| 摘要 |
<P>PROBLEM TO BE SOLVED: To miniaturize an optical pickup device using three wavelengths. <P>SOLUTION: In an optical pickup device equipped with: light sources 101A, 101B which emit rays of light of three wavelengths; an optical path coupling means 104 which makes advancing directions of the rays of light of first to third wavelengths into one; a condensing means 105 which condenses rays of light from the optical path coupling means 4 on an optical information recording medium 106 ; a diffraction element 103 which diffracts the reflected rays of light from the the optical information recording medium 106; and a plurality of photodetectors 102 (102A, 102C, 102BD) which receive diffracted rays of light from the diffraction element 103, the optical path coupling means 104 makes optical axes agree with each other, and the diffraction element 103 makes ±second-order diffracted rays of the light of light of the first wavelength, ±first-order diffracted rays of light of the light of the second wavelength and the light of the third wavelength signal rays of light from the optical information recording medium and condenses the +second-order diffracted light of the light of the first wavelength, +first-order diffracted rays of light of the light of the second wavelength and the light of the third wavelength on a first photodetector 102A, and condenses the -second-order diffracted light of the light of the first wavelength and the -first-order diffracted light of the light of the third wavelength on a second photodetector 102BD, and condenses the -first-order diffracted light of the light of the second wavelength on a photodetector 102C. <P>COPYRIGHT: (C)2007,JPO&INPIT |
