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Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines (2017)

Chapter: Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems

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Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
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D

Millimeter Wave Advanced Imaging Technology: Passive Systems

The human body naturally emits radiation in the millimeter, submillimeter, and infrared ranges. For example, all warm objects emit heat, or infrared radiation, as discussed in Appendix C. Imaging using this natural radiation is termed “passive imaging,” to contrast with imaging using spotlight or “active” sources. Figure D.1 illustrates passive submillimeter and millimeter range detection of concealed weapons.

The temperature of the clothed human body is close to 28°C (298 K). Hence, according to Wien’s law, the peak of the emission is at the wavelength of

Image (D.1)

Here, bw is the Wien constant (in Km) and T is temperature, see Figure D.2. This roughly corresponds to frequency close to 30 THz. At lower temperatures, the maximum emission shifts into the millimeter and submillimeter range.

While passive millimeter wave imaging systems have been under investigation and development for over a decade, no such system has yet achieved widespread adoption in the United States.1

A new approach of the terahertz sensing for the detection of concealed objects is represented by the passive detection implemented in the ThruVision TS4.C and ThruVision TS5.C machines from Digital Barriers, LLC. ThruVision TS4.C detects

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1 L. Yujiri, 2006, “Passive Millimeter Wave Imaging,” Microwave Symposium Digest, IEEE MTT-S International, pp. 98-101, doi:10.1109/MWSYM.2006.249938.

Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
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Image
FIGURE D.1 Passive millimeter-wave image of concealed contraband (handgun and ceramic knife). SOURCE: NIST.

objects at distances between 3 and 10 m depending on their sizes and conditions. ThruVision TS5.C detects large objects at distances between 6 and 15 m. Both machines use 0.25 THz sensing arrays with output for closed-circuit television color camera with the frame rate of 6 Hz.2Figure D.3 shows the installation schematic, and Figure D.4 shows an example.

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2 M. Shur, 2016, Recent developments in terahertz sensing technology, Proceedings of SPIE 9836, Micro- and Nanotechnology Sensors, Systems, and Applications VIII, 98362Q (May 25, 2016), doi:10.1117/12.2218682.

Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
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Image
FIGURE D.2 Wien’s law and the maximum emission wavelength in the millimeter and submillimeter ranges in the shaded temperature region.
Image
FIGURE D.3 Schematic of ThruVision TS4.C installation. SOURCE: Digital Barriers.
Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Image
FIGURE D.4 An example of the ThruVision TS4.C scan. SOURCE: Digital Barriers.
Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 158
Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 159
Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 160
Suggested Citation:"Appendix D: Millimeter Wave Advanced Imaging Technology: Passive Systems." National Academies of Sciences, Engineering, and Medicine. 2017. Airport Passenger Screening Using Millimeter Wave Machines: Compliance with Guidelines. Washington, DC: The National Academies Press. doi: 10.17226/24936.
×
Page 161
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The Transportation Security Administration requested a study by the National Research Council (NRC) to establish the Committee on Airport Passenger Screening: Millimeter Wave Machines to evaluate two models of active millimeter wave scanners: the L3 ProVision 1 and L3 ProVision 2.

Airport Passenger Screening Using Millimeter Wave Machines provides findings and recommendations on compliance with applicable health and safety guidelines and appropriateness of system design and procedures for preventing over exposure. This study addresses the issue of whether millimeter wave machines used at airports comply with existing guidelines and whether it would be possible for anything to go wrong with the machines so that, by mistake, it exposes a person to more than 10 W/m2.

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