Integrated Fabry-Perot Filter Arrays for Reduced Optical Crosstalk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Spectral imaging devices using patterned thin-film Fabry-Pérot filters suffer from optical crosstalk due to the presence of highly reflective mirrors forming optical cavities, which cause light to be trapped and propagate between adjacent filters, leading to reduced spatial and spectral resolution.
Innovation Solution
The filters are arranged in specific patterns, such as the 'rumba sleeve' pattern, where the central wavelengths decrease with distance from the optical axis, minimizing optical crosstalk by exploiting asymmetrical crosstalk dependence on incident light direction, rather than adding physical barriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thin-film Fabry-Pérot filters with highly reflective mirrors are used to create spectral imaging devices, then spectral resolution and miniaturization are improved, but optical crosstalk increases due to light being trapped and propagating between adjacent filters
Solution Approach 1:
The patent applies asymmetry by arranging filters with different central wavelengths in a specific asymmetric pattern (the 'rumba sleeve' pattern) where the central wavelengths decrease with distance from the optical axis. This asymmetric arrangement exploits the asymmetrical nature of optical crosstalk propagation to minimize the harmful effects of light trapping between adjacent filters, thereby reducing optical crosstalk while maintaining spectral resolution.
2Object-generated harmful factors
If physical barriers are added between filter elements to reduce optical crosstalk, then crosstalk is reduced, but manufacturing complexity and cost increase due to additional wafer processing steps
Solution Approach 1:
The patent applies parameter changes by modifying the arrangement pattern of existing filters rather than adding physical barriers. Specifically, it changes the spatial distribution parameter of filter central wavelengths according to the 'rumba sleeve' pattern, where wavelengths decrease with distance from the optical axis. This approach reduces optical crosstalk through parameter optimization without requiring additional wafer processing steps or physical barrier structures, thereby maintaining ease of manufacture.
3Ease of manufacture
If filters are arranged in conventional patterns, then fabrication is simplified, but angle-dependent optical crosstalk remains significant and is not well understood
Solution Approach 1:
The patent applies local quality by implementing position-dependent filter wavelength assignment in the 'rumba sleeve' pattern. Each filter's central wavelength is locally optimized based on its position relative to the optical axis, with wavelengths decreasing as distance from the axis increases. This local customization of filter properties across the array reduces angle-dependent optical crosstalk while remaining compatible with existing fabrication techniques.
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 effectively reduces optical crosstalk without additional wafer processing costs, enhancing spatial and spectral resolution in spectral imaging devices.
Implementation Method 1
each of the Fabry-Pérot optical filter elements has an optical cavity with an optical path length tuned to a central wavelength
Implementation Method 2
thin-film Fabry-Pérot filters have a distinct type of crosstalk due to the presence of highly reflective mirrors which form an optical cavity between which light can remain trapped
Data Source
AI summary
An integrated spectral imaging device has a sensor array comprising image sensor elements; and a filter array comprising Fabry-Perot optical filter elements; where each of the Fabry-Perot optical filter elements is fabricated above one of the image sensor elements; where each of the Fabry-Perot optical filter elements has an optical cavity with an optical path length tuned to a central wavelength; where the Fabry-Perot optical hlter elements are configured such that they are grouped in rectangular cells such that central wavelengths of filter elements within each of the rectangular cells decrease with distance from an optical axis located at a central position in the filter array.