SEMICONDUCTOR LASER DEFECT DETECTOR

PURPOSE:To detect the defect of a semiconductor laser and to prevent information tracks or information on a recording carrier from being damaged by switching laser power to recording power before executing focus control, and operating a laser defect discriminating means according to the detection signal of a light quantity detector. CONSTITUTION:A laser defect discriminating means 7 is composed of a microcomputer equipped with a central arithmetic unit, etc., and after confirming the raising of rotation speed for a disk 5, a laser power control circuit 1 is switched to the recording power control according to the detection signal from a rotation detector 4 before executing the focus control. When it is detected by the detection signal of a light quantity detector 3 that the semiconductor laser can not output the quantity of light necessary for recording, a focus control circuit 8 is not driven but the semiconductor laser is stopped being driven. At such a time, since focus is not loaded even when outputting the recording power from the semiconductor laser, power concentration on a disk 5 is small and nothing is recorded onto the information tracks.