<title>Stray light design and analysis of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) telescope</title>

Abstract

The Sounding of the Atmosphere using Broadband Emission Radiometiy (SABER) instrument is a 10-channel earth limbviewing sensor that is to measure atmospheric emissions in the spectral range of 1.27 jm to 16.9 iim. Presented in this paper is the stray light design and analysis of SABER Unwanted radiation from the eaith and atmosphere are suppressed by the use of stiay light features that are Critical to mission success. These include the use ofan intermediate field stop, an inner and outer Lyot stop, and super-polished mirrors. The point source normalized irradiance transmission (PSNIT) curve, which characterizes the sensor's off-axis response, was computed using the stray light analysis program APART. An initial calculation of the non-rejected radiance (NRR) due to emissions and scatter from the earth and atmosphere was made using the PSNTT data. The results indicate that stray light will not impede the mission objectives.

Off-axis response measurement of the sounding of the atmosphere using broadband emission radiometry (SABER) telescope

“…The stray light analysis program APART was used to predict SABER's off-axis response and to aid in the telescope design 5,6 . The software model showed that mirror scatter is the dominant source of stray light for the short wavelength channels.…”

“…The instrument description and mission objectives are described in greater detail elsewhere 1,2 . Stray light analyses performed using the software programs APART 3 and ASAP 4 have also been documented [5][6][7] . The results of the off-axis response measurement of SABER are presented in this report.…”

Contamination control of the SABER cryogenic infrared telescope

“…1,2 High off-axis rejection performance was obtained by extensive straylight analyses and optimization during design and the required use of nearly pristine, superpolished fore-optics. 3,4 Furthermore, an intermediate field stop and an inner Lyot stop are incorporated to eliminate the stray light and diffraction effects that are typically associated with on-axis telescope designs. 5 The scan mirror has approximately 100° range of motion that allows it to scan across the entrance aperture or rotate to a position for on-orbit calibration using the inflight calibrator (IFC) blackbody.…”

Recent Interferometry Applications in Topography and Astronomy

“…Radiation blocking scheme might also produce a great amount of reflected and absorbed radiation that travels all over and causes stray-light noise (Scholl, 1994b;Stauder & Esplin, 1998) and heating. Such scattered radiation might easily drown the faint signal (Scholl, 1996b).…”