Transparent polycrystalline spinel substrate and method of producing same, and optical article using said substrate

Abstract

There is provided a transparent polycrystalline spinel substrate characterized in having a transmittance of 0.005% or less in a crossed Nicol system at a thickness of 1 mm and a wavelength of 450 nm, which does not generate image blurring or light-dark change when used in optical products. There is also provided a method for producing the transparent polycrystalline spinel substrate comprising a step for preparing a spinel powder, a step for molding the spinel powder and producing a spinel formed body, a step for sintering the spinel formed body and producing a spinel sintered body, and a step for subjecting the spinel sintered body to hot isostatic pressing (HIP) and producing a spinel polycrystalline body. There is further provided a liquid crystal projector and a receiver for rear-projection television having the aforementioned transparent polycrystalline spinel substrate.

Dependencies are inferred from the claim text.