| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect light quantity of laser beams of different frequency regions by a common light quantity detector. <P>SOLUTION: This light quantity detector has a light quantity detecting element 23 for monitor for detecting light quantity by receiving laser beams having different wavelengths outputted from a laser beam source and light source discriminating and receiving sections 24 (240, 241) discriminating a laser beam source, and is provided with a sensitivity adjusting section 25 for adjusting sensitivity of the light quantity detecting element 23 for monitor on the basis of the discrimination result of the section 24. The light quantity detector can be used for an optical pickup device. The light quantity detecting element can automatically select wavelength by only the element and can adjust sensitivity, then a plurality of light quantity detectors are not required. a control circuit and a control signal line in an external control system are not required, and a manufacturing cost can be reduced. <P>COPYRIGHT: (C)2004,JPO |
