Portable detection system for standoff sensing of explosives and hazardous materials

• Published in: Optics communications 2013-11, Vol.309, p.44-49
• Main Authors: Sharma, Ramesh C., Kumar, Deepak, Bhardwaj, Neha, Gupta, Saurabh, Chandra, Hukum, Maini, Anil K.
• Format: Article
• Language: English
• Subjects: Biological; Explosive materials; Explosives; Hazardous; Hazardous chemicals; Nitrobenzenes; PETN; Photo-acoustic spectroscopy; Polyethylenes; Portability; Quantum cascade laser; Standoff detection; Trolleys
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2013.06.025

Standoff Quartz Enhanced Laser Photoacoustic Spectroscopy (QE-LPAS) technique is emerging as a powerful technique for detection of hazardous chemicals, biological and explosive agents. Experimentally, we have recorded standoff photoacoustic spectrum of hazardous molecules adsorbed at diffused surfaces from a distance of up to 25m. Tunable mid infrared quantum cascade lasers (MIR-QCL) in the wavelength range 7.0–12.0μm are being used as optical source. Samples of Dinitrotoluene (DNT), Pentaerythritoltetranitrate (PETN) having adsorbed concentration of approximately 5.0μg/cm2 were detected. Acetone and nitrobenzene samples in liquid having concentration 200nl approximately sealed in polythene sachet were detected from a standoff distance of up to 25m. All the above measurements are reported for a Signal to Noise Ratio (SNR) of 10, optimized for maintaining very less false alarm rates for field measurements. A portable trolley mounted system has been developed for field applications.