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Technology under development to find concealed weapons. Coming to a street corner near you.

Concealed Weapons System Detection Systems

Efforts to eliminate or ignore the Second Amendment and the right to keep and bear arms.


On March 9, 1995, the National Institute of Justice (NIJ) launched an initiative to fund and field test three concealed weapons detection technologies. Each technology employs different physical principles and each has situation specific strengths and weaknesses.

NIJ expects one or more of the new weapons detection technologies to be in commercial production within 3 years. The technologies, described below, include Passive Millimeter Wave Imaging, Low Frequency Electromagnetic Radiation, and Magnetic Gradient Measurements.

In addition, under a memorandum of understanding, NIJ and the U.S. Department of Defense, through the Defense Advanced Research Projects Agency, have embarked on a joint research effort to explore additional weapons detection technologies. To date, the joint effort has initiated research on four weapons detection systems, which include: Low-Level Scattered X Rays and Computer Image Processing, Millimeter Wave (MMW) and Long Wave Infrared Receivers, Integrated Radar and Ultrasound, and Low- Frequency Magnetic Imaging

NIJ-Sponsored R&D Programs

Passive Millimeter Wave Imaging - Millitech

Under development by Millitech Corporation, Passive Millimeter Wave Imaging is a new technology that offers the opportunity for rapid and remote detection at a distance of up to 12 feet without a direct physical search of metallic and nonmetallic weapons, plastic explosives, drugs, and other contraband concealed under multiple layers of clothing.

This technology is based on the fact that all objects naturally emit a broad spectrum of electromagnetic radiation. Heat generated by the body in the infrared region is most familiar; less well known is the fact that humans are especially good emitters at millimeter wavelengths. When a person is scanned using technology with sensors sensitive to this wavelength, any concealed item shows up as a dark image against the lighter background image of the individual. This difference in image brightness is due to the differences in electromagnetic radiation emitted by the object and the individual. Because this purely passive imaging technique relies solely on existing natural emissions from objects, it does not require manmade irradiation. Observations can be made remotely and with discretion as required. Although passive millimeter wave imaging devices do literally see through clothing, the resulting image display does not reveal intimate anatomical details.

The versatility of passive imaging allows for a variety of camera systems to be used for different applications. To demonstrate the technology, Millitech is currently developing a proof-of-concept camera with a 300mm aperture and monitoring console for fixed entranceway surveillance. Also planned is a handheld camera with a video screen, in addition to designs for a totally portable, battery-powered camera and a standoff camera system that can be used from a police car.

Low Frequency Electromagnetic Radiation - Raytheon

In development by The Raytheon Company, this concealed weapons technology involves illuminating an individual with a low intensity electromagnetic or Heaviside pulse and then measuring the time decay of the reradiated energy from the metal objects carried by the person.

The intensity and the time decay of the secondary radiation can be characterized and the signatures identified as a gun or non-threatening metal object.

Much of the basic development work has been completed by Raytheon. In the NIJ project, the company will conduct an experiment testing the system's feasibility and provide performance data on probabilities of detection and false alarm rates. The experiment will establish whether sufficient discriminating ability exists to meet police probable cause requirements for a physical search for weapons. When fully developed, the system is expected to have a low probability of false alarms.

Possible locations to use this technology range from large gathering place such as shopping malls, schools, meeting places, and airports to small stores and banks.

Magnetic Gradient Measurements - INEL

The concealed weapons detection initiative being explored by Idaho National Engineering Laboratory (INEL) utilizes a proven, existing technology used in mineral exploration, environmental characterization, military navigation, and submarine detection.

This technology is based on passive sampling of the Earth's magnetic field. Local aberrations in the magnetic field produced by ferromagnetic objects such as guns and knives can be detected by extremely sensitive magnetometers. This is a new application of an existing technology magnetometer sensors, which are commercially available. INEL s approach is to construct a more reliable scanner that can be used as a stand-alone unit, much like an airport scanner system, or incorporated directly into building doorways or hallways.

Sensors in the system will simultaneously collect the data, thus providing a top-to- bottom magnetic profile of an individual. Reasonable suspicion will be dictated by the location and magnitude of the recorded magnetic anomalies. An electronic catalog of magnetic signatures will be established through the collection of magnetic profiles of a variety of weapons in differing locations and a number of non-weapon personal artifacts. These signatures will later be used in analysis schemes that will determine the presence, location, and, potentially, type of weapon carried. However, this technology will only detect ferromagnetic materials.

