Passive imaging using millimeter waves (mmWs) has many advantages and applications in the defense and security
markets. All terrestrial bodies emit mmW radiation and these wavelengths are able to penetrate smoke, blowing dust or
sand, fog/clouds/marine layers, and even clothing. One primary obstacle to imaging in this spectrum is that longer
wavelengths require larger apertures to achieve the resolutions typically desired in surveillance applications. As a
result, lens-based focal plane systems tend to require large aperture optics, which severely limit the minimum
achievable volume and weight of such systems. To overcome this limitation, a distributed aperture detection scheme is
used in which the effective aperture size can be increased without the associated volumetric increase in imager size.
However, such systems typically require high frequency (~ 30 - 300 GHz) signal routing and down conversion as well
as large correlator banks. Herein, we describe an alternate approach to distributed aperture mmW imaging using optical
upconversion of the mmW signal onto an optical carrier. This conversion serves, in essence, to scale the mmW sparse
aperture array signals onto a complementary optical array. The optical side bands are subsequently stripped from the
optical carrier and optically recombined to provide a real-time snapshot of the mmW signal. In this paper, the design
tradeoffs of resolution, bandwidth, number of elements, and field of view inherent in this type of system will be
discussed. We also will present the performance of a 30 element distributed aperture proof of concept imaging system
operating at 35 GHz.