Dielectric Mirror Filter Array for Low-Shift Multispectral Sensing
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Solution Overview
Problem
Existing multispectral imaging devices face challenges in integrating filters effectively due to high angle shift, small spectral ranges, and environmental sensitivity, particularly when using linear variable filters or circular variable filters, which affect the accuracy and durability of spectral data capture.
Innovation Solution
The implementation of a multispectral filter array using dielectric mirrors, such as quarterwave stacks and distributed Bragg reflectors, with spacer layers to enhance durability, spectral range, and reduce thermal and angle shifts, integrated with a semiconductor-based sensor element array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear variable filters or circular variable filters are used in multispectral imaging devices, then spectral data can be captured, but high angle shift and environmental sensitivity occur which reduce accuracy and durability
Solution Approach 1:
The patent uses dielectric mirrors composed of multiple alternating layers of high-index and low-index materials (such as TiO2/SiO2, Nb2O5/SiO2, or Ta2O5/SiO2) to create a composite structure that provides both spectral filtering accuracy and environmental durability. This composite layering resolves the contradiction by combining the optical precision needed for accurate spectral measurement with the structural stability required for reliability in varying environmental conditions
Solution Approach 2:
The patent controls the thickness of each dielectric layer (typically quarter-wave thickness) and the refractive index contrast between layers to precisely tune the spectral response. By changing these parameters, the filter achieves high measurement precision for spectral data while maintaining environmental stability, eliminating the angle shift problems associated with variable filters
2Adaptability or versatility
If variable filters are used to capture multiple spectral bands, then spectral range can be achieved, but small spectral ranges and high angle shift limit the effectiveness
Solution Approach 1:
The patent segments the spectral filtering function into multiple discrete dielectric mirror layers, each with specific thickness and material properties. This segmentation allows each layer to be precisely manufactured with controlled thickness (e.g., 50-200 nm), achieving accurate spectral range coverage while avoiding the angle shift and manufacturing precision issues of continuous variable filters
Solution Approach 2:
The dielectric mirror structure serves multiple functions simultaneously: it provides spectral filtering, environmental stability, and broad spectral range coverage. The same multi-layer structure that enables versatile spectral band selection also inherently provides durability and reduces angle sensitivity, eliminating the need for separate mechanisms to address these requirements
3Measurement precision
If complex filter integration methods are used to achieve multispectral sensing, then spectral data capture is enabled, but manufacturing complexity increases
Solution Approach 1:
The patent merges the filter structure directly with the sensor array by depositing dielectric mirror layers onto the sensor surface or integrating them in a single stacked structure. This combining of filtering and sensing functions into one integrated assembly reduces manufacturing complexity while maintaining spectral measurement precision, avoiding the need for separate filter modules and complex alignment procedures
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
The solution provides improved durability, spectral range, and reduced thermal and angle shifts, enabling accurate and reliable multispectral sensing with reduced manufacturing complexity.
Implementation Method 1
The first dielectric mirror may include a first quarterwave stack of high-index and low-index layers. The second dielectric mirror may include a second quarterwave stack of high-index and low-index layers.
Implementation Method 2
The third layer may be a second dielectric mirror to reflect a portion of light directed toward the third layer.
Implementation Method 3
A channel, of the set of channels, may be associated with a particular thickness corresponding to a particular wavelength of light that is to be directed toward a particular optical sensor of the set of optical sensors.
Data Source
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AI summary
An optical sensor device may include a set of optical sensors. The optical sensor device may include a substrate. The optical sensor device may include a multispectral filter array disposed on the substrate. The multispectral filter array may include a first dielectric mirror disposed on the substrate. The multispectral filter array may include a spacer disposed on the first dielectric mirror. The spacer may include a set of layers. The multispectral filter array may include a second dielectric mirror disposed on the spacer. The second dielectric mirror may be aligned with two or more sensor elements of a set of sensor elements.