Thermal annealing of deep ultraviolet (193 nm) induced compaction in fusedsilica

Different 1995-1996 ultraviolet (UV) grade experimental fused silica sample s were evaluated for their resistance to UV-induced compaction at 193 nm un der elevated sample temperature conditions. We found that the compaction ra te decreases with increasing sample temperature. Compaction recoveries were observed at temperatures as low as 120 degrees C, this suggests that the r ecovery of UV-induced compaction in fused silica is a thermally excited pro cess with a low activation energy. Isothermal annealing experiments were pe rformed on two different sets of precompacted fused silica samples. An acti vation energy of 0.13 eV was found for both cases. (C) 1998 American Vacuum Society.