| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain satisfactory characteristic by using a light source of good productivity and small optical output rating and to realize the precise output power control of the light source by reducing the necessary variation of the output power of the light source between a recording time and reproducing time or among different kinds of optical recording mediums and with respect to the respective recording surfaces of a multilayer optical recording medium. <P>SOLUTION: Optical coupling efficiency about a luminous flux emitted to the optical recording medium 102 by an optical head 104 is controlled according to the kind of the optical recording medium 102, a recording surface of the multilayer optical recording medium and an operation mode by optical coupling efficiency variable elements 214 and 215. Thus, the power of the luminous flux to be emitted to the optical recording medium 102 is markedly varied without extremely increasing the variation of the output power of the light source 212. With rising of temperature, the optical coupling efficiency is lowered. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
