The micro fourier transform interferometer (μFTIR) — A new field spectrometer for acquisition of infrared data of natural surfaces

A lightweight, rugged, high-spectral-resolution interferometer has been built by Designs and Prototypes based on a set of specifications provided by the Jet Propulsion Laboratory and Dr. J. W. Salisbury (Johns Hopkins University). The instrument, the micro Fourier Transform Interferometer (μFTIR), permits the acquisition of infrared spectra of natural surfaces. Such data can be used to validate low and high spectral resolution data acquired remotely from aircraft and spacecraft in the 3–5 μm and 8–14 μm atmospheric windows. The instrument has a spectral resolution of ∼ 6 wavenumbers, weighs 16 kg including batteries and computer, and can be operated easily by two people in the field. Laboratory analysis indicates the instrument is spectrally calibrated to better than 1 wavenumber and the radiometric accuracy is < 0.5K if the radiances from the blackbodies used for calibration bracket the radiance from the sample. Several examples of field spectra are provided for a variety of rock types, minerals, and vegetation.