Waveform synthesis for the design and image reconstruction of step FMCW ultrasound imaging systems with conformal transducer arrays

摘要

In this paper, we present the image reconstruction algorithm developed for a conformal ultrasound array imaging system operating in the step frequency-modulated continuous wave (FMCW) mode. The image formation procedure is based on a key relationship that establishes the equivalence between pulse-echo and step FMCW modalities, and thus permits conversion between the data types. Prior step FMCW simulation work could then be merged with pulse-echo data collected experimentally to achieve full-scale synthesis between laboratory data and a structured theoretical framework. We describe how an experimentally acquired pulse-echo waveform was extracted and incorporated into a step FMCW imaging simulation to increase image accuracy and improve visualization of physical effects. With knowledge of the transducer element positions in a multistatic configuration, image reconstruction was achieved by mapping the complex range profiles over to a target region. Included in this paper are images reconstructed after waveform synthesis, which feature transducer elements uniformly spaced around a circular aperture imaging several enclosed targets with different bandwidths.