Space qualification studies of AOTF devices under the MISSE-11 mission

The Acousto-Optic Tunable Filter (AOTF) devices are used in a variety of applications including hyperspectral and spectrapolarimetric based imaging. The AOTF devices provide several advantages including speed and random access to desired spectral bands and enable all-solid-state operation that are attractive for space applications. In this paper, the performance of Tellurium Dioxide (TeO₂) and Mercurous Bromide (Hg₂Br₂) AOTF devices in space environment carried out under the NASA's Materials International Space Station Experiments 11 (MISSE-11) mission is discussed. The purpose of the MISSE-11 mission was to study materials and devices subjected to space conditions for long term while attached to the International Space Station (ISS). The TeO₂ AOTF was developed for Short Wavelength IR (SWIR) operation while the Hg₂Br₂ AOTF device was developed for Long Wavelength IR (LWIR) operation. These devices were attached to the ISS platform for more than a year. Pre-flight and post-flight performance characterization were performed on these devices. In the case of TeO₂ AOTF, the preflight efficiency was around 87% with a center frequency at 68MHz while the post-flight efficiency was around 83%. However, the optical transmission of Hg₂Br₂ AOTF had deteriorated considerably. The details of performance testing and analysis of both AOTF devices are discussed.