Bulk Phase Error Calculation in Optical Coherence Tomography
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Solution Overview
Problem
The phase-contrast method for estimating bulk phase errors in optical coherence tomography (OCT) images suffers from low accuracy due to cumulative summation of errors, and existing smoothing techniques lack a logical basis and can result in compromised or failed estimations.
Innovation Solution
A signal processing device and method that calculate bulk phase errors by integrating phase gradients along multiple paths between determined and undetermined sample points, combining path-specific phase errors to determine the bulk phase error at each destination, and optionally using weighted averages based on path lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the phase-contrast method is used to estimate bulk phase error, then the estimation can be obtained, but the accuracy is low due to cumulative summation of errors
Solution Approach 1:
The patent segments the estimation process by calculating phase gradients between adjacent sample points and then integrating these gradients along multiple independent paths. This segmentation approach avoids direct cumulative summation of raw phase errors, instead accumulating gradients which have reduced error components. The phase gradient calculation divides the problem into local differences that can be more accurately measured and then integrated.
Solution Approach 2:
The patent introduces a path integration dimension by calculating bulk phase error through multiple different paths between the same start and end points. By integrating phase gradients along multiple paths and averaging the results, the method exploits the additional dimensional information to reduce the impact of random errors and provide a more reliable estimation than single-path cumulative summation.
2Reliability
If smoothing processing is applied to reduce error, then error reduction is attempted, but the logical basis is insufficient and may compromise estimation accuracy
Solution Approach 1:
The patent implements a feedback mechanism by calculating phase gradients from the OCT signal and using these gradients to determine bulk phase error, which is then used to correct the original signal. The corrected signal can be reprocessed to refine the gradient calculations, creating an iterative feedback loop that continuously improves estimation accuracy without requiring ad hoc smoothing operations.
3Measurement precision
If multiple paths are used for integration, then random error components are reduced, but the calculation complexity increases
Solution Approach 1:
The patent segments the complex multi-path integration problem into manageable local phase gradient calculations between adjacent sample points. These pre-calculated gradients are then reused across multiple paths, avoiding redundant calculations. This segmentation strategy reduces the overall computational complexity while still benefiting from multiple path integration for error reduction.
Data Source
AI summary
A phase gradient calculation unit calculates a phase gradient on a plane intersecting an irradiation direction of light corresponding to an optical coherence tomography signal indicating a state of a sample for each of sample points arranged on the plane. A bulk phase error calculation unit integrates, for each of plurality of paths from an origin that is a sample point where a bulk phase error is determined to a destination that is a sample point where the bulk phase error is not determined, the phase gradient for each of the sample points along each of the plurality of corresponding paths to calculate a path specific phase error at the destination, and combines the path specific phase errors among the plurality of corresponding paths to determine the bulk phase error at the destination.