Optical Waveguide Distance Sensing for Laser Lithotripsy
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Solution Overview
Problem
Existing laser lithotripsy devices face challenges in accurately determining the distance between the end of an optical waveguide and a body stone, leading to reduced treatment efficacy and potential tissue damage due to varying fluorescence intensities and surface reflectances, which affect the positioning of the laser light.
Innovation Solution
A method and device using electromagnetic radiation of two wavelengths, where one is more strongly absorbed by the medium than the other, to measure the distance by calculating the ratio of reflection signals, allowing for precise determination of the waveguide's end proximity to the stone surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If fluorescence measurement is used for stone detection, then automatic stone detection is enabled, but distance measurement accuracy deteriorates due to varying fluorescence intensities of different stones
Solution Approach 1:
The patent changes the measurement parameter from fluorescence intensity to light reflection intensity. By using reflection measurement at a wavelength (e.g., 1310 nm) where the medium has strong absorption, the measurement becomes independent of stone-specific fluorescence properties, enabling accurate distance measurement while maintaining automatic detection capability
Solution Approach 2:
The patent introduces an intermediary measurement approach by using the medium's absorption properties as a reference. The strong absorption of the medium at the measurement wavelength creates a consistent reference signal that mediates between the variable stone properties and the distance measurement, allowing accurate distance determination through ratio calculation
2Loss of information
If reflection measurement is used for distance determination, then distance information becomes available, but measurement accuracy deteriorates due to varying surface structures and reflectances of different stones
Solution Approach 1:
The patent changes the measurement approach by using the ratio of reflection signals at two different wavelengths. This parameter transformation converts the absolute reflection intensity (which varies with surface properties) into a ratio that cancels out surface-specific variations, leaving only the distance-dependent component
Solution Approach 2:
The patent implements a feedback mechanism by continuously measuring the reflection signal ratio and using it to determine and adjust the distance. The system uses the measured ratio to feedback control the positioning or laser parameters, ensuring accurate distance maintenance despite variations in stone surface properties
3Object-affected harmful factors
If the waveguide end is positioned too far from the stone, then treatment safety is improved by avoiding tissue damage, but treatment efficacy deteriorates due to reduced laser effect and temperature rise
Solution Approach 1:
The patent implements real-time feedback control by continuously measuring the distance between the waveguide end and the stone surface using the reflection signal ratio. This feedback enables dynamic adjustment of the waveguide positioning or laser parameters to maintain the optimal distance range, ensuring both safety and efficacy
Solution Approach 2:
The patent introduces dynamic control of the treatment process by enabling real-time distance measurement and adjustment. The system transitions from static positioning to dynamic control, where the waveguide position or laser parameters can be continuously optimized based on the measured distance, maintaining treatment effectiveness while preventing tissue damage
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 reliable and accurate distance measurement, ensuring effective laser treatment by preventing tissue damage and optimizing laser energy delivery, particularly in laser lithotripsy applications.
Implementation Method 1
wherein the medium more strongly absorbs the electromagnetic measuring radiation of the second wavelength than the electromagnetic measuring radiation of the first wavelength
Implementation Method 2
measuring a first reflection signal of the electromagnetic measuring radiation of the first wavelength reflected from the surface, and measuring a second reflection signal of the electromagnetic measuring radiation of the second wavelength reflected from the surface
Data Source
AI summary
A measuring method for optically determining a distance (z) of a surface located in a medium from an end of an optical waveguide is described and has the following steps: emitting electromagnetic measuring radiation of a first wavelength (λ1) and of a second wavelength (λ2) from the end of the waveguide towards the surface, wherein the medium more strongly absorbs the electromagnetic measuring radiation of the second wavelength (λ2) than the electromagnetic measuring radiation of the first wavelength (λ1); measuring a first reflection signal (I1) of the electromagnetic measuring radiation of the first wavelength (λ1) reflected from the surface, and measuring a second reflection signal (I2) of the electromagnetic measuring radiation of the second wavelength (λ2) reflected from the surface, and determining the distance (z) from a ratio (I2:I1) of the second and the first reflection signal. Furthermore, a measuring device and a laser lithotripsy device are described.