| 摘要 |
An apparatus for recording a defective-position indicating signal on a nonrecorded WO disk, comprising a laser beam source such as a laser diode for generating a laser beam to be irradiated onto the disk; an optical detector supplied with the laser beam reflected from the disk; an FM demodulator for demodulating the FM output signal of the optical detector; a defect detector for detecting a defect on the disk by comparing the output signal level of the FM demodulator with a reference value; and a laser power controller normally functioning to modulate the power of the laser beam by a fixed-frequency signal, or functioning, in response to detection of a defect, to maintain the laser beam power at an adequate recordable level for a first predetermined time after such detection. A detection controller is also included for interrupting the operation of the defect detector under control for a second predetermined time after the detection of the defect. The first predetermined time is approximately equal to one period of an FM carrier, and any dropout inclusive of micro DO can be completely detected.
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