| 摘要 |
PURPOSE:To obtain excellent playback signal over the entire recording region, by adding the means which gives the radial correction in which the recording pattern has 50% duty factor even in the case of shorter recorded wavelength, to the modulator circuit for stabilizing laser beam flux. CONSTITUTION:The video signal is modulated so that the duty factor of the recording pattern is 50% even in the case of shorter recorded wavlength, at the frequency modulator FMD, comparator COMP, variable gain amplifier VCA2, clamp circuit CCT2 and light modulator PMD2. On the other hand, the output of the photodetector PR of beam through the light modulator PMOD1 is negatively fed- back to the light modulator PMOD1 via the subtractor SVB2 and the bias voltage is given via the sample holding circuit SH and subtractor SVB1. Further, the correction to the X directional movement of condensed beam is added via the control voltage generator CGS and variable gain amplifier VCA1. Thus, excellent playback signal over the entire recording region can be obtained. |
