Standoff Micro-Raman Sensor Using Optical Filtering
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Solution Overview
Problem
Raman spectroscopy for identifying substances is hindered by the need for direct physical contact, shielding from ambient radiation, and the use of continuous wave lasers, which complicates measurements, especially in space exploration where substances are difficult to retrieve and analyze.
Innovation Solution
A stand-off ultra-compact Raman sensor that uses a laser to isolate Raman scattering and laser-induced fluorescence from ambient radiation without direct contact, employing beam expanders, lenses, filters, and adjustable laser properties to filter out Rayleigh scattering and analyze the spectrum for substance identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional Raman spectroscopy is used to identify substances, then substance identification can be achieved, but direct physical contact and shielding from ambient radiation are required, complicating measurements in space exploration
Solution Approach 1:
The patent introduces an optical system with beam expanders, lenses, and filters as intermediaries between the laser and the substance. This optical intermediary enables stand-off measurement by expanding the laser beam to cover larger areas, focusing scattered light onto detectors, and filtering out ambient radiation, thereby eliminating the need for direct physical contact and manual shielding
Solution Approach 2:
The patent replaces the mechanical shielding approach (physical covers and dark rooms) with an optical filtering system. The filter selectively transmits Raman scattered light while blocking ambient radiation, and the optical components (beam expanders, lenses) replace mechanical collection and positioning mechanisms, enabling non-contact measurement
2Measurement precision
If continuous wave laser is used for Raman spectroscopy, then measurement can be performed, but accuracy is impeded by inability to distinguish between short-lived biofluorescence and long-lived luminescence
Solution Approach 1:
The patent employs pulsed laser operation instead of continuous wave laser. The periodic pulsed action creates distinct temporal signatures for different fluorescence types: short-lived biofluorescence occurs immediately with each pulse while long-lived luminescence persists between pulses. This periodic excitation enables temporal resolution and accurate distinction between different substance types
Solution Approach 2:
The patent introduces temporal dynamics to the measurement system by using pulsed laser excitation and time-resolved detection. The system measures the decay characteristics of fluorescent signals over time, transforming a static measurement into a dynamic process that captures temporal information about the substance's photophysical properties
3Measurement precision
If substance is collected and shielded for Raman analysis, then accurate measurement can be obtained, but mechanical stresses and operational difficulty increase for hard, heavy, or fragile substances
Solution Approach 1:
The patent uses an optical intermediary system (beam expander, lenses, filters) that enables measurement through the atmosphere without physical contact. The expanded laser beam illuminates the substance from a distance, and the optical system collects and filters the scattered light, eliminating the need for mechanical collection devices that would add weight and cause stress to fragile substances
Solution Approach 2:
The patent replaces the mechanical collection and shielding system with an optical stand-off measurement system. Instead of physically gathering and protecting the substance, the system uses optical filtering to block ambient radiation and optical focusing to collect Raman signal, thereby eliminating mechanical stresses and reducing equipment weight
Data Source
AI summary
Standoff ultra-compact micro-Raman sensors configured to receive Raman scattering from a substance are disclosed. A laser device may be configured to transmit a laser at a first wavelength. The laser may be expanded to a predetermined size, focused through a lens, and made incident on an unknown substance. A filter may reflect the laser and Rayleigh scattering from the substance, but may permit Raman scattering and laser-induced fluorescence from the substance. One or more lenses and/or filters may receive and pass the Raman scattering and/or laser-induced fluorescence to a light sensor. The received Raman scattering and/or laser-induced fluorescence may be compared to known fingerprints of substances to determine an identity of the substance. The wavelength of the laser, the width of the laser, and other parameters may be varied based on the distance between the standoff ultra-compact micro-Raman sensor and the substance.