Birefringent Fourier-transform imaging spectrometer

Abstract

Fourier-transform imaging spectrometers offer important advantages over other spectral imaging modalities, such as, a wider free spectral range, higher spectral resolutions and, in low-photon-flux conditions, higher signal-to-noise ratios can be achieved. Unfortunately, for application in harsh environments, deployment of Fourier-transform instruments based on traditional moving-mirror interferometers is problematic due to their inherent sensitivity to vibration. We describe a new Fourier-transform imaging spectrometer, based on a scanning birefringent interferometer. This system retains the advantages of traditional Fourier transform instruments, but is inherently compact and insensitive to vibration. Furthermore, the precision requirements of the movement can be relaxed by typically two orders of magnitude in comparison to a traditional two-beam interferometer. The instrument promises to enable application of Fourier-transform imaging spectrometry to applications, such as airborne reconnaissance and industrial inspection, for the first time. Example spectral images are presented.