POLYCRYSTALLINE ZINC SULFIDE OPTICAL PARTS AND THEIR PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide visible light shieldable polycrystalline zinc sulfide optical parts having a high transmittance of IR light of a wavelength 8 to 12μm band by drastically reducing the transmittance of visible light and IR light of a wavelength <=3μm. SOLUTION: These optical parts consist of the polycrystalline zinc sulfide sintered compacts formed by the hot compression molding of fine zinc sulfide powder of high purity at 900 to 1000 deg.C under pressure of 150 to 800 kg/cm<2> in a nonoxidizing atmosphere. The transmittance of light at thickness 2 mm is 0% to 3% in a visible light wavelength region, 0% to 20% in a 2.5 to 3μm wavelength region and 30% to 75% in a wavelength of 8 to 12μm. The transmittance in the same wavelength region is 50% to 90% by forming an antireflection film.