Interpolation-free 3-D millimeter-wave imaging for security inspection

Millimeter-wave imaging has been regarded as key technique for next-generation personnel security inspection. Holographic imaging based on Fast Fourier Transform (FFT) is one of the most efficient algorithm for millimeter-wave imaging. However, during the process of holographic imaging, Stolt interpolation in the wavenumber-domain is employed to resample the 3-dimentional (3-D) data, which is time-consuming and also introduces additionally interpolation error. To overcome this weakness, an interpolation-free 3-D imaging algorithm is presented in this paper. The proposed algorithm reconstructs 3-D image exploiting 2-D FFT and inverse FFT (IFFT), and no interpolation is needed in the process. The algorithm is very suitable for parallel computation, and with prior knowledge of the position range of the target, the computation load of the 3-D image reconstruction could be further reduced. Numerical simulated data and real data from practical millimeter-wave imaging system have been used to verify the performance of the proposed algorithm. The results demonstrate that the proposed algorithm can achieve good image quality with high efficiency.