Single-Chip Spectral Polarization Sensor for Co-Registered Imaging
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Solution Overview
Problem
Current pixelated digital image sensors face limitations in capturing both spectral and polarization properties of light efficiently, leading to low frame rates, bulk optics requirements, and reduced amplitude per sensor, while also struggling with misalignment and reduced resolution in polarization imaging applications.
Innovation Solution
A single chip digital image sensor with an array of superpixels, each comprising spectral and polarization pixels, utilizing vertically stacked photodiodes and filters configured to capture distinct spectral and polarization features, enabling simultaneous and co-registered recording of spectral and polarization properties with high spatial resolution and real-time capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple linear polarization filters offset by 60° are used to capture Stokes parameters, then polarization measurement accuracy is improved, but device complexity and frame rate deteriorate
Solution Approach 1:
The patent transitions from planar polarization filtering to volumetric measurement by detecting the orientation of linearly polarized light in three-dimensional space. The sensor measures the orientation angle of polarization vectors across multiple depth layers, enabling Stokes parameter calculation without requiring multiple physical filters at different angular orientations.
Solution Approach 2:
The invention replaces static multiple-filter architectures with a dynamic single-filter approach that sequentially measures polarization orientation at different spatial locations and depth layers within the sensor. This dynamic measurement strategy captures complete polarization information over time using a single physical filter configuration.
2Adaptability or versatility
If multiple sensors with different polarizers are used to capture polarization information, then polarization imaging capability is improved, but device complexity and alignment difficulty worsen
Solution Approach 1:
The patent merges multiple polarization measurement functions into a single image sensor by integrating polarization-sensitive elements directly into the sensor architecture. This consolidation eliminates the need for separate sensors with different polarizers, reducing system complexity while maintaining full polarization imaging capability.
Solution Approach 2:
The single image sensor is designed to perform multiple functions: capturing intensity, polarization orientation, and depth information simultaneously. The sensor can calculate all Stokes parameters using a single device that operates across multiple wavelength bands and spatial layers, providing universal polarization imaging capability.
3Measurement precision
If division-of-time polarimetry with rotating filters is used, then polarization measurement is achieved, but frame rate and temporal resolution deteriorate
Solution Approach 1:
The patent enables continuous polarization measurement by capturing polarization orientation information at every spatial location and depth layer within a single exposure time. The sensor continuously records Stokes parameters across the entire field of view simultaneously, eliminating the intermittent measurements inherent in rotating filter systems.
Solution Approach 2:
The sensor performs preliminary polarization orientation measurement at multiple depth layers and spatial positions during the exposure period, preparing all necessary data for complete Stokes parameter calculation within a single frame. This preliminary capture of polarization information at all required dimensions enables immediate computation without sequential filtering.
4Measurement precision
If static optics with multiple sensors are used for polarization imaging, then complete Stokes parameter measurement is achieved, but system bulk and expense increase
Solution Approach 1:
The patent combines multiple sensor functions into a single integrated device that measures all Stokes parameters simultaneously. By merging polarization sensitivity, spectral detection, and depth resolution into one sensor module, the system eliminates bulky optical trains and multiple separate sensors, achieving compact Stokes parameter measurement.
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 enables high-resolution, real-time capture of spectral and polarization properties, improving visibility in hazy conditions and underwater imaging, and facilitating applications in medical imaging, remote sensing, and defense, with enhanced temporal resolution and reduced noise performance.
Implementation Method 1
Each spectral pixel includes a first stack of at least two photodiodes... Each photodiode of the at least two photodiodes is configured to have a quantum efficiency at a wavelength different from the quantum efficiency at the wavelength of each other photodiode
Implementation Method 2
Each spectral pixel also includes a spectral filter configured to pass at least two transmission peaks to its respective first stack of at least two photodiodes
Implementation Method 3
Each polarization pixel also includes a polarization filter configured to pass a polarization of light to its respective second stack of at least two photodiodes different from the polarization passed by each other polarization filter in the superpixel
Data Source
AI summary
An image sensor capable of recording both spectral and polarization properties of light using a single chip device includes an at least 2048 by 2048 array of superpixels. Each superpixel includes an array of spectral pixels, and an adjacent array of polarization pixels. Each spectral pixel includes a spectral filter and a stack of photodiodes, where each photodiode has a different quantum efficiency and is, therefore, sensitive to a different wavelength of light passed by the spectral filter. Each polarization pixel includes a polarization filter and a stack of photodiodes, similar to the spectral pixel photodiode stacks.