Variable Phase Plate Polarization Imaging
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Solution Overview
Problem
Existing image pickup systems require complex mechanisms or user intervention to acquire polarization information, often resulting in reduced resolution or increased costs due to the need for multiple polarization plates and complicated control systems.
Innovation Solution
An optical apparatus comprising a λ/4 plate, a variable phase plate, and a polarizer, where the variable phase plate's phase difference is controlled to capture images with different polarization states without rotating the polarization plate, allowing for high-quality image acquisition with embedded polarization information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a wire grid polarization plate is used to acquire polarization information from a single image, then the need for rotating the polarization plate is eliminated, but resolution or color information is lost due to pixel allocation for polarization measurement
Solution Approach 1:
The image pickup element is divided into multiple regions (first region and second region) with different polarization filter configurations. The first region has polarization filters oriented in specific directions while the second region has different orientations, allowing simultaneous capture of polarization information in different directions without rotating the plate, thereby preserving full spatial resolution and color information across the entire image
Solution Approach 2:
Instead of rotating the polarization plate in the temporal dimension (acquiring images at different times with different orientations), the invention transitions to a spatial dimension solution by arranging polarization filters in different regions of the image sensor simultaneously. This allows all polarization information to be captured in a single image without temporal or spatial loss
2Adaptability or versatility
If two liquid crystal wavelength plates are used to change the fast axis without rotating the polarization plate, then multiple polarization images can be acquired, but the control becomes complicated and cost increases
Solution Approach 1:
The invention extracts and eliminates the complex liquid crystal wavelength plates and their control mechanisms from the system. Instead, it uses a simplified configuration with a polarization plate and a phase difference plate that can be passively controlled, removing the need for active liquid crystal control while still achieving multiple polarization image acquisition
Solution Approach 2:
The invention replaces expensive, complex liquid crystal wavelength plates with simpler, more cost-effective optical elements (polarization plate and phase difference plate) that achieve the same functional result of acquiring multiple polarization states without requiring complex electronic control systems
3Loss of information
If multiple pixels are allocated to acquire polarization information, then polarization information can be obtained from a single image, but resolution or color information is lost
Solution Approach 1:
The image sensor is segmented into different regions with different polarization filter orientations. Each region captures polarization information in its specific orientation, but all regions together provide complete spatial coverage. This segmentation allows polarization information to be preserved without sacrificing overall image resolution or color information, as each pixel contributes to both spatial and polarization data
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 the acquisition of polarization information with a simple configuration, maintaining high image quality and reducing the complexity and cost associated with multiple polarization plates, while allowing for the emphasis of object features and suppression of unwanted light components.
Implementation Method 1
a first phase plate configured to give a fixed relative phase difference by π/2 between a polarization component in a slow axis direction and a polarization component in a fast axis direction
Implementation Method 2
a second phase plate configured to give a relative phase difference between a polarization component in a slow axis direction and a polarization component in a fast axis direction
Implementation Method 3
a polarizer configured to extract a polarization component to be guided to the image pickup element
Data Source
AI summary
An optical apparatus includes a first phase plate which gives a fixed relative phase difference by π/2 between a polarization component in a slow axis direction and a polarization component in a fast axis direction, a second phase plate which gives a relative phase difference between a polarization component in a slow axis direction and a polarization component in a fast axis direction, a polarizer which extracts a polarization component to be guided to the image pickup element, and a setter which sets the relative phase difference of the second phase plate, the slow axis direction of the second phase plate is inclined with respect to each of the slow and fast axes directions of the first phase plate, and the setter sets the relative phase difference of the second phase plate depending on the polarization component of light.