P10 - Project of the Security Portals for Explosives Detection using CEAS Sensor
- Event
- SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Nürnberg - Band
- Proceedings IRS² 2011
- Chapter
- IP - Poster Session
- Author(s)
- R. Mędrzycki, J. Wawer, Z. Bielecki, J. Mikołajczyk, J. Wojtas, M. Nowakowski - Military University of Technology, Warsaw (Poland)
- Pages
- 139 - 144
- DOI
- 10.5162/irs11/ip10
- ISBN
- 978-3-9810993-9-3
- Price
- free
Abstract
Detection of explosives is current problem for antiterrorist activities. This is particularly important for security of national buildings and installations. Explosives detection technology can be divided into two groups: sensor systems of trace amounts of explosives (Trace Detection) or of anomalies ones caused by presence of explosives charge (Bulk Detection). In the trace detection portals, there is examined the composition of contained air. If explosives are detected, the installed sensor will identify the chemical signature and will alert the operator. However, both the location and quantities of the explosives are not known in this case. For the detection of anomalies, the main task of detector system is to study area distortions caused by explosives charges. The obtained results are mainly presented visually. Therefore, these portals can detect suspicious objects such as dangerous items (weapons), packages (bomb), vests (suicide bomb), which could be filled with explosives. They are
equipped with complex sensor systems, which provide a wide range of explosives detection. For the trace detection: mass spectroscopy, ion mobility spectroscopy, gas chromatography, and chemical sensors are used. The main disadvantages of these devices are the high price and limited sensitivity.
The paper presents a concept of the security portal construction. In the portal, an optoelectronic NO2 sensor operating on basis of Cavity Enhanced Absorption Spectroscopy (CEAS) is applied. The CEAS technique is a modification of Cavity Ring Down Spectroscopy (CRDS) technique. It is based on off-axis arrangement of an optical cavity. Due to its advantages, CEAS has becoming a widely used technique for optical absorption analysis of atoms and molecules. Commonly used setup includes a resonance optical cavity, which is equipped with spherical and high reflectance mirrors, violet pulsed diode laser (TopGaN, POLAND), and electronic signal processing system. In order to ensure registration of low level signals and accurate decay time measurements, special signal processing system was developed. Investigations of a designed sensor show that it is possible to build a NO2 sensor, the sensitivity of reaches 1 ppb level. Thank to this, it is possible to detect some explosives materials by use of the NO2 sensor.
The presented portal could become a very effective tool for explosives detection. That is why, it could be used to control entries of important objects e.g. airports, government buildings, skyscrapers, military bases, and so on.