Abstract

Acoustooptic tunable filters (AOTFs) provide continuously tunable spectral imaging in two orthogonal polarizations. They offer multiple advantages over circular variable filter wheel spectrometers, including higher spectral resolving power, highly specific polarization selection, larger optical aperture, all-solid-state operation, and rapid frequency agile tunability. Although they will enable the development of compact, space qualifiable visible and infrared imaging spectrometers, only a few isolated demonstrations have so far been made at telescopes and in the laboratory.¹ We have constructed a robust 500–1000-nm AOTF imaging spectropolarimeter for ground based and aircraft measurements, as part of a larger program of visible/IR AOTF camera development. Spectral resolving power (λ/Δλ) ranges from 500 at λ = 500 nm to 250 at λ = 1000 nm. The key components of this instrument are a TeO₂ noncollinear AOTF, CCD camera, and an all-reflective optical relay assembly that uses a single elliptical mirror to form side-by-side orthogonally polarized spectral images. Spectral coverage is limited by the CCD response and bandwidth limitations in the rf matching network at the transducer. The instrument is now being used at the Goddard Optical Ranging Facility for telescopic observations of astronomical sources.

© 1991 Optical Society of America