DARPA- Funded Technologies

Low-Level Scattered X Rays and Computer Image Processing - Nicolet Imaging

Under development by Nicolet Imaging Systems of San Diego, California, this technology uses extremely low doses of scattered x rays, in conjunction with advanced computer image processing techniques, to detect weapons, explosives, illegal chemicals, and other contraband concealed under a person's clothing. An individual being scanned stands in front of the system for approximately 3 seconds. Almost immediately a computer-enhanced image appears on a monitor displaying the outline of the person and any concealed objects. Multiple views such as front, rear, and sides require individuals to turn their bodies for additional scans. The system is suitable for fixed-site configurations in controlled areas, such as prisons.

This technology requires only a fraction of the radiation level previously thought necessary to detect concealed objects. Each 3 second scan exposes a person to 3 microRem of radiation. This level compares with the 10 to 20 microRem per hour that a person receives from naturally occurring background radiation, 500 microRem per hour received during a commercial airline flight at 35,000 feet above sea level, and 30,000 to 300,000 microRem received during medical x ray examinations.

Through a process known as Compton scattering, the low-dose x rays collide with and bounce off electrons in the body or another object. When the x rays penetrate materials composed of elements with a low atomic number, such as body tissue, they are more likely to bounce back, causing the image on the monitor to appear light. However, when x rays pass through materials with a high atomic number composition, such as metal or bone, the radiation is more likely to release energy through the photoelectric effect, producing a dark image on the screen. Thus, a concealed handgun would appear as a dark mass against the light background of a person s body. Because of the low dose used in this method, most of the radiation reaches only the skin or penetrates a few centimeters into the body. The bones of the lower legs are the only internal structures likely to show up on the monitor, because they are so close to the skin.

Millimeter Wave (MMW) and Long Wave Infrared Receiver - Lockheed- Martin

A passive approach under development by the Lockheed-Martin Corporation would use a millimeter wave (MMW) receiver and a long wave infrared receiver, either individually or together, to measure the difference in temperature between a concealed weapon and an individual s body. When the two types of receivers, which are still being developed, are used in tandem and linked with a computer imaging system, it is expected that the probability of detecting a concealed weapon will increase substantially. Initially, the MMW receiver is planned for fixed-site operation only. However, it is expected that the long wave infrared receiver will be suitable for fixed-site and handheld use.

Radar and Ultrasound - JAYCOR

An active approach that combines radar and ultrasound is being explored by JAYCOR. The system operator will have to be trained to interpret ultrasound images. It is expected that the radar component will be suitable for fixed-site operation and that the ultrasound component will be suitable for either fixed-site or handheld use.

Low-Frequency Magnetic Imaging - Systems & Process Engineering Corp.

An active approach using a Low Frequency magnetic imaging system suitable for fixed- site operation is being developed by Systems and Process Engineering Corporation.

New, Non-lethal Technologies Offer
More Options to Police

by Robert Hausman


Current NIJ Projects

With the US military increasingly engaging in peacekeeping missions abroad, there is a growing similarity between the various technologies of interest to the military and domestic police. Identifying persons illegally carrying firearms, the safe restraint of individuals and quickly but safely stopping a fleeing vehicle are examples.

Some of the current NIJ research projects include: improved security systems for prisons; concealed weapons/contraband detection technologies; tracking systems for use in the monitoring of suspects or persons on parole; surveillance technologies; illicit substance detection systems; digital information systems; GPS/GIS technologies (Global Positioning Systems/Geographic Information Systems); better methods of DNA identification; improved fingerprinting technologies; and, a less-than-lethal means to subdue suspects without injury.

The Office of Law Enforcement Technology Commercialization (OLETC) located at Wheeling Jesuit College, Wheeling, WV, is actively involved in commercializing law enforcement technology developed in the federal laboratory system. The OLETC is charged with assessing the needs of law enforcement agencies, approaching the research and development community regarding the development of suitable new technologies and to assist in prototyping and commercialization processes. Examples of projects that the OLETC is currently working on with federal labs and private companies include: a disabling net and launcher system that deploys a lightweight net to capture escaping suspects, which is primarily of interest to correctional institutions; and, a pepper spray launcher/dispenser to be used in hostage situations.

Sniper Detection

The Lawrence Livermore National Laboratories of Livermore, CA, has developed a portable anti-sniper detection device called the Lifeguard System. It is said to have the capability of tracking bullets in flight and displaying the flight track to an operator, who can then pinpoint the source of fire within hundredths of a second and engage the sniper with a variety of response devices.

