Patent ID: 8305865
Filing Date: 2012-11-06
Classification: G11B

Abstract:
1. An objective lens for an optical information recording/reproducing optical system for recording information to and/or reproducing information from an optical disc by letting a laser beam impinge on a recording layer of the optical disc, wherein: a center wavelength λ (unit: nm) of the laser beam falls within a range defined by a following condition: a base material of the objective lens is made of resin; the resin has a glass transition temperature Tg and light transmissivity T (unit: %) per a path length of 3 mm at a wavelength of 406 nm defined by following conditions: same antireflection films or different types of antireflection films are respectively formed on optical surfaces of the objective lens; and each of the antireflection films formed on the objective lens has a thickness of 100 nm or more in a vicinity of an optical axis of the objective lens.