INVESTIGATION OF THE FEASIBILITY OF USE OF LASER OPTOACOUSTIC DETECTION FOR THE DETECTION OF EXPLOSIVE FINAL REPORT

• NCJ Number: 19973
• Author(s): ANON
• Date Published: 1975
• Length: 86 pages
• Contract Number(s): 44343-V; J-LEAA-025-73
• Sponsoring Agency: US Dept of Justice; Aerospace Corporation; US Dept of Justice NIJ Pub
• Corporate Author: Case Western Reserve University
• Sale Source: National Institute of Justice/
• Publication Type: Statistics
• Language: English
• Country: United States of America

Annotation

THE PRESENCE OF MINUTE QUANTITIES OF EXPLOSIVES VAPOR CAN BE DETECTED BY EXPLOSING THE GAS TO MONOCHROMATIC INFRARED RADIATION AND THEN MEASURING THE SOUND WAVES THUS PRODUCED WHICH HAVE SPECIFIC CHARACTERISTICS.

Abstract

THE RADIATION IF ABSORBED BY THE EXPLOSIVES MOLECULE WHICH STORE THE ENERGY INTERNALLY IN THE FORM OF VIBRATIONAL ENERGY. NON-RESONANT COLLISIONS WITH CARRIER GAS MOLECULES RESULT IN TRANSFER OF THE INTERNAL VIBRATIONAL ENERGY (IN THE EXPLOSIVES MOLECULE) TO THE MOLECULES OF THE CARRIER GAS, IN THE FORM OF EXTERNAL TRANSLATIONAL ENERGY. THIS BECOMES MANIFEST IN THE FORM OF MINUTE INCREASES IN TEMPERATURE AND PRESSURE. IF THE INCIDENT RADIATION IS MODULATED, SOUND WAVES ARE PRODUCED IN THE GAS AND THESE CAN BE DETECTED WITH VERY SENSITIVE MICROPHONES. THE REPORT DEMONSTRATES THAT THE USE OF OPTOACOUSTIC EQUIPMENT IS FEASIBLE, ESPECIALLY SINCE THE EQUIPMENT CAN BE MADE PORTABLE. (AUTHOR ABSTRACT)