Computationally effective 2D and 3D fast phase unwrapping algorithms and their applications to Doppler optical coherence tomography.

Ewelina Pijewska,Maciej Szkulmowski,Iwona Gorczynska

doi:10.1364/boe.10.001365

Ewelina Pijewska, Maciej Szkulmowski + Show 1 more

Open Access

https://doi.org/10.1364/boe.10.001365

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Abstract

We propose a simplification for a robust and easy to implement fast phase unwrapping (FPU) algorithm that is used to solve the phase wrapping problem encountered in various fields of optical imaging and metrology. We show that the number of necessary computations using the algorithm can be reduced compared to its original version. FPU can be easily extended from two to three spatial dimensions. We demonstrate the applicability of the two- and three-dimensional FPU algorithm for Doppler optical coherence tomography (DOCT) in numerical simulations, and in the imaging of a flow phantom and blood flow in the human retina in vivo. We introduce an FPU applicability plot for use as a guide in the selection of the most suitable version of the algorithm depending on the phase noise in the acquired data. This plot uses the circular standard deviation of the wrapped phase distribution as a measure of noise and relates it to the root-mean-square error of the recovered, unwrapped phase.

Highlights

Optical coherence tomography (OCT) is a micrometer-scale imaging technique [1, 2] most commonly used in medical diagnostics to visualize structures and detect the functions of biological tissues and cells
The fast phase unwrapping algorithm is well suited for applications in Doppler OCT
We have demonstrated that the inclusion of additional information on the phase distribution improved the performance of the 4FT fast phase unwrapping (FPU) algorithm when it was applied to data with high noise levels

Summary

Introduction

Optical coherence tomography (OCT) is a micrometer-scale imaging technique [1, 2] most commonly used in medical diagnostics to visualize structures and detect the functions of biological tissues and cells. Analysis of the interference signals originating from backscattered light within the tissue and backreflected from the reference mirror of an interferometer provides information about the spatial distribution of scattering structures within the object. The motion/flow detection methods are typically used in biomedical OCT imaging for the visualization of the circulatory systems within the living tissues. Their most common application is the use of blood motion to generate contrast for the visualization of vessels using a family of techniques known as optical coherence angiography (OCA or OCTA) [3,4,5]. Quantitative motion detection and the Doppler OCT methods are often jointly referred to as OCT velocimetry

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