A new stationary imaging interferometer: first results

In this paper we present some laboratory measurements obtained by a new imaging interferometer. This instrument has been derived from the so called “stationary interferometers,” which do not employ any moving part to optically scan the instrument field-of-view. The device acquires the image of an object superimposed to a fixed (stationary) pattern of autocorrelation functions of the energy coming from each pixel. The interference pattern, constituted by a system of vertical fringes, is scanned by moving the observed target with respect to the imaging device. In order to calibrate the optical-path-difference axis of the raw interferograms, we have executed a set of measurements employing a He-Ne laser source spread by a pair of planar diffusers. The dependence of the optical-path-difference values on the source spectral content has been addressed performing a set of measurements after filtering a 600W halogen lamp with interference filters of 10nm bandwidth. We have described the procedure of pre-processing of the acquired data to retrieve the spectrum of at-sensor radiance (dark signal subtraction, spectral instrument response compensation, effects of vignetting and Fourier transform algorithm). Some hints are given about the use of this instrument from airborne platforms for remote sensing of the Earth.