ALISEO: a new stationary imaging interferometer

ALISEO (Aerospace Leap-frog Imaging Static Interferometer for Earth Observation) is a prototype of a new imaging interferometer for Earth Observation from the Space. This instrument has been derived from the so called "static interferometers", which do not employ any moving part to optically scan the instrument field-of-view. The device acquires the image of an object with superimposed a pattern of autocorrelation functions of the electromagnetic field coming from each pixel. The complete interferogram, constituted by a system of vertical fringes, is retrieved by moving the observed target with respect to the imaging device. The dependence of the OPD on the radiation-source spectral content, has been addressed performing a set of measurements by spectrally pre-filtering a 600W halogen lamp by means of interference filters with bandwidth of 10nm. We also describe the procedure of pre-elaboration 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). Laboratory measurements obtained by ALISEO are presented and discussed. This instrument was partially developed under a contract of Agenzia Spaziale Italiana (ASI).