Tapered Waveguide Axial Resolution for Deep Tissue Fluorescence
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Solution Overview
Problem
Current optical spectroscopy techniques face limitations in depth resolution, particularly in tissues, as photons are often absorbed or scattered before reaching the light collecting device, making it difficult to assess fluorescence depth beyond a few hundred micrometers, and existing methods are invasive and limited in depth penetration.
Innovation Solution
A minimally invasive optical spectroscopy system using a single optical fiber with a tapered waveguide that acts as a mode division multiplexer, allowing for depth-resolved fluorescence detection by discriminating guided modes based on their modal content, enabling collection of signals from several millimeters deep with high axial resolution and minimal invasiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical spectroscopy techniques are used, then the measurement can be performed with simple equipment, but the depth resolution is limited to a few hundred micrometers due to light absorption and scattering in tissue
Solution Approach 1:
The optical fiber is segmented into multiple functional zones along its length, with each zone acting as an independent light collection point. The fiber is divided into a proximal section and a distal section, each capable of collecting light from different tissue depths, enabling depth-resolved spectroscopy without requiring complex external imaging systems.
Solution Approach 2:
The invention transitions from planar, surface-level optical measurement to axial, depth-resolved measurement by utilizing the length dimension of the optical fiber. Light is collected at multiple positions along the fiber axis, converting a two-dimensional surface measurement into a three-dimensional depth-resolved measurement capability.
2Measurement precision
If fiber optic probes are used for in vivo measurements, then the system can be minimally invasive, but the depth penetration is limited to a few hundred micrometers
Solution Approach 1:
The tapered waveguide acts as an intermediary structure that enhances light extraction efficiency from deep tissue. The taper geometry serves as a mediator between the deep tissue fluorescence sources and the optical fiber core, enabling effective light collection from depths of several millimeters despite tissue opacity.
Solution Approach 2:
The optical fiber parameters are changed by introducing a taper with specific geometric parameters (angle, length, diameter) that optimize light extraction. The taper transforms the mode structure of light propagating in the fiber, enabling enhanced collection efficiency from deep tissue sources by changing the spatial distribution of light modes.
3Reliability
If multiple collection fibers are used to improve signal collection, then the signal-to-noise ratio improves, but the invasiveness and device size increase
Solution Approach 1:
Multiple light collection functions are merged into a single optical fiber by utilizing its length dimension. Instead of requiring multiple separate fibers to collect light from different depths, the single fiber is designed with a taper that enables different sections to collect light from different tissue depths, reducing invasiveness while maintaining signal quality.
Solution Approach 2:
The optical fiber is designed to perform multiple functions simultaneously: it can collect light from different tissue depths, provide structural support, and maintain minimal invasiveness. The tapered waveguide structure enables the single fiber to serve as a multi-point collection device, eliminating the need for multiple separate fibers.
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
The system achieves in-depth light collection with high axial resolution and minimal invasiveness, allowing for multi-point light collection and improved depth resolution, adjustable according to specific needs, and can be used for both in vivo and ex vivo applications.
Implementation Method 1
a waveguide formed by a single optical fiber and having a proximal end and a distal end, said proximal end being formed with a taper along which at least one optical window is positioned
Implementation Method 2
at least one optical window is positioned along the taper for collecting light entering an axial section of the taper
Data Source
AI summary
A system for optical spectroscopy through a probe implanted in a tissue is provided. The system includes a light collecting probe comprising a waveguide formed by a single optical fiber and having a proximal end and a distal end, the proximal end being formed with a taper along which at least one optical window is positioned, wherein light entering at an axial section of the taper generates a specific subset of guided modes defined by the diameter of the single optical fiber at the axial section, the guided modes propagating toward the distal end of the waveguide and generating an output at the distal end of the waveguide; a demultiplexer configured to receive outputs provided by the light collecting probe and discriminate the outputs based on their modal content of origin; and a detector configured to detect the discriminated outputs.