| 摘要 |
PURPOSE:To increase capacity recorded on an information medium and a reproducing rate by providing the titled processor with at least two light sources different in wavelength and a grating type objective lens for converging and irradiating optical beams from the light sources to an information surface. CONSTITUTION:A beam with wavelength lambda1 radiated from the 1st light source 21 is turned to a parallel beam by a collimater lens 23, converged and irradiated to the 1st information pit surface of an information medium 5 as a fine spot by an objective lens 25, modulated by the pit, reflected by a filter layer 2, converged again by the objective lens 25, lead into the detecting side by a beam splitter 24, and then converged and detected by the 1st photodetector 27. A beam with wavelength lambda2 radiated from the 2nd light source 22 is turned to a parallel beam by a lens 23, passed through the filter layer 2, converged and irradiated on the 2nd information pit surface as a fine spot, modulated by the pit, reflected, separated through a filter 26, and then converged and detected by the 2nd photodetector 25. Consequently, the capacity recorded on the medium and the reproducing rate can be increased. |
