JPH01228183A - Metal vapor laser oscillator - Google Patents

Abstract

PURPOSE:To obtain an oscillator stable in performance for a long period by a method wherein a core tube is formed in a cylinder whose diameter decreases gradually from both its ends toward its center in the axial direction. CONSTITUTION:Electrodes 2 and 3 are provided facing each other in an axial direction of a core tube 4, a pulse high voltage power source 7 is connected, and the core tube 4 is provided surrounding a discharge region A formed between the electrodes 2 and 3, and the core tube 4 is formed into such a shape that its diameter is smallest at the center as compared with both the ends. Therefore, when an oscillator starts operating, the core tube 4 is kept at a high temperature through the discharge plasma generated inside the core tube 4 and deformed due to the thermal expansion, temperature is distributed in such state that temperature of the center is higher than those of both the ends, so that the center part expands more than the other part in diameter, but the core tube 4 is previously formed so that its center is smaller than the ends in diameter at a normal temperature. Therefore the core tube is made a right circle cylinder at high temperature. By these processes, a metal vapor oscillator 1 capable of operating stably and continuously for a long period can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a metal vapor laser oscillation device having an improved reactor core tube.

(Prior Art) Laser oscillation devices are used in a wide range of fields such as material cutting, optical communications, medical care, and the chemical industry. Particularly in the chemical industry, it is used as a light source for lasers that selectively excite, for example, metal isotopes in order to separate and concentrate isotopes.

FIG. 2 is a vertical cross-sectional view showing the structure of a conventional metal vapor laser oscillation device 1 incorporated in a device for separating and concentrating metal isotopes, which uses copper vapor as the operating substance of the laser. be. In this copper vapor laser oscillation device 1, a furnace tube 4 is arranged so as to surround a discharge region A formed between electrodes 2 and 3 arranged opposite to each other in the central axis direction.
A multilayer metal foil 5 is wound around the outside as a heat insulating material to provide a radiation insulation structure. Note that a heat insulating layer may be formed on the outer periphery of the furnace tube 4 using a heat insulating material such as alumina or ceramic fiber, and a vacuum heat insulating layer may be further formed to provide a double heat insulating structure.

A discharge buffer gas such as helium (He) or neon (Ne) is supplied from a gas supply system 6 to the discharge region A inside the reactor core tube 4 .

When a pulsed high voltage from the pulsed high voltage power supply 7 is applied between the electrodes 2 and 3 which are arranged facing each other in the axial direction, a discharge occurs between the electrodes 2 and 3, and discharge plasma is generated in the discharge area A. occurs. Here, the pulse high voltage is generally several KV.
~10-odd KV, repetition frequency is several KHz to 10-odd KHz
is set to

Inside the reactor core tube 4, a plurality of metal copper particles 8 are provided as a metal vapor source.
are placed in advance, and the metal copper particles 8 come into contact with the discharge plasma and are heated to a high temperature of about 1500° C. and evaporated, thereby generating metal vapor that becomes the operating substance of the laser. Metal vapor is temporarily excited by free electrons in the discharge plasma, and when it returns from the excited level to the ground level, laser light with a wavelength unique to the metal is oscillated in response to the change in energy level. . The laser beam passes through Brewster windows 10 provided at both ends of the outer cylinder 9, and reciprocates through a resonator consisting of an output mirror 11 and a total reflection mirror 12 arranged outside the Brewster window 10. While doing so, it is amplified and output as a coherent laser beam having a single wavelength from the output mirror 11 side.

During operation of the metal vapor laser oscillator 1, in order to maintain the core tube 4 at a high temperature and ensure a constant laser output, the outer periphery of the core tube 4 is provided with a multilayer metal foil 5 that blocks radiant heat as described above. While winding the vacuum insulation chamber 13
This is to prevent heat loss due to gas convection and conduction that would occur if this part were surrounded by gas.

Rotary pumps 14a and 14b are connected to the vacuum insulation chamber 13 and the space forming the discharge area A, respectively, and the degree of vacuum in the vacuum insulation chamber 13 is generally set higher than that of the space forming the discharge area A. be done.

(Problem to be Solved by the Invention) However, in the conventional metal vapor laser oscillator 1, the furnace tube 4 is kept at a high temperature of about 1500°C by the discharge plasma generated in the discharge area A, and therefore due to thermal expansion. , the furnace core tube 4 is deformed into a barrel shape including the central portion. This deformation of the furnace core tube 4 changes the temperature distribution inside the furnace core tube 4, and the output of the laser beam may become unstable.

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide a metal vapor laser oscillation device that reduces the effects of deformation of the furnace core tube and exhibits stable performance over a long period of time. shall be.

[Structure of the invention]

(Means for Solving the Problems) In the present invention, a core tube of a metal vapor laser oscillator having a core tube in which the inner cavity to which a metal vapor source is attached is heated by discharge and becomes a light emitting source of an ion laser, It is characterized by being formed into a cylindrical shape whose diameter is gradually reduced from both ends to the center in the axial direction.

