JPH05110166A - Raman laser device - Google Patents

Abstract

PURPOSE:To enable non-uniformity of temperature of laser medium gas at a multiplex reflection part of laser beam to be eliminated and prevent refraction of laser beam for achieving an accurate multiple reflection. CONSTITUTION:Edge plates 22 and 23 are fixed at both edge parts of an inside cylinder 3 and recessed mirrors 1 and 2 are inserted into short tubes 20 and 21 of the edge plates 22 and 23. A Jacket 7 for cooling is formed at an outer periphery of the inside cylinder 3 and then a cooling cylinder 8 which is formed by a material with a large thermal conductivity is installed within the inside cylinder 3 so that a multiple reflection part 24 may be surrounded, thus enabling non-uniformity in temperature due to heat conviction of laser medium gas which is cooled by a refrigerant within a Jacket 7 to be suppressed by the cooling cylinder 8 and a temperature of the laser medium gas to be uniform at the multiple reflection part 24.

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.

[0002]

2. Description of the Related Art A Raman laser is one that converts the wavelength of a laser beam to a long wavelength side by the rotational scattering transition of gas molecules, and it is known that a laser beam is multiple-reflected by a pair of mirrors. (Reference: Ishikawajima Harima Technical Report Vol. 24, No. 5, September 1984)

An example of the Raman laser device is shown in FIG. 4, and a conventional technique will be described with reference to FIG. 4 and FIG. 2 for explaining multiple reflection of laser light.

As shown in FIG. 4, end plates 22 and 2 are respectively provided.
Short pipes 20 and 21 are fixed to 3 and short pipes 20 and 21
The concave mirrors 1 and 2 inserted in are fixed to both end flanges 3A and 3B of the inner cylinder 3 via 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 is performed at the multiple reflection portion 24 between them. 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 window 5 for emitting laser light of the end plate 23.

On the other hand, a multiple reflection portion 24 between the concave mirrors 1 and 2 is filled with a coolant such as liquid nitrogen from a coolant inlet 6A in a jacket 7 formed by an outer cylinder 6 provided on the outer circumference of the circular cylinder 3. The laser medium gas existing in is maintained at a low temperature.

[0006]

As described above, the cooling medium is put into the jacket 7 to uniformly cool the inner cylinder 3 covering the multiple reflection portion 24 from the outer peripheral side. Thus, thermal convection of the laser medium gas occurs. As a result, the temperature of the laser medium gas located on the upper side in the inner cylinder 3 becomes higher than the temperature of the laser medium gas located on the lower side, and a large temperature difference occurs in the laser medium gas.

As described above, the refractive index of the laser medium gas also differs depending on the position in the inner cylinder 3, and the laser beam is refracted, which causes a problem that accurate multiple reflection is difficult.

[0008]

SUMMARY OF THE INVENTION A Raman laser device of the present invention is a Raman laser in which a pair of concave mirrors are provided at both ends in a cylindrical container that is cooled from the outer peripheral side, and laser light is multiply reflected between these concave mirrors. The apparatus is characterized in that a cooling cylinder formed of a material having good thermal conductivity is attached to the inside of the container so as to surround a portion where the laser light is multiply reflected.

[0009]

The laser light is multiply reflected between the pair of concave mirrors, and the Raman laser light is emitted from the inside of the container.

At this time, a cooling cylinder having a good thermal conductivity surrounds a portion where the laser light is multiply reflected, the temperature of the laser medium gas in the container is kept constant, and the laser light is refracted due to the non-uniformity of the laser medium gas density. Prevent.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the Raman laser device of the present invention is shown in FIG. 1, and this embodiment will be described with reference to FIGS. 1, 2 and 3. The same members as those described in the related art are designated by the same reference numerals.

As shown in FIG. 1, a pair of concave mirrors 1 and 2 are attached to short tubes 20 and 21, respectively, and are attached to both end flanges 3B and 3A constituting the end of an inner cylinder 3 which is a cylindrical container. Short tubes 20 and 21 are fixed to end plates 23 and 22 that seal the inner cylinder 3. End plate 2 located on the right side
2, a window 4 for laser light incidence is installed, and the concave mirror 2 has an entrance hole 2A corresponding to the window 4.
An emission hole 1A is formed in the concave mirror 1, and a window 5 for emitting laser light is installed in the end plate 23 located on the left side so as to correspond to the hole 1A. An outer cylinder 6 having a refrigerant inlet 6A is provided on the outer peripheral side of the inner cylinder 3.
Therefore, the inside of the inner cylinder 3 is cooled by the refrigerant inside the jacket 7 formed by the outer cylinder 6.

On the other hand, inside the inner cylinder 3, a material having a large thermal conductivity and a good thermal conductivity is positioned coaxially with the inner cylinder 3 so as to surround the multiple reflection portion 24 where the laser light is multiply reflected. A cooling cylinder 8 formed of a certain aluminum material in a cylindrical shape is installed and attached.

Next, the operation of the Raman laser device of this embodiment will be described.

When the laser light 30 enters through the window 4 of the end plate 23, it passes through the hole 2A of the concave mirror 2 and is multiply reflected by the multiple reflection portion 24 between the concave mirror 1 and the concave mirror 2 as shown in FIG. As a result, the laser light 30 finally becomes the Raman laser light 31, passes through the hole 1A of the concave mirror 1, and is emitted from the window 5 of the end plate 23.

On the other hand, when the refrigerant is introduced from the refrigerant inlet 6A into the jacket 7 formed by the outer cylinder 6, the inner cylinder 3 located inside the jacket 7 is cooled, and the multiple cylinders located between the concave mirrors 1 and 2 are cooled. The reflective portion 24 is kept cool. Along with this, the cooling cylinder 8 in the inner cylinder 3
Is cooled by heat transfer with the inner cylinder 3 cooled by the refrigerant, and the multiple reflection portion 24 surrounded by the cooling cylinder 8 is uniformly cooled through the cooling cylinder 8. ..

