JPH06244481A - Raman laser device - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of multiple reflection of a laser and besides, prevent the damage of a concave mirror. CONSTITUTION:A pair of concave mirrors 1 and 2 are arranged in condition that the concaves are opposed to each other. An incoming laser beam 30 are reflected multiply between the concave mirrors 1 and 2, and a laser beam 31, which has become a Raman laser beam, is outputted. Refrigerant jackets 1B and 2B are formed in the concave mirrors 1 and 2, and refrigerants are supplied to the refrigerant jackets 1B and 2B through supply pipes 1C and 2C, and are discharged through return pipes 1D and 2D. Adjusting the temperatures of refrigerants changes the radius of curvature of the concave mirror, and enables the condition of reflection to be controlled. Moreover, the cooling can also be done.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved Raman laser device.

[Prior art]

A Raman laser is a laser that converts the wavelength of a laser beam to a long wavelength side by a rotational scattering transition of gas molecules, and it is known that a laser beam is multiple-reflected by a pair of mirrors.

A Raman laser device will be described with reference to FIG. 4, which is a structural view, and FIG. 5, which is an explanatory view of multiple reflection of laser light. As shown in FIG. 4, the short pipes 20 and 21 are fixed to the end plates 22 and 23, respectively, and the concave mirrors 1 and 2 inserted in the short pipes 20 and 21 are the both end flanges 3A and 3 of the cylinder 3.
It is being fixed to B through the end plates 22 and 23. Therefore, the laser light 30 enters between the concave mirrors 1 and 2 through the laser light entrance window 4 of the end plate 22 and the entrance hole 2A of the concave mirror 2 and, as shown in FIG. Multiple reflection occurs at the reflecting portion 24. Then, the laser light 31 that has been multiply reflected and becomes Raman laser light is emitted to the outside of the device through the emission hole 1A of the concave mirror 1 and the laser light emission window 5 of the end plate 23.

The end plates 22 and 23 are fastened together by tie bolts 40, and by utilizing the elasticity of the bellows 3C at the center of the cylinder 3, the distance between the end plates 22 and 23 is adjusted so that the concave mirror 1 and the concave mirror 1 are separated from each other. Adjust the distance of. This makes it possible to accurately perform multiple reflections of laser light.

[0005]

However, the above-mentioned prior art has the following problems.

The first problem is the problem of adjusting the distance between concave mirrors. That is, in order to perform accurate multiple reflection, it is necessary to accurately adjust the distance between concave mirrors according to the radius of curvature of the concave mirrors. However, conventionally, both end plates 2 to which the concave mirror is attached are attached.
2 and 23 are fastened with tie bolts 40, and the distance between the concave mirrors is adjusted by these tie bolts 40. This makes adjustment work difficult and, at the same time, makes both or one of both end plates movable, which is complicated.

The second problem is that the surface of the concave mirror is damaged. That is, at the laser spot point, which is the reflection point of the laser light of the concave mirror, heat is repeatedly applied by the high-power laser light for a very short time, and the laser spot portion is locally damaged, so that it does not function as a concave mirror.

In view of the above-mentioned prior art, it is an object of the present invention to provide a Raman laser device in which the distance between concave mirrors can be easily adjusted and the surface of the concave mirror is not damaged.

[Means for Solving the Problems]

According to the structure of the present invention for solving the above-mentioned problems, the concave mirror itself is provided with a coolant jacket, and the radius of curvature of the concave mirror can be arbitrarily adjusted by changing the coolant temperature, and the cylinder is not opened. The refrigerant can be introduced and discharged from the outside.

[0010]

The radius of curvature of the concave mirror is R (mm) and the coefficient of thermal expansion is α
(1 / ° C), initial temperature is T ₁ (° C), refrigerant temperature is T
_{Assuming that the} temperature is ₂ (° C.), the change amount ΔR of the radius of curvature when the temperature is changed from T ₁ to T ₂ is given by the following expression (1).

[0011]

[Equation 1]

On the other hand, the relationship between the concave mirror distance L and the concave mirror curvature radius R is expressed by the following equations (2) and (3) in order to accurately perform the multiple reflection of the laser light.

