| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain good characteristics and to ensure the exact output power control of a light source by making the required variation of the output power of the light source smaller at the time of recording or reproducing or in relation to the respective recording surfaces of optical recording media and multilayered optical recording media and by using the light source of smaller optical output rating having good productivity. <P>SOLUTION: The optical coupling efficiency relating to the luminous flux with which the optical recording medium 102 is irradiated from an optical head 104 is controlled by optical coupling efficiency variable elements 214 and 215 according to the kind of the medium 102 and the recording surface and operation mode of the multilayered optical recording medium to change the power of the luminous flux with which the medium 102 is irradiated to a large extent without excessively increasing the variation of the output power of the light source 212. Also, the optical coupling efficiency is fixed regardless of the operation mode at a temperature lower than the prescribed temperature. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
