Method and apparatus for reducing the effect of laser noise in a scanning laser read system

摘要

The output beam from a laser scans an input document and the signal reflected therefrom, corresponding to information on the document, is detected and amplified in a first amplifier and converted to an electrical signal. The laser beam is also sampled prior to scanning the document, the beam being detected and converted to an electrical signal which is then amplified in a second amplifier. The outputs of the first and second amplifiers are coupled to a gain control device. The gain versus control voltage characteristic of the device is selected such that the voltage from the second amplifier controls the voltage output from the device whereby noise present in the output laser beam which modulates the output signal from the first amplifier is substantially eliminated.