[0013]

[Equation 2]

When L is defined, there is only one R that satisfies the above equation. Conventionally, R is fixed, so L is R
However, the present invention defines L and adjusts R according to L by utilizing thermal expansion. By arbitrarily changing T ₂ , ΔR can be arbitrarily changed and R can be changed. Change.

[0015]

EXAMPLES Examples of the present invention will be described below. In addition, the same symbols are attached to the portions having the same functions as those of the conventional technique, and the duplicated description will be omitted.

FIG. 1 shows an embodiment of the present invention. Only the structure of the concave mirror is different from the prior art. That is, concave mirrors 1 and 2
Refrigerant jackets 1B and 2B are formed in the refrigerant jacket 1B, a supply pipe 1C and a return pipe 1D are connected to the refrigerant jacket 1B, and a supply pipe 2C and a return pipe 2D are connected to the refrigerant jacket 2B. Therefore, the supply pipe 1
The refrigerant is sent from C and 2C to the refrigerant jackets 1B and 2B,
Furthermore, the refrigerant can be returned and discharged from the pipes 1D and 2D. At this time, the temperature of the concave mirrors 1 and 2 and thus the radius of curvature R can be changed by changing the temperature of the refrigerant.

The laser light 30 enters through the window 4 and the concave mirrors 1 and 2 are used.
The laser light 31 that has been multiply reflected between and becomes Raman laser light is output from the window 5.

In this embodiment, since the distance between the concave mirrors is fixed, when the radius of curvature of the concave mirrors 1 and 2 does not satisfy the equations (2) and (3), the multiple reflection is not accurately performed, but the coolant temperature is not. The state of multiple reflection can be corrected by controlling the radius of curvature R so as to satisfy the equations (2) and (3).

Whether or not the multiple reflection is accurate can be evaluated by whether or not the laser spots arranged on the concave mirror surface are arranged at equal intervals on a perfect circle. FIG. 2 shows the laser spot arrangement when the radius of curvature of the concave mirror is increased by 5% of the correct radius.
The laser spots are arranged on a perfect circle, but the intervals are unequal. FIG. 3 shows the result of correcting the concave mirror temperature (absolute temperature) by 5% and correcting the concave mirror curvature radius to the correct radius by the heat shrinkage effect. In FIG. 3, the laser spots are arranged on a perfect circle at equal intervals, and it can be seen that accurate multiple reflection has occurred. 4 and 5 show the spot locus on the mirror surface as viewed from the mirror side.

[0020]

According to the present invention, the following effects can be obtained. (1) Multiple reflection of laser light can be accurately adjusted only by changing the coolant temperature without changing the distance between the concave mirrors. (2) This requires only changing the temperature of the refrigerant, is extremely simple, and does not require changing the distance between the concave mirrors, which simplifies the structure. (3) Since the concave mirror is cooled, heat of the laser spot is easily removed, damage to the laser spot is easily avoided, and the life of the concave mirror can be maintained for a long time.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a spot trajectory on a mirror surface.

FIG. 3 is an explanatory diagram showing a spot trajectory on a mirror surface.

FIG. 4 is a configuration diagram showing a conventional technique.

FIG. 5 is an explanatory view showing multiple reflection of laser light.

[Explanation of symbols]

 1, 2 concave mirror 1A exit hole 2A entrance hole 1B, 2B refrigerant jacket 1C, 2C supply pipe 1D, 2D return pipe 3 cylinder 3A, 3B both ends flange 3C bellows 4,5 window 20,21 short pipe 22,23 end plate 24 Multiple reflection part 30, 31 Laser light 40 Tyvolt

Claims (1)

[Claims] 1. A Raman laser device in which a pair of concave mirrors are arranged with concave surfaces facing each other, and laser light is multiple-reflected between the pair of concave mirrors and output as Raman laser light, wherein a coolant jacket is formed on each of the concave mirrors. At the same time, a supply pipe for supplying a refrigerant to the refrigerant jacket is connected to the refrigerant jacket, and a return pipe for discharging the refrigerant from the refrigerant jacket is connected to the refrigerant jacket.