Spot-shadowing deployment for mitigating damage-growth of optics in high-power lasers based on a programmable spatial beam-shaping system

Damage growth in optical components is a bottleneck problem of large solid state laser, which limits the system operating energy, interrupts the use and increases the maintenance cost dramatically. A spot-shadowing technique aimed to obscure damage pits in downstream optics in high-power laser is investigated in this work, whose goal is decreasing local fluence to mitigate damage growth upon subsequent laser shots exposure by shadowing small, isolated flaws on downstream optical components. The method to determine the quantity, geometrical shape, size, and spatial location of blockers is discussed in detail, which is applicable to other large solid lasers in principle. We also find that the local fluence around flaw sites decreases dramatically from ∼5.87 J/cm2 to ∼1.10 J/cm2 (far below laser-induced damage growth threshold ∼4.50 J/cm2) after spot-shadowing is deployed, which proves the feasibility of spot-shadowing for mitigating damage growth.