Multiple laser beam scanner with beam intensity control

摘要

A semiconductor laser beam scanning device includes a plurality of semiconductor lasers for emitting respective laser beams which are combined into a single laser beam to scan a desired surface. The amount of energy of the single laser beam is detected by a laser beam energy detector which applies a laser beam energy signal to a laser drive/control circuit. Alternatively, the laser beam energy signal is applied to a comparator which compares the laser beam energy signal with a reference signal and issues a difference signal to a control circuit connected to a laser drive circuit. The laser drive/control circuit or the control circuit is responsive to the applied signal for controllably energizing at least one of the semiconductor lasers to control the amount of energy of the laser beam emitted therefrom to thereby keep the amount of energy of the single laser beam at a constant level. The laser beam energy detector may be disposed adjacent to the surface to be scanned for detecting the amount of energy of the single laser beam in each scanning cycle, or may detect a laser beam divided from the single laser beam by a beam splitter disposed on a beam path for the single laser beam.