Optical Coherence Tomography Signal Processing via Minimum-Phase Function
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Solution Overview
Problem
Conventional frequency-domain optical coherence tomography (OCT) systems face challenges in achieving high signal-to-noise ratio and measurement range due to spatial aliasing and the need for large reference arm offsets, which degrade image quality and limit accessible depth information.
Innovation Solution
The application of minimum-phase function (MPF) processing techniques allows for the recovery of the complex scattering function from Fourier transform magnitude data alone, using iterative error-reduction methods and Hilbert transformations, which improves signal-to-noise ratio and measurement range without requiring high-resolution optical spectrum analyzers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional frequency-domain OCT systems use large reference arm offsets to achieve measurement range, then the measurement range is improved, but spatial aliasing occurs and image quality degrades
Solution Approach 1:
The patent extracts and removes the auto-correlation terms from the OCT signal processing, isolating only the tissue scattering function. This is achieved through mathematical operations that separate the desired tissue information from the interfering auto-correlation components, thereby eliminating spatial aliasing while preserving the full measurement range provided by the large reference arm offset
Solution Approach 2:
The patent changes the processing approach by applying minimum-phase function (MPF) techniques and iterative error-reduction methods to recover the complex scattering function from magnitude data alone. This parameter transformation allows the system to achieve high resolution and signal-to-noise ratio without being constrained by the traditional limitations of large reference arm offsets
2Device complexity
If conventional frequency-domain OCT systems operate without high-resolution optical spectrum analyzers, then device complexity is reduced, but signal-to-noise ratio and resolution deteriorate
Solution Approach 1:
The patent replaces the need for high-resolution optical spectrum analyzers with computational processing methods. By using iterative error-reduction algorithms and minimum-phase function techniques, the system achieves high signal-to-noise ratio and resolution through software-based processing rather than relying on high-resolution hardware components
Solution Approach 2:
The patent introduces minimum-phase function processing as an intermediary step between the raw magnitude data and the final tissue scattering function. This intermediary processing technique enables the recovery of phase information and enhancement of signal quality without requiring high-resolution spectral measurement capabilities
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 enhances the resolution and signal-to-noise ratio of OCT images, allowing for better depth measurement range and reduced noise sensitivity, even in noisy configurations, by effectively isolating the tissue scattering function from auto-correlation terms.
Implementation Method 1
the spectrum of the interference between the two reflected signals coming from each arm of the interferometer is recorded
Implementation Method 2
The reflected light from the tissue and from the reference mirror are combined collinearly at the detector
Implementation Method 3
providing a magnitude spectrum of a complex spatial Fourier transform of a complex intermediate function
Data Source
AI summary
An apparatus and method process optical coherence tomography (OCT) imaging data from a sample. The method includes using a magnitude spectrum and an estimated phase term of a complex spatial Fourier transform of a complex intermediate function to generate an estimated complex spatial Fourier transform. The method further includes calculating an inverse Fourier transform of the estimated complex spatial Fourier transform and calculating an estimated intermediate function by applying at least one constraint to the inverse Fourier transform. The apparatus includes a partially reflective element configured to reflect a first portion of light and to allow a second portion of light to propagate through the partially reflective element and to reflect from the sample. The apparatus further includes a detector that measures the OCT power spectrum in response to the first and second portions of light.