Ports and harbors serve vital economic and interior defense functions. In the United States, more than 95% of the nation's overseas cargo moves through ports. About 5.8 billion tons of goods were traded internationally by sea in 2001, accounting for more than 80% of world trade by volume. Cruise ships calling at U.S. ports carry more than 6 million passengers per year.1 Ports thus serve as both entry points and high-value targets for terrorists.
To defend ports, the U.S. Department of Homeland Security (DHS) has established a layered approach, dividing the problem into four sectors: overseas, in transit, in U.S. waters, and on U.S. shores.2 The requirements for each sector are different, though all sectors present opportunities for photonic technology.
The overseas and in-transit sectors present significant challenges. Approximately 16 million cargo containers enter the United States annually. Security measures to detect penetration of containers must be compatible with rapid transit, especially for perishable and seasonal goods. An appropriate balance is needed between inspecting every container and keeping trade moving. Beyond the tamper-detection device requirement on container doors, it is important for an internal sensor to detect entry through container sidewalls. Sensors must register violations of doors and sidewalls in a way that is quickly and accurately readable by appropriate officials, such as customs and border patrol agents. A global-positioning capability could provide a real-time location history. The economic benefit of knowing where a container is in real time would add logistical value that could offset the additional sensor cost per container.
In-port container inspectors can use large-scale gamma- and x-ray imaging systems to safely and efficiently screen for contraband, including weapons of mass destruction. Fiberoptic probes provide an alternative for non-intrusive container inspection and offer excellent opportunities for image-processing software.
Preventing terrorists from entering sensitive areas of the transportation system is critical. The DHS Transportation and Security Administration provided more than $516 million in grants through June 2004. Funds assisted ports in analyzing vulnerabilities and closing gaps in security through physical enhancements like access control gates, fencing, lighting, and advanced communication and surveillance systems. The program also funds the implementation of security strategies that prevent and respond to terror threats. The DHS must also identify crewmembers. Optical and photonic technology can address this area by providing unique biometric identifiers.
Perimeter-penetration detection benefits from night-vision technologies, but it is important to differentiate between IR sensors and low-light visible cameras. Low-light cameras typically cost less, but they offer fewer capabilities than long-wavelength thermal imagers. Constant monitoring of extensive perimeters requires cost-effective, robust, and reliable imaging systems and networks, as well as sophisticated algorithms and software to provide automatic detection, warning, and tracking. Military Requirements
Naval port and harbor security faces additional tasks and requirements. Key sources of information for the Navy include: the Afloat Anti-Terrorism/Force Protection Program Office (PMS 480); the Ashore Anti-Terrorism/Force Protection Program Office (CNI); the Fleet Forces Command-N9; the Maritime Force Protection Command; the Navy Anti-Terrorism Technology Coordination Office (NATTCO); and the anti-terrorism and force-protection (AT/FP) documents associated with the Joint Capability Integration and Development System (JCIDS).
CNI and PMS 480 sponsor NATTCO, which collects information on candidate commercial off-the-shelf/ government off-the-shelf (COTS/GOTS), AT/FP-related technologies. It maps technologies to existing and approved mission-essential AT/FP tasks. In addition to assessing technologies and the potential for reduced manpower, NATTCO assists capability needs derivations and evaluates operational feasibility, technical/programmatic risks, and transition potential.
JCIDS analyses are key to understanding war fighter requirements and operational contexts. Several key analyses support JCIDS documents. The functional area analysis identifies the operational tasks, conditions, and standards needed to accomplish military objectives. It specifies tasks to be analyzed in the functional needs analysis, which assesses the ability of current and programmed capabilities to accomplish given tasks, and results in a list of capability gaps. The functional solutions analysis (FSA) is an operations-based assessment conducted across a broad range of available considerations, including doctrine, organization, training, material solutions (technologies), leadership, personnel, and facilities. The FSA includes an analysis of material approaches akin to a cursory analysis of alternatives that points decision makers to material solutions that best address identified capability gaps. The last analytical component is a post-independent analysis similar to an independent review of the method, rigor, and apparent recommendations resulting from the FSA. Once completed, these analyses form the underpinnings of the beginning JCIDS initial capabilities document (ICD).
The Navy has concerns with infiltration from land and must establish entry control points and perimeter security around naval bases. Combat swimmers, mini-submarines, and unmanned underwater vehicles (UUVs) are also concerns. Effective systems should provide detection, identification, and classification of these threats, with specific requirements addressed in ICDs. Photonic Answers
Although underwater surveillance and detection depends heavily on acoustics, there is a growing recognition that acoustics alone cannot provide a complete solution, especially in shallow water with complex bottom topography. Optical systems offer advantages in spatial resolution, compactness, speed of deployment, and human interpretation. Conse-quently, optical techniques developed for de-mining are now being adapted for port security. We foresee that both optical and acoustic components will eventually be integrated into "systems-of-systems" for maritime security.
