Spectrometer Oblique Illumination Spatial Filtering
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Solution Overview
Problem
Conventional Raman spectroscopy methods face interference issues when an illumination beam passes through materials adjacent to the sample, such as container materials, which can obscure the Raman scattering signal from the sample of interest.
Innovation Solution
The implementation of a spectrometer that directs the excitation beam at a non-zero angle relative to the sample, using a spatial filter to separate and remove interference signals from adjacent materials, allowing for the detection of Raman scattering from the sample while minimizing interference from container or proximity materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If zero-degree epi-illumination is used, then alignment is simplified and ease of operation is improved, but interference from adjacent materials increases and measurement precision deteriorates
Solution Approach 1:
The patent transitions from zero-degree illumination to oblique-angle illumination, changing the spatial dimension of light incidence. This dimensional change allows the excitation beam to enter the sample at an angle rather than perpendicular to the surface, thereby separating the illumination path from the collection path and eliminating interference from adjacent materials while maintaining ease of operation through pre-aligned optical components
2Measurement precision
If off-axis excitation is used, then interference from adjacent materials is reduced and measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces a beam splitter as an intermediary optical component that separates the excitation and collection paths. The beam splitter allows the excitation beam to enter at an oblique angle while directing the Raman scattered light to the collection optics, thereby achieving interference reduction without significantly increasing overall device complexity through the use of a single additional optical element
3Measurement precision
If spatial filtering is applied, then interference signals are removed and measurement precision is improved, but loss of useful signal increases
Solution Approach 1:
The patent applies spatial filtering selectively to specific regions in the optical path where interference signals are localized. By positioning the spatial filter to block only the specific angular directions from which interference originates while allowing Raman scattered light from the sample to pass through, the system removes interference signals without significantly attenuating the useful signal
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 reduces interference from adjacent materials, enabling accurate detection and analysis of Raman spectra from the sample of interest, even when samples are embedded within or behind container layers, by using off-axis excitation and statistical methods to isolate the sample's signal.
Implementation Method 1
Raman spectroscopy can be performed at angles other than zero degrees
Implementation Method 2
the optical system is configured to direct the excitation incident beam toward a sample at a non-zero angle from a zero-angle reference
Implementation Method 3
The detector is configured to remove a spectral interference component of the spectroscopy signal
Data Source
AI summary
Spectrometers and methods for determining the presence or absence of a material in proximity to and/or combined with another material are provided. In one particular example, a spectrometer is provided that includes a light source, a detector and an optical system. In this implementation, the light source is configured to provide an excitation incident beam. The detector is configured to detect a spectroscopy signal. The optical system is configured to direct the excitation incident beam toward a sample at a non-zero angle from a zero-angle reference. The optical system is further configured to receive a spectroscopy signal from the sample and provide the spectroscopy signal to the detector. The detector is configured to remove a spectral interference component of the spectroscopy signal.