Patent ID: 6349083
Filing Date: 2002-02-19
Classification: B82Y,G11B

Abstract:
A near field type optical disk recording and/or reproducing apparatus, comprising:a light source; an objective single lens to converse light from the light source to a focusing point; an optical disk; and a rotating device to rotate the optical disk, wherein the objective lens has a first surface at the light source side and a second surface at the focusing point side, and the first surface is a curved surface on which a diffraction surface is provided, and wherein the following formula is satisfied, (1âˆ’1/n)<R0/d<(1+1/n) â€ƒwherein n is a refractive index of the objective lens, R0 is a paraxial curvature radius of the objective lens, and d is a thickness of the objective lens on the optical axis.