Tunable Fabry-Perot Interferometer Calibration for Hyperspectral Imaging
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Solution Overview
Problem
Traditional methods for acquiring three-dimensional hyper-spectral measurements are costly and prone to errors due to the complex mapping of pixel measurements to source spectra and temperature variations in Fabry-Pérot etalon-based systems, which complicates the interpretation of raw image measurements.
Innovation Solution
A calibrated spectral measurement system using a tunable Fabry-Pérot etalon with a settable gap, a detector, and a processor that employs a reconstruction matrix based on calibration measurements to estimate the target's optical spectrum, accounting for temperature variations and various illumination sources, including narrow band, multiband, and broadband sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used for acquiring hyper-spectral measurements, then comprehensive spectral data can be obtained, but the computational effort required is intensive and the cost is high
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing a lookup table that maps camera pixel responses to spectral values before actual measurements are taken. This pre-computed reference data eliminates the need for intensive real-time computational processing during hyper-spectral acquisition, while still maintaining measurement accuracy through the stored calibration information.
2Ease of manufacture
If a Fabry-Perot etalon is used to reduce cost, then the system becomes more affordable, but temperature variations cause measurement errors due to etalon gap shifts
Solution Approach 1:
The patent implements feedback by continuously monitoring the temperature of the Fabry-Perot etalon and using this temperature information to select appropriate calibration data from the lookup table. The system measures temperature, uses it to index into pre-calibrated temperature-specific spectral responses, and thereby compensates for thermal drift effects, maintaining measurement reliability across varying temperatures.
Solution Approach 2:
The patent applies parameter changes by creating and storing calibration data for multiple temperature conditions in the lookup table. Instead of attempting to physically stabilize the etalon temperature, the system adapts to temperature variations by selecting the appropriate calibrated spectral response corresponding to the measured temperature, effectively compensating for thermal effects through data selection rather than physical control.
3Adaptability or versatility
If multiple narrow peaks are transmitted through the etalon, then spectral coverage is achieved, but the mapping from pixel measurements to source spectra becomes complex and ambiguous
Solution Approach 1:
The patent resolves the spectral reconstruction ambiguity through preliminary action by pre-computing the relationship between pixel measurements and source spectra for each etalon peak position and storing this information in the lookup table. During operation, the system simply retrieves the pre-computed spectral response corresponding to the observed peak positions, eliminating the need for complex real-time spectral unmixing or inversion algorithms.
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
Resolves ambiguities in spectral estimation, eliminates artifacts, and provides accurate three-dimensional hyper-spectral cube measurements across different illumination types and camera configurations, improving the reliability and accuracy of hyper-spectral imaging.
Implementation Method 1
tunable Fabry-Pérot etalons that can be used for making low-cost hyper-spectral measurements. These etalons have transmission spectrums that exhibit peaks of transmission as a function of a settable gap between two reflective glass optical flats.
Data Source
AI summary
A system for determining a calibrated spectral measurement includes a tunable Fabry-Perot etalon, a detector, and a processor. The tunable Fabry-Perot etalon has a settable gap. The detector measures light intensity. The processor is configured to determine the calibrated spectral measurement. The calibrated spectral measurement is based at least in part on a measurement set of detected light intensities for a plurality of settable gaps and a reconstruction matrix. The reconstruction matrix is based at least in part on calibration measurements. For a calibration measurement, a settable gap is selected and a set of input monochromatic source wavelengths is used to measure responses at a detector after transmission through the Fabry-Perot etalon. Each input monochromatic source wavelength is also measured using a radiometer to scale detector measurements.