Tunable Fabry-Perot Etalon Calibration for Hyper-Spectral Measurement
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Solution Overview
Problem
Traditional methods for acquiring three-dimensional hyper-spectral measurements are computationally intensive and costly, and Fabry-Pérot etalons with fixed camera pixel sensitivity spectra complicate direct interpretation of spectral content due to multiple narrow peaks in the transmission spectrum.
Innovation Solution
A calibrated spectral measurement system using a tunable Fabry-Pérot etalon with a settable gap, a detector, and a processor that determines calibrated spectral measurements based on detected light intensities and a reconstruction matrix, allowing for the estimation of a target's optical spectrum by acquiring images for multiple gap settings and illumination types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used for acquiring hyper-spectral measurements, then measurement capability is achieved, but computational effort and cost are excessive
Solution Approach 1:
The patent replaces traditional complex mechanical/optical spectrometry systems with a Fabry-Pérot etalon-based interferometric system combined with digital reconstruction. The physical measurement system is simplified to capture only intensity data at multiple gap settings, while the spectral information is recovered computationally through a reconstruction matrix, substituting complex optical components with a simpler optical system plus algorithmic processing.
Solution Approach 2:
The patent changes the measurement parameters by using a tunable Fabry-Pérot etalon with variable gap distance instead of fixed optical components. By varying the gap parameter and capturing intensity measurements at multiple settings, the system enables spectral reconstruction through mathematical transformation of the intensity data, achieving hyper-spectral measurements with a simpler optical system.
2Measurement precision
If Fabry-Pérot etalon with multiple narrow peaks is used, then spectral resolution is improved, but direct interpretation of spectral content becomes difficult
Solution Approach 1:
The patent introduces a reconstruction matrix as an intermediary computational tool that bridges the gap between the raw intensity measurements from the Fabry-Pérot etalon and the desired spectral content. This matrix, pre-computed from calibration data, transforms the difficult-to-interpret intensity data into meaningful spectral information, making the system easy to use despite the complex underlying physics.
Solution Approach 2:
The patent performs preliminary calibration measurements to pre-compute the reconstruction matrix before actual spectral measurements are taken. This preliminary action captures the system's response characteristics and stores them in a lookup table, enabling rapid and straightforward spectral reconstruction during operation without requiring real-time complex calculations or expert interpretation.
3Ease of operation
If camera pixel sensitivity spectra are used, then detection is simplified, but one-to-one mapping to source spectra is lost
Solution Approach 1:
The patent incorporates feedback by using calibration measurements with known spectral sources to determine the system's actual response characteristics. This feedback information is used to construct the reconstruction matrix, which compensates for the camera's broad sensitivity and the etalon's multiple peaks, restoring the lost spectral mapping information through iterative optimization and validation.
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 and eliminates artifacts by utilizing the full set of gap measurements, enabling accurate three-dimensional hyper-spectral cube measurements with various illumination sources and camera types, including RGB and RGB+IR cameras.
Implementation Method 1
Traditional methods for acquiring three-dimensional (x,y,λ) hyper-spectral measurements typically require intensive computational efforts and expensive optical components. However, recent advances in fabrication techniques have allowed the creation of very precise tunable Fabry-Pérot etalons that can be used for making low-cost hyper-spectral measurements. These etalons have a transmission spectrum 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 transmitted through the tunable Fabry-Perot etalon. 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 using multiple source wavelengths and multiple settable gaps.