Speed-Improved Off-Focus Imaging Technique for Real-Aperture Imaging System Based on Wavenumber Spectrum Fusion

This letter introduces a speed-improved imaging technique for a real-aperture MIMO system engaged in off-focus imaging. The existing off-focus imaging algorithm is time-intensive due to the extensive interpolation and reliance on traditional frequency-domain back-projection algorithms (FDBPA). To address its limitation, the least squares (LS) method is used to fit the non-analytical single-trip history function into a second-order polynomial function. Both MIMO array and the wideband received chirp signal are subdivided into multiple sub-arrays and sub-bands to reconstruct the low-resolution images using FDBPA. The wavenumber spectrums of these low-resolution images are band-limited, thus they can be combined to get the global high-resolution image. Simulation and experiment confirmed the efficacy of the proposed technique called Fusion-BPA. It is a state-of-art, fast algorithm to deal with the non-linear scene imaging problem.