1. Imager assembly comprising a synthetic aperture instrument comprising a plurality of separate pupils ( 10, 12, 14 ; 30, 32, 34, 36 ) with sampling detection means, characterized in that: the values of the column and row sampling frequencies are less than the values conforming to the Shannon criterion and are such that modulation transfer function regions of replicas resulting from sampling are inserted into null modulation transfer function regions of the central section of the modulation transfer function so that these regions do not intersect and a central section smaller than the central section of the modulation transfer function contains all the regions representing the central section of the modulation transfer function, and it comprises means for reconfiguring the spectrum of the image acquired in order to reconstruct it, said means being used to position the regions of the smaller central section ( 40 ′ 0,0 ; 22 0 ) so that they correspond to the positions of the regions of the original central section.