| 摘要 |
PURPOSE:To attain high information recording density based upon multiplex recording by guiding optical beams with plural different wavelengths to a fixed optical path by means of an optical element having reflective index wavelength dispersing property and concentrating the beams into a medium. CONSTITUTION:Recording, data erasing, focusing/tracking, and focusing wavelength variable lasers LD1-LD4 are arranged on an optical head 10. These lasers LD1-LD4 emit laser beams having respectively different wavelengths. A dichroic mirror (DM) 111 transmits only the wavelength band light of the LD1 and reflects beams having other wavelength bands. Respective DMs 112-114 reflect only the beams of wavelengths corresponding to the LD2-LD4 and transmit other beams. Thereby, all beams are made incident upon a deflecting beam splitter 105 and condensed into the medium 5. The emitted beams and reflected beams from the medium 5 are simultaneously and dispersely condensed into different positions corresponding to respective wavelengths by a hologram lens 108. Said constitution makes it possible to attain high information recording density. |
