Patent ID: 8797834

Claim:
An objective lens made from synthetic resin, that converges a laser beam emitted from a laser light source onto an information recording surface of an information recording medium, the objective lens comprising: a lens having a first surface facing the laser light source and a second surface facing the information recording medium; and an anti-reflection coat formed on the second surface, wherein the lens converges a first laser beam having a first wavelength λ 1 (390 nm≦λ 1 ≦430 nm) that transmits through an area, of which radius from an optical axis of the objective lens is R 1 , of the first surface, onto an information recording surface of a first information recording medium, and converges a second laser beam having a second wavelength λ 2 (630 nm≦λ 2 ≦680 nm) that transmits through an area, of which radius from the optical axis of the objective lens is R 2 (R 2 <R 1 ), of the first surface, onto an information recording surface of a second information recording medium that is different from the first information recording medium, a transmittance T 1 _ 0 [%] of the anti-reflection coat when an incident angle of the first laser beam is 0° and a transmittance T 1 _ 40 [%] of the anti-reflection coat when the incident angle of the first laser beam is 40° satisfy 0.95≦T 1 _ 0 /T 1 _ 40 ≦1.05, in the area of which radius is R 2 , a transmittance of the first laser beam satisfies the transmittance ≧92%, a transmittance T 2 _ 0 [%] of the anti-reflection coat when an incident angle of the second laser beam is 0° satisfies 85%≦T 2 _ 0 <96%, and a transmittance T 2 _ 40 [%] of the anti-reflection coat when the incident angle of the second laser beam is 40° satisfies T 2 _ 40 ≧94%, and the transmittance T 2 _ 0 and the transmittance T 2 _ 40 satisfy 0.85≦T 2 _ 0 /T 2 _ 40 ≦0.97.