That is, when the multiple reflection portion 24 is cooled, it is formed of a material having a large thermal conductivity even if a temperature difference occurs due to the thermal convection action of the laser medium gas 9 between the upper and lower positions in the inner cylinder 3. Since the entire cooling cylinder 8 is easily brought to a uniform temperature, heat is transferred between the cooling cylinder 8 and the laser medium gas 9 to eliminate the temperature difference. As a result, the multiple reflection portion 24 between the concave mirrors 1 and 2 is cooled uniformly.

Next, the analysis result of the test conducted to confirm the effect of the cooling cylinder 8 of this embodiment will be described with reference to FIG. 3 and Table 1.

Here, FIG. 3 is a diagram showing the temperature measurement points. Table 1 is a table of the measured values at the measurement points in FIG. 3, and the analysis result of the circumferential temperature distribution will be shown.

The method of calculating the measured value is described in the literature name "Tra.
nport Phenomena (Author: R. BYR
ON BIRD, WARREN E. STEWART,
EDWIN N.E. LIGHTFOOT, Publisher: Top
pan Company, Ltd. ) ”Described in“ 9.7 Heat Condition ina ”
Cooling Fin "(pages 288-291).

[0021]

[Table 1]

Here, the case 1 has a structure of the prior art, and is a case without a cooling cylinder. Case 2 is a case where an aluminum cylinder member (diameter d ₁ = 345 mm, plate thickness t ₁ = 20 mm) is used for the cooling cylinder 3. Case 3 is a case in which a cylindrical member (diameter d ₁ = 345 mm, plate thickness t ₁ = 30 mm) made of aluminum but different in plate thickness is used for the cooling cylinder 3.

The cases 1 to 3 are made of the same stainless steel inner cylinder 3 (diameter d ₂ = 355.
The temperature was measured at the position shown in FIG. 3 (6 mm, plate thickness t ₂ = 5 mm) (the position of the inner cylinder 3 at the same angle in case 1). The thermal conductivity of the inner cylinder 3 was 14 kcal / mh ° C, and the thermal conductivity of the cooling cylinder 8 was 175 kcal / mh ° C. Further, the upper layer temperature Ta ₁ of the space inside the inner cylinder 3 in the case ₁ is −130.
The temperature Ta _{2 of the} lower layer was −196 ° C.

From the above measurement results, the maximum temperature of case 1 is -138.1 ° C and the minimum temperature is -196.0 ° C.
And a temperature difference of about 58 ° C. occurred. The maximum temperature of Case 2 is -188.7 ° C, and the minimum temperature is -196.0 ° C.
And the temperature difference was about 7 ° C. Furthermore, the maximum temperature of case 3 is -190.9 ° C and the minimum temperature is -196 ° C, which is a temperature difference of about 5 ° C.

As a result, by providing the cooling cylinder 8,
It became clear that the temperature distribution in the circumferential direction inside the inner cylinder 3 can be made largely uniform, and the temperature of the laser medium gas can be made largely uniform.

In this embodiment, the cooling cylinder 8 is made of aluminum, but the cooling cylinder 8 is not limited to this, and other well-known materials having good thermal conductivity such as aluminum alloy, copper, copper alloy, etc. It may be a cooling cylinder using.

In this embodiment, the cooling cylinder 8 is a single member, but it may be a plurality of members divided in the axial direction.

[0028]

According to the present invention, the portion where multiple reflections of laser light are surrounded by the cooling cylinder formed of a material having good thermal conductivity results in the laser medium in the portion where multiple reflections of laser light occur. The temperature of the gas is made uniform, and the refraction of the laser light is prevented by making the density of the laser medium gas uniform.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a Raman laser device according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating multiple reflection of laser light.

FIG. 3 is a diagram showing a temperature measurement point according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a Raman laser device according to a conventional technique.

[Explanation of symbols]

 1, 2 concave mirror 3 inner cylinder 4,5 window 6 outer cylinder 7 jacket 8 cooling cylinder 9 laser medium gas 24 multiple reflection part 30, 31 laser light

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayoshi Hagiwara Masayoshi Hagiwara, Tokai-mura, Naka-gun, Ibaraki Prefecture 4-3 Muramatsu, Tokai Plant, Reactor and Nuclear Fuel Development Corporation (72) Shin Hasegawa Tokai-mura, Naka-gun, Ibaraki Prefecture Muramatsu No.33 33 Reactor / Nuclear Fuel Development Corporation Tokai Works (72) Inventor Yufumi Inoue Tokai-mura Naka-gun, Ibaraki Prefecture Muramatsu No.33 33 Reactor / Nuclear Fuel Development Corporation Tokai Works (72) Inventor Yado Yumio 33 Muramatsu, Tokai-mura, Naka-gun, Ibaraki Prefecture 33 Muramatsu, Power Reactor and Nuclear Fuel Development Corporation Tokai Works (72) Inventor Hideo Tashiro 2-1, Hirosawa, Wako City, Saitama Prefecture (72) Inventor Keiji Yoshimura 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries Ltd. Hiroshima Works

Claims (1)

[Claims] 1. In a Raman laser device in which a pair of concave mirrors are provided at both ends in a cylindrical container cooled from the outer peripheral side and the laser light is multiply reflected between the concave mirrors, a portion for multiple reflection of laser light is provided. A Raman laser device characterized in that a cooling cylinder formed of a material having good heat conductivity is attached to the inside of the container.