Polarimetric Image Sensor With In-Pixel Diffraction and Polarization
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Solution Overview
Problem
Existing polarimetric image sensors face limitations in measuring light polarization efficiently due to bulky acquisition systems and reduced sensitivity caused by polarizer filters, especially when scenes change over time.
Innovation Solution
A polarimetric image sensor is designed with a semiconductor substrate, featuring pixels with diffraction and polarization structures that promote absorption of specific polarizations, using metallic parallel bars and trenches to enhance sensitivity and quantum efficiency, allowing for simultaneous measurement of different polarizations without the need for external polarizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If polarizing filters are placed in front of the sensor to measure polarization information, then polarization measurement capability is improved, but the sensitivity and quantum efficiency of the sensor deteriorate because the filters block part of the light signal
Solution Approach 1:
The patent combines the polarization filtering function and the light detection function into a single integrated pixel structure. The polarization structure (metallic parallel bars) and photosensitive region are formed within the same semiconductor substrate, eliminating the need for separate external polarizing filters that block light. This merging allows the sensor to maintain high sensitivity while achieving polarization measurement capability.
Solution Approach 2:
The patent replaces the traditional mechanical/optical system of external polarizing filters with an integrated semiconductor-based polarization structure. Instead of using separate polarizing filter elements that physically block light, the invention uses sub-wavelength metallic structures formed within the sensor itself to achieve polarization selectivity through electromagnetic interaction, thereby maintaining light transmission and sensor sensitivity.
2Productivity
If a matrix of polarizing filters is placed opposite the image sensor to overcome limitations of sequential acquisition, then simultaneous polarization measurement is improved, but the overall sensitivity of the acquisition system deteriorates due to light blocking
Solution Approach 1:
The patent integrates multiple polarization measurement capabilities directly into the sensor matrix, with each pixel containing polarization structures oriented in different directions. This allows simultaneous measurement of multiple polarization states without requiring external filter matrices that would block light, thereby maintaining high system sensitivity while achieving productive simultaneous measurement.
Solution Approach 2:
The patent transitions from using external two-dimensional filter matrices to integrating polarization functionality within the three-dimensional pixel structure itself. By forming polarization structures (metallic parallel bars) within the semiconductor substrate at the pixel level, the invention achieves simultaneous polarization measurement while preserving light transmission through the sensor.
3Measurement precision
If sequential acquisition with rotating polarizers is used to measure polarization information, then polarization states can be recorded, but the system becomes bulky and cannot capture real-time changes in the scene
Solution Approach 1:
The patent extracts the polarization measurement functionality from external rotating mechanisms and sequential acquisition systems, integrating it directly into the sensor pixels. By removing the need for external polarizers and rotating stages, the invention eliminates system bulkiness while maintaining the capability to record polarization states through in-pixel polarization structures.
Solution Approach 2:
The patent enables the sensor to perform polarization measurement independently without requiring external polarizing equipment or sequential mechanical operations. Each pixel contains self-contained polarization structures that directly interact with incident light, allowing the sensor to autonomously measure polarization states in real-time without bulky external systems.
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
This design improves the sensitivity and quantum efficiency of the sensor, enabling effective measurement of light polarization without the bulkiness and sensitivity losses of traditional systems, while allowing for real-time changes in the scene.
Implementation Method 1
a diffraction structure formed on the side of an illumination face of the photosensitive region; the diffraction structure of the first pixel is adapted to promote the absorption, in the photosensitive region of the pixel, of radiation according to the first polarization relative to radiation according to the second polarization
Implementation Method 2
a polarization structure formed on the side of the diffraction structure opposite the photosensitive region; the polarization structure of the first pixel is adapted to transmit mainly radiation according to the first polarization and the polarization structure of the second pixel is adapted to transmit mainly radiation according to the second polarization
Data Source
Figure 1~3
Figure 4A~4D
Figure 4E~4G
AI summary
The present description relates to a polarimetric image sensor (100) formed in and on a semiconductor substrate (101), the sensor comprising a plurality of pixels (P) each comprising: - a photosensitive region (103) formed in the semiconductor substrate (101); - a diffraction structure (119) formed on the side of an illumination face of the photosensitive region (103); and - a polarization structure (111) formed on the side of the diffraction structure (119) opposite the photosensitive region (103).