| 摘要 |
PURPOSE:To write a signal on a next track while keeping accurately a track pitch, by making a recording optical beam and a reproducing optical beam incident to the same optical deflector and an objective lens for aperture and positioning the two beams so that they are parted radially on a disc by a prescribed track pitch so as to eliminate the effect such as eccentricity or the like. CONSTITUTION:An output of a constant voltage source 21 is added to a tracking error signal 20 at an adder 17 and frequency-converted at a frequency converter 18. The frequency-converted signal is inputted to an optical deflector 4 through a summing amplifier circuit 19. A laser beam 5 is deflected in this case. Further, an optical beam 7 is polarized in a direction having a deflecting angle into a collected beam 7 at a condensor lens 3' to form an optical spot 9 on the disc. In this case, the deflection angle of the optical beams 6, 7 is constant. That is, the pitch between the optical spots 9 and 8 is kept constant. |
