Patent ID: 7745361
Filing Date: 2010-06-29
Classification: C03C

Abstract:
1. An optical glass comprising: a glass wherein (i) SiO (ii) the combined quantity of SiO (iii) the mole ratio (SiO (iv) the quantity of La (v) the quantity of Gd wherein said glass has a refractive index (nd) within the range of 1.65 to 1.70 and an Abbé number (ν (nu)d) of greater than or equal to 50 for use in precision press molding, exhibiting that a ratio α (alpha)1/α (alpha)2 is less than 17 when temperature denoting maximum value of differential in amount of elongation of glass relative to temperature differential DELTAT (where DELTAT denotes a constant value of 1° C. or less) over a temperature range from glass transition temperature (Tg) to sag temperature (Ts) is denoted as T1, average coefficient of linear expansion over a range from T1−5° C. to T1+5° C. is denoted as alpha1, and average coefficient of linear expansion over a range from the glass transition temperature (Tg)−160° C. to the glass transition temperature (Tg)−140° C. is denoted as alpha2.