| 摘要 |
The present invention is directed to an optical head adapted for performing recording or reproduction of information signals with respect to an optical disc ( 102 ), which controls light coupling efficiency with respect to light beams irradiated onto the optical disc ( 102 ) by light coupling efficiency adjustable element such as a liquid crystal element ( 214 ), etc. in accordance with type of the optical disc ( 102 ), recording surface of multi-layer optical disc and/or operation mode to change power of light beams irradiated onto the optical disc ( 102 ) to a large extent without excessively increasing change quantity of output power of a semiconductor laser element ( 212 ). A beam splitter ( 218 ) divides incident light beams of P-polarized light at a predetermined ratio to allow the light beams thus obtained to be incident on a light detector ( 219 ) for disc surface power monitor. |
