| 摘要 |
PROBLEM TO BE SOLVED: To receive luminous fluxes reflected from plural kinds of optical information recording media which are each different in wavelength in use with a single photodetector and make it possible to detect a signal as in the case of an optical pickup device for a single wavelength. SOLUTION: An optical pickup device executes at least one of the operations selected from the recording, the reproducing and the erasing of information to the plural kinds of optical information recording media 7 and 8 which are each different in wavelength in use. In this case, light sources 1 and 2 that radiate lights which are each different in wavelength, an objective lens 6 which converges each luminous flux from the light sources directing it toward an optical information recording media corresponding to wavelengths and forms optical spots on the recording surface of the optical information recording media, a photodetector 10 which receives the reflected luminous fluxes reflected by the recording surface and a hologram element 9 which diffracts the reflected luminous fluxes toward the photodetector are provided. Besides, the photodetecor 10 is made common to the reflected luminous fluxes, and the hologram element 9 is composed of a combination of plural kinds of hologram groups corresponding to each of the luminous fluxes different in wavelength. |
