Multispectral Filter Layout for Diffraction-Aware Sensor Sampling
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Solution Overview
Problem
Existing multispectral filters do not adequately consider the sensor's sampling capabilities in relation to the diffraction of the optical system, leading to reduced accuracy and fidelity in image reconstruction due to inconsistent image quality across different colors.
Innovation Solution
A multispectral filter with a filtering matrix is designed, where the positions of elementary cells sensitive to central wavelengths are determined to minimize the distance between them and their associated wavelengths, ensuring a constant product of integers and wavelengths, thus accounting for the sensor's spatial sampling frequency and optical cutoff frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a multispectral filter with a basic pattern (e.g., 3x3) is used to detect a larger number of spectral bands, then the number of detectable wavelengths increases, but image quality becomes inconsistent across colors due to sampling issues related to optical diffraction
Solution Approach 1:
The patent changes the spatial sampling parameters by positioning photosites according to the formula position = (e_k * λ_k) / C, where e_k is an integer, λ_k is the central wavelength, and C is a constant. This parameter-based positioning ensures that the sampling frequency adapts to each wavelength's diffraction characteristics, resolving the inconsistency in image quality across different spectral bands while maintaining a manageable number of photosites.
2Device complexity
If each photosite detects only one color, then the filter structure is simple, but the optronic chain must interpolate the remaining colors, reducing accuracy and fidelity
Solution Approach 1:
The patent performs preliminary action by strategically positioning photosites to capture specific wavelengths at optimal locations before the demosaicing process. By pre-positioning photosites according to wavelength-specific diffraction patterns, the system reduces the interpolation burden and improves reconstruction accuracy, as the sampling is already optimized for each wavelength's optical characteristics.
3Ease of manufacture
If the filter does not take into account the sensor's sampling capabilities in relation to diffraction, then the filter design is straightforward, but the accuracy and fidelity of the optronic chain are reduced
Solution Approach 1:
The patent introduces wavelength-dependent positioning parameters (e_k integers) that adjust the spatial location of photosites based on each wavelength's diffraction characteristics. This parameter change transforms the filter design from a simple geometric pattern to an optimized spatial arrangement that accounts for optical physics, thereby improving accuracy without significantly complicating the manufacturing process.
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 filter matrix enhances image accuracy and reduces post-interpolation errors by standardizing the transfer function of the image sensor, resulting in a more reliable and precise image reconstruction process.
Implementation Method 1
this response is itself linked by diffraction phenomena to the wavelength and aperture number
Implementation Method 2
takes into account the sensor's sampling capabilities in relation to the diffraction of the optical system at the photosites
Data Source
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AI summary
The present invention relates to a multi-spectral filter employing a filtering matrix array (200), said filter being for a sensor comprising a matrix array of elementary sensors, said filtering matrix array comprising an elementary pattern formed from an arrangement of N elementary cells able to filter central wavelengths λ1, λk,..., λN, the position of the central wavelengths in the elementary pattern being determined so that: each wavelength being associated with an integer e1, ek,..., eN, chosen so that each of the products e1xλ1,..., ekXλk,..., eNX λN is substantially constant, each central wavelength λk is positioned in ek positions in the elementary pattern so that the maximum ratio between the distance between two proximal positions of said central wavelength and the associated central wavelength is minimal.