Raman Spectroscopy Background Fluorescence Subtraction
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Solution Overview
Problem
Raman spectroscopy in tissue analysis is hindered by background fluorescence, which masks the weak Raman signals, and existing methods for subtraction or compensation are not effective enough.
Innovation Solution
A method and system that apply excitation light at multiple linewidths to differentiate and interpolate the background fluorescence, using a spread-spectrum approach to broaden the excitation light source linewidth beyond the instrument bandwidth, allowing precise determination and subtraction of the autofluorescence signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Raman spectroscopy is used to analyze tissue, then the ability to distinguish between cancerous and normal tissue is improved, but the weak Raman signals are masked by background fluorescence
Solution Approach 1:
The patent changes the linewidth parameter of the excitation light source from narrow to broad. By broadening the excitation linewidth beyond the instrument bandwidth, the Raman peaks are spread across multiple detector pixels, allowing the fluorescence background to be determined and subtracted from the total signal, thereby recovering the Raman spectral information.
Solution Approach 2:
The patent introduces an intermediary measurement approach where the fluorescence background is determined as a separate component. By measuring the total signal (Raman + fluorescence) and the fluorescence background independently through linewidth broadening, the Raman signal can be extracted by subtraction, effectively separating the harmful fluorescence from the useful Raman signal.
2Measurement precision
If curve fitting algorithms are used to subtract background fluorescence, then some background removal is achieved, but the methods are not effective enough for detailed Raman spectral analysis
Solution Approach 1:
The patent replaces the mathematical curve fitting approach with a physical measurement approach. Instead of using algorithms to estimate and subtract fluorescence, the method physically separates the fluorescence signal by broadening the excitation linewidth, allowing direct measurement of the fluorescence background and more reliable subtraction.
3Measurement precision
If multiple excitation wavelengths are used in SERDS, then Raman signals can be shifted over the fluorescent background, but the approach requires complex multiple laser systems or step-wise wavelength variation
Solution Approach 1:
The patent changes the linewidth parameter of a single excitation source instead of varying the wavelength. By broadening the linewidth of a single laser source beyond the instrument bandwidth, the method achieves signal separation without requiring multiple lasers or complex wavelength tuning mechanisms, thereby reducing device complexity while maintaining effectiveness.
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 approach effectively separates and accounts for background fluorescence, enhancing the analysis of Raman spectral signatures by interpolating the background level, thereby improving the accuracy of tissue analysis.
Implementation Method 1
the light emitted from the sample including Raman scattered light and background fluorescent light
Implementation Method 2
the light emitted from the sample including Raman scattered light and background fluorescent light
Data Source
AI summary
A method and apparatus for determining a level of background fluorescent light produced during photometric interrogation of a sample is provided. The method includes applying an excitation light to a sample using a laser at a plurality linewidths different from one another, the excitation light at each of the plurality of different linewidths applied at an excitation wavelength operable to cause emission of light from the sample, the light emitted from the sample including Raman scattered light and background fluorescent light; detecting light emitted from the tissue sample at each of the plurality of linewidths using a detector and producing light signals representative of the detected light; and determining a level of the background fluorescent using the light signals representative of the detected light for each of the plurality of different linewidths.