Active energy control for diode pumped laser systems using pulsewidth modulation

An active energy control circuit for use with a diode pumped laser system comprising a laser cavity, a laser rod, a Q-switch, a Q-switch pulse circuit, and a current controlled pulse drive circuit coupled to a plurality of pump diodes, said control circuit comprising:

• optical to electrical sampling means for sampling the output energy of the diode pumped laser system and for converting the sampled output energy into a digitized energy signal;
• a controller comprising:
• repetition rate logic for setting a repetition rate of the laser system;
• pulse duration logic for setting a desired initial pulse duration of the output energy pulse of the pump diodes;
• threshold logic coupled to the optical to electrical sampling means for comparing the digitized energy signal comprising the sampled output energy of the laser system to a predetermined energy threshold, and for providing output signals that are adapted to increase or decrease the pulse duration of the pulse provided by the current controlled pulse drive circuit depending upon whether the sampled output energy is below or above the predetermined energy threshold, respectively;
• pulse duration output logic coupled to the laser firing logic and to the current controlled pulse drive circuit for providing an output signal that is adapted to set the pulse duration of the output energy pulse in the pulse drive circuit;
• laser firing logic coupled to the pulse duration output logic and to the Q-switch firing pulse circuit for causing the firing pulse circuit to generate the firing signal that is adapted to switch the Q-switch and generate the output energy pulse from the laser system;
• and
• whereby the controller is adapted to maintain the output energy of the diode pumped laser system at a desired level.

A method for use with a diode pumped laser system comprising a laser cavity, a laser rod, a Q-switch, a Q-switch pulse circuit, and a current controlled pulse drive circuit coupled to a plurality of pump diodes, that is adapted to provide for active energy control of the laser system, said method comprising the steps of:

• setting a desired initial pulse duration value for the output energy pulse of the pump diodes;
• sampling the output energy of the diode pumped laser system;
• converting the sampled output energy into a digitized output energy signal;
• comparing the digitized output energy signal to a predetermined energy threshold;
• providing a control signal indicative of increasing or decreasing the pulse duration value of the pump diode output energy pulse depending upon whether the sampled output energy is below or above the predetermined energy threshold, respectively;
• generating a new pump diode output energy pulse based upon the increased or decreased pulse duration value of the control signal;
• and
• generating a new laser energy pulse from the energy stored in the laser rod from the prior pump diode pulse, which produces a corresponding increase or decrease in the energy of the new laser energy pulse;
• whereby the output energy of the diode pumped laser system is maintained at a desired level.