Raman Probe Fiber Segmentation for Noise Reduction
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Solution Overview
Problem
Raman spectrum measurements of biological tissue are hindered by noise from optical fibers and background light signals, such as Rayleigh scattered light and autofluorescence, which complicate the acquisition of high signal-to-noise ratios.
Innovation Solution
A Raman probe system with a first and second illuminating fiber of different materials, an optical filter that transmits wavelengths shorter than a predetermined wavelength, and a light-collecting fiber, where the second illuminating and collecting fibers are made of the same material, allowing for the subtraction of fiber Raman spectra and background signals from the observed spectrum using a calculated coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fibers are used to guide laser beams and receive Raman scattered light, then the Raman spectrum of the examination subject can be acquired, but the observed spectrum contains Raman spectrum of the optical fiber as noise
Solution Approach 1:
The optical fiber system is segmented into multiple fibers with different materials (first illuminating fiber, second illuminating fiber, light-collecting fiber). By using different materials, the Raman spectra of different fibers occur at different wavelengths, allowing selective subtraction of fiber Raman signals from the observed spectrum.
Solution Approach 2:
The material composition parameter of the optical fibers is changed to create distinct Raman spectral signatures. The first illuminating fiber uses a material whose Raman spectrum does not overlap with the examination subject, while the second illuminating fiber and light-collecting fiber use the same material. This parameter change enables mathematical separation of fiber Raman signals from the target signal.
2Measurement precision
If optical filters are added to cut Raman scattered light and transmit only laser beam, then fiber Raman noise is reduced, but the device structure becomes more complex
Solution Approach 1:
Instead of using optical filters to remove fiber Raman noise, the invention extracts the fiber Raman signal components mathematically from the observed spectrum. By measuring the Raman spectra of the first and second illuminating fibers separately and subtracting them with appropriate coefficients, the fiber noise is removed without adding physical filters to the probe structure.
3Measurement precision
If background light signals such as Rayleigh scattered light and autofluorescence are present, then the observed spectrum contains additional noise, but polynomial fitting and subtraction methods increase computational complexity
Solution Approach 1:
The background light signals are removed in advance through polynomial fitting and subtraction before the final Raman spectrum analysis. By performing this preprocessing step, the subsequent spectral analysis works with cleaner data, reducing the overall computational burden despite the initial fitting operation.
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 configuration enables accurate removal of optical fiber Raman spectra and background signals, resulting in a high signal-to-noise Raman spectrum of the examination subject with reduced computational complexity.
Implementation Method 1
an optical filter that is disposed between the first illuminating fiber and the second illuminating fiber, that transmits, of the light emitted from the first illuminating fiber, light having a wavelength equal to or shorter than a predetermined wavelength, the light containing the laser beam, and that blocks light having a wavelength longer than the predetermined wavelength
Implementation Method 2
receives Raman scattered light from the examination subject excited by the laser beam
Implementation Method 3
a laser light source that supplies the laser beam to the first illuminating fiber
Data Source
AI summary
A Raman probe includes: a first illuminating fiber and a second illuminating fiber that are arranged in series and that are formed of different materials from each other; a coupling optical system for optically coupling the first and second illuminating fibers; a light-collecting fiber that is formed of the same material as the second illuminating fiber and that collects Raman scattered light from an examination subject; and an optical filter that is disposed between the first and second illuminating fibers and that selectively transmits a laser beam being guided by the first illuminating fiber and, of Raman scattered light of the first illuminating fiber excited by the laser beam, Raman scattered light the amount of Raman shift of which is smaller than a predetermined amount of Raman shift in a Raman spectrum of the examination subject.