Metasurface Devices Based Polarimetry for Remote Underwater Imaging Technology
Abstract
A mission unique to the U.S. Navy is to facilitate the safe amphibious landing of U.S. Marines. The path to enemy shores is often mined, especially in the Surf Zone (SZ, 0~10 ft), where a minefield can be easily and cost effectively established using unsophisticated technology. Mine countermeasure (MCM) operations, including the accurate detection, classification, identification and clearing of sea mines, remain a dangerous, time consuming and costly process, especially in the Surf Zone. State-of-the-art optical sensor approaches still face challenges in the formation of SZ underwater images with sufficient quality for accurate object detection and discrimination due to the high water turbidity and waves. To overcome these challenges and enhance the Navy’s MCM mission effectiveness, this proposal seeks to investigate compact and miniaturized ‘4D’ polarimetry Lidar imaging enabled by novel metasurfaces as a multifunctional sensor approach that can be deployed on small airborne tactical platforms. This will be complemented with the investigation of novel image fusion techniques that leverage learning-based, high-dimensional, joint domain data. There is clear evidence of the benefits of polarimetry for underwater imaging. State-of-the-art research suggests that optical polarization detection is more sensitive than other conventional optical detection methods through scattering media. The polarization state of light can be quantified using parameters such as the total degree of polarization, of linear polarization, of circular polarization, and the angle of linear polarization. However, there is a critical technological gap in collecting meaningful polarimetry data, and/or carrying out surveillance where the effects of external environmental factors, such as wind, waves, and other fluctuations of the water surface change the geometry of the air-water interface. In addition, a complex biological ecosystem in SZ waters interferes with imaging and provides easy camouflage for hidden objects. Integrating the depth profiling and resolution characteristics of Lidar with the ability to quantitatively determine the polarization components of the return optical signal is especially advantageous when attempting to image the turbid SZ coastal waters. Combining with the proposed learning-based image fusion techniques will mitigate the optical distortions arising from air-water interfaces in the optical path. Deploying the proposed technology on an autonomous airborne drone platform would represent a true force multiplier that would keep sailors and assets out of harm’s way, while increasing areal search rates at a reduced financial and human cost. The proposed metasurface-based innovation approach to imaging polarimetry is able to yield the full polarization state of incident light on each pixel of a scene simultaneously. This can be done by utilizing a single metasurface instead of multiple stacks and/or rotating conventional optics components. This can thus greatly enhance current imaging capabilities without increasing complexity, volume or weight, but has not been fully explored yet.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 06, 2021
- Source ID
- N000142112268
Entities
People
- Seongsin Kim
Organizations
- Office of Naval Research
- United States Navy
- University of Alabama