Stacked Image Sensor with Interlayer Polarizer for Polarization Sensitivity
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Solution Overview
Problem
Conventional image sensors are insensitive to light polarization, leading to a 50% reduction in detected light for unpolarized incident light due to the use of polarizers, which either absorb or reflect one polarization state, resulting in reduced sensitivity and signal-to-noise ratio.
Innovation Solution
A stacked configuration of two image sensors with a polarizing layer in between, where the upper sensor is partially transmissive to incident light, allowing detection of both pass and block state polarized light, enabling the determination of polarization ratios and improving signal-to-noise ratio by retaining both polarization states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an absorptive or reflective polarizer is placed in the path of incident light to achieve polarization sensitivity, then polarization sensitivity is improved, but light intensity is reduced by approximately 50% for unpolarized incident light
Solution Approach 1:
The sensor is divided into two separate sensor layers: a first sensor that detects light in a first spectral range and a second sensor that detects light in a second spectral range. Each sensor can be independently optimized for its respective spectral range, allowing both sensors to contribute useful signal information without one blocking the other's optimal detection band.
Solution Approach 2:
The patent introduces a spectral dimension by using two sensors with different spectral sensitivity ranges. Instead of using a single sensor with a polarizer that blocks 50% of light, the system uses the spectral dimension to separate detection channels, allowing both polarization states to be detected across different spectral ranges simultaneously.
2Measurement precision
If a polarizer blocks one polarization state to achieve polarization sensitivity, then polarization state discrimination is improved, but signal-to-noise ratio deteriorates due to discarding half the incident light
Solution Approach 1:
The detection system is segmented into two independent sensor layers, each optimized for different spectral ranges. This segmentation allows both polarization states to be detected simultaneously by assigning them to different spectral detection channels, preserving signal information that would otherwise be discarded by a traditional polarizer.
Solution Approach 2:
The patent changes the detection parameter from spatial blocking (using a polarizer to physically block one polarization state) to spectral separation (detecting different polarization states in different spectral ranges). This parameter change allows full utilization of incident light across the spectrum while maintaining polarization sensitivity.
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 allows for improved polarization sensitivity and signal-to-noise ratio by detecting both pass and block state polarized light without discarding one polarization state, enhancing imaging and spectroscopic applications.
Implementation Method 1
A portion of light having a first polarization state incident on the device along a first direction is transmitted through the first image sensor
Implementation Method 2
is transmitted through the polarizing layer
Implementation Method 3
light having a second polarization state orthogonal to the first polarization state incident on the device along the first direction is transmitted through the first image sensor, is blocked by the polarizing layer
Implementation Method 4
is detected by the second image sensor
Implementation Method 5
If the polarizer is a reflective polarizer, most of the blocked polarization state is reflected back to the upper sensor
Data Source
AI summary
A device includes a first multi-element image sensor; a second multi-element image sensor; and a polarizing layer positioned between the first and second multi-element image sensors. A portion of light having a first polarization state incident on the device along a first direction is transmitted through the first image sensor, is transmitted through the polarizing layer, and is detected by the second image sensor, and light having a second polarization state orthogonal to the first polarization state incident on the device along the first direction is transmitted through the first image sensor, is blocked by the polarizing layer.