Iterative Optical Diffraction Tomography for High RI Contrast Imaging

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Solution Overview

Problem

Conventional optical diffraction tomography (ODT) methods fail to accurately reconstruct phase objects with high refractive index contrast, complex structures, and large optical path differences due to multiple scattering, leading to ineffective inversion and artifacts in imaging.

Innovation Solution

The iterative Optical Diffraction Tomography (iODT) method iteratively reduces errors between measured and reconstructed diffracted fields using a constraint operator and propagation solver, applying perturbative Rytov phase corrections to improve object reconstruction quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional ODT methods are used for reconstruction, then the imaging process is simple and fast, but the reconstruction accuracy deteriorates for objects with high RI contrast, complex structures, and large OPDs due to multiple scattering

Engineering Contradiction:

Improvereconstruction accuracyVSAvoidimaging method complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The imaging process is divided into multiple iterations, where each iteration refines the reconstruction by reducing errors between measured and simulated diffracted fields. This segmentation of the inversion process into sequential steps allows progressive improvement of reconstruction accuracy for multiply-scattering objects.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method employs feedback by comparing the diffracted fields simulated from the current reconstruction with the actually measured diffracted fields, then using this error information to update and improve the reconstruction in subsequent iterations. This closed-loop feedback mechanism enables accurate reconstruction of objects with high RI contrast and complex structures.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If iterative correction methods are applied to improve reconstruction quality, then the accuracy improves for multiply-scattering objects, but the computation time increases

Engineering Contradiction:

Improvereconstruction accuracyVSAvoidcomputation time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The method performs preliminary actions by pre-calculating propagation operators and using efficient numerical methods for the forward and adjoint simulations. This preparation work enables the iterative correction process to converge faster, reducing the overall computation time while maintaining high reconstruction accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The method changes parameters by adapting the iteration count and correction strength based on the specific object properties and measurement quality. This parameter optimization allows the algorithm to achieve accurate reconstructions with fewer iterations for simpler objects, reducing computation time while maintaining accuracy for complex multiply-scattering objects.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

iODT achieves accurate reconstruction of phase objects with high refractive index contrast and complex structures by iteratively reducing errors, providing improved resolution and artifact suppression, even in scenarios where conventional ODT methods fail.

Implementation Method 1

applying the propagation solver, S, to the known incident wave, u0, through Cƒ(m) for each illumination angle, θ, to generate a forward propagating field, u(m)fwd(θ)

Methodology Applied

Scientific EffectBeam propagation method:

Implementation Method 2

applying an inverse of the propagation solver, S−1, to the true diffracted field, ut, through Cƒ(m) for each illumination angle, θ, to generate a backward propagating field, u(m)bwd(θ)

Methodology Applied

Scientific EffectAdjoint beam propagation method:

Implementation Method 3

computing the perturbative Rytov phase Δφ(m)R(θ) as ln[u(m)fwd (θ)/u(m)bwd(θ)

Methodology Applied

Scientific EffectRytov approximation:

Implementation Method 4

ODT reconstructs the RI distributions of transparent samples by interferometrically measuring diffracted fields over multiple illumination angles

Methodology Applied

Scientific EffectInterferometric measurement: Interference

Implementation Method 5

when the wavelength of illumination is on a scale similar to the sample feature size, the wave nature of light must be accounted for. Optical diffraction tomography (ODT) was developed for this purpose.

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS11221205B2Iterative optical diffraction tomography (iODT) method and applications

Publication Date: 2022.01.11 UNIVERSITY OF CENTRAL FLORIDA RESEARCH FOUNDATION INC

AI summary

A non-destructive iterative interferometric tomographic technique for imaging and reconstruction of phase objects as well as objects with complex permittivity and, particularly, to iterative optical diffraction tomographic (iODT) imaging and reconstruction of phase objects with high refractive index (RI) contrast, complex structures, and/or large optical path differences (OPDs) against the background, which cause multiple scattering, and applications thereof.