Multi-Wavelength Laser Inspection With Gated Fluorescence Capture
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Solution Overview
Problem
Existing fluorescent spectroscopy methods struggle to achieve high signal-to-noise ratios and chemical specificity when inspecting surfaces, often leading to inaccurate material identification and surface cleanliness assessment.
Innovation Solution
A system comprising a laser that emits light with varying wavelengths over time, an optical system that directs this light to specific points along a scan line, and a gated camera that records fluorescent responses at each wavelength, synchronized with the laser to minimize noise and maximize chemical information capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fluorescent spectroscopy methods are used to illuminate the entire surface at once, then the inspection process is simple and fast, but the signal-to-noise ratio is low and chemical specificity is poor
Solution Approach 1:
The inspection surface is divided into multiple discrete points along a scan line, with each point inspected sequentially rather than the entire surface simultaneously. This segmentation allows the system to concentrate illumination and detection resources on individual points, improving the signal-to-noise ratio while maintaining manageable system complexity through structured sequential processing
Solution Approach 2:
The system employs periodic pulsed illumination at varying wavelengths, with each pulse targeting a specific point on the scan line. This periodic action enables time-gated detection to capture fluorescence signals during specific time windows, enhancing signal-to-noise ratio by synchronizing detection with the periodic illumination cycles
2Loss of information
If traditional methods illuminate the entire surface simultaneously, then the inspection is fast, but chemical information detail is insufficient for accurate material identification
Solution Approach 1:
The system varies the wavelength parameter of illumination light across multiple discrete wavelengths, with each wavelength providing specific chemical information about surface materials. This parameter variation enables detailed chemical analysis and accurate material identification while maintaining inspection speed through efficient sequential scanning and parallel wavelength acquisition
3Measurement precision
If the laser emits continuous light at a single wavelength, then the system is simple to control, but it cannot provide detailed chemical information about surface materials
Solution Approach 1:
The laser wavelength is dynamically varied over time to emit light at multiple discrete wavelengths sequentially, with the wavelength changing as a function of time. This dynamic wavelength modulation enables detailed chemical information acquisition for accurate material identification while maintaining controlled system complexity through synchronized timing and coordination between wavelength modulation and detection
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 enhances the signal-to-noise ratio and provides more detailed chemical information about surface materials, enabling more accurate identification of materials and surface cleanliness assessment compared to traditional methods.
Implementation Method 1
Molecules of some compounds can be excited from a ground state to an excited state using a beam of light. During this excitation, individual molecules absorb photons and shortly thereafter emit light having a longer wavelength than the beam of light. This emission of light after absorbing a photon is referred to as fluorescence.
Implementation Method 2
The optical system includes at least one optical element, and is configured to direct light emitted by the laser to points along a scan line during a plurality of time intervals such that: the wavelength of the light directed to each point along the scan line varies from point to point within time intervals of the plurality of time intervals
Implementation Method 3
The gated camera is configured to record a fluorescent response of the surface from the light having each wavelength of the plurality of wavelengths at each point along the scan line
Data Source
AI summary
An example system for inspecting a surface includes a laser, an optical system, a gated camera, and a control system. The laser is configured to emit pulses of light, with respective wavelengths of the pulses of light varying over time. The optical system includes at least one optical element, and is configured to direct light emitted by the laser to points along a scan line one point at a time. The gated camera is configured to record a fluorescent response of the surface from light having each wavelength of a plurality of wavelengths at each point along the scan line. The control system is configured to control the gated camera such that an aperture of the gated camera is open during fluorescence of the surface but closed during exposure of the surface to light emitted by the laser.