ACOUSTOOPTIC IMAGING SPECTROPOLARIMETRY FOR REMOTE-SENSING

We review the operating principles of noncollinear acousto-optic tunab le filters (AOTF's), emphasizing the use of two orthogonally polarized beams for narrow-band imaging. Spectral characterization and spectral broadening measurements of commercially available AOTF's agree with t heoretical predictions and reveal difficulties associated with imaging noncollimated light. An AOTF imaging spectropolarimeter for ground-ba sed astronomy that uses CCD's has been constructed at NASA Goddard Spa ce Flight Center. It uses a TeO2 noncollinear AOTF and a simple optica l relay assembly to produce side-by-side orthogonally polarized spectr al images. We summarize the instrument design and initial performance tests. We include sample spectral images acquired at the Goddard Geoph ysical and Astronomical Observatory.