Tunable Laser Surface Contaminant Detection via On-Off Imaging
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Solution Overview
Problem
Current methods for detecting trace chemicals on surfaces at a distance, such as high power point detection and thermal emission detection, are limited by sensitivity to distance, require expensive and power-intensive equipment, and can be unsafe or destructive, making them inefficient for imaging large areas or detecting contaminants effectively.
Innovation Solution
A system utilizing a tunable laser to intermittently direct electromagnetic radiation at a surface, capturing 'on' and 'off' images with an imaging device, and processing these images to identify target materials based on thermodynamic responses, which allows for reversible and less destructive detection without the need for high-power lasers or expensive long-wave infrared detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high power lasers are used for point detection (Raman scattering or LIBS), then detection sensitivity is improved, but safety hazards increase and the methods are limited to point detection making imaging inefficient
Solution Approach 1:
The patent uses pulsed laser illumination at specific wavelengths to periodically excite target materials, causing them to emit characteristic spectral signals. This periodic action allows for safe, low-power operation while maintaining detection sensitivity through time-gated detection of the emitted signals during and after each pulse.
Solution Approach 2:
The patent changes the wavelength parameter of the laser to match specific absorption bands of target materials, maximizing the efficiency of energy transfer and signal generation. By tuning the laser wavelength to resonate with molecular vibrations or electronic transitions of the target, detection sensitivity is enhanced without requiring high power levels.
2Measurement precision
If thermal emission detection is used, then material identification is achieved, but the detection requires expensive, slow, actively cooled long wave infrared detectors and large receiver apertures
Solution Approach 1:
Instead of directly detecting thermal emission in the expensive LWIR range, the patent uses visible or near-infrared lasers to excite the target material, causing it to emit characteristic spectral fingerprints in the visible/NIR range. This creates an optical copy of the thermal emission information that can be detected by inexpensive, high-speed silicon-based detectors.
Solution Approach 2:
The patent replaces the mechanical/thermal detection system (LWIR detectors requiring active cooling) with an optical detection system using visible/NIR lasers and standard silicon detectors. This substitution eliminates the need for expensive, slow, actively cooled detectors while maintaining material identification capability.
3Measurement precision
If thermal emission detection is used, then material temperature changes are detected, but the detection sensitivity follows a 1/R2 manner making it highly sensitive to range
Solution Approach 1:
The patent uses resonant vibrational modes of molecules excited by tunable laser wavelengths to generate strong, characteristic emission signals. This resonant excitation produces signals that are much stronger and more stable with range compared to passive thermal emission detection, as the laser provides active energy input at the molecular resonance frequency.
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 enables effective detection and identification of materials at greater distances with less expensive and less range-sensitive equipment, providing higher resolution and sensitivity by leveraging thermodynamic responses in the visible or near-infrared spectrum, reducing the need for large apertures and actively cooled detectors.
Implementation Method 1
A detection system uses a laser to heat a target material
Implementation Method 2
capture at least one 'on' image of the surface when the electromagnetic radiation of the at least one selected wavelength is directed at the surface
Data Source
AI summary
Aspects of the subject technology relate to methods and systems for identifying a target material. The system includes a tunable laser, an imaging device, and a signal processor. The tunable laser is configured to intermittently direct electromagnetic radiation of at least one selected wavelength at a surface of a target material. The imaging device is configured to capture at least one “on” image of the surface when the electromagnetic radiation of the at least one selected wavelength is directed at the surface and capture at least one “off” image of the surface when electromagnetic radiation of the at least one selected wavelength is not directed at the surface. The signal processor is configured to compare, for each selected wavelength, the “on” image(s) corresponding to the selected wavelength with the “off” image(s) corresponding to the selected wavelength and identify the target material based on the comparison.