Multi-Wavelength Standoff Raman Spectroscopy System
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Solution Overview
Problem
Conventional Raman spectroscopy systems face challenges in efficiently detecting trace materials at long distances due to alignment issues, sample degradation, and interference from absorption and fluorescence, particularly when using deep-UV excitation wavelengths.
Innovation Solution
A multi-wavelength single-pulse stand-off Raman spectroscopy system using an unfocused laser with a hybrid diffraction grating and fiber optic bundle, allowing simultaneous collection of Raman spectra from large sample areas with minimal alignment requirements and reduced sample damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focused laser beams are used in conventional Raman spectroscopy systems, then measurement precision is improved, but alignment complexity and device complexity increase significantly
Solution Approach 1:
The patent removes the focusing optics from the system, extracting the alignment complexity component while maintaining measurement capability through direct collection of scattered light from the unfocused beam area
Solution Approach 2:
The unfocused laser beam serves multiple functions simultaneously: it provides the excitation source for Raman scattering and defines the measurement area, eliminating the need for separate focusing optics and alignment mechanisms
2Measurement precision
If deep-UV excitation wavelengths are used to detect trace materials, then measurement precision is improved, but sample degradation increases
Solution Approach 1:
The system uses pulsed laser excitation rather than continuous illumination, providing periodic action that allows trace material detection while limiting total energy exposure to prevent sample degradation and fluorescence interference
Solution Approach 2:
The patent uses unfocused laser beams that provide sufficient excitation energy for trace material detection without concentrating excessive energy at a single point, thereby avoiding sample damage while achieving detection sensitivity
3Productivity
If focused beams are used to increase Raman signal intensity, then productivity is improved, but alignment time and operational complexity increase
Solution Approach 1:
The patent extracts the focusing optics from the system, eliminating alignment requirements and simplifying operation while maintaining detection capability through direct collection of scattered light from the unfocused beam area
Solution Approach 2:
The unfocused laser beam automatically defines the measurement area and provides uniform excitation across the target surface, eliminating the need for manual alignment adjustments and making the system self-aligning
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 efficient detection of trace materials over long distances with reduced sample degradation and interference, achieving high sensitivity and accuracy in identifying chemical species without the need for focal plane adjustments.
Implementation Method 1
The Raman effect, or Raman scattering, is well known. Briefly and simply, when a beam of light impinges on substances, light is scattered. This scattering is of several different types, the predominant type being Rayleigh scattering, wherein the wavelength of the scattered light is the same as that of the incident light. In the type utilized in the present invention, Raman scattering, the scattered light is of different wavelengths than the incident light
Implementation Method 2
a customized spectrograph, which separates the individual spectra from the scattered wavelengths using a hybrid diffraction grating
Implementation Method 3
Rayleigh filtered and focused using a singlet lens into a stacked fiber bundle
Data Source
AI summary
The invention provides methods and apparatus comprising a multi-wavelength laser source that uses a single unfocused pulse of a low intensity but high power laser over a large sample area to collect Raman scattered collimated light, which is then Rayleigh filtered and focused using a singlet lens into a stacked fiber bundle connected to a customized spectrograph, which separates the individual spectra from the scattered wavelengths using a hybrid diffraction grating for collection onto spectra-specific sections of an array photodetector to measure spectral intensity and thereby identify one or more compounds in the sample.