Proceedings of the Society of Photo-Optical Instrumentation Engineers (Cryogenic Optical Systems and Instruments)
Disordered thin film SiO2/SiOx coatings undergoing electron-beam bombardment exhibit cathodoluminescence, which can produce deleterious stray background light in cryogenic space-based astronomical observatories exposed to high- energy electron fluxes from space plasmas. As future observatory missions push the envelope into more extreme environments and more complex and sensitive detection, a fundamental understanding of the dependencies of this cathodoluminescence becomes critical to meet performance objectives of these advanced space-based observatories. Measurements of absolute radiance and emission spectra as functions of incident electron energy, flux, and power typical of space environments are presented for thin (~60-200 nm) SiO2/SiOx optical coatings on reflective metal substrates over a range of sample temperatures (~40-400 K) and emission wavelengths (~260-5000 nm). Luminescent intensity and peak wavelengths of four distinct bands were observed in UV/VIS/NIR emission spectra, ranging from 300 nm to 1000 nm. A simple model is proposed that describes the dependence of cathodoluminescence on irradiation time, incident flux and energy, sample thickness, and temperature.
Amberly Evans Jensen, JR Dennison, Gregory Wilson, Justin Dekany, Charles W. Bowers, Robert Meloy and James B. Heaney, Properties of Cathodoluminescence for Cryogenic Applications of SiO2-based Space Observatory Optics and Coatings,” Proceedings of the Society of Photo-Optical Instrumentation Engineers Cryogenic Optical Systems and Instruments Conference, Vol. 8863, 2013, pp. 88630A1-88630A10. DOI: 10.1117/12.2030231