Abstract: A laser light output control apparatus is provided with first and second D/A converters, a current source for supplying a laser with a current, a monitor circuit for monitoring a laser light, a comparator for comparing output of the second D/A converter with output of the monitor circuit, and a microcomputer for setting values in the first and second D/A converters. A value to be given to the first D/A converter to set the laser light output at a specified value P1 and a value to be given to the first D/A converter to set the laser light output at another specified value P2 are both stored in the microcomputer. The laser light outputs of these specified values are obtained by using a feedback by the monitor circuit and the comparator. For light output between the specified values P1 and P2, an optional output value between the specified values P1 and P2 is set by calculating by the microcomputer a value to be given to the first D/A converter.

Abstract: An apparatus for driving a semiconductor laser device wherein the optical output of the laser device is maintained at a predetermined level by a feedback control. The apparatus includes at least two D/A converters. One of the D/A converters is used for conducting a coarse adjustment of the optical output level, and another of the D/A converters is used for conducting a fine adjustment of the optical output level.