title: Pit formation observed in a multilayer dielectric coating as a result of simulated space environmental exposure.
abstract: Certain spaceborne telescope designs require that dielectric-coated lenses be exposed to the energetic electrons and protons associated with the space environment. Test coupons that were exposed to a simulated space environment showed extensive pitting as a result of dielectric breakdown. A typical pit was 50-100 microm at the surface and extended to the substrate material, in which a 10-microm-diameter melt region was found. Pitting was not observed on similar samples that had also been overcoated with a transparent conductive thin film. Measurement of the bidirectional reflectance distribution transfer function showed that pitting caused a fivefold to tenfold increase in the scattering of visible light.
authors.affiliation: The Ivan A. Getting Laboratories, The Aerospace Corporation, Los Angeles, California 90009-2957, USA. fuqua@aero.org
authors.forename: Peter D
authors.initials: PD
authors.lastname: Fuqua
authors.forename: Nathan
authors.initials: N
authors.lastname: Presser
authors.forename: James D
authors.initials: JD
authors.lastname: Barrie
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Meshishnek
authors.forename: Dianne J
authors.initials: DJ
authors.lastname: Coleman