Fiber-Based PS-OCT System with Polarization Diversity Detection
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Solution Overview
Problem
Current optical coherence tomography (OCT) and fluorescence imaging systems face challenges in providing detailed structural and biochemical information, especially in narrow airways like those in the lung, with existing systems being costly, cumbersome, and difficult to miniaturize, and lacking effective co-registration of OCT and autofluorescence imaging.
Innovation Solution
A fiber-based OCT system with polarization diversity detection and hybrid optical couplers, combined with a dual-clad fiber probe for co-registered AF-OCT imaging, allowing for robust, cost-effective imaging of narrow passages with improved resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If free-space interferometers with bulk optical components are used for PS-OCT, then polarization control and stability are improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical free-space interferometer system with bulk optical components with a fiber-based interferometer system using optical fibers and integrated components. This substitution maintains polarization control through fiber design while eliminating the complexity of aligning and stabilizing bulk optical components in free space.
Solution Approach 2:
The fiber-based interferometer design integrates multiple functions into the fiber optic structure itself, allowing the same system to perform both OCT imaging and polarization-sensitive measurements without requiring separate bulk optical components for each function.
2Ease of operation
If fiber-based interferometers are used, then ease of operation and robustness are improved, but polarization control and stability worsen
Solution Approach 1:
The patent applies different properties to different parts of the fiber system: standard single-mode fibers are used where flexibility and ease of operation are needed, while polarization-maintaining fibers are used in specific sections where polarization stability is critical. This localized application of different fiber types optimizes both ease of operation and polarization control.
Solution Approach 2:
The fiber-based interferometer design intentionally introduces asymmetric polarization control elements at strategic locations within the fiber path, allowing the system to maintain robustness and ease of operation while achieving the necessary polarization stability for PS-OCT imaging.
3Measurement precision
If alternating polarization states are used for PS-OCT measurement, then measurement precision is improved, but productivity decreases due to oversampling requirements
Solution Approach 1:
The patent uses periodic modulation of the polarization state at high frequency, allowing multiple polarization measurements to be taken during each oscillation cycle. This periodic action enables accurate birefringence measurement without requiring slow mechanical scanning, thereby maintaining both measurement precision and scanning speed.
Solution Approach 2:
The system pre-establishes the polarization modulation scheme and calibration parameters before actual imaging begins, allowing the alternating polarization states to be implemented efficiently during scanning without real-time computation delays that would reduce productivity.
4Measurement precision
If frequency multiplexing is used to measure multiple polarization states, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex frequency multiplexing hardware with a fiber-based polarization modulation approach that uses integrated optical modulators within the fiber path. This substitution achieves the same measurement precision while eliminating the need for elaborate synchronization between multiple frequency channels.
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
Enables high-resolution, cost-effective imaging of airway tissues with co-registered structural and biochemical information, reducing the need for biopsies and improving cancer screening and treatment applications.
Implementation Method 1
The light combiner is configured to allow interference of the light received from the source and reference arms
Implementation Method 2
The first and second polarizing beam splitters are respectively connected to first and second polarization maintaining optical fiber paths to deliver light having a first state of polarization to a first light detector and light having a second state of polarization distinct from the first state of polarization to a second light detector
Implementation Method 3
polarization maintaining optical fiber paths to deliver light having a first state of polarization
Data Source
AI summary
A fiber-based polarization sensitive optical coherence tomography (PS-OCT) system uses a new polarization diversity detection (PDD) scheme and requires no active polarization modulating components. Retardation of the sample can be determined from amplitudes of arbitrarily-oriented x- and y-components of the reflected light. A hybrid custom 50/50 coupler with single-mode fiber inputs and polarization maintaining (PM) fiber outputs combines light from sample and reference arms of an interferometer. Another embodiment provides a system adapted to provide co-registered autofluorescence-optical coherence tomography (AF-OCT) imaging. AF excitation light is introduced and collected AF light is extracted at a fiber optic rotary joint (FORJ) equipped with an embedded dichroic mirror. A probe tip that uses a clad fiber to supply light to a focusing element provides enhanced OCT and AF performance.