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Published April 2012 | Published
Journal Article Open

Dependence of photoacoustic speckles on boundary roughness

Abstract

Speckles have been considered ubiquitous in all scattering-based coherent imaging technologies. However, as an optical-absorption-based coherent imaging technology, photoacoustic (PA) tomography (PAT) suppresses speckles by building up prominent boundary signals. We theoretically study the dependence of PAT speckles on the boundary roughness, which is quantified by the root-mean-squared value and the correlation length of the boundary height. Both the speckle visibility and the correlation coefficient between the reconstructed and actual boundaries are quantified. If the root-mean-squared height fluctuation is much greater than, and the height correlation length is much smaller than the imaging resolution, the reconstructed boundaries become fully developed speckles. In other words, speckle formation requires large uncorrelated height fluctuations within the resolution cell. The first- and second-order statistics of PAT speckles are also studied experimentally. While the amplitude of the speckles follows a Gaussian distribution, the autocorrelation of the speckle patterns tracks that of the system point spread function.

Additional Information

© 2012 SPIE. Paper 11724 received Dec. 7, 2011; revised manuscript received Feb. 9, 2012; accepted for publication Feb. 13, 2012; published online Apr. 19, 2012. The authors would like to thank Li Li, Yan Liu, and Alejandro Garcia-Uribe for their helpful discussions. This work has been supported in part by National Institutes of Health Grant Nos. R01 EB000712, R01 EB008085, R01 CA134539, R01 CA157277, R01 EB010049, and U54 CA136398. L.W. has a financial interest in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.

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August 22, 2023
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