Patent ID: 7986605
Filing Date: 2011-07-26
Classification: G11B

Abstract:
1. An optical pickup comprising: a light source emitting a light beam; an objective lens condensing the light beam emitted from the light source onto an optical disc; at least one divergent angle conversion lens disposed between the light source and the objective lens and changing a divergent angle of the light beam; driving means for driving the at least one divergent angle conversion lens in a direction of an optical axis; an optical detection device detecting a return light beam reflected at the optical disc; and an environmental change detecting unit configured to detect change in environmental temperature, wherein the objective lens is made of a refractive element having, on one surface thereof, a diffraction structure in a stepped shape or a blazed sectional shape, which generates diffraction light providing a spot adapted to perform satisfactory recording and/or reproducing, the objective lens satisfying a relationship of 2.5×10 wherein the at least one divergent angle conversion lens is driven step by step in accordance with a detection result of the environmental change detecting unit.