Accession Number : ADA321087

Title :   Diode-Pumped Solid State Laser Based Sensors for Cone Penetrometer Applications.

Descriptive Note : Final rept. 1 Dec 95-1 Nov 96,

Corporate Author : AERODYNE RESEARCH INC BILLERICA MA

Personal Author(s) : Wormhoudt, J. ; Shorter, J