Author Topic: Forget the TSA Millimeter wave cameras soon to be commonplace EVERYWHERE.  (Read 6150 times)

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Offline agentbluescreen

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Passive Millimeter Wave Imaging System
with White Noise Illumination for Concealed Weapons Detection

Introducing passive mm-wave camera with additional incoherent illumination

While first commercial millimeter wavelength imaging security camera prototypes already come to the market, there are some obstacles on their way. Most important of them which come behind of the cost of the scanners, is relatively long exposure intervals required to get good image on the scanner screen. Why a long exposure required? It is easy to understand the answer if you can consider mm-wave scanner as a usual security camera, but only working in mm-wave band of spectrum. The long exposure is the effect of the fact that a human body emits very light mm-wave radiation while most of it comes at visible and infrared bands of spectrum. So to get a good picture in mm-wave band, you have to wait some time – exactly like first photographers had to wait for seconds to make pictures at the early days of photography.

By analogy with photography, to shorten an exposure in mm-wave band of spectrum, you can just light up an object that you shoot. This obvious solution has the only drawback, - it is not easy to design mm-wave sources of light (so called noise sources) that are true incoherent. Beams are incoherent if the phase relationship changes rapidly and randomly. Otherwise, when lighten up by coherent noise sources, an interference pattern consisting of dark and bright fringes may be formed resulting in practically unintelligible image on the screen of millimeter wavelength imaging security scanner.

To respond to this requirement of incoherent "white noise" mm-wave noise sources, ELVA's pulse noise sources deliver the real incoherent radiation within 5 GHz bandwidth. They employ specially designed silicon IMPATT diodes, operating in a pulse mode. Average 50mW level of output power allows using the device for illumination of targets for the improvement of sensitivity of passive imaging system. The sources are available for all frequencies from 26 to 140 GHz; the typical pulse duration is about 100ns.

Project Description:

 ELVA-1 proposes a project on design of passive millimeter wave imaging system (also called “mm-wave camera”) equipped with additional mm-wave spectrum illumination for concealed weapons detection. The camera will work in 94GHz frequency band and be able to remotely scan groups of individuals for metallic and nonmetallic (dielectric) weapons using passive millimeter wave detectors. The 94GHz frequency was chosen because it’s known as atmosphere transparency window in mm-wave band and therefore this frequency is well researched and has many mm-wave components already designed for. 94GHz imaging system allows get image resolution as high as 3-5mm. The imaging system intended to monitor in the mm-wave spectrum the body of an individual and objects that he/she might carry.

Unlike prototypes proposed by other companies, ELVA-1 camera will be equipped with low-powered mm-wave spectrum light sources of ELVA-1 proprietary design. The additional illumination is intended to boost up the quality of obtained images and significantly shorter the time required to create the image. Therefore, it will make much shorter the time to spend on checking of an each individual compare to other existed camera prototypes. The light sources have output power comparable with the power of usual mobile phones to be safe enough for using in public areas with no health risks. The contrasts in mm-wave reflection from objects can be captured in images providing a visual representation of a human body and concealed objects if any of them exist under the clothes.

Project Status (May 2004):

ELVA-1 successfully designed a single-element prototype as demonstration of the technology. The prototype includes two mm-wave spectrum light incoherent sources (so called “white noise sources”) and one receiver with scanning antenna. The antenna has a mechanical scanning drive, which allows building a picture of an object in mm-wave spectrum by scanning it in X- and Y- axis. The lab prototype intended to prove an ability to create a mm-wave spectrum picture based on ELVA’s receiver and noise sources (lighting elements).

 The principal distinguish of lab prototype from a real operational mm-wave imaging system prototype, which is intended to work on security check points -  is the number of channels (mm-wave receivers). The lab prototype has only one channel, while an operational mm-wave imaging system prototype will have to have a matrix or receivers. The number of receivers will be determined by picture resolution and the technique for creating pictures. In case of still graphic imaging system a matrix of receiver required (exactly like in photo digital cameras) where a one receiver represents a one pixel of the image. For example, for a picture of 100x100 pixels the total number of receivers will be 100x100=10,000. Same time using scanning antenna it could be possible to use just 1-dimensional antenna, and in this example it will be 100 receivers only. The advantage of matrix receiver is image creation speed (like in digital camera, you need just press “Shoot” button and see the picture). The advantage of scanning antenna is its cost as the number of required receivers decreased tremendously.

