Comparison of acousto-optic tunable filters and acousto-optic dispersive filters for hyperspectral imaging

The acoustooptic tunable filter (AOTF) has a narrow passband and a large angular acceptance angle, which allows for imaging at a given wavelength without having to assemble an image cube, as with grating based imagers. It is also possible to use an acousto-optic dispersive filter (AODF), which has a small acceptance angle and a broad spectral passband to form spatial images similar to the grating imager. Although the processing is more complex, the advantages of the AODF are that pixel registration and temporal fluctuations of the spectra are greatly reduced compared to the AOTF. Both the AOTF and AODF can operate in a birefringent mode, allowing for the use of high efficiency materials such as Tl3AsSe3 (TAS) in the infrared region They can both be multiplexed to increase the sensitivity, and reduce the spectral fluctuation problem of the AOTF. The AODF can also operate in an isotropic mode, which allows for the use of deflector materials such as Ge. The issues of complexity, fluctuations, efficiency, and multiplexing are compared for AOTFs and AODFs operating in the infrared. A comparison is also made for both systems using TAS, along with AODFs using Ge.