Digital piston error control for high-power laser system employing diffractive optical element beam combiner

A method of operating a laser comprising:

• producing a plurality of laser beamlets, one of said beamlets being definable as a reference beamlet, and all other beamlets being definable as non-reference beamlets via an array detector;
• combining said beamlets via a diffractive optical element (DOE) into an output beam, wherein each of said non-reference beamlets exhibit a respective piston error characteristic and said piston error characteristics produce piston error artifacts in said output beam;
• measuring said piston error artifacts in said output beam and producing a coded correction signal using a code generator related to said piston error characteristic of one of said beamlets;
• and
• minimizing said piston error characteristic by phase-modulating said beamlet responsive to said correction signal.

A method for controlling an error characteristic in a laser system comprising the steps of:

• tagging a plurality of beamlets from a detector array produced by laser amplifiers prior to beam combination with an identification tag using a code generator;
• sampling a combined output beam resulting from combining said plurality of beamlets via a diffractive optical element;
• from said sampled combined output beam, measuring a piston error affecting one of said beamlets distinct from piston errors affecting any other of said beamlets;
• generating an error correction signal to reduce said piston error of one of said beamlets responsive to said measured piston error;
• and
• adjusting a physical characteristic of said one beamlet accordingly to reduce the piston error.