Tunable Spectro-Polarimeter for Underwater Target Detection
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Solution Overview
Problem
Conventional methods for detecting underwater objects from remote distances suffer from low confidence-of-detection, high false alarm rates, and low area coverage, particularly due to the limitations of unmanned underwater vehicles, aerial vehicles, and surface-deployed sensors.
Innovation Solution
A tunable multi-band spectro-polarimetric imaging system that employs a combination of spectral and polarimetric imaging techniques, using tunable spectral filters and polarization filters to differentiate between electromagnetic radiation penetrating and not penetrating beneath the water surface, allowing for high-confidence detections by subtracting clutter from target data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional remote sensors are deployed on buoys or static structures to detect underwater objects, then the detection area coverage is limited, but the system complexity and deployment cost increase
Solution Approach 1:
The patent replaces complex mechanical deployment systems (buoys, static structures, underwater vehicles) with a simplified aerial platform carrying optical sensors. The detection system uses electromagnetic radiation in the 3-5 micrometer wavelength range to penetrate water surfaces, eliminating the need for complex mechanical systems while achieving wide area coverage from aerial platforms.
Solution Approach 2:
The patent changes the operational parameters by selecting specific electromagnetic radiation wavelengths (3-5 micrometers) that optimize water penetration characteristics. This parameter selection allows detection from aerial platforms at altitudes of 100-10,000 feet, dramatically expanding detection area coverage without increasing system complexity.
2Area of stationary object
If aerial vehicles are used to comb waters for near-surface objects, then area coverage improves, but detection confidence decreases due to surface clutter
Solution Approach 1:
The patent applies local quality by selecting specific wavelength bands (3-5 micrometers) that have different penetration characteristics through the water surface. This allows the system to selectively detect signals from underwater targets while filtering out surface clutter, thereby maintaining high detection confidence across wide areas.
Solution Approach 2:
The patent introduces electromagnetic radiation in the 3-5 micrometer range as an intermediary that selectively interacts with underwater targets while being blocked by or distinguishable from surface clutter. This intermediary enables reliable detection by creating a clear signal differentiation between targets and background interference.
3Measurement precision
If multiple spectral bands are used to improve target differentiation, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent segments the electromagnetic spectrum into specific wavelength ranges (3-5 micrometers) and assigns different detection functions to different spectral bands. This segmentation enables sophisticated target differentiation while maintaining relatively simple device architecture by focusing on specific wavelength ranges rather than attempting to analyze the entire spectrum.
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 system achieves wide-area, high-confidence detection of underwater objects with low false alarms, capable of distinguishing submerged targets from clutter across various environmental conditions, enhancing detection performance and accuracy.
Implementation Method 1
certain embodiments employ a combination of tunable spectral and polarimetric imaging techniques to provide wide area, high confidence detections over a variety of different environmental conditions
Implementation Method 2
a plurality of polarization filters positioned in the optical path between the optical sub-system and the imaging detector, the plurality of polarization filters being configured to selectively alter a polarization state of the incident electromagnetic radiation
Data Source
AI summary
Methods and apparatus for remote, passive detection of underwater objects using combined spectral and polarimetric imaging. In one example, a tunable multi-band spectro-polarimeter includes an imaging detector array that receives electromagnetic radiation from a viewed scene, a plurality of tunable spectral filters configured to filter the electromagnetic radiation into at least first and second spectral bands, and a plurality of polarization filters configured to filter each of the first and second spectral bands into at least two different polarization states, a first region of the detector array receiving the first spectral band and producing first polarimetric image data, and a second region of the detector array simultaneously receiving the second spectral band and producing second polarimetric image data, and a controller that receives and processes the first and second polarimetric image data to detect a target object in the viewed scene.