Full-Stokes Polarization Camera With Dispersive Retarder
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Solution Overview
Problem
Existing polarization cameras struggle to measure the complete Stokes vector, particularly the S3 parameter, due to complex and costly setups involving multiple cameras or micro-retarder arrays, which are difficult to fabricate and align, limiting their application in remote sensing and biomedical imaging.
Innovation Solution
A full-Stokes polarization camera system integrating a homogeneous dispersive retarder with a polarization sensor, utilizing a single camera to measure all components of the Stokes vector by leveraging wavelength-dependent retardation, avoiding the need for multiple cameras or micro-retarder arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple cameras or micro-retarder arrays are used to measure the complete Stokes vector, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple polarization measurement functions into a single camera system by integrating a polarizer array with multiple orientations directly onto the camera sensor. This merging approach eliminates the need for multiple separate cameras or complex micro-retarder arrays, achieving complete Stokes vector measurement (including S3) while reducing overall system complexity.
Solution Approach 2:
The polarizer array integrated on the camera sensor performs multiple functions simultaneously: it measures linear polarization components (S1, S2) and, when combined with circular polarizers, measures circular polarization components (S3). This multi-functional design allows a single device to capture the complete Stokes vector without requiring separate measurement systems.
2Measurement precision
If micro-retarder arrays are fabricated and integrated, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The polarizer array is pre-integrated onto the camera sensor during the sensor manufacturing process itself, rather than being added as a separate component requiring post-fabrication alignment. This preliminary integration ensures precise alignment between the polarizer orientations and the underlying photodiode pixels, eliminating the complex alignment procedures that would otherwise be required.
3Measurement precision
If multiple polarization cameras are used with beam splitters, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple polarization cameras into a single camera by integrating a polarizer array with at least four different orientations directly on the sensor. This allows all necessary polarization measurements for complete Stokes vector determination to be captured simultaneously by one device, eliminating the need for multiple cameras and beam splitter arrangements.
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
Enables simultaneous measurement of the full Stokes vector, enhancing polarization imaging capabilities for applications like remote sensing and biomedical imaging by providing comprehensive polarization information without the fabrication and alignment challenges of existing methods.
Implementation Method 1
A retarder, in the context of the present invention, refers to a component that introduces a controlled delay or phase shift to linearly polarized light passing through it. This delay varies with the wavelength of light, making it dispersive.
Implementation Method 2
taking advantage of the wavelength sensitivity that is inherent to the photodiodes of camera sensors
Data Source
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Figure 3~4
AI summary
The present invention discloses a polarization camera system that integrates a commercially available polarization sensor with a homogeneous dispersive retarder to detect and measure simultaneously the four components of the Stokes vector of polarized light. Unlike existing methods that require complex setups or expensive components, this approach uses a single sensor setup, combining the division of focal plane method with wavelength sensitivity inherent in many camera sensors. The system (1) comprises: a polarization sensor (2) having a polarizer array (2a) and a color channel filter (2b); a photodiode array (2c) configured to measure at least four intensities; a light entrance (4); a microprocessor (5); a first homogeneous dispersive retarder (3). The first homogeneous dispersive retarder is configured to introduce wavelength-dependent retardation δ(λ) to the incident polarized light, so that [δ(λi) ≠ δ(λj)]; and, the microprocessor is configured to calculate a complete Stokes vector of incident polarized light from the measured intensities.