Three-Dimensional Active Incoherent Millimeter-Wave Imaging

A new 3-D active incoherent millimeter-wave (3-D AIM) imaging method is introduced in this article. By utilizing a sparse interferometric receive array and pulse modulation in the transmitted noise signals we demonstrate far-field incoherent imaging in three dimensions. Interferometric image formation is based on the spatio-temporal incoherence of the signals emitted by or scattered from the imaging scene. To support this, we use active noise transmission from multiple independent transmitters which provide incoherent illumination in space (azimuth and elevation) and time. Two-dimensional (azimuth-elevation) image formation in this manner only requires statistical knowledge of the waveforms, greatly simplifying the imaging system. In this work, we modulate the transmitted waveforms to impart range-dependent information that can be used to also obtain range, supporting imaging in three dimensions. We modulate a Gaussian pulse onto the noise waveforms and apply incoherent pulse integration to provide sufficient spatio-temporal decorrelation of the signals. We introduce a new 3-D Fourier image formation algorithm, provide imaging simulations, and include experimental image reconstructions from a 38 GHz millimeter-wave imaging system. Video-rate 3-D imagery of a moving target is presented to demonstrate the feasibility of the approach for real-time 3-D imaging applications.