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Proceedings Paper

Upper limit for angular compounding speckle reduction
Author(s): Yonatan Winetraub; Chris Wu; Steven Chu; Adam de la Zerda
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Paper Abstract

Angular compounding is a technique for reducing speckle noise in optical coherence tomography that is claimed to significantly improve the signal-to-noise ratio of images without impairing their spatial resolution. Here we examine how focal point movements caused by optical aberrations in an angular compounding system may produce unintended spatial averaging and concomitant loss of spatial resolution. Experimentally, we accounted for such aberrations by aligning our system and measuring distortions in images, and found that when the distortions were corrected the speckle reduction by angular compounding was limited. Our theoretical analysis using Monte Carlo simulations indicates that “pure” angular compounding (i.e., with no spatial averaging) over our full numerical aperture (13° in air) can improve the signal-to-noise ratio by no more than a factor of 1.3. Illuminating only a partial aperture cannot improve this factor compared to a spatial averaging system with equivalent loss of resolution. We conclude that speckle reduction using angular compounding is equivalent to spatial averaging. Nonetheless, angular compounding may be useful for improving images in applications where depth of field is important. The distortions tend to be greatest off the focal plane, so angular compounding combined with our correction technique can reduce speckle with a minimal loss of resolution across a large depth of field.

Paper Details

Date Published: 22 February 2019
PDF: 13 pages
Proc. SPIE 10867, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXIII, 108672O (22 February 2019); doi: 10.1117/12.2511428
Show Author Affiliations
Yonatan Winetraub, Stanford Univ. (United States)
Chris Wu, Stanford Univ. (United States)
Steven Chu, Stanford Univ. (United States)
Adam de la Zerda, Stanford Univ. (United States)
The Chan Zuckerberg Biohub (United States)

Published in SPIE Proceedings Vol. 10867:
Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXIII
James G. Fujimoto; Joseph A. Izatt, Editor(s)

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