A special camera is used to detect the gunfire; a computer then plots the trajectory of each bullet fired and a positioner device (employing a camera with telescopic lens and spotlight) points back at the sniper and has the capability of firing back at the sniper with a lethal or nonlethal projectile.

"We think the potential is there for Lifeguard to have a revolutionary impact on crime prevention," said Tom Karr, head of the Livermore team that developed the device. "Anybody who shoots at you from any direction would be immediately located. The aggressor can no longer hide."

Lifeguard's key components include a sensor that identifies a moving bullet through its unique signals and a computer that processes the signals into an image. During a recent demonstration, the equivalent of an M-16 rifle was fired at a target. The sensor spotted the bullets, while Lifeguard's video screen recreated each bullet's flight path back to its source. A small red rectangle on the computer screen outlined the area where the "sniper" stood.

Potential applications include attaching the device on police helicopters, VIP protection details, use in high-crime neighborhoods, and providing security at large gatherings.

Secures System

A $2 million grant from the Defense Department's Advanced Research Projects Agency is funding the development of yet another gunfire detection system. Called SECURES (System for the Effective Control of Urban Environmental Security), it employs acoustic sensors to detect, recognize and pinpoint the location of gunfire. Successful testing of the system has reportedly been completed by the FBI and the Metropolitan Police Department of Washington, DC.

SECURES' main component is a battery-powered two-square-inch device that can be mounted on utility poles or buildings. The device "listens" for and detects the unique audio characteristics of gunfire, and can immediately notify local police. The developer, Alliant Techsystems Inc., of Minneapolis, MN, adapted the system from its work in submarine detection technology performed for the US Navy. The NIJ is reported to be planning an independent test and evaluation of the technology.

Other Devices

The Department of Justice, through the NIJ, is helping to fund three different technologies for the detection of concealed weapons and contraband.

The first, a passive imaging technology development by Millitech Corp., of South Deerfield, MA, is claimed to offer rapid and remote detection of metallic and nonmetallic weapons, plastic explosives, and drugs concealed under multiple layers of clothing without the need for a direct physical search.

Passive imaging is based on existing natural emissions from the objects, and is said to be harmless to the subject. An image of the subject is reproduced on a monitor, based on the differences in emissivity of the human body, compared to the emissivity of a metallic object. A camera system, employing the concealed arms detection technology and suitable for use from a police vehicle, is also under development.

A second concealed arms detection system based on low-frequency electromagnetic radiation is under development by the Raytheon Co. It is said to have a low probability of false alarms and does not require a subject to walk through a portal equipped with a magnetic sensor. Its unobtrusive operational characteristics would not make a person under surveillance aware of the monitoring.

And thirdly, the Idaho National Engineering Laboratory (INEL), of Idaho Falls, ID, is developing a scanner that can be used as a stand- alone unit or directly incorporated into hallways and doorways of buildings to detect ferro-magnetic objects. It utilizes an existing technology used in mineral exploration, military navigation and submarine detection, which is based on a passive sampling of the earth's magnetic field. Local aberrations in the magnetic field produced by ferro-magnetic objects such as guns and knives can be measured and detected by sensitive magnetometers.

The NIJ's Law Enforcement Technology Center in Rome, NY, will be funded to provide technical and engineering support for the management of these concealed arms detection systems.


Airport travelers may soon have to undergo holographic imaging by security personnel in which a computer-generated image of their bodies will appear on a monitor screen. This technology can actually see through clothing and show the contrast between the body and the outlines of unnatural objects that the subject may be carrying. The holographic imaging technology is under development by the Pacific Northwest Lab of Richland, WA, at the request of the Federal Aviation Administration (FAA).


Non-lethal Devices

Meanwhile, the Oak Ridge National Laboratory of Oak Ridge, TN, is reportedly working on less-than-lethal technologies to temporarily disable fleeing or unruly suspects. One device is a thermal gun which can raise a person's body temperature to 105 or 107 degrees, thereby simulating a disabling fever.

Another project utilizes electromagnetics to induce a subject to go into an epileptic fit. And a third device being developed by Oak Ridge uses magnetic phosbeams to affect the retina of the eye to make a subject groggy and disoriented, as if struck over the head.

A variety of non-lethal nets that can be hand-deployed or fired from 37mm or 40mm grenade launchers are being developed by Foster-Miller Inc. of Waltham, MA. The anti-personnel system consists of three versions: Sticky Net, a net containing a nontoxic adhesive coating making escape nearly impossible; Snare Net, a personnel entanglement net; and Sting Net, which employs a high-voltage pulse generator to quickly immobilize armed combatants and other highly dangerous individuals.


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