The most cost-effective way to survey a large area is via aerial passive imaging. The largest impediment to airborne imaging the wavy sea surface, which creates distortions that can make underwater objects unrecognizable. In addition, surface reflections, especially those of sunlight and moonlight, are typically much brighter than the light reflected from subsurface objects. Wave-generated foam is highly reflective and scattering, to the point that foam is generally considered an impossible surface through which to image.
Multiframe image capture and processing can remove surface effects. Here, surface distortions and glints have been removed, clearly revealing bottom features including coral, sand, macro-algae, and reef damage caused by human activity.
Unaided human vision has difficulty dealing with surface effects, but multispectral digital imaging and high-speed multi-frame image processing can greatly reduce glints, distortions, and foam obscuration (see figure). Using information from many frames, we can remove obscuring surface effects to clearly reveal subsurface features like the sea floor.
Once sea-surface effects have been handled, other problems with the optical properties of water arise. Water "drinks" light - the total reflectance of deep water may be just 2% and the exponential attenuation of light in water will cause the contrast of subsurface objects to decrease with depth. These optical properties depend on wavelength in a predictable way, however. Jerlov developed a widely used classification scheme that allows estimation of marine optical properties over the entire visible spectrum using measurements at a few well- chosen wavelengths.3 With this information, it is possible to classify an object and determine its depth simultaneously.
The maximum depth at which passive detection can be achieved depends on the sensitivity and dynamic range of the optical system, the number of independent spectral bands it uses, and the quality of the spectral libraries available. The ultimate limit on depth penetration for passive imaging is scattering in the water. Even the clearest natural waters backscatter light, causing a fog-like foreground glow and reducing the target contrast. Scattering also blurs the outlines of distant objects; as the range increases, successively larger objects blur into the background. Emerging Alternatives
When airborne imaging is impractical, underwater optical surveillance and detection can be accomplished via remotely operated underwater vehicles and UUVs. Equipped with visible cameras that operate over well-chosen spectral bands, UUVs can help maintain underwater perimeters and identify submerged threats. UUVs with optical capability can inspect hulls for explosives or other threats, relieving marine mammals and humans of dangerous tasks. A human diver, for example, can easily become disoriented while investigating the acres of steel on the underside of an aircraft carrier.
For cases that permit cooling, volume, and power, active (lidar) imaging systems can reduce foreground haze, greatly improving target contrast and resolution. Fournier reported that gating increases range by three to five times more than ungated imagers. Range-gated systems transmit a short laser pulse, and after time delay Δt, open the shutter. Light arriving before the shutter opens is blocked, so that only light returning from a desired distance is detected.
Port and harbor security is a daunting task for which optics and photonics offer significant solutions. In addition to imaging techniques, there are methods like total internal reflection fluorescence that can be used to "sniff" for traces of explosives or contaminants in marine environments. We encourage colleagues to join our technical group and help us make our ports and harbors more secure. oe
- Optics & Photonics In Global Homeland Security 2003, CDS-110, ISBN 0-8194-5183-5, Bellingham, WA (2004).
- "Secure Seas, Open Port, Keeping our Water Safe, Secure and Open for Business," Department of Homeland Security, Washington, D.C., June 21, 2004. www.dhs.gov/interweb/assetlibrary/DHSPortSecurityFactSheet-062104.pdf
- N. Jerlov, Marine Optics, Elsevier Scientific Publishing Co., Amsterdam, Netherlands (1976).
This work was performed, in part, under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
The events of 9/11 were a sobering wake-up call to the threat posed by terrorism. Beyond the tragedy of lost lives, the day's economic and social impact on our world has been immense. Responding to this impact and recognizing the potential of photonic technology to counter terrorism, SPIE formed the Global Homeland Security Technical Group (GHSTG). The mission of the GHSTG is to stimulate and focus the contributions of the optics and photonics community to enhance safety, improve the population's sense of well-being, and counter terrorist threats. In addition to our efforts to connect small businesses and stimulate standards, we have two other major initiatives: the Drinking-Water Safety Initiative, chaired by Dan Kroll, Hach Co. (Loveland, CO); and the Port and Harbor Security Initiative, chaired by Michael DeWeert, BAE Systems Spectral Solutions (Honolulu, HI).
The Port and Harbor Security Initiative is dedicated to promoting the development of photonic technologies and applications for use in deterrence, prevention, and detection of terrorist actions against ports and harbors. The initiative addresses container and shipping security; marine-vehicle and swimmer detection and interdiction; underwater chemical, biological, radiological, nuclear, and explosive threat detection; and security against piracy, hijacking, and landward threats. In addition, the initiative includes sensor integration into manned and unmanned platforms; sensor networking and fusion activities; requirements and standards for homeland security; and integration with air defense, law enforcement, and first responders.
-T.S., H.G., and M.D.
For more information about SPIE's Global Homeland Security Technical Group and its upcoming meetings, go to http://spie.org/x1720.xml.
Ted Saito is senior staff engineer at Lawrence Livermore National Laboratory, Livermore, CA.
Harry Guthmuller is coastal and maritime security branch head at the Naval Surface Warfare Center, Panama City, FL.
Michael DeWeert is senior principal scientist at BAE Systems Spectral Solutions, Honolulu, HI.