and CO ₂
It is thought that this is because not enough is generated, and a large amount of solid or liquid substances are present in the discharge tube. Such solid or liquid impurities not only absorb laser light but also significantly contaminate the inner wall of the laser tube near the gas inlet. When xylene, toluene, ethanol, and methanol were used as organic compounds, stable output was obtained for more than 30 minutes. In particular, when xylene was used, the output fluctuation was within 3% within 3 hours. Next, FIG. 2 shows the pressure dependence of laser light output when xylene, toluene, ethanol, and methanol are used as organic compounds. For comparison, conventional CO ₂ mixed gas (CO ₂ :N ₂ :He
= 1:1:18) is also shown. Laser light output is contained in the reaction product
Highly dependent on the amount of _H2O . If the amount of H ₂ O is too large, as in the case of methanol, the deactivation of the upper level of CO ₂ by H ₂ O limits the operating pressure, and as shown in Figure 2, the output of the laser beam increases due to the high pressure. prevent the development of When xylene was used, the laser light output increased linearly with increasing pressure. In the present invention, He gas was not used, but H ₂ O formed by discharge acts as a substitute for He, and when xylene is used as an organic compound, an appropriate amount of H ₂ O is generated. As shown in Figure 2, we were able to obtain almost the same level of output as when using conventional CO ₂ mixed gas. In addition, the above xylene, toluene, ethanol,
Laser oscillation was also possible with organic compounds other than methanol. (Effects of the Invention) The present invention provides, instead of mixing CO ₂ , N ₂ and He at a predetermined partial pressure and performing discharge in this mixed atmosphere,
Since the discharge is performed in a mixed atmosphere of organic compound vapor and air, a complicated piping system is not required, and the device is simple and compact, resulting in lower costs. Furthermore, even when a high-output laser beam is continuously oscillated, the active medium can be stored as a liquid, which provides the advantage that the entire device can be made small-scale.

[Brief explanation of drawings]

FIG. 1 is a schematic illustration of the method and apparatus of the present invention. FIG. 2 is a graph showing the dependence of laser beam oscillation intensity on total pressure. 1...discharge tube, 2a, 2b...reflector, 3...
Liquid reservoir, 4...exhaust pump, 6...power supply, 7...laser light.

Claims (1)

[Claims] 1. A carbon dioxide laser oscillation method characterized by performing discharge in an atmosphere consisting of air and organic compound vapor. 2. The carbon dioxide laser oscillation method according to claim 1, wherein the organic compound is at least one of xylene, toluene, ethanol, and methanol. 3. A carbon dioxide laser comprising a discharge tube, means for supplying a mixed gas of air and organic compound vapor from one end of the discharge tube, and an exhaust pump connected to the other end of the discharge tube. Oscillation device.