OPTICAL GLASS, PREFORM FOR PRECISION PRESS MOLDING, AND OPTICAL ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide: optical glass which is excellent in stability and has a high refractive index and high dispersion; a preform for precision press molding, formed of the optical glass; an optical element; and methods for producing them.

SOLUTION: The optical glass is composed of oxide glass containing Bi3+in an amount of 30-70% in terms of cation and has a liquid-phase temperature of≤800°C. In the optical glass, the wave lengthλ70 at which the spectral transmittance is 70% is≤590 nm, and the viscosity at a liquid-phase temperature is≥2 dPa s. Further, the optical glass contains Bi3+in an amount of 5-50%, Si4+in an amount of 0.5-50%, and Al3+in an amount of 1-20%, each in terms of cation.

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