(Function) When the device is started, the core tube is kept at a high temperature by the discharge plasma generated in the inner cavity, causing thermal expansion and deformation. is higher, and therefore the diameter expansion due to expansion of the center part is also larger, but since the center part is formed in advance to have a smaller diameter than both ends at room temperature, the shape of the core tube at high temperatures becomes almost a perfect cylinder. , stable laser output can be obtained.

(Example) Next, an example of the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing an embodiment of a metal vapor laser oscillation device according to the present invention. Note that the same parts and elements as those of the conventional device shown in FIG. 2 are given the same reference numerals.

In FIG. 1, a metal vapor laser oscillation device 1 has electrodes 2 and 3 arranged opposite to each other in the axial direction of the main body, and a pulsed high voltage power source 7 is connected to these electrodes. A furnace core tube 4 made of a heat insulating material such as ceramic is provided so as to surround the discharge area A formed between the electrodes 2 and 3.

A plurality of metal copper particles 8 serving as a metal vapor source are arranged at the inner bottom of the furnace core tube 4 .

Here, the furnace core tube 4 is formed into a roughly cylindrical shape, but more precisely, it is formed into a drum-shaped shape so that the diameter at the center is the smallest compared to the diameter at both ends. .

An outer cylinder 9 is attached to the outermost part of the furnace core tube 4, and a vacuum insulation chamber 13 is formed between the outer cylinder 9 and the furnace core tube 4. The vacuum insulation chamber 13 is connected to a rotary pump 14a, and is maintained at a predetermined degree of vacuum by its suction action. Further, a heat shield such as a multilayer metal foil 5 is housed in the outer circumference of the core tube 4 in the vacuum insulation chamber 13 .

An outer ring 17 is attached to both ends of the furnace core tube 4, and the outer ring 17 and the inner peripheral edge of the outer cylinder 9 are connected by a bellows 18. This bellows 18 absorbs the expansion and contraction of the furnace core tube 4 in the axial direction due to heat.

Further, the outer ring 17 of the furnace core tube 4 is attached to the furnace core tube 4 via a sealing material 19, and the vacuum insulation chamber 13 is airtightly sealed.

On the other hand, the internal space of the outer cylinder 9 communicating with the discharge area A is connected to the gas supply system 6 and the rotary pump 14b. The gas supply system 6 supplies a discharge buffer gas such as helium or neon into the discharge area A.

ing.

Brewster windows 10 and 10 are provided at both ends of the outer cylinder 9, facing the electrodes 2 and 3, respectively.
An output mirror 11 and a total reflection mirror 12 are arranged on the outer side of 0.10, respectively, and both constitute an optical resonator.

The outer cylinder 9 around which the cold water pipe 20 is wound forms a partition wall of the vacuum insulation chamber 13 and also serves as a return path for the discharge current.

Further, the insulating tube 21 interposed in the outer cylinder 9 has an insulating function to maintain a good discharge state between the electrodes 2 and 3.

Next, the effect of this will be explained.

First, the rotary pumps 14a and 14b are operated to evacuate the discharge region A and the vacuum insulation chamber 13, and a predetermined degree of vacuum is set.A buffer gas such as helium is supplied from the zero-order gas supply system 6. When a pulsed high voltage is applied from the pulsed high voltage power supply 7 in this state, discharge plasma is generated in the discharge area A, and the reactor core tube 4 is heated by the heat, and the
At the stage of heating to 00° C., the metal copper particles 8 evaporate, and metal vapor that becomes the operating substance of the laser is generated.

The metal vapor is excited by the free electrons of the discharge plasma and oscillates a laser beam of a predetermined wavelength. The laser beam passes through the Brewster window 10, and then passes through the output mirror 11 and the total reflection mirror 12.
While reciprocating, it is amplified and transmitted through the output mirror 11,
It is output as coherent laser light.

A detailed look at the state of the furnace core tube 4 after double heating shows that the temperature rise is highest at the axial center of the furnace tube 4 and decreases as it approaches both ends. Along with this, the expansion of the tube diameter due to thermal expansion is greatest at the center, but since the core tube 4 is manufactured so that the diameter at the center is smaller than at both ends at room temperature, the operating temperature (approximately 1500 If the diameter of the center at room temperature is determined so that the diameter of the center at 30°F (°C) is approximately the same as that of both ends, the core tube 4 will be maintained in a nearly perfect cylindrical shape when the device is in operation, and the irregular shape of the core tube 4 will be avoided. Accordingly, it is possible to prevent the occurrence of an unstable state of the laser light output.

〔Effect of the invention〕

According to the present invention, it is possible to provide a metal vapor laser oscillation device that can avoid the temperature distribution inside the reactor core tube changing during use and that the laser light output becomes unstable, and can operate stably and continuously for a long period of time. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional metal vapor laser oscillation device. 4...Reactor core tube 8...Metallic copper particle agent
Patent Attorney Noriyuki Chika Yudo Ken Daishimaru

Claims (1)

[Claims] 1. In a metal vapor laser oscillator having a core tube, the inner cavity of which is attached with a metal vapor source is discharge-heated and becomes a light emitting source of an ion laser, the diameter of the core tube is gradually reduced from both ends to form a central portion in the axial direction. A metal vapor laser oscillation device characterized by being formed into a cylindrical shape.