Imager Using Scanning Mirror and Stitching for Wide Field of View
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Solution Overview
Problem
Current wide field of view (WFOV) multispectral imaging solutions are expensive, large, heavy, and consume high power, making them unsuitable for extensive deployment in portable applications, particularly for large format infrared (IR) and short wave infrared (SWIR) imagers.
Innovation Solution
The use of small format array image detectors and a small scanning mirror, combined with 'smart scanning' techniques such as variable dwell times and signal processing algorithms, allows for the construction of a larger effective field of view by stitching sub-images, enabling enhanced sensitivity and reduced size, weight, and power consumption without significant performance loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If large format infrared (IR) and short wave infrared (SWIR) imagers are used to achieve wide field of view multispectral imaging, then imaging performance and field of view are improved, but cost, size, weight, and power consumption increase significantly
Solution Approach 1:
The patent divides the imaging task into multiple sub-images captured by a small format detector, which are then stitched together to form a composite wide field of view image. This segmentation approach allows using a small detector to achieve the effect of a large detector, reducing weight while maintaining wide FOV capability.
Solution Approach 2:
The patent introduces a scanning mirror as an intermediary component that directs light from different field of view regions to the small format detector at different times. This mediator enables a small detector to capture information that would otherwise require a large detector, achieving wide FOV with reduced weight.
2Area of stationary object
If large format infrared (IR) and short wave infrared (SWIR) imagers are used to achieve wide field of view multispectral imaging, then imaging performance and field of view are improved, but cost, size, weight, and power consumption increase significantly
Solution Approach 1:
The patent segments the wide field of view into multiple smaller regions captured sequentially by a small format detector. This allows using a low-power small detector instead of a high-power large detector, achieving the same effective FOV with significantly reduced power consumption.
Solution Approach 2:
The patent employs periodic scanning motion of the mirror to sequentially capture different regions of the field of view. This periodic action allows a small detector to gather information from the entire wide FOV over time, reducing the power requirements compared to a static large format imager.
3Weight of stationary object
If a small format array image detector is used instead of a large format detector, then size, weight, and power consumption are reduced, but field of view and imaging performance deteriorate
Solution Approach 1:
The patent divides the wide field of view into multiple sub-fields, each captured by the small format detector during different scanning positions. The sub-images are then stitched together to reconstruct the complete wide FOV image, allowing a small detector to achieve large FOV coverage.
Solution Approach 2:
The scanning mirror acts as an intermediary that expands the effective field of view of the small detector by redirecting light from different angular regions to the detector surface at different times, enabling the small detector to capture a wide FOV through temporal multiplexing.
4Measurement precision
If uniform sampling is applied across the entire field of view, then complete scene coverage is achieved, but sensitivity in critical areas is insufficient
Solution Approach 1:
The patent applies different sampling strategies to different regions of the field of view based on their importance. Areas of interest receive enhanced sampling with longer dwell times and possible re-scanning, while less critical areas use standard sampling, optimizing both sensitivity and scanning efficiency.
Solution Approach 2:
The patent implements dynamic scanning control where the mirror dwell time and scanning speed are adjusted in real-time based on the detected importance of different regions. This dynamic adaptation allows concentrating resources on critical areas while maintaining acceptable coverage of other regions.
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 approach results in a more compact, cost-effective, and power-efficient imaging system that maintains performance by selectively sampling and oversampling areas of interest, improving sensitivity and reducing artifacts, while allowing for real-time adjustment based on operator input or image content.
Implementation Method 1
a visible light and/or SWIR/IR micro-electro-mechanical system (MEMS) reflective scanner
Implementation Method 2
two-dimensional (2D), ±20° effective field of view (FOV), scanner may be made with a small image detector
Data Source
AI summary
Selected embodiments use a relatively small image detector and a scanning mirror to obtain effective performance of a larger image detector. An imager with folded optics captures images of different field positions of a field of view (FOV), and stitches the images together for a larger image of the FOV. The stitched image is processed to identify portions of interest within the larger image, for example, using a cuing algorithm. The portions of interest are scanned again to capture enhanced quality images using, for example, longer dwell time for enhanced contrast. Another image of the FOV or a part of the FOV is stitched together using the enhanced quality images.