JP2684927B2 - Optical element substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate of an optical element used to utilize radiation emitted from an electron accelerator, for example.

[0002]

2. Description of the Related Art For example, an optical element such as a vent mirror for converging light emitted by synchrotron radiation requires that its surface be a plane with extremely high precision. Therefore, a hard material whose precision is easily obtained by polishing is suitable for the substrate of the optical element. Therefore, conventionally, sintered ceramics such as SiC are often used as a substrate material of an optical element used for X-rays and the like. Ceramics such as SiC are used which have a porosity close to zero in order to obtain mechanical strength.

In particular, SiC is most often used as a substrate material for an optical element used for X-rays. This is because when the optical element is irradiated with X-rays, the energy thereof raises the temperature of the optical element. In order to efficiently cool this optical element, it is required that the substrate has high thermal conductivity. Therefore, among ceramics, SiC having a relatively high thermal conductivity of about 100 W / m · K is used.

[0004]

As described above, when the energy of the X-rays applied to the optical element using ceramics such as SiC as the substrate becomes larger, even if the optical element is cooled, the temperature of the surface of the optical element becomes higher. The unevenness occurs. As a result, the optical element may be deformed by heat and may not be usable. In order to prevent this, it is preferable to further increase the thermal conductivity of the substrate and cool the optical element so that the temperature distribution is as uniform as possible. However, it is difficult to increase the thermal conductivity of ceramics such as SiC, and it has been difficult to cool the optical element so that the temperature distribution is as uniform as possible.

Further, when an optical element is used as a bent mirror to collect X-rays and the like, a bending stress acts on the optical element, so that the substrate material is required to have high toughness and ductility. However, the mechanical properties of ceramics such as SiC itself are limited, and it often breaks when a bending stress is applied for use as a vent mirror.

The present invention has been made to solve the above disadvantages, and an object of the present invention is to obtain an optical element substrate which has improved thermal conductivity and mechanical properties and can be stably used. .

[0007]

The optical element substrate according to the present invention uses ceramics having a porosity of 5 to 50% as a raw material, and the thermal conductivity of the ceramics is approximately within the pores.
It is characterized by being impregnated with 400 W / m · K of copper or silver .

The above ceramics have a porosity of 5 to 50.
% SiC and copper is preferably used as the metallic material.

[0009]

Function: In the present invention, 5 to 50% of ceramics
The pores are impregnated with a metal having a high thermal conductivity, such as copper, so that the thermal conductivity is higher than that of the ceramic itself and the mechanical properties such as overall toughness and ductility are enhanced.

[0010]

1 is a sectional view showing a mirror according to an embodiment of the present invention. As shown in the figure, a mirror 1 used for reflecting and condensing X-rays 5 is a substrate 2, a vapor deposition film 3 formed on the surface of the substrate 2, and a thin film of platinum, for example, formed on the surface of the vapor deposition film 3. Have 4. The substrate 2 is made of a material in which a SiC sintered body having a porosity of 5 to 50% is used as a material, and the pores of the SiC sintered body are impregnated with copper.
The surface of the substrate 2 is made flat by polishing, and a vapor deposition film 3 is formed by vapor-depositing SiC on the surface of the substrate 2. A method of impregnating the pores of a sintered SiC body with copper is known.
Method, for example, JP-A-49-99512 and Japanese Patent
No. 2-808114 (Japanese Patent Application No. 2-502390)
High pressure vessel containing molten copper bath as shown in
Put the SiC sintered body into the inside and make it a vacuum.
After degassing the gas in the pores, melt the SiC sintered body with molten copper.
Submerge in bath and pressurize high pressure vessel with nitrogen or argon gas
Then, copper is impregnated into the pores of the SiC sintered body. This copper
The SiC sintered body impregnated with is taken out from the molten copper bath and slowly
By cooling, the pores of the SiC sintered body are impregnated with copper.
Can obtain the material.

FIG. 2 shows the texture of the substrate 2 in which 5 to 50% of the pores of the SiC sintered body are impregnated with copper as described above.
As shown in FIG. 2, the grain boundaries 7 and pores 8 that are boundaries between the SiC crystal grains 6 are filled with copper 9 and have an extremely dense structure. In this way, by making the grain boundaries 7 and the pores 8 that hinder the heat conduction close by the copper 9 having good heat conductivity, the factors that hinder the heat conduction can be reduced. That is, S
The thermal conductivity is about 100W / when it is composed only of the sintered body of iC.
Although it is m · K, when a SiC sintered body having 5 to 50% of pores 8 is impregnated with copper 9 having a thermal conductivity of about 400 W / m · K, the thermal conductivity is about 200 W / m · K. I was able to double. Therefore, even if heat is applied to the Mira-1 by being irradiated with high-energy X-rays, it is possible to enhance the dispersion of the heat and enhance the cooling effect, so that the temperature distribution of the Mira-1 can be made uniform. it can.

Further, the grain boundaries 7 and pores 8 of SiC are filled with copper 9, so that the mechanical properties such as toughness and ductility of the substrate 2 as a whole can be improved. Therefore, even when the mirror 1 is bent to form a bent mirror to collect X-rays, the mirror 1 can be stably curved.

Here, the porosity of the SiC sintered body is 5 to 50%.
The reason is that when the porosity is 5% or less, mechanical properties such as toughness and ductility are not improved so much, and when the porosity is 50% or more, the heat resistance of the substrate is deteriorated.

In the above embodiment, the case where the pores 8 and the like of the SiC sintered body are filled with copper 9 has been described, but silver or the like having good thermal conductivity may be filled.

[0015]

As described above, the present invention has a thermal conductivity of about 400 W / m in 5 to 50% of the pores of ceramics.
· Impregnated with copper or silver of K to form a substrate for optical elements,
As a result, the thermal conductivity of the substrate becomes higher than that of the ceramic itself, so that the substrate can be cooled uniformly and the occurrence of temperature unevenness due to irradiation with X-rays or the like can be prevented.

Further, by filling the pores of the ceramic with copper or silver to enhance the adhesive force between the tissues, the mechanical properties such as toughness and ductility of the entire substrate can be enhanced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a mirror of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a textured state of a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mira 2 Substrate 3 Evaporated film 4 Thin film 6 SiC crystal particles 8 Porosity 9 Copper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoichi Yoshinaga 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Within Nippon Kokan Co., Ltd. (72) Inventor Mikiyuki Asano 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (56) References Japanese Patent Laid-Open No. 1-28000 (JP, A)

Claims (2)

(57) [Claims] 1. A ceramic material having a porosity of 5 to 50% is used as a material, and pores of the ceramic are impregnated with copper or silver having a thermal conductivity of about 400 W / m · K. An optical element substrate characterized by the above. 2. The optical element substrate according to claim 1, wherein the ceramic is SiC.