| 摘要 |
PROBLEM TO BE SOLVED: To provide a composite optical unit which is dealable with an optical device using plural light sources of different wavelengths with one composite optical device, may be reduced in cost without complication of the structure and is applicable to an optical pickup as well. SOLUTION: This composite optical unit has a housing 51 mounted at the optical pickup 100. A semiconductor laser 52, a photodetecting member 54 and a composite optical member 55 are mounted and fixed to the housing 51. The semiconductor laser 52 has a laser diode 53a for emitting a short-wavelength laser for DVDs and a laser diode 53b for emitting a long-wavelength laser for CDs. The composite optical member 55 is provided with an incident surface 55a on which the light emitted from the semiconductor laser 52 is made incident, an exit surface 55b from which the light is emitted, a diffraction grating 55f which is disposed on the exit surface 55b and diffracts the return light reflected by an optical disk D1 (D2) disposed at the exit surface 55b and a reflection surface 55d' which reflects the light diffracted by the diffraction grating 55f to the photodetecting member 54. The reflection surface 55d' is provided with a diffraction grating 55g which images the light of different wavelengths onto the photodetecting position P of the photodetector 54. |
