To provide a preform for precision press molding including an optical glass having a wide dispersion characteristic, a low press temperature and a high stability and its manufacturing method, an optical device obtained by precision-press molding the preform and its manufacturing method.
The preform for precision press molding comprises an optical glass which contains by mole% 15-70% of P2O5, 1-30% of Nb2O5, 0-20% of TiO2(excluding 0%), 0-30% of Bi2O3(excluding 0% and over 4 wt.%), 0-30% of B2O3, 1-20% of WO3, 0-15% of BaO, 3-15% of Li2O (excluding 3 wt.%), 0-5% of SiO2(excluding 5 wt.%), and 0-10% of ZnO (excluding 10 wt.%) and has a weight ratio of less than 0.5 (TiO2 content/Bi2O3 content), a refractive index (nd) of 1.7 and an Abbe's number (d) of 32. The optical device is manufactured from the preform.
KASUGA YOSHIKO
FUJIWARA YASUHIRO
| JP2003238197A | 2003-08-27 |