| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a collimator lens capable of correcting a spherical aberration and on-axial chromatic aberration by using a simple, inexpensive lens. <P>SOLUTION: The collimator lens comprises a bonded lens which is provided on a light path from a laser light source D to an information recording medium and in which two glass lenses of a biconvex lens L1 and a meniscus lens L2 are bonded to convert the laser beam emitted from the laser light source D into a parallel luminous flux. The bonded lens is constituted so that the biconvex lens L1 is placed facing the information recording medium side and a non-spherical plastic lens L3 made of a thin film of a transparent resin is layered over a lens surface of the biconvex lens L1. When the quantity of on-axial chromatic aberration is (a) and the number of apertures is NA, in terms of its composite focal length (f) of 10 mm, the condition of (1) a<2.2μm/nm and (2) 0.4>NA≥0.12, is satisfied. <P>COPYRIGHT: (C)2007,JPO&INPIT |
