Abstract
This paper describes a newly proposed image reconstruction algorithm and experimental results of a 3-D acoustical holographic imaging system which has an array composed of sparsely distributed transducer elements. The new algorithm is based on the Projection Onto Convex Sets (POCS) method. The POCS method allows the addition of convex sets constrained by a priori information to reduce ambiguity in the image reconstruction process.
By several experiments, it is proved that the concept of the image reconstruction algorithm has following improvements: 1. the artefacts caused by the grating lobes can be reduced under the condition the interspacing of elements is much larger than the wave length, 2. the storage of the entire inverse matrix of the degradation matrix of the imaging system is not required because the new image reconstruction algorithm is based on the localized projection procedures, 3. the instability to the noise caused by the lack of the knowledge of the point spread function can be reduced.
