Non-metallic Weapons Research Articles

57–64 GHz Imaging/Detection Sensor—Part II: Experiments on Concealed Weapons and Threatening Materials Detection

In this paper, experimental evaluations over the frequency range of a 57–64 GHz for an improved millimeter wave (MMW) imaging/detection system have been conducted. The main objective behind this work is to examine the performance of a high gain and low profile multi sine corrugated AFTSA antenna sensor in the detection of metallic, non-metallic weapons and suspected liquids hidden by clothing, plywood, and plastics. A microwave holography technique based on time domain reflectometry (TDR), which utilizes amplitude information recorded over a 2D aperture, reconstructs a focused image of the target. 60 GHz ISM band imaging detection experiments elaborate the ability for the detection of concealed weapons or other threatening items placed on a body phantom, easily penetrating clothing material of different thicknesses, as well as able to detect through plywood and plastics. The MMW image is detected using a 2D linear scanning platform which generates XY movement, with a $30\times30$ cm2 mechanical range for the object field of view and oriented perpendicular with respect to a lens focal plane. This work is performed with a cross range resolution of $\delta {x}=\delta {y}= 3$ mm achieving a $100\times100$ pixels MMW image. The mechanical setup scanning method is similar to synthetic aperture array with a single AFTSA antenna element measurement, ideal for investigating the probe for 60 GHz band imaging and in detecting concealed threatening items at security surveillance checkpoints.

TIME DOMAIN TERAHERTZ IMAGING OF THREATS IN LUGGAGE AND PERSONNEL

We demonstrate a large area time domain terahertz (THz) imaging system capable of scanning 1 meter square area in less than 20-100 minutes for several security applications. The detection of concealed explosives; metallic and non-metallic weapons (such as ceramic, plastic or composite guns and knives); and flammables in luggage, packages and personnel has been demonstrated. Transmission mode images of luggage containing threat items are discussed. Reflection mode images of luggage and personnel are discussed. Time domain THz images can be analyzed for 3 dimensional and volumetric information. Time domain THz images have advantages over coherent narrow band imaging methods, with freedom from interference artifacts and with greater ability to discard irrelevant or intervening reflections through time discrimination.

Large area terahertz imaging and non-destructive evaluation applications

Terahertz (THz) imaging is being adopted for non-destructive evaluation (NDE) applications in aerospace and other government and industrial settings [1-3] . NASA is currently employing THz reflection NDE to examine the space shuttle external tank sprayed on foam insulation (SOFI) for voids and disbonds. Homeland security applications such as the inspection of personnel [2] , the detection of concealed explosives [2] , biological agents, chemical weapons, flammables, metallic and non-metallic weapons, and other potentially dangerous items are the subject of active investigation. Advancement of many of these applications beyond small table top experimentation had been limited by slow imaging speed (tens of minutes or hours), small scan areas (<10 square cm) and in many cases the requirement that the sample itself be mechanically raster scanned. We report the development and applications of a high-speed large-area time domain terahertz non-destructive evaluation imaging system.