Filter Array Layout With Varied FSR for Hyperspectral Resolution
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Solution Overview
Problem
Existing hyperspectral cameras face issues with deteriorated spectral resolution due to the use of filter arrays with uniform free spectral ranges (FSR), leading to inaccurate spectral images.
Innovation Solution
Designing a filter array where at least two filters have different FSRs, with a specific interval ratio (ΔFSR/σ ≥ 0.25) and varying transmission spectra, to enhance spectral resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filter arrays with uniform free spectral ranges are used, then the device complexity is reduced and manufacturing is simplified, but the spectral resolution deteriorates and spectral image accuracy decreases
Solution Approach 1:
The patent applies local quality by making each filter in the filter array have different free spectral range characteristics. Specifically, the filter array includes filters with different FSR values, where each filter's transmission spectrum has unique peak intervals. This local differentiation in filter characteristics enables improved spectral resolution and accurate spectral image generation while avoiding the need for complex uniform FSR filter designs across the entire array.
2Measurement precision
If filter arrays with uniform free spectral ranges are used, then the ease of manufacture is improved, but the spectral image accuracy deteriorates
Solution Approach 1:
The patent applies parameter changes by varying the free spectral range parameter across different filters in the array. The transmission spectrum of each filter is designed with different FSR values, creating a diverse set of spectral responses. This parameter variation approach improves spectral image accuracy by providing more discriminative spectral information, while the filters can still be manufactured using standard optical filter fabrication techniques.
3Measurement precision
If filters with different FSRs are introduced, then the spectral resolution is improved, but the device complexity increases
Solution Approach 1:
The patent implements local quality by assigning different FSR characteristics to individual filters within the array. Each filter maintains its unique transmission spectrum with specific peak intervals, creating localized spectral filtering capabilities. This approach improves spectral resolution by capturing more detailed spectral information, while the filter array configuration remains manageable through systematic design of the transmission spectra.
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
Improves the accuracy of spectral image generation and enhances the spectral resolution of hyperspectral cameras, allowing for more precise spectral analysis.
Implementation Method 1
an optical filter array having at least two transmittance peaks (i.e., maximum values) within a target wavelength range is used as the encoder
Implementation Method 2
U.S. Pat. No. 9,466,628 discloses an example of a filter array including a Fabry-Perot resonator in which a dielectric multilayer film is used as a reflective layer
Data Source
AI summary
A filter array includes filters disposed in a two-dimensional plane and having different transmission spectra. The filters include a first filter with a transmission spectrum having a first peak group including first and second peaks adjacent to each other, and at least one second filter with a transmission spectrum having a second peak group including third and fourth peaks adjacent to each other. Of peaks included in the second peak group, the third peak has a wavelength closest to a wavelength at the first peak. A first interval between the wavelength at the first peak and a wavelength at the second peak is different from a second interval between the wavelength at the third peak and a wavelength at the fourth peak. ΔFSR/σ≥0.25, where ΔFSR denotes an absolute value of a difference between the first and second intervals and σ denotes a half-width of the first peak.