Polarization-Sensitive OCT Phase Artifact Cancellation
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Solution Overview
Problem
Existing polarization sensitive OCT methods face challenges in distinguishing phase changes caused by birefringence from global phase differences, leading to artifacts in tomographic images, which affect the signal-to-noise ratio (SNR) and image quality.
Innovation Solution
The proposed solution involves modeling the Jones matrix for each pixel using global phase and unitary matrices to calculate the relative global phase, canceling the phase shift caused by birefringence, and applying weighting processing such as Gaussian waveform averaging to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If moving average processing is applied to reduce speckle noise, then image quality improves, but phase artifacts caused by birefringence cannot be distinguished from global phase
Solution Approach 1:
The patent segments the phase information into two distinct components: global phase and birefringence-induced phase. By separating these components through mathematical modeling of the Jones matrix, the system can process each component differently - applying moving average to reduce noise in the global phase while preserving the birefringence phase information for artifact-free imaging.
Solution Approach 2:
The patent introduces an intermediary mathematical model (Jones matrix decomposition) that acts as a mediator between the raw interference signal and the final image. This intermediary representation allows the system to distinguish and separately process different phase components, enabling noise reduction without information loss.
2Measurement precision
If global phase cancellation is performed to remove artifacts, then measurement precision improves, but signal-to-noise ratio decreases
Solution Approach 1:
Instead of completely canceling the global phase, the patent applies partial cancellation by selectively removing only the birefringence-induced phase component while retaining the global phase information. This partial action approach maintains the signal-to-noise ratio by preserving useful phase information while eliminating artifacts.
Solution Approach 2:
The patent changes the parameter representation from raw phase values to decomposed phase components (global phase and birefringence phase). This parameter transformation enables selective processing where the birefringence phase component can be removed for artifact elimination while the global phase component is preserved for maintaining signal-to-noise ratio.
3Measurement precision
If phase cancellation is applied to each pixel independently, then local phase accuracy improves, but global phase consistency is lost
Solution Approach 1:
The patent merges the local phase cancellation operation with global phase reference by calculating the birefringence phase relative to a reference pixel. This combination ensures that each pixel's phase is corrected locally while maintaining consistency with the global phase structure, preventing phase discontinuities and preserving overall phase stability.
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
This approach effectively cancels the phase shift due to birefringence, resulting in higher SNR and quality for two-dimensional or three-dimensional tomographic images acquired by polarization sensitive OCT.
Implementation Method 1
a wavelength scanning light source that sweeps wavelengths of broadband light
Implementation Method 2
a spectroscope for detecting a spectrum of the interference signal
Data Source
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AI summary
There is provided a polarization-sensitive optical tomographic imaging apparatus capable of acquiring a two-dimensional or/and three-dimensional tomographic image having higher SNR and quality by cancelling phase change caused by birefringence of a sample in average processing using a predetermined kernel region, and calculating a global phase difference of each pixel in the kernel. The PS-OCT imaging apparatus includes a processing unit configured to: set a predetermined kernel to a B scan image or/and C scan image (volume data) acquired corresponding to a Jones matrix; model the Jones matrix of each pixel in the set predetermined kernel by using one or more unitary matrices to calculate a relative global phase of each pixel, which may be due to speckle noise, for instance; and cancel the calculated relative global phase in each pixel in the predetermined kernel to average each element of the Jones matrix in the predetermined kernel.