Third Harmonic Generator Optics Loop Transportation and Handling

Abstract

The National Ignition Facility (NIF) uses crystal optics made from Potassium Di-Hydrogen Phosphate (KDP) for frequency conversion, changing the fundamental wavelength of 1053 nm to the third harmonic at 351 nm. The crystal optics are manufactured at a vendor and shipped to Lawrence Livermore National Laboratory (LLNL) where they are measured, mitigated, cleaned, coated, and placed into line replaceable units (LRUs) in the Optics Processing Facility (OPF) clean room and transported to the NIF where they are stored under Nitrogen purge until they are installed in the beamline. The KDP crystal optics are sensitive to humidity and temperature, so they are stored under Nitrogen purge providing a clean and dry environment. The sensitivity to the environment and the brittle nature of the crystals makes transportation and handling (T&H) challenging. Coupled with challenges in holding the crystal optics in the LRU to not distort the optic, there is a balance between T&H and fixturing the optic in the laser system. The purpose of the LRU is to make the optics interchangeable allowing for a relatively quick interchange. Kinematic mounts and ceramic frames aid in making this possible. Optics in the NIF that are frequently changed out have an established recycle loop. The loop for an optic can be complex depending on the amount of processing and rework necessary. Some optics can’t be reconditioned so they are replaced with new optics.