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25 July 2014 The FIREBall-2 UV sample grating efficiency at 200-208nm
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The FIREBall-2 (Faint Intergalactic Redshifted Emission Balloon-2) is a balloon-borne ultraviolet spectro-imaging mission optimized for the study of faint diffuse emission around galaxies. A key optical component of the new spectrograph design is the high throughput cost-effective holographic 2400 ℓ =mm, 110x130mm aspherized reflective grating used in the range 200 - 208nm, near 28°deviation angle. In order to anticipate the efficiency in flight conditions, we have developed a PCGrate model for the FIREBall grating calibrated on linearly polarized measurements at 12° deviation angle in the range 240-350nm of a 50x50mm replica of the same master selected for the flight grating. This model predicts an efficiency within [64:7; 64:9]±0:7% (S polarization) and [38:3; 45]±2:2% (P-polarization) for the baseline aluminum coated grating with an Al2O3 natural oxidation layer and within [63:5; 65] ±1% (S-polarization) and [51:3; 54:8] ±2:8% (P-polarization) for an aluminum plus a 70nm MgF2 coating, in the range 200 - 208nm and for a 28°deviation angle. The model also shows there is room for significant improvements at shorter wavelengths, of interest for future deep UV spectroscopic missions.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. Quiret, B. Milliard, R. Grange, G. R. Lemaitre, A. Caillat, M. Belhadi, and A. Cotel "The FIREBall-2 UV sample grating efficiency at 200-208nm", Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 914432 (25 July 2014);


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