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High intensity solar irradiation testing of UV opticsThe Orbiting Solar Observatory-I (OSO-8 in orbit) incorporates two high resolution solar pointing spectrometers operating from 1000 A to 4000 A. Energy from the sun enters a Cassegrainian telescope and is focused on a slit while the solar disk is scanned to one arc-second resolution. The stability of the secondary mirrors reflectance was of concern since they would be exposed to intense focused solar energy up to 27 suns. A test program was initiated to simulate this energy input on sample UV mirrors of the MgF2 and LiF types and to evaluate their performance after irradiation. Tests were conducted to simulate the solar spectrum at high intensities (25 suns) and at a single wavelength near Lyman-alpha, but with twenty times the solar intensity at Lyman-alpha. Post-test measurements after every exposure were made at wavelengths from 1025 A to 1849 A. After 75 simulated 'orbits', reflectance changes due to temperature effects were noted to be less than 10%. Reductions in reflectance under high intensity solar radiation were generally greater than 10%. Polymerization of surface contaminations on the LiF mirrors reduced reflectances at short wavelengths by 40%.
Document ID
19760059351
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Greyerbiehl, J. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Oberright, J. E.
(NASA Goddard Space Flight Center Greenbelt, Md., United States)
Date Acquired
August 8, 2013
Publication Date
August 1, 1976
Publication Information
Publication: Journal of Environmental Sciences
Volume: 19
Subject Category
Ground Support Systems And Facilities (Space)
Accession Number
76A42317
Distribution Limits
Public
Copyright
Other

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