| 摘要 |
<P>PROBLEM TO BE SOLVED: To minimize fluctuation of a reproducing signal for each wavelength of an optical beam when pieces of information are recorded in three or more types of optical disks different from one another in format or pieces of information are reproduced from the optical disks. <P>SOLUTION: The optical head device is provided with two or more light sources 21 and 23, an objective lens 31 for condensing lights of predetermined wavelengths from the light sources in the recording layer of a recording medium to capture reflected lights reflected on the recording layer, a polarization control unit 39 disposed between the light source and the objective lens to optimize the polarizing directions of the lights from the light sources and the reflected lights reflected on the recording layer according to an applied voltage and according to wavelengths, a photodetector 43 for receiving the reflected lights captured by the objective lens to output predetermined signals, and a polarization control circuit 6 for changing the polarizing directions set by the polarization control unit based on the output of the photodetector. Thus, the fluctuation of reproducing signal are minimized for each wavelength of an optical beams when pieces of information are recorded in optical disks different from one another in recording density and format, or reproduced. <P>COPYRIGHT: (C)2008,JPO&INPIT |
