| 摘要 |
PROBLEM TO BE SOLVED: To make the device miniature and thin structive by conforming optical paths for different luminous fluxes in wavelength, equipping a means for separat ing their reflected light beams from each other and disposing their optical systems in the same plane. SOLUTION: At the time of recording and reproducing a high density disk 6, a light beam 650nm in wavelength from a light emitting element 1 is transmitted through a polarizing beam splitter 3 and is transmitted through a dichroic mirror 4, and is then converged on the surface of the disk 6 by an objective lens 5 corresponding to the high density disk. Its reflected light beam is transmitted again through the mirror 4, and is reflected by polarization of the polarizing beam splitter 3, so as to be incident upon a detector 8. At the time of recording and reproducing the conventional disk 12, a light beam 780nm is wavelength emitted from a module integrated with a laser detector corresponding to the conventional disk is made to be incident upon the mirror 4 at an angle <=45 deg., and is conformed by this characteristic with the optical path of the high density optical system, so as to be converged on the surface of the disk 12. Its reflected light beam is separated from the high density system optical path and is incident upon the module 9 integrated with the detector. |
