Space Radiation Environment Tests on HOEs

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Space Radiation Environment Tests on HOEs

• Geary Schwemmer
• NASA GSFC
• Work Supported by NASA and IPO
• new affiliation Science and Engineering
  Services, Inc. Columbia, MD

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Radiation Environment

• Electron (gamma) radiation
• Proton radiation
• Ultraviolet

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Five-HOE ShADOE Samples
5.7 mm PPG Starphire glass
10 µm DCG hologram
10 µm Epoxy
5.7 mm PPG Starphire glass
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Optical Tests Before After Exposure

• Diffraction efficiency at 355 nm
• 0 incidence transmission at 355 nm and 2-µm
  wavelengths
• 355 nm absorption

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30
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Gamma Tests
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Gamma exposure effect on diffraction efficiency,
preliminary results
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Gamma exposure effect on transmission at 355 nm,
preliminary results
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Co 60 1.25 MeV gamma ray exposures
0 KRad
3 KRad
30 KRad
300 KRad
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Spectral Transmission
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254 nm UV exposure
_at_ 100 nW/cm2 for 12 min 3.15 J/cm2 equivalent
to 1 year in orbit
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355 nm transmission loss vs. 254 nm exposure
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Conclusions future tests

• Moderate 355 nm absorption due to gamma radiation
  over NPOESS mission life 25 thru 11.4 mm of
  glass.
• Little to no hologram fading due to 254 nm or
  gamma radiation exposure.
• No degradation at 2-microns.
• Thinner glass will decrease absorption.
• Proton radiation high intensity 355nm UV tests
  TBD