Optical glass

Abstract

There is provided an optical glass suitable for precision mold pressing having optical constants of a refractive index (nd) within a range from 1.75 to 1.85 and an Abbe number ( nu d) within a range from 35 to 45, comprising in mass % on oxide basis: having a transition point (Tg) within a range from 500 DEG C to 590 DEG C and a yield point (At) within a range from 530 DEG C to 630 DEG C, and being free from devitrification in a devitrification test conducted under a condition of 950 DEG C / 2 hours.

Description

technical field

[0001] The present invention relates to having refractive index (n d ) is 1.75~1.85 and the Abbe number (ν d ) is an optical glass suitable for precision molding (precision mold press) molding with an optical constant in the range of 35 to 45. Background technique

[0002] In recent years, the miniaturization and weight reduction of optical devices has been remarkably advanced, and aspheric lenses have been widely used in order to reduce the number of lenses constituting the optical system of the optical device. The mainstream aspheric lens manufacturing method is to heat and soften a preform obtained from a gob or a glass blank, press it with a high-precision metal mold, and copy the surface of the metal mold. The aspherical lens obtained by this method does not require grinding or grinding or basically does not require grinding or grinding, and molded products of desired shapes can be produced with high production efficiency. Glass precision press moldin...