DEIMOS Archive

  • Coating Degradation

    Click on pictures for larger versions.



    Coatings

    In May 2002, it was noted that spots had appeared on both collimator and tent mirrors which had Newport Optics over-coated silver coatings. When these optics had been installed, roughly 6 weeks earlier, they appeared flawless. However, over the next approx. 8 weeks, there were no obvious growth in these spots. The following photos are half-size; the originals have roughly twice the resolution. For scale, the label (425#) tape is about 1/2 inch wide.
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    May 2002

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    June 2002

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    July 2002

    Collimator at center (one epoch only):

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    May 2002 This area of the collimator is at the inner edge of the mask at the center (the bare aluminum fixture is and alignment fixture which has since been removed).

    Collimator under bright light (one epoch only):

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    July 2002 This photo taken from about 4 feet away (note camera reflection near inner edge of collimator, just above the bright spot). Illumination is provided by an extremely bright spot lamp, hand-held so as not to reflect directly into the camera.

    Tent Mirror Corner (one epoch only):

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    July 2002 The location can be identified by the angle in the tent mirror edge and the bolts above.

    Tent Mirror Full (one epoch only):

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    May (?) 2002 The tent mirror is in the lower portion of the picture (look for the edges of the tent mirror and corresponding dummy mirror with the central sighting hole, then identify the reflecting portion just below the slitmask). A similar picture will help monitor the reflectance of the mirror.



    Last modified: 30 jan 04

    Andrew C. Phillips / Lick Observatory

    phillips@ucolick.org