Optical Fiber Distance Estimation via Numerical Aperture Modulation
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Solution Overview
Problem
Current laser treatment devices face challenges in accurately determining the position and orientation of the optical fiber tip relative to the target tissue due to its permanent motion and changing environment, making it difficult to measure the distance effectively.
Innovation Solution
Modulating the numerical aperture of a light beam transmitted through an optical fiber, measuring the intensity values of reflections from the target tissue, and estimating the distance by comparing these values associated with different numerical aperture settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fiber tip position and orientation are measured using conventional methods, then the treatment can be performed, but the measurement precision is poor due to permanent motion of the fiber and changes in the treated tissue and its environment
Solution Approach 1:
The patent applies periodic modulation of the numerical aperture of the light beam transmitted through the optical fiber. By periodically varying the numerical aperture and measuring the corresponding reflected light intensity at different modulation phases, the system can estimate the distance between the fiber tip and tissue. This periodic action allows the system to distinguish between signal variations caused by fiber motion and those caused by actual distance changes, thereby improving measurement precision despite fiber instability.
Solution Approach 2:
The patent changes the numerical aperture parameter of the light beam to enable distance estimation. By modulating the numerical aperture and observing the corresponding changes in reflected light intensity, the system can infer distance information. This parameter change approach transforms an unstable measurement problem into a controllable modulation problem, where the known modulation pattern serves as a reference for extracting distance information.
2Reliability
If the numerical aperture is modulated to estimate distance, then the signal-to-noise ratio is improved, but the device complexity increases due to additional modulation and measurement components
Solution Approach 1:
The patent makes the existing optical fiber system multi-functional by using the same optical fiber to both transmit treatment laser energy and to perform distance estimation measurements. The numerical aperture modulation is applied to the treatment beam itself, and the reflected light from the tissue is measured through the same fiber. This eliminates the need for separate measurement fibers or additional optical paths, thereby improving signal-to-noise ratio without significantly increasing device complexity.
3Productivity
If conventional distance measurement methods are used, then the system remains simple, but the treatment efficiency is reduced due to lack of accurate fiber tip location information
Solution Approach 1:
The patent implements a feedback mechanism where the distance estimation information obtained through numerical aperture modulation is used to guide the treatment process. By continuously monitoring the reflected light intensity at different modulation phases and calculating the distance between the fiber tip and tissue, the system provides real-time feedback about the fiber position. This feedback enables the operator to adjust the fiber position and orientation to optimize treatment efficiency, compensating for the lack of direct visual information about fiber tip location.
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 method improves the signal-to-noise ratio and allows for a crude estimation of the distance between the fiber tip and the target tissue, overcoming issues of unpredictable tissue reflectivity and environmental changes, enhancing treatment efficiency.
Implementation Method 1
delivering energy to a tissue by irradiating the tissue with a laser beam through an optical fiber
Implementation Method 2
measuring intensity values of reflections of the light beam reflected from the target tissue and transmitted backward through the optical fiber
Data Source
AI summary
A system and method of estimating a distance between the distal end of an optical fiber and treated tissue, to improve treatment efficiency, is provided herein. The estimation is achieved by modulating the numerical aperture of a light beam transmitted through the fiber to receive reflections from the tissue and distinguish them from other reflections in the fiber, and further by calculating the distance by comparing reflection intensities of beams having different numerical aperture values that illuminate the tissue over a very short period, so that tissue and environment conditions do not change much. Distance estimation may be carried out by modulating the treatment beam itself, or by a light beam transmitted between pulses of a pulsed treatment beam.