| 摘要 |
PURPOSE:To secure a sufficient operation distance for a condenser lens for an optical disk which consists of two positive lenses by making the 2nd surface of the 1st lens aspherical and satisfying specific conditions. CONSTITUTION:The condenser lens consists of two positive lenses 2 and 3 and the 2nd surface 2b of the 1st lens 2 is made aspherical. Further, two specific conditional inequalities 1 and 2 hold, where R1 is the radius of curvature of the 1st surface of the 1st lens, d2 is the air gap between both lenses, and (f) is the focal length of the entire system. |
