Passive polarimetric imaging of millimeter and terahertz waves for personnel security screening

Abstract

Passive millimeter and terahertz wave imaging is a powerful way for personnel security inspection and scene monitoring. The existing systems usually have a single polarization mode. To obtain more information, polarimetric imaging has been preliminarily explored recently. However, there is no work exhibiting high-performance polarimetric imaging to analyze and interpret polarization characteristics. In this Letter, we report on the development of a W-band passive polarimetric imaging system for human body screening and present the polarization characteristics analysis of several typical scenarios. The experimental system has a spatial resolution of better than 2 cm at 2.5 m distance and has a thermal sensitivity of better than 0.3 K. The system can display polarization properties of human bodies and concealed objects. The experimental results demonstrate that passive polarimetric imaging has a great potential for object contrast enhancement, detection, segmentation, and recognition.

Transcriptome profiling of guinea pig skin exposed to a high‐power terahertz source

“…Since the single photon energy of THz radiation is weak because of its long wavelengths, it has good tolerability and a favorable safety profile theoretically. Due to the recent technological development of the THz technique, it has been widely used in many fields including diagnostics of skin melanoma, dysplasia, scars, or security, quality control, artwork examination (Cheng et al, 2021; Ohrstrom et al, 2015). Understanding the interaction between the lasers and tissues enables selection of the most appropriate laser, energy, power, fluence, and irradiance (Carroll and Humphreys, 2006).…”

“…Until recently, there was no easy and direct process for generating THz sources whose strength are comparable to the powerful high‐energy lasers (Fedorov and Tzortzakis, 2020). The THz has a wide range of potential applications in areas related to imaging such as diagnostics, industrial quality control, security, food inspection, or artwork examination (Afsah‐Hejri et al, 2019; Cheng et al, 2021; Ohrstrom et al, 2015).…”

Advanced THz MIMO Sparse Imaging Scheme Using Multipass Synthetic Aperture Focusing and Low-Rank Matrix Completion Techniques

“…This kind of imaging systems whatever frequency band is used can be categorized into passive, active imaging systems and their combination. The passive imaging system utilizes emissivity or temperature differences of objects to form the target images [10]- [15]. It is capable of achieving a fast imaging rate due to exempting from transmitting signal but challenging in achieving a sufficient sensitivity to detect a small noise equivalent temperature difference (NETD or NE∆T) below 1K, which is desirable to detect items warmed up by body contact.…”

Simplified Reflectivity Model and Its Application in Millimeter-Wave Radiometry

“…independently of the time of day, MMW radiometry has been used in astronomy [2], [3] and remote sensing [4], [5], [6], [7]. Since the 1990s, with the development of MMW devices [8], MMW radiometry has been gradually applied to the information acquisition of close-range (compared with remote sensing) targets, such as the detection of guns, explosives and other dangerous goods in security inspection [9], [10], the acquisition of road type, slope, and obstacles [11], environmental mapping and monitoring [12], [13], fire fighting [14] and military applications [15], [16]. Comparing the MMW radiation Manuscript received XX XX, 2022; revised XX XX, 2022.…”