Automatic control of laser diode current and optical power output

An automatic power control system provides a control signal that regulates the output power of at least one laser diode. Coarse adjustment of the control signal is provided by a first means, preferably a digital variable resistor, while fine adjustment and compensation is provided by a second means, preferably by a digital-to-analog converter that receives an input signal proportional to a sensed control system parameter. The control system includes an operational amplifier having a first input coupled to sense output power, and a second input coupled to a DAC to provide finer resolution control. Memory can store system parameter or system parameter variations that can be coupled to the DAC and/or variable resistor to enhance system stability over ambient variations.