Band pass active aperture synthesis using spatial frequency heterodyning

In this aperture synthesis three snapshots are required to synthesis the aperture: one is obtained with simple illumination of the scene, the second when the scene is projected with cosine fringes and the third with the fringes quadrature phase shifted. The spatial frequency of the fringes is set to twice the cut off frequency of the imager. Due to spatial frequency heterodyning bands of scene spatial frequencies lying both above and below the fringe spatial frequency are heterodyned simultaneously into the low-pass band of the imager. Computer simulation results show extension of cut off frequency of the imager to three times the cut off frequency without aperture synthesis. © 2005 IOP Publishing Ltd.