Single-End Multimode Fiber Transfer Matrix Estimation
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Solution Overview
Problem
Conventional methods for measuring the transfer matrix of multimode optical fibers require access to both ends, which is not feasible in many imaging applications, especially when the fiber is inserted deep into a bodily cavity and bent, making prior measurements unusable.
Innovation Solution
An optical frequency-domain reflectometer (OFDR) system that estimates the transfer matrix from a single end of the multimode optical fiber using mode-selective measurements and distributed reflectors, employing a tunable laser, configurable optical filters, and a digital signal processor to determine the single-direction transfer matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to measure the transfer matrix of multimode optical fibers, then measurement accuracy can be achieved, but access to both ends of the fiber is required which is not feasible in many imaging applications
Solution Approach 1:
The fiber is divided into multiple segments with distributed reflectors at specific locations. The transfer matrix measurement is performed segment by segment starting from the accessible proximal end, rather than requiring simultaneous access to both ends. This segmentation allows sequential measurement of each segment's transfer matrix using only the proximal end access.
Solution Approach 2:
Distributed reflectors are pre-installed at known locations along the fiber before insertion into the patient's body. These reflectors serve as predetermined measurement points that enable the system to perform transfer matrix measurements at specific segments without requiring access to the distal end of the fiber.
2Adaptability or versatility
If the fiber is inserted deep into a bodily cavity and bent, then imaging applications become feasible, but prior transfer matrix measurements become unusable
Solution Approach 1:
The system performs transfer matrix measurements dynamically at the time of use rather than relying on pre-measured static values. The distributed reflectors enable real-time measurement of each segment's transfer matrix even after the fiber has been inserted and bent, ensuring the measurements reflect the actual in-vivo conditions.
Solution Approach 2:
Distributed reflectors act as intermediaries that enable measurement of the fiber's transfer characteristics without requiring direct access to the distal end. These reflectors provide reference points along the fiber that allow the proximal-end measurement system to characterize the entire fiber path, including bent sections deep in the body cavity.
3Ease of operation
If distributed reflectors are used to enable single-end measurement, then ease of operation improves, but device complexity increases
Solution Approach 1:
The distributed reflectors are passive elements that automatically provide the necessary reflection points for measurement without requiring active control or additional complex components. The fiber structure itself serves the dual purpose of light transmission and measurement reference, eliminating the need for separate active sensing mechanisms at the distal end.
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 remote characterization and imaging applications by accurately estimating the transfer matrix without direct access to the distal end of the fiber, even when it is bent or perturbed, improving image quality in OCT and other applications.
Implementation Method 1
an optical interferometer connected to mix other part of the probe light with the light transmitted by the second configurable optical filter to generate an optical interference signal
Implementation Method 2
a tunable laser configured to generate probe light and controllable to sweep a wavelength of said probe light
Implementation Method 3
a first configurable optical filter to transmit a received part of said probe light primarily to a selectable spatial propagation mode of the multimode optical fiber
Implementation Method 4
the multimode optical fiber includes distributed reflectors designed to generate relatively strong light reflections along the length of the fiber
Data Source
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AI summary
An optical frequency-domain reflectometer (OFDR) capable of estimating the transfer matrix of a multimode optical fiber using mode-selective measurements performed from a single end of the fiber. In an example embodiment, the multimode optical fiber includes distributed reflectors designed to generate relatively strong light reflections along the length of the fiber at a desired spatial resolution. The embodiments may employ a signal-processing algorithm to estimate the fiber's transfer matrix by estimating segment transfer matrices corresponding to the fiber segments located between different ones of the distributed reflectors. Different embodiments of the disclosed OFDR can beneficially be adapted for use in different applications, such as fiber-optic component and module characterization, distributed optical sensing, biomedical imaging, OCT, etc.