Published online by Cambridge University Press: 02 July 2020
A new infrared spectroscopic imaging technique has been described, combining step-scan Fourier transform (FT) Michelson interferometry with indium antimonide (InSb) focal-plane array (FPA) image detection [1-3], for use in the range 3950-1975 cm−1. The coupling of such detector to an interferometer provides an optimized method for infrared spectroscopic imaging by simultaneously realizing both a multiplex and multichannel advantage. Specifically, the multiple detector elements enable spectra at all pixels to be collected simultaneously, while the interferometer allows all the spectral frequencies to be measured concurrently. This technique can rapidly generate very high quality, chemically specific images from a wide variety of samples. Preliminary results from the use of a mid-infrared liquid-helium-cooled arsenic-doped-silicon array have also been reported recently [4]. Focal-plane arrays using mercury-cadmium-telluride (MCT) are now commercially available, giving access to the range 3950-800 cm−1, and greatly broadening the applicability of this technique [5].
FT-IR microscopy does not require exotic sample preparation -- samples can be examined in transmission and reflectance, do not need to be stained or coated, and a vacuum is not required.