An extended algebraic reconstruction technique (ART) for density-gradient projections: laser speckle photographic tomography

An extended algebraic reconstruction technique (ART) is presented for tomog raphic image reconstruction from the density-gradient projections, such as laser speckle photography. The essence of the extended ART is that the dens ity-gradient projection data of speckle photography (Eq. (1)) are first num erically integrated to the algebraic representation of interferometric frin ge number data (Eq. (12)), which ART can readily reconstruct into the cross -sectional held. The extended ART is numerically examined by using two comp uter synthesized phantom fields, and experimentally by using asymmetric sin gle and double helium jets in air. The experimentally reconstructed images were also compared with the direct measurements of helium concentration usi ng an oxygen analyzing probe. The extended ART method shows an improved acc uracy and is proposed to use to tomographically reconstruct the density-gra dient projections over the previous Fourier convolution (FC) method (Liu el al, 1989).