| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical pickup utilizing a plastic lens having high NA as an objective lens in which the temperature characteristic is sustained suitably. SOLUTION: The optical pickup comprises a finite convergence optical system 100 where a converging light enters into an objective lens 70 from a coupling lens 40. The coupling lens 40 is mounted fixedly on a lens holder while being integrated with the objective lens 70. Since converging light enters into an objective lens 70, temperature characteristics can be sustained suitably even if a plastic lens having high NA is employed as an objective lens. Furthermore, since the coupling lens 40 is integrated with the objective lens 70 and the distance thereof is fixed, optical relationships are not shifted due to adjustment of focusing, tracking, etc., and deterioration of the focusing performance can be avoided. |
