JPS5849904A - Metallic mirror - Google Patents

Abstract

PURPOSE:To obtain a metallic mirror having no difference in level among crystal grains and uniform surface properties, undergoing hardly thermal damage, etc. due to laser light and giving high work efficiency by forming the mirror surface part of a metallic mirror with a single crystalline metallic material. CONSTITUTION:A metallic mirror is manufactured by forming at least the mirror surface part with a single crystalline mild metallic material such as Cu or Al. Since the metallic material has no grain boundary unlike a polycrystalline material, the mirror surface having no difference in level among crystal grains and extremely high accuracy is obtd. under the same cutting conditions over the whole surface. The mirror undergoes hardly external unfavorable influence such as thermal damage due to laser light with high energy density, and it has high durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal mirror used for a laser reflecting mirror or the like.

Metal mirrors are generally manufactured by mirror-finishing a soft metal material such as Cu or Al using a diamond cutting tool. However, since these conventionally used metal materials have a polycrystalline structure, which is the most commonly obtained, crystal grain steps occur on the processed mirror surface due to crystal anisotropy. This crystal grain level difference, together with the difference in reflectance between crystal planes, reduces the precision of the mirror. This grain level difference can be reduced by cutting it in extremely small amounts with an extremely sharp diamond cutting tool.
There are limits to that.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a metal mirror with uniform mirror surface properties.

This object is achieved by forming at least the mirror surface portion of the metal mirror from a single crystal metal material. As this single crystal metal material, Cu is used in order to minimize surface roughness and obtain a highly accurate mirror surface.

Soft metal materials such as AI are preferred.

Single-crystal metal materials have a uniform crystal structure on a mirror surface, and there are no grain boundaries, so it is possible to obtain an extremely high-precision mirror with no crystal grain steps, and since it is a single crystal,
The cutting conditions are also the same, so highly accurate cutting can be performed.

The inventors of the present invention performed mirror polishing using polycrystalline and single-crystalline Cu under the same cutting conditions.
The single crystal has no crystal grain steps, and not only does it have a uniform mirror surface, but it also has a very bright mirror that can be seen with the naked eye.

Moreover, since this metal mirror does not have grain boundaries on its mirror surface, it can maintain a good mirror surface state for a long period of time without being affected by external adverse effects such as thermal damage caused by high-energy-density laser light.

As described above, according to the present invention, it is possible to obtain a high-precision mirror surface with uniform mirror surface properties, and the desired mirror surface can be obtained without requiring very small amounts of cutting. Great effects can be obtained, such as processing becomes possible and a good mirror surface condition can be maintained for a long period of time.

Applicant: Toshiba Machine Co., Ltd.

Claims (1)

[Claims] / A metal mirror characterized in that at least a mirror surface portion is formed of a single crystal metal material. The metal mirror according to claim 1, wherein the single-crystal metal material is a single-crystal soft metal material. 3. The metal mirror according to claim 1, wherein the single crystal soft metal material is Cu. The metal mirror according to claim 1, wherein the single crystal soft metal material is A1.