A Chemical Precursor to Optical Damage? Studies by Laser Ionization Mass Spectrometry Available to Purchase

Mass spectrometry has been used in conjunction with Nomarski microscopy to characterize the initiation of optical damage in selected commercial optics. For a sample with a Al₂O₃/SiO₂ multilayer coating (351 nm) on a Si substrate, our results suggest layer by layer removal of the coating material with low-fluence irradiation at 1.06 μ. Inaddition, carbon impurities were observed in the low-damage threshold sample. For the Sc₂O₃/SiO₂ multilayer coated (351 nm) 7940 substrates, transient iron signals were observed at each increasing fluence level, with concomitant appearance of small circular (10μ) pits in the surface. These pits were also associated with macroscopic damage features due to threshold testing.