Along the Laser Beampath

Programmable Spatial Shaper
A system of customized spatial light modulators called "spatial shapers" has been installed in the preamplifier modules (PAMs) at the front end of the NIF laser system. The spatial shapers can obscure the laser light at programmed locations within the beam profile to keep the light from striking small, isolated flaws on downstream optical components. Such flaws can act as small initiation sites for damage that could grow during subsequent high-fluence (high laser energy per unit area) laser shots, potentially limiting NIF's operating energy. The ability to temporarily "shadow" these isolated sites from high-fluence laser pulses helps protect the laser system and enhances operational flexibility. The obscurations that produce the shadows, called "blockers," are introduced in the PAMs feeding NIF's beamlines in the laser's low-fluence, 1,053-nanometer (infrared) region, upstream of the main amplifier chain. Imaging and aligning the shadows onto flaws in the output 351-nanometer (ultraviolet) optics ensures that these flaws are protected with only a modest loss of beam area. The programmable spatial shaper packages, in combination with a flaw inspection system and optic registration strategy, have provided NIF with a robust approach for extending the operational lifetime of the system's high-energy laser optics (see next photo).

Photo Number: NIF-1209-18044
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