| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup which can separate a plurality of optical beams and stably guide the optical beams to corresponding objective lenses. <P>SOLUTION: The optical pickup comprises a light source section 10 emitting the optical beams of different wavelengths, a diffraction grating 11 for branching the optical beams to main beams and sub-beams, a collimating lens 12 for converting the exit light to parallel pencils, a first beam splitter 13 for branching the exit light and return light, a photodetector 14 for adjusting the exit optical beam, an expander 15 for expanding the exit optical beam diameter, and a collimating lens l6 for converting the optical beam transmitted through the expander 15 again to the parallel pencils. The optical pickup is provided with a first objective lens 19 having a first numerical aperture for condensing the first optical beam 51 onto a BD recording surface, and a second objective lens 20 having a second numerical aperture for condensing the second optical beam 52 and the third optical beam 53 onto the recording surface of a DVD or CD, and is provided with a luminous flux separating and starting-up section 17 in common use as a luminous flux separating means for separating an optical path so as to make the optical beams of the different wavelengths incident on the respective objective lenses and a means for guiding the separated optical beams to the corresponding objective lenses. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
