Coherent optical beam forming with passive millimeter-wave arrays

Passive millimeter-wave imaging requires large apertures to achieve an angu lar resolution comparable to that of typical infrared imagers. Aperture syn thesis offers a route to achieving high resolution without using a single l arge aperture, by interferometrically combining the signals from a number o f smaller distributed apertures. In such a system the individual millimeter -wave signals must be transported to a common location with good phase fide lity and combined to form the image, This paper discusses a technique calle d coherent optical beam forming which performs optical transport of the up converted millimeter-wave signal and direct image formation at the optical frequency, Proof of principle experiments are described that demonstrate co herent optical beam forming with a point source and a method of self-calibr ating the array to remove phase errors.