JPS59157000A - Method for polishing optical parts - Google Patents

Abstract

PURPOSE:To provide finished smooth surfaces almost free from flaws to the surfaces of optical parts made of a specified bromide or iodide by chemically polishing the surfaces of the optical parts with concd. hydrobromic acid. CONSTITUTION:The surfaces of optical parts made of CsBr, RbBr, KBr, NaBr, CsI, RbI, KI, NaI or a solid soln. thereof are chemically polished with concd. hydrobromic acid. By this polishing method, chemical polishing is carried out while almost preventing the pitting of the surface of said bromide or iodide due to etching, and smooth surfaces can be easily obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for polishing optical components using bromide or iodide as abrasive.

[Technical background of the invention and its problems] In recent years, application technology of infrared light with a wavelength of several μm to several tens of μmη has been developed.
It is being actively researched. In particular, progress has been remarkable in the processing and medical applications of high-power carbon dioxide laser light with a wavelength of 106 μm. Lenses, window materials, optical fibers, etc. used in this wavelength range are required to have high transmittance, and monovalent metals such as Cs, Rh, Na, etc. are in the wavelength range where absorption by lattice vibration is long enough. halides are widely used.

Among the monovalent metal halides mentioned above, bromide and iodide are materials with high transmittance in the wavelength region of around 10 μm or longer wavelengths, and for optical components with long optical paths such as optical fibers, other materials in this region are used. It exhibits particularly superior transmittance compared to other materials. However, since these bromides and iodides are extremely soft, mechanical polishing or mechanochemical polishing is difficult. Furthermore, even after repeated polishing, many linear polishing scratches can be observed by microscopic observation at a magnification of around 100 times. Such scratches scatter light, lowering the transmittance of the optical component, and serve as a starting point for destruction when transmitting high-output light, thereby significantly deteriorating the performance of the optical component.

Furthermore, the bromide or iodide crystals cause many etch spots due to organic solvents, organic acids, etc., and have very high solubility in water, causing many problems in surface polishing and cleaning.

[Objective of the Invention] The present invention solves the problems of the conventional polishing techniques described above, and improves the surface of optical parts made of bromide or iodide of Cs, Rb, K, and Na to a smooth surface with almost no fear of scratches. The purpose is to provide a polishing method that achieves a perfect finish.

[The present invention relates to CsBr, RbBr, KBr, NaBr.
Alternatively, in this method of polishing optical components made of a lano solid solution, a method of chemically polishing the bromide components with concentrated hydrobromic acid to obtain a smooth surface, and CsI, RbI, KI, N
In this method of polishing an optical component made of a solid solution of aI or a solid solution thereof, a smooth surface is obtained by chemically polishing the iodide with concentrated hydrobromic acid.

[Effects of the Invention] A smooth surface can be easily obtained by chemically polishing the surface of the bromide or iodide mentioned above without generating etch bits or the like.

[Embodiments of the Invention] Example 1 CsBr single crystal was formed into a string 7- (String S
aw) It was cut off. Stringing is a method in which the silk thread is constantly wetted with a fresh ethanol aqueous solution, and the dissolving action of the solution cuts the crystals.Although it can be cut without applying stress to the crystals, it often leaves stripes on the surface. Alternatively, ripple-like unevenness may occur. This surface was polished on a polishing plate covered with a polishing cloth soaked in an ethanol aqueous solution. As described above, a polishing method that combines the dissolving action of a liquid and a mechanical polishing action, ie, mechanochemical borage, is widely used.

When the polished surface was observed under a 100x optical microscope, the ripple-like irregularities mentioned above disappeared and it became almost flat.
Kanashi abrasions were observed. On this surface, the scratches that existed on the chess floor outside the Mechanochemical Boridge disappeared, and a smooth surface appeared. If the time is shorter than this, the scratches will not disappear completely, and if the time is too long, new roughness may be observed. This optimum time also depends on the single crystal growth conditions. For crystals with a high density of defects such as dislocations, if the chemical polishing time is prolonged, the surface becomes rough around the defects, but on the other hand, for single crystals with few defects, it takes a relatively long time to obtain a very smooth surface. Example 2: C5I single crystals were prepared using concentrated hydroiodic acid (HI57, Section 2).

i.e. 10.3 mol/1kg H2OI)
When polished using the same method as in Example 1, a smooth surface was obtained. The optimum immersion time for chemical polishing was 5 to 20 seconds.

Claims (1)

[Claims] (1) CsBr, 11bBr, KBr, NaB
An 'Alf polishing method for optical components, which is characterized by chemically polishing the surface of an optical component made of a r or these C solution with concentrated hydrobromic acid. (2) A method for polishing an optical component, which comprises chemically polishing the surface of an optical component made of CsI, RbI, KI, NaI, or a solid solution thereof using concentrated hydrogen bromide.