| 摘要 |
PURPOSE:To easily form a sharp wobbling pit, by constituting the driving circuit of an acoustic and optical modulator by using the eta/4 phase distributor of a high frequency signal, a frequency converter, and a zero phase synthesizer. CONSTITUTION:The frequencies F1 and F2 of oscillators 1 and 2 are converted to signals (k) and (l), and (m) and (n) having the lead and lug of the phase of eta/4, and furthermore, an output (f) whose frequency is either (F1+F2) or (F1-F2) can be obtained by the frequency converters 3-1 and 3-2 and the zero phase synthesizer 9. Now then, when the wobbling pit is formed by shifting pits by the same distance leftward and rightward from the center of a track, either frequency (F1+F2) or (F1-F2) is selected by using the comparatively low frequency F2 equivalent to the displaced share of the pit for the central driving frequency F1 by the above stated method. In such a way, it is possible to perform the diffraction of an optical beam stably, and to obtain an sharp pit, by controlling the low frequency signal. |
