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
description
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. Radiation Environment. Electron (gamma) radiation Proton radiation Ultraviolet. Five-HOE ShADOE Samples. - PowerPoint PPT Presentation
Transcript of Space Radiation Environment Tests on HOEs
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
Radiation Environment
• Electron (gamma) radiation
• Proton radiation
• Ultraviolet
Five-HOE ShADOE Samples
5.7 mm PPG Starphire glass
5.7 mm PPG Starphire glass
10 µm DCG hologram
10 µm Epoxy
Optical Tests Before & After Exposure
• Diffraction efficiency at 355 nm
• 0° incidence transmission at 355 nm and 2-µm wavelengths
• 355 nm absorption
30°
30°
Gamma TestsMission profile (polar orbits)
Approximate dose
1-3 year, 400 km 3 KRad
5-10 year, 833 km 30 KRad
>10 yr, >1000 km altitude or planetary
300 KRad
Gamma exposure effect on diffraction efficiency, preliminary
resultsRadiation Dose (KRad)
η0, Pre-radiation % Diffraction Efficiency
ηm, Post-radiation % Diffraction Efficiency
300 50±10 14.5±1.0
30 62.8±13 41.2±9.2
3 60±15 36.6±8.0
Control
Gamma exposure effect on transmission at 355 nm, preliminary
resultsRadiation Dose (KRad)
T0, Pre-radiation % Transmission (sum of 0+1 orders)
Tm2, Post-radiation % Transmission (sum of 0+1 orders)
Tm1, Post-radiation % Transmission (0°-incidence)
Tm3, Post-radiation % Transmission (spectro-photometer)
300 69 ±10 28.91.5 13.8±0.1 2.6
30 93 10 63.12.6 56.1±1.5 52.5
3 88 11 65.98.0 76.5±0.1 75.6
Control 76.8±0.4 78.9
Co 60 1.25 MeV gamma ray exposures
300 KRad30 KRad
3 KRad 0 KRad
Spectral TransmissionSample Comparison
0
10
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30
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60
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200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Wavelength 9nm)
Tra
ns
mis
sio
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%T
)
Non-Radiated
3 kRad
30 kRad
300 kRad
254 nm UV exposure
@ 100 nW/cm^2 for 12 min = 3.15 J/cm2 equivalent to ~ 1 year in orbit
355 nm transmission loss vs. 254 nm exposure
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
