| 摘要 |
PURPOSE:To reduce the variance of the optical power of a diffracted beam to record, reproduce, and erase information stably by modulating the frequency applied at the erasing time with a prescribed frequency and oscillation plural condensed spots in the track direction with a prescribed frequency. CONSTITUTION:An A/O driver 9 consists of an oscillating circuit 101 which has (n+1) oscillators having frequencies f0-fn, a mixer circuit 102 which controls signal intensities of these frequencies, an adding circuit 103 which adds these signal intensities, and an RF amplifier 104 which amplifies the synthesized signal. Frequencies are applied to a transducer 105 attached to an A/O element 3 to obtain (n+1) beams at the erasing time, and an artificial elliptic spot consisting of one circular spot for reproducing and n circular spots for erasing is formed. The frequency f0 for the recording/reproducing spot is fixed in the oscillating circuit 101, but frequencies f1-fn for erasing spots are modulated and this frequency modulation is controlled by the signal from an external controller 106. |
