Image resolution improvement of underwater synthetic aperture ultrasonic holography by virtual aperture augmentation technique

This paper studies the image resolution improvement technique for the underwater synthetic aperture ultrasonic holographic (SAUH) imaging system in which the aperture size is limited For conventional SAUH imaging systems, the better image resolution call be improved by increasing the aperture size at the expense of aperture distortion and the scanning time. In this paper, we propose an algorithm to make the effective synthetic aperture size larger than the physical one, called virtual aperture augmentation technique (VAAT), based on the assumption that the targets are finite size. Results show, the VAAT is an effective method to achieve larger equivalent apertures and improve the image resolution of SAUH imaging system