OPTICAL GLASS, OPTICAL ELEMENT INCLUDING THE OPTICAL GLASS AND OPTICAL INSTRUMENT INCLUDING THE OPTICAL ELEMENT

摘要

Maternal glass composition for optical element, comprising thallium and, as an indispensable component, boron oxide, so that the composition exhibits low melting temperature and excels in moldability to thereby enable production of a homogeneous glass body. A gradient index lens having a refractive index distribution needed for optical design, realizing wide effective visual field and excelling in weather resistance can be produced by bringing the glass body into contact with a molten salt of alkali metal so as to effect ion exchange. Further, optical parts and optical instruments excelling in optical characteristics can be provided by the use of the gradient index lens.