Electronically Agile Multiple Aperture Imager Receiver

Abstract

This paper presents results of a study of a new multiple aperture imaging technique, including a proof-of-concept simulation. The result of the study is a large aperture, imaging laser radar receiver concept that can be used to access multiple targets in a large field of view with no mechanical motion. The receiver diameter is not limited by current optical fabrication techniques. The proof-of-concept simulation incorporates the effects of background radiation and detector shot noise, which set requirements for the receiver subaperture components and the laser transmitter power. The multiple aperture receiver concept involves the area illumination of a target scene with a coherent, multiple pulse laser transmitter. The re-flected radiation from the scene creates a series of speckle patterns at the plane of the multiple aperture receiver, which are sampled by the sub-apertures and then processed to produce an estimate of the image auto-correlation. Background suppression is achieved by a combination of spectral, temporal, and spatial filtering. By Fourier transforming the image autocorrelation, we produce an estimate of the image power spectral density, which is low-pass filtered to minimize noise and then used to reconstruct the image using phase retrieval techniques. Examples of this reconstruction process are presented.