The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
and the noise amplitude have been so estimated, and their plots 
are shown in Figure 7. 
Noise 
450 550 650 ,750, 850 950 1050 
wavelength (mj 
Figure 7: Plot of SNR and noise amplitude (standard deviation) 
as computed from 40 interferograms collected observing the 
same radiation source. 
2.3 Reflectance spectra reconstruction 
Standard reflectance tiles together with diffusers doped with 
Holmium and Rare Earths have been used to check the 
reflectance spectra retrieved from ALISEO interferograms. For 
each tile a complete interferogram has been reconstructed, then 
the at-sensor radiance have been computed. Reflectance spectra 
are calculated taking as reference the radiance spectrum 
extracted from a Spectralon tile. Results of these measurements 
are plotted in Figure 8. 
Retrieved reflectance spectra have been used to verify the 
wavelength calibration of the instrument. The obtained results 
are in fair agreement with reference data. We suppose that 
partial departure of retrieved spectra from refemces is caused 
by the still insufficient compensation of the spectral dispersion 
ofOPD. 
450 550 650 750 850 950 
Wavelength (nm) 
Wavelngth (nm) 
Figure 8: Standard tiles reflectance spectra : reconstructed 
spectra from measured interferograms are shown with a bold 
line. Labsphere reflectance spectra are plotted with a thin line. 
5.CONCLUSIONS 
In this paper an imaging interferometer laboratory prototype of 
the ALISEO sensor has been presented. The optical layout and 
the configuration of the instrument have been analysed, and the 
main differences with existing interferometers have been 
assessed. A procedure to retrieve the at-sensor radiance has 
been presented and discussed. Experimental investigation 
carried out at our Institute allowed us to measure the 
interferometer spectral resolution and the range of wavelengths 
that can be reconstructed. Future activities will be devoted to 
the implementation of a procedure for performing atmospheric 
corrections of the acquired images on board of an aircraft. 
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