Short-Wavelength Chiral Raman Spectrometer Fluorescence Reduction
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Solution Overview
Problem
Commercial chiral Raman spectrometers with 532nm excitation lasers face challenges due to low sensitivity and fluorescence interference, making it difficult to study chiral samples with low concentrations.
Innovation Solution
A short-wavelength laser-excitation chiral Raman Spectrometer using a laser light source between 325nm and 532nm, combined with a linear polarized homogeneous system, circularly polarized light converter, and a Y-type double beam bifurcated optical fiber, enhances sensitivity by transforming between Incident Circular Polarization (ICP) and Scattered Circular Polarization (SCP) detection methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 532nm excitation laser is used in commercial chiral Raman spectrometers, then the instrument can operate with standard components, but the detection sensitivity is low and fluorescence interference occurs
Solution Approach 1:
The patent changes the excitation wavelength parameter from the conventional 532nm to short-wavelength range (325nm-532nm). This parameter change shifts the excitation energy to higher frequencies, which increases Raman scattering intensity and improves detection sensitivity while avoiding the fluorescence interference that plagues longer wavelength excitation
2Measurement precision
If short-wavelength laser excitation is used, then detection sensitivity and signal-to-noise ratio are improved, but the requirement for optical component performance and system complexity increases
Solution Approach 1:
The patent segments the optical detection path into distinct functional modules: the Y-type double beam bifurcated optical fiber separates right and left circularly polarized Raman signals into different channels, the Rayleigh line filter removes elastic scattering, and the imaging spectrograph disperses the Raman signals. This segmentation allows each component to be optimized independently for short-wavelength operation while maintaining overall system manageability
Solution Approach 2:
The patent introduces a Rayleigh line filter as an intermediary component between the sample cell and the detector. This filter specifically removes the intense Rayleigh scattered light at the excitation wavelength, allowing the much weaker Raman signals to be detected with high signal-to-noise ratio without being overwhelmed by elastic scattering
Data Source
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AI summary
A short-wavelength laser-excitation chiral Raman Spectrometer (A short-wavelength laser-excitation Raman Optical Activity Spectrometer) comprises a laser-excitation light source between 325nm and 532nm, the linear polarized homogeneous system, circularly polarized light converter, sample cell holder, circularly polarized light splitter, double beam bifurcated optical fiber, Rayleigh line filter, imaging spectrometer, CCD sensitive to short-wavelength range and data processing system. The laser coming from laser-excitation light source goes through the linear polarized homogeneous system then exposures to the sample cell, or the laser coming from laser-excitation light source goes through the linear polarized homogeneous system and circularly polarized light converter then exposures to the sample cell. The left/right circularly polarized Raman signals coming from sample cell go through the Rayleigh line filter, then enter into the incidence end of Y-type double-beam optical fiber, divided into two beams of polarized light via circularly polarized light splitter, present as a linear array on the other end of the optical fiber, then enter into the incident slit of imaging spectrograph. The Raman signals are separated by the imaging spectrograph then enter the CCD on the exit of spectrograph which is sensitive in a wide range of short wavelength, and incident upon the top half and the bottom of it. CCD's acquisition system collects the light signals of the top half and the bottom half, that is, the right and the left ciculaly polarized Raman signals, converting them into electrical signals and transmitting the signals to the computer. After data processing, the sum of right and left circularly polarized Raman signals is counted as the total Raman signal, and the difference between right and left circularly polarized Raman signals as the circularly polarized Raman difference signal, that is, the Raman optical activity signal, and One acquisition when normalized difference of circular polarization intensity is computed as the circularly polarized Raman difference signal divided by the total Raman signal. The short-wavelength chiral Raman Spectrometer that can be applied to confirmation of chiral molecules' and biomolecules' absolute configurations, is a powerful tool for determination of absolute configuration and conformation of chiral molecules in wide region of chemistry, biology and medicine.