Composite Multi-Wavelength Photothermal Infrared Imaging for Drift Control
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Solution Overview
Problem
Conventional multi-wavelength photothermal infrared imaging techniques suffer from thermal drift and sample movement issues, leading to inaccurate normalization of IR absorption images due to thermal drift and thin film interference, which complicates the comparison of images taken at different wavelengths.
Innovation Solution
Implement rapid wavelength shifting during sequential scanning of sample lines to minimize thermal drift by rescanning the same lines at different wavelengths within a short time frame, ensuring accurate alignment and normalization of IR absorption images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional multi-wavelength photothermal infrared imaging is performed with sequential scanning at different wavelengths, then spectral information can be collected, but thermal drift and sample movement cause inaccurate normalization and imaging artifacts
Solution Approach 1:
The patent applies preliminary action by acquiring reference images at multiple wavelengths before the main measurement sequence. These pre-acquired reference images are used to calculate normalization factors that compensate for thermal drift and thin film interference effects during subsequent spectral scanning, thereby maintaining imaging accuracy without requiring real-time correction
Solution Approach 2:
The patent implements feedback through an iterative correction process where the measured photothermal images are normalized using reference images acquired at different wavelengths. The normalization factors derived from reference images are fed back into the measurement process to correct for thermal drift and interference artifacts, progressively improving image quality
2Measurement precision
If rapid wavelength shifting is implemented to minimize thermal drift, then imaging accuracy improves, but system complexity and scanning time management become more challenging
Solution Approach 1:
The patent applies segmentation by dividing the spectral scanning process into discrete wavelength steps with dedicated reference image acquisition at each wavelength. This segmented approach allows independent optimization of reference images for each wavelength, simplifying the control logic while maintaining high normalization accuracy through systematic wavelength-by-wavelength reference acquisition
3Loss of information
If thin film interference is present in the sample, then structural information can be obtained, but it complicates the comparison of IR absorption images at different wavelengths
Solution Approach 1:
The patent uses reference images acquired at multiple wavelengths as intermediary elements to mediate the comparison of spectral data. These reference images serve as a common baseline that accounts for thin film interference effects, allowing the actual chemical species information to be extracted through normalization while the interference artifacts are compensated for by the reference data
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 significantly reduces artifacts caused by thermal drift, resulting in more precise composite multi-wavelength photothermal IR imaging that accurately reflects chemical species distribution, even in the presence of thin film interference.
Implementation Method 1
measuring the amount of light absorbed, transmitted, reflected and/or scattered from the sample
Implementation Method 2
OPTIR achieves higher spatial resolution than conventional IR spectroscopy by using a shorter wavelength 'probe beam' to sense photothermal distortions in infrared absorbing regions of the sample
Implementation Method 3
sense photothermal distortions in infrared absorbing regions of the sample
Data Source
AI summary
Methods described herein provide improvements on composite infrared absorption imaging. Scanning patterns described herein reduce erroneous measurements caused by thermal drift, as well as optical interference that occurs between light scattering from the top surface of the sample and light scattering from an underlying substrate.