Hyperspectral Sensor Pixels Using Diffractive Focusing and Partial Filters
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Solution Overview
Problem
Conventional image sensors suffer from low sensitivity, signal-to-noise ratio, color crosstalk, and reduced spatial resolution due to the use of absorptive color filters, and non-focusing diffractive gratings result in light loss and require complex adjustments for high chief ray angles.
Innovation Solution
An image sensor with a plurality of wavelength sensing pixels, each comprising photosensitive sub-pixels and diffraction features formed from a transparent material with a higher refractive index than the substrate, along with wavelength selective filters, allows for accurate determination of incident light wavelength by analyzing the relative signal ratios of sub-pixels using a system of linear equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absorptive color filters are used in conventional color image sensors, then color information can be obtained, but sensitivity and signal to noise ratio decrease significantly at low light conditions
Solution Approach 1:
The patent removes absorptive color filters from the optical path and extracts only the necessary wavelength selection function, implementing it instead through computational methods that analyze the full spectrum light detected by each pixel. This eliminates the light absorption loss while preserving color information capability.
Solution Approach 2:
The patent replaces the mechanical/optical filtering system (absorptive color filters) with a computational system that processes the full spectral information captured by each pixel. The wavelength determination is achieved through algorithms that analyze the intensity distribution across different wavelengths rather than physically filtering light before detection.
2Measurement precision
If absorptive color filters are used, then color information can be obtained, but color crosstalk and color shading occur at high chief ray angles
Solution Approach 1:
The patent removes absorptive color filters that cause color crosstalk and shading effects at high angles, replacing them with a computational approach that determines wavelength from the full spectral distribution captured by each pixel, eliminating the source of these optical defects.
Solution Approach 2:
The patent substitutes the optical filtering mechanism with computational wavelength determination. By analyzing the complete spectral information available at each pixel without physical filters, the system eliminates color crosstalk and shading artifacts that inherently occur with absorptive filter-based systems at high chief ray angles.
3Measurement precision
If absorptive color filters are used, then color detection is enabled, but spatial resolution decreases due to color filter patterning
Solution Approach 1:
The patent removes the spatial patterning of absorptive color filters and extracts color information instead through computational analysis of the full spectrum light detected by each uniformly structured pixel, preserving the full spatial resolution capability of the sensor array.
Solution Approach 2:
The patent replaces the spatially patterned filter architecture with a computational wavelength determination system. Each pixel maintains its full spatial resolution contribution while color information is derived algorithmically from the spectral distribution of light detected at each pixel location, eliminating the spatial resolution penalty of filter patterning.
4Measurement precision
If non-focusing diffractive gratings are used, then wavelength characteristics can be determined, but light loss occurs before light reaches the substrate
Solution Approach 1:
The patent removes non-focusing diffractive gratings that cause light loss and extracts wavelength information instead through computational analysis of the intensity distribution across pixels, eliminating the source of light loss while preserving spectral detection capability.
Solution Approach 2:
The patent substitutes the diffractive grating optical system with a computational wavelength determination approach. By analyzing the spatial distribution of light intensity across the pixel array without physical diffraction elements, the system determines wavelength characteristics while avoiding the light loss inherent in grating-based systems.
5Measurement precision
If non-focusing diffractive gratings are used, then wavelength characteristics can be determined, but complex adjustments are required to accommodate high chief ray angles
Solution Approach 1:
The patent removes non-focusing diffractive gratings and the associated complex adjustment mechanisms for high chief ray angles, replacing wavelength determination with computational analysis that processes light intensity distribution across pixels without requiring optical element repositioning.
Solution Approach 2:
The patent replaces the mechanically complex diffractive grating system with computational wavelength determination. The system analyzes the spatial intensity distribution of light across the pixel array through algorithms, eliminating the need for microlens and grating position adjustments that are required in grating-based systems to accommodate varying chief ray angles.
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 high color and wavelength resolution with improved sensitivity, accurately determining light wavelengths even in noisy conditions without the need for micro lenses or color filters, enhancing spatial resolution and reducing noise interference.
Implementation Method 1
utilize uniform, non-focusing metal gratings, to diffract light in a wavelength dependent manner
Implementation Method 2
The diffraction elements can be formed from a transparent material having an index of refraction that is higher than an index of refraction of the material layer or substrate in which they are embedded
Implementation Method 3
Each pixel can include a photodiode that generates charge in an amount that is generally proportional to the amount of light (i.e. the number of photons) incident on the pixel
Data Source
AI summary
Color image sensors and systems are provided. A sensor as disclosed includes a plurality of color sensing pixels disposed within an array, each of which includes a plurality of sub-pixels. Each color sensing pixel within the image sensor is associated with a set of diffraction features and a plurality of wavelength selective filters that only partially overlay an area of the pixel. The diffraction features can be formed from materials having an index of refraction that is higher than an index of refraction of the surrounding material. Color information regarding light incident on a pixel can be determined by applying ratios of signals obtained by pairs of included sub-pixels and calibrated ratios for different colors to a set of equations.