In optics, engineers developed compound eyes that mimic nature. The characteristics enabled new advanced optical systems. Also in acoustics, viewing is a valuable technique for technical engineering applications. Acoustic systems are different by wave lengths. Millimeter waves allow a design concept without lenses. Sensor elements with apertures less than half a wave length sample wave field data for image reconstruction.
We built an active acoustic eye with one centered element for insonification. The prototype has got a uniform sensitivity in 360° with selectable cone angle of up to 140°. 3-D image repetition rates are above 500 Hz. 64 receiver elements are distributed in the sparse system aperture. Reconstruction artifacts and noise were eliminated by optimized element arrangement and stochastic phase filter. We could demonstrate high resolution and contrast characteristics provided by the inherent synthetic focusing capacity. We begin with the implementation of beam forming algorithms for selected viewing and resolution improvement, and with the development of contrast enhancing algorithms applying image sequence analysis techniques.