Polarimetric Image Sensor Pixel Structure
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Solution Overview
Problem
Existing polarimetric image acquisition systems are bulky and have low sensitivity due to the need for multiple images to be taken with different polarizers, which can be impractical when scenes change over time, and polarizing filters block part of the light signal, reducing system sensitivity.
Innovation Solution
A polarimetric image sensor with pixels featuring a photosensitive region, a diffraction structure, and a polarization structure on a semiconductor substrate, where each pixel is adapted to measure specific polarizations, with metallic parallel bars and trenches to enhance absorption and transmission based on polarization, allowing for simultaneous measurement of multiple polarization states without the need for external polarizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If polarizing filters are placed in front of the image sensor to measure polarization information, then the measurement of light polarization is enabled, but the sensitivity and quantum efficiency of the acquisition system are reduced due to light blocking
Solution Approach 1:
The patent merges the polarizing filter function directly into the pixel structure by integrating polarization-sensitive photodetection elements within each pixel. This integration allows the sensor to measure polarization information without requiring external polarizing filters that would block light, thereby maintaining high quantum efficiency while enabling polarization measurement capability.
Solution Approach 2:
The patent replaces the mechanical/optical system of external polarizing filters with an integrated photodetection system that inherently senses polarization through the orientation of photodetection elements within the pixels. This substitution eliminates the need for light-blocking filters while preserving polarization measurement functionality.
2Measurement precision
If multiple images are successively acquired with different polarizers to measure polarization states, then complete polarization information is obtained, but the system becomes bulky and complex due to the need for rotating mechanisms
Solution Approach 1:
The patent combines multiple polarization measurement capabilities into a single image acquisition by integrating photodetection elements with different orientation sensitivities within the same pixel array. This allows simultaneous measurement of multiple polarization states in one shot, eliminating the need for sequential acquisitions and rotating polarizer mechanisms.
Solution Approach 2:
The patent segments each pixel into multiple photodetection elements with different orientation sensitivities (e.g., horizontal, vertical, diagonal orientations). This segmentation allows each pixel to independently measure multiple polarization components, enabling complete polarization information to be obtained from a single image without requiring external rotating polarizers.
3Measurement precision
If multiple images are successively acquired to record multiple polarization states, then polarization information is obtained, but the acquisition time increases which is problematic when scenes vary over time
Solution Approach 1:
The patent merges the measurement of multiple polarization states into a single simultaneous acquisition by using photodetection elements with different orientation sensitivities within the same pixel array. This allows complete polarization information to be captured in one image exposure, eliminating the time delay associated with sequential acquisitions and ensuring accuracy in dynamic scenes.
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 sensor improves sensitivity and reduces bulkiness by allowing simultaneous measurement of multiple polarization states, enhancing the quantum efficiency and contrast of the image acquisition system while maintaining practicality in dynamic scenes.
Implementation Method 1
a diffraction structure formed on the side of an illumination surface of the photosensitive region
Implementation Method 2
the diffraction structure of the first pixel is adapted to favoring the absorption, in the photosensitive region of the pixel, of radiations according to the first polarization with respect over radiations according to the second polarization
Implementation Method 3
the polarization structure of the first pixel is adapted to mainly transmitting radiations according to the first polarization and the polarization structure of the second pixel is adapted to mainly transmitting radiations according to the second polarization
Data Source
AI summary
The present description concerns a polarimetric image sensor formed inside and on top of a semiconductor substrate, the second comprising a plurality of pixels, each comprising: —a photosensitive region formed in the semiconductor substrate; —a diffraction structure formed on the side of an illumination surface of the photosensitive region; and —a polarization structure formed on the side of the diffraction structure opposite to the photosensitive region.