Spectral Sensor Filter Array Layout for Chief Ray Angle Compensation
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Solution Overview
Problem
Spectral image sensors using interference-based filters, such as Fabry-Perot filters, are susceptible to non-ideal angular responses due to varying chief ray angles (CRA), leading to unstable and inaccurate spectral responses, particularly in applications with high CRA lenses like smart mobile phones and smart watches.
Innovation Solution
Implementing a pre-compensated filter array with spatially modified center wavelengths and cavity thicknesses, using techniques like etching and sub-pixel level layout, to stabilize the filter response across the sensor array, and incorporating reverse telecentric lens designs to uniform angularity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interference-based filters are used in spectral sensors, then controlled light wavelengths can be achieved, but the angular response becomes unstable due to varying chief ray angles
Solution Approach 1:
The patent applies local quality by modifying the center wavelengths of filters at different spatial locations across the sensor array. Each filter's center wavelength is specifically tuned according to its position and the expected chief ray angle at that location, creating non-uniform local properties that compensate for the varying angular responses across the array.
Solution Approach 2:
The patent implements preliminary action by pre-compensating the filter center wavelengths during manufacturing based on predicted chief ray angles. This pre-adjustment is performed before the sensor operates, so that when light enters at various angles, the filters are already optimized to maintain stable spectral responses without requiring real-time adjustment.
2Volume of moving object
If high CRA lenses are used in compact devices, then device size is reduced, but spectral response uniformity across the sensor array deteriorates
Solution Approach 1:
The patent addresses this contradiction by making the filter array non-uniform, with each location having specifically tailored center wavelengths matched to the local chief ray angle produced by the high CRA lens. This local customization allows the system to maintain spectral uniformity despite the lens-induced angular variations.
Solution Approach 2:
The patent changes the parameter of filter center wavelengths across the array to compensate for the optical parameters introduced by high CRA lenses. By adjusting wavelengths as a function of position, the system maintains spectral accuracy while using compact lens designs.
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
Stabilizes the spectral response by minimizing the effect of varying CRA, ensuring uniformity and accuracy of spectral analysis across the sensor array, enhancing performance in devices with high CRA lenses.
Implementation Method 1
Interference-based filters, such as Fabry-Perot filters, when used in conjunction with spectral sensors have been shown to be capable of providing controlled light wavelengths
Data Source
AI summary
A sensor system has a plurality of optical sensors configured in an array on an integrated circuit and a lens system located proximal to a top surface of the array, where the intersection of the optical axis of the lens system with the plurality of optical sensors defines a reference point for light passing through the lens system. The sensor system includes a plurality of sets of optical filters overlaying the array between the lens system and the array, with each set of optical filters being associated with a set of optical sensors of the plurality of optical sensors and a set of optical filters of the plurality of sets of optical filters includes a plurality of optical filters where each set of optical filters has a center wavelength for light transmitted through the set of optical filters. In the sensor system each optical filter of the plurality of optical filters is configured to pass light in a different wavelength range, with at least some sets of optical filters configured to provide a center wavelength that is higher than a center wavelength of a set of optical filters at the reference point. An interface is provided for receiving output signal representative of received light from the optical sensors and to output signal from the plurality of optical sensors, with the output signal being representative of received light from the plurality of optical sensors and a spectral response is determined for each set of optical sensors associated with a set of optical filters.