Patent ID: 6014271
Filing Date: 2000-01-11
Classification: G11B

Abstract:
An objective lens for an optical disc comprising a positive single lens, disposed between a light source and the optical disc, said objective lens having:a first surface directed to said light source; anda second surface directed to said optical disc,wherein:said first surface has a convex shape; andboth said surfaces are aspheric,said objective lens satisfies the following conditions:(a) 1.0<.vertline.R2/R1.vertline.<1.2(b) 0.15.ltoreq..vertline.M.vertline..ltoreq.0.3(c) .vertline.ZR1.vertline.<.vertline.ZR2.vertline.(d) .vertline.Z1 (H).vertline.<.vertline.Z1 (Y).vertline. and 0<H<Y(e) .vertline.Z2 (H).vertline.<.vertline.Z2 (Y) and 0<H<YwhereR1 is the paraxial radius of curvature on the light source side surface;R2 is the paraxial radius of curvature on the optical disc side surface;M is the transverse magnification of the lens;ZR1 is the diameter of the light source side surface;ZR2 is the diameter of the optical disc side surface;Z1 (H) is the distance from a point on the light source side surface to the origin point, where height from the optical axis is H;Z1 (Y) is the distance from a point on the light source side surface to the origin point, where height from the optical axis is Y;Z2 (H) is the distance from a point on the optical disc side surface to the origin point, where height from the optical axis is H; andZ2 (Y) is the distance from a point on the optical disc side surface to the origin point, where height from the optical axis is Y,wherein H and Y are within the corresponding paraxial radius.