| 摘要 |
<p>A cutting apparatus is provided, in which a recording laser beam from a laser light source(1) is ON/Off-modulated by an optical modulating device (8) on the basis of a square output signal in which a video FM wave signal is pulse width modulated by an audio FM wave signal thereby to form exposure pits on a master disc(15,16). This cutting apparatus includes a photodetector (38) for receiving one portion of the recording laser beam irradiated on the master disc (15,1 from the laser light source(1) or a photodetector (38a) for receiving a reflected light of the recording laser beam irradiated on the master disc from the laser light source (i) and which is reflected on the master disc (15,16). A detected output signal from the photodetector (38,38a) is supplied through a low-pass filter(39,39a) to a control circuit which controls an intensity of an output laser beam from the laser light source(1), and an offset of a source system line is adjusted so that a secondary higher harmonic component of a main carrier in the detected output from the photodetector (38,38a) is minimized.</p> |
