Narrow Results

Recent advances in the technique of terahertz time-domain spectroscopy have led to the development of the first fiber-coupled room-temperature broadband terahertz sources and detectors. The fiber coupling permits the repositioning of the emitter and receiver antennas without loss of temporal calibration or alignment, thus enabling multistatic imaging. We describe a new imaging method which exploits this new capability. This technique emulates the data collection and image processing procedures developed for geophysical prospecting. We use a migration procedure to solve the inverse problem; this permits us to reconstruct the location, shape, and refractive index of targets. We show examples for both metallic and dielectric model targets, and we perform velocity analysis on dielectric targets to estimate the refractive indices of imaged components. These results broaden the capabilities of terahertz imaging systems, and also demonstrate the viability of the THz system as a test bed for the exploration of new seismic processing methods.

Terahertz radiation, which lies between microwave and infrared, has been shown to have the potential to use very low levels of this non-ionising radiation to detect and identify objects, such as weapons and explosives, hidden under clothing. This paper describes recent work on the development of prototype systems using terahertz to provide new capabilities in people screening. In particular, it explores how multi-spectral terahertz imaging and the use of both specularly reflected and scattered terahertz radiation can enhance the detection of threat objects.

There are occasions when identification of individuals in civil clothes or uniform may be necessary. In such a case, the ability of terahertz radiation to react to different configuration of, for example, plastic objects, such as tablets, etc. may be used to give a warning sign if the approaching subject is foreign, be he or she in uniform (the one that looks like your own) or in civil clothes. The identification gives an advantage of “checking the credentials” without asking for them. This feature may be especially useful when a military detachment is located close to the adversary occupied territory. The idea for such an identification device came from real situations similar to those that have taken place in Iraq, etc. The code for identification is built in the password tablet. The tablet coatings are semi-transparent to the THz radiation and do not scatter it significantly. The THz pulses, incident on the tablet surface, penetrate through the different coating layers. At each interface a portion of the pulse is reflected back to the detector. The amplitude of the reflected radiation is recorded as a function of time. The resulting pattern is compared with the password.

Terahertz radiation, which lies between microwave and infrared, has been shown to have the potential to use very low levels of this non-ionising radiation to detect and identify objects, such as weapons and explosives, hidden under clothing. This paper describes recent work on the development of prototype systems using terahertz to provide new capabilities in people screening. In particular, it explores how multi-spectral terahertz imaging and the use of both specularly reflected and scattered terahertz radiation can enhance the detection of threat objects.

There are occasions when identification of individuals in civil clothes or uniform may be necessary. In such a case, the ability of terahertz radiation to react to different configuration of, for example, plastic objects, such as tablets, etc. may be used to give a warning sign if the approaching subject is foreign, be he or she in uniform (the one that looks like your own) or in civil clothes. The identification gives an advantage of “checking the credentials” without asking for them. This feature may be especially useful when a military detachment is located close to the adversary occupied territory. The idea for such an identification device came from real situations similar to those that have taken place in Iraq, etc. The code for identification is built in the password tablet. The tablet coatings are semi-transparent to the THz radiation and do not scatter it significantly. The THz pulses, incident on the tablet surface, penetrate through the different coating layers. At each interface a portion of the pulse is reflected back to the detector. The amplitude of the reflected radiation is recorded as a function of time. The resulting pattern is compared with the password.

Recent advances in the technique of terahertz time-domain spectroscopy have led to the development of the first fiber-coupled room-temperature broadband terahertz sources and detectors. The fiber coupling permits the repositioning of the emitter and receiver antennas without loss of temporal calibration or alignment, thus enabling multistatic imaging. We describe a new imaging method which exploits this new capability. This technique emulates the data collection and image processing procedures developed for geophysical prospecting. We use a migration procedure to solve the inverse problem; this permits us to reconstruct the location, shape, and refractive index of targets. We show examples for both metallic and dielectric model targets, and we perform velocity analysis on dielectric targets to estimate the refractive indices of imaged components. These results broaden the capabilities of terahertz imaging systems, and also demonstrate the viability of the THz system as a test bed for the exploration of new seismic processing methods.