Current efforts seek to improve the resolution of the system and to develop a functional prototype (with phased array or scanning antenna) suitable for operational evaluation. Delivery of this prototype should occur in 6-8 month after project will receive financing.

Offline agentbluescreen

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This primitive and relatively low-tech version only surveils passersby for concealed items that generate "hits" against the backdrop of their clothed body video image, it is a sort of low budget contraband camera-detector that does not produce naked images of clothed suspects.

Do you know what your visitors, workforce, passengers or spectators, are concealing past your metal detectors, bringing onto your transit system, into your stadiums or are taking out the door with them?

Is your security staff forced to guess who is hiding something without stopping and questioning each one?

The Brijot GEN 2 System will allow you an easier way to know who to search and pinpoint where to look!

With full-motion, real-time passive millimeter wave imaging capabilities, the GEN 2 enables you to detect concealed threats sooner, minimize loss prevention more effectively and virtually pat down and screen people in areas that you have not been able to search them before.
Brijot’s standoff passive millimeter wave imaging system offers security and loss prevention officials a quick and discrete method for detecting suspicious hidden items … whether they’re explosives, weapons, contraband, stolen electronics, or other items.

The GEN 2 also reveals hidden liquids and gels. Brijot’s millimeter wave imaging solution is the most effective high-throughput people screening system available today to effectively detect these potential threats.

Feature Highlights:

Detects concealed objects in as little as 0.5 second
Subjects walk through the screening area when deployed in two-camera configurations
Anatomical details are not revealed thereby eliminating personal privacy issues
Completely passive system — no transmission of radiation or energy of any kind
Seamless integration facilitating remote operation and administration of man-traps
Monitoring and detection displayed to the operator in real-time
Provides standoff detection of large explosives, liquids, gels and other ferrous and non-ferrous items

Offline jeremystalked1

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Conductive clothing.

Offline agentbluescreen

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This 10 year old bulkier and far more expensive avionics instrumentation version is the first generation of the full scale real time camera (like the old 2nd generation ELVA 1994 concept)

Our aviation passive millimeter-wave camera combines the imaging properties of infrared systems with the penetration capabilities of radar.  Like an infrared system, there is no minimum or maximum range of the system, only a decrease in spatial resolution with range.  The system only needs to focus at the desired distance.  Our system produces a recognizable image without extensive computer processing.

Imaging through 400 ft. of dense fog at 2,000 ft. range along Hwy 58, Tehachapi, CA in December 1999


Developed for aircraft enhanced vision
Produces quality images with no clutter
“Sees” through opaque materials
"See" through fog, clouds, rain, and smoke
Provides day/night adverse weather imaging capability
Autonomous landing guidance
Runway incursion detection
Tactical battlefield reconnaissance
Search and rescue
Covert insertion/extraction
U.S. Customs aviation support
Maintains radio silence

©2008 Trex Enterprises Corporation. All rights reserved.Site Map

Offline agentbluescreen

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Old SPIE article. Note that common CCD cameras actually incorporate IR (heat) filters (Sony example) to prevent "naked through the clothing imaging" which would be an example of covert "sensor fusion" mentioned below.

Passive millimeter wave imaging growing fast

Yvonne Carts-Powell
From OE Reports Number 159 - March 1997
28 March 1997, SPIE Newsroom. DOI: 10.1117/2.6199703.0004
The area of passive millimeter wave imaging is still in development, but both commercial and military applications abound for the technology. A conference on passive millimeter wave imaging technologies will be held at Aerosense in March. "Most of the world leaders and renown people [in this area] will be there," says Chair Roger Smith of the Air Force Wright Laboratory (Eglin AFB, Florida).

Desire and past
Active radar at longer wavelengths and infrared (and optical) systems at shorter wavelengths are more mature technologies, but passive millimeter wave sensing could add some imaging capability, either in use alone or as one part of an imaging system that allows sensor fusion (The technology has been shown to be compatible with sensor fusion systems.). Millimeter waves can penetrate many sorts of inclement weather, as well as opaque solids, and offers a lot of contrast. The emissivity of objects in this region is over a range about 10 times that in the infrared. Millimeter wave sensing can detect metal targets well because they reflect the sky, which is very cold. "On a nice clear day," says Smith, "there's nearly 300 degrees K temperature difference to work with," between the metal object and its background.

Although there are applications in which active millimeter-wave sensing is more appropriate, passive sensing can avoid some problems of active sensing, including glint. Another advantage for military applications is that passive sensing is covert.

Work on passive millimeter-wave sensing was strong during the 1960s and 1970s, says Smith, but attention was diverted by the advent of FLIR (forward-looking infrared) systems. At the time, equipment for this region of the spectrum was bulky, but now(13 years ago) MMIC (microwave and millimeter wave integrated circuit) technology allows sensing in this region from small integrated chips. Single-element scanners and imagers exist now for sensing at 35, 94, 140, and 220 GHz, says Smith.

Current work is pushing the technology in several areas. TRW (Redondo Beach, CA) has been actively involved in developing a passive millimeter wave camera. A report on the camera will be given at the conference by Larry Yujiri and others.

The development of focal plane arrays are needed to advance the field, and several papers deal with this issue during the sessions that focus on components. In another TRW paper, G. S. Dow and others report on a focal plane arrays for millimeter wave sensing. A notable development also reported by A. Rahman and others at MIT in Cambridge, MA is a room-temperature microbolometer array for this part of the spectrum. Other developments, says Smith, include superheterodyne techniques, direct detection, and MMIC component technology advances.

The science of modeling and understanding the phenomena of millimeter wave images also requires development. Researchers from the Air Force, Nichols Research Corporation, the University of Saint Andrews, TRW, and the Institute of Radio Engineering and Electronics in Russia all report work in this area. In addition, a program on millimeter wave analysis of passive signatures (MAPS), by Millitech Corp. in South Deerfield, MA and the Wright Lab provides a mobile testbed system consisting of three radiometers operating at frequencies of 35, 60, and 95 GHz. The conference's opening paper is by Doc Ewen of Millitech about MAPS.

The final session of the conference is concerned with increasing the resolution of images. Higher resolution is needed because the pixel size is larger than microwave (and shorter wavelength) sensors. David Gleed at the Defence Research Agency Malvern, in England, "is doing some tremendous work in resolution enhancement techniques," says Smith. At the conference, A. H. Lettington of the University of Reading in England, and Gleed report on a "new high-speed method for super-resolving passive millimeter wave images."

Millimeter imaging has, "tons of applications" says Smith. The ability to penetrate fog, dust, smoke, and light rain is at the root of several potential applications, including military target acquisition and aircraft navigation. The military would like a weatherproof imaging system to avoid situations such as sorties during Operation Desert Storm that had to turn back because the laser targeting systems would not work in inclement weather. Such a system could also be valuable for a covert unmanned autonomous vehicle.

For military airborne applications, says Smith, systems must build an image more quickly than current systems can-his group is working toward building a system that provides an image in 1 s as a demonstration of the technology.

For passive millimeter wave imaging to work for military, Smith cautions, it needs to be exploited in the commercial sector first, to drive costs down. There are numerous civilian applications. Civilian air transportation would benefit from systems, such as the autonomous landing guidance systems under development, that could aid pilots in landing during Category III conditions. In such conditions now, landings are not permitted. TRW is actively working on in this field. Because of the penetration at millimeter wave frequencies, imaging systems could be used to fight fires, by seeing through smoke. It might also be used for inland waterway navigation in fog.

Applications that make use of penetration of solids include concealed weapon detection for airport security-Smith says that tests in this area have detected plastic as well as metal weapons through clothing and even through 0.5 in. of sheetrock. This same ability might make the system useful for remote sensing of earth resources or ice.

Passive millimeter wave sensing has already been used by TRW to detect oil spills. The contrast between oil and water in the millimeter wave regime is sufficient to differentiate the two.

As the technology advances-and the activity of research in this area assures that it will -- other applications are likely to become apparent.

Yvonne Carts-Powell
Yvonne Carts-Powell, based in Boston, writes about optoelectronics and the Internet