In-situ surface debris inspection and removal system for upward-facing transport mirrors of the National Ignition Facility

摘要

We describe a system to inspect and remove surface debris in-situ from the surfaces of upward-facing mirrors that transport 1053 nm laser light to the target chamber of the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory. Grazing angle (2-5°) illumination with a bar light highlights debris ≈10 μm in size and larger, which is then viewed through windows in the enclosures of selected mirrors. Debris is removed with 1-second bursts of high velocity (76 m/s) clean air delivered across the optic surfaces by a commercially available linear nozzle ("gas knife"). Experiments with aluminum, stainless steel, glass and polystyrene particles of various sizes > 30 μm show that particle removal efficiency is near 100% over most of the mirror surfaces for all sizes tested.