STP954: Scanning Electron Microscopy Studies of Laser Damage Initiating Defects in ZnSe/ThF4 and SiH/SiO2 Multilayer Coatings

    Johnson, LF
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

    Ashley, EJ
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

    Donovan, TM
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

    Franck, JB
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

    Woolever, RW
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

    Dalbey, RZ
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

    Pages: 15    Published: Jan 1986


    Abstract

    Scanning electron microscopy (SEM) was used to identify four distinct laser damage morphologies in ZnSe/ThF4 multilayer mirrors. There were three types of defect-initiated damage morphologies. Oblong-shaped damage sites oriented perpendicular to the electric field vector of the laser were associated with particulates on or near the surface of the ZnSe/ThF4 multilayers. Circular-shaped damage sites were initiated by particulates embedded beneath the top ZnSe layer. Selective laser damage at pinholes was identified as the third defect-initiated damage morphology. In addition to defect-initiated damage, stress-related damage was indicated by cracks near or within laser damage craters and erosion sites. Selective laser damage at nodular growth defects in SiH/SiO2 multilayers was also observed using SEM. Samples with different numbers of nodules were prepared in-house using RF-diode, reactive sputtering. The low-defect mirror had the highest laser damage onset, and the mirror with the highest number of nodules had the lowest laser damage onset.

    Keywords:

    defect-initiated laser damage, laser damage, nodular growth defects, optical thin films, particulate impurities, pinholes, scanning Auger microscopy, scanning electron microscopy, SiH/SiO, 2, multilayer mirrors, ZnSe/ThF, 4, multilayer mirrors


    Paper ID: STP23137S

    Committee/Subcommittee: F01.02

    DOI: 10.1520/STP23137S


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