Hyperspectral Filter Mosaic Integration for CMOS Spectral Imaging
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Solution Overview
Problem
Existing spectroscopy devices using interference-based filters, such as Fabry-Pérot filters, face challenges in efficiently integrating them with image sensors like CMOS image sensors due to the need for additional manufacturing steps and precise control over filter layer thickness, composition, and deposition accuracy.
Innovation Solution
The integration of interference filters, including Fabry-Pérot filters, with image sensors is achieved through a method involving deposition of alternating layers with varying refractive indices, use of etch stops for precise control, and patterned etch processes to create mosaic patterns of filters tailored for different wavelengths, allowing for efficient spectral imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If interference-based filters are integrated with image sensors, then spectral imaging capability is improved, but manufacturing complexity increases due to additional manufacturing steps
Solution Approach 1:
The patent combines the interference filter structure directly with the image sensor by integrating multiple layers (substrate, buffer layer, interference filter layers with alternating high and low refractive indices, and protective layer) into a single manufactured component. This merging of the filter and sensor into one integrated structure eliminates the need for separate filter assembly steps, thereby reducing manufacturing complexity while maintaining spectral imaging capability.
2Manufacturing precision
If interference-based filters are applied to image sensors, then controlled light wavelengths are achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves precise wavelength control by carefully adjusting the thickness parameters of the interference filter layers (high refractive index layers and low refractive index layers). By optimizing these thickness parameters during the manufacturing process, the filter can be tuned to transmit specific wavelengths of light. This parameter-based control allows for precise spectral selection while using standard manufacturing techniques, balancing manufacturing precision requirements with ease of manufacture.
3Reliability
If alternating layers with varying refractive indices are deposited, then spectral response is improved, but deposition process complexity increases
Solution Approach 1:
The patent improves spectral response by creating local variations in refractive index through alternating layers of high and low refractive index materials. Each layer is designed with specific optical properties tailored to its position in the stack, allowing precise control over which wavelengths are transmitted or reflected. This local quality approach enables enhanced spectral discrimination while using conventional deposition processes to create the layered structure.
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 enables the creation of small-scale spectral image sensors with improved spectral response and spatial separation of light spectra across the sensor array, enhancing the accuracy and efficiency of spectral imaging.
Implementation Method 1
interference-based filters, such as Fabry-Pérot filters
Implementation Method 2
deposition of alternating layers with varying refractive indices
Data Source
AI summary
A sensor system includes a plurality of optical sensors implemented in a pixel layer of an integrated circuit and a plurality of sets of optical filters, where a set of optical filters including a first optical layer common to each optical filter of the set of optical filters, where the first optical layer includes a plurality of alternating sub-layers. The sensor system further includes a second optical layer formed of an optical material common to each optical filter of the set of optical filters, the second optical material for each optical filter of the set of optical filters configured to have a different thickness than any other optical filter of the set of optical filters. Finally, the sensor system includes a third optical layer common to each optical filter of the set of optical filters, the third optical layer having a plurality of alternating sub-layers, wherein the sublayers for the first optical layer and the third optical layer including one or more sublayers having a higher relative refractivity than the refractivity of at least one other sublayer of the plurality of alternating sub-layers.