摘要 |
<P>PROBLEM TO BE SOLVED: To provide a laser light source which projects a plurality of wavelengths and reduces return optical noise, and also to provide an optical pickup. <P>SOLUTION: The difference (n1 L1-n2 L2) of the product of first and second effective refractive indexes n1, n2 in each of first and second light emitting parts and first and second resonator lengths L1, L2 is made larger than 0.065mm corresponding to thickness difference or the like of each protection layer of a DVD and a CD. Thereby, the relation between the distance to an optical disc (external resonator length) and a resonator length (inner resonator length) is kept in the state of reduced return noise as for both first and second light emitting parts by setting the distance of a laser light source properly to a DVD and a CD. <P>COPYRIGHT: (C)2005,JPO&NCIPI |