Status of Optics on the OMEGA Laser after Eighteen Months of Operation

LLE Review, Volume 70 51 The OMEGA laser has sustained approximately 1000 target shots over its first 18 months of operation without significant damage to the optics. Both rod and disk amplifiers are used in the OMEGA laser chain; after each amplification stage at 1ω the beams are spatially filtered to remove high-spatial-frequency noise in the beam and to ensure correct image relaying. Optical damage thresholds dictated the minimum beam diameter in each stage and fixed the magnification between stages. The final 28-cm beam propagates through thin-film polarizers before reaching the frequency-conversion cells.1–3 Frequency conversion to the third harmonic (351 nm) is carried out using the polarization-mismatch method developed at LLE.4,5 A set of mirrors transports the 3ω beams through a final focus lens, and the last optic in the beam path serves as the vacuum barrier for the target chamber.