Reflective Cavity Spectroscopy for Sub-Surface Signal Collection
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Solution Overview
Problem
Conventional optical spectroscopy methods are limited by their focus on small sample volumes, potential damage to delicate samples, and inability to measure sub-surface signals in diffusely scattering samples, leading to non-representative spectra and incomplete material characterization.
Innovation Solution
A light delivery and collection device with a reflective cavity that diverges excitation light over a large area, allowing for sub-surface signal excitation and enhanced collection efficiency through multiple reflections, using high-reflectivity materials and apertures to cover and enclose the sample, thereby improving signal collection from both surface and sub-surface layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a tightly focused laser beam is used to excite the sample, then the signal excitation efficiency is improved, but the sample damage risk increases and the measurement area is limited to a small volume
Solution Approach 1:
The invention divides the excitation process into two distinct functions: a focused laser beam for efficient signal excitation, and a reflective cavity with large aperture for distributing excitation light over a large sample area. This segmentation allows the system to achieve both high signal efficiency and large area coverage without directly focusing the entire excitation energy on one point.
Solution Approach 2:
The reflective cavity acts as an intermediary between the laser source and the sample. It takes the focused excitation light and redistributes it over a large area through multiple reflections, thereby reducing the energy density on any single point of the sample while maintaining overall excitation efficiency.
2Productivity
If a tightly focused laser beam is used, then the signal excitation efficiency is improved, but the measurement area is limited to a small volume
Solution Approach 1:
The invention divides the excitation process into two distinct functions: a focused laser beam for efficient signal excitation, and a reflective cavity with large aperture for distributing excitation light over a large sample area. This segmentation allows the system to achieve both high signal efficiency and large area coverage without directly focusing the entire excitation energy on one point.
Solution Approach 2:
The reflective cavity introduces an additional spatial dimension to the excitation geometry. Instead of only axial focusing, the cavity extends the excitation volume laterally through its large aperture and multiple reflection paths, effectively transforming a 1D focused beam into a 3D distributed excitation field.
3Measurement precision
If a tightly focused laser beam is used on diffusely scattering samples, then the surface signal is obtained, but the sub-surface material cannot be measured
Solution Approach 1:
The reflective cavity introduces an additional spatial dimension to the excitation geometry. Instead of only axial focusing, the cavity extends the excitation volume laterally through its large aperture and multiple reflection paths, effectively transforming a 1D focused beam into a 3D distributed excitation field that penetrates deeper into diffusely scattering samples.
Solution Approach 2:
The multiple reflections within the reflective cavity create a continuous excitation field that persists throughout the sample volume. Rather than a single-pass focused beam that terminates at the surface, the cavity maintains circulating excitation light that continuously interacts with both surface and sub-surface regions of diffusely scattering samples.
4Ease of operation
If conventional spectroscopy is used on non-uniform samples, then the measurement process is simple, but the collected spectra are not representative
Solution Approach 1:
The invention divides the excitation process into two distinct functions: a focused laser beam for efficient signal excitation, and a reflective cavity with large aperture for distributing excitation light over a large sample area. This segmentation allows the system to achieve both high signal efficiency and large area coverage without directly focusing the entire excitation energy on one point.
Data Source
AI summary
This invention relates to a light delivery and collection device for performing spectroscopic analysis of a subject. The light delivery and collection device comprises a reflective cavity with two apertures. The first aperture is configured to receive excitation light which then diverges and projects onto the second aperture. The second aperture is configured to be applied close to the subject such that the reflective cavity substantially forms an enclosure covering a large area of the subject. The excitation light enters and interacts with the covered area of the subject to produce inelastic scattering and/or fluorescence emission from the subject. The reflective cavity has a specular reflective surface with high reflectivity to the excitation light as well as to the inelastic scattering and/or fluorescence emission from the subject. The reflective cavity reflects the excitation light that is reflected and/or back-scattered from the subject and redirects it towards the subject. This causes more excitation light to penetrate into a diffusely scattering subject to produce inelastic scattering and/or fluorescence emission from inside of the subject hence enabling sub-surface measurement. In addition, the reflective cavity reflects the inelastic scattering and/or fluorescence emission from the subject unless the inelastic scattering and/or fluorescence emission either emits from the first aperture of the reflective cavity to be measured with a spectrometer device, or re-enters the subject at the second aperture. This multi-reflection process improves the collection efficiency of the inelastic scattering or fluorescence emission from the subject.