| 摘要 |
PURPOSE:To raise the degree of signal modulation to its maximum by controlling the direction of polarization of light of a light source based on a maximum bit density in the bit array direction and that in the direction perpendicular to the bit array direction as prescribed. CONSTITUTION:Laser light, whose direction of polarization is matched to the bit characteristic of a medium 6 like an optical disk, from a laser diode 1 of the light source provided with a polarization plane rotating mechanism 10 is converted to coherent light by a collimator lens 2 and is thrown to the medium 6 to perform bit recording or the like. The direction of polarization of coherent light is adjusted in the direction perpendicular to the bit array direction by a polarization direction rotating element 9 in the case of Dt<Dr where Dt is a maximum bit density in the bit array direction and Dr is that in the direction perpendicular to the bit array direction, and it is adjusted in the direction parallel with the bit array direction in the case of Dt>Dr. The polarization state of the light beam is adjusted to a condition most suitable for the optical disk to obtain the optical disk device where the degree of signal modulation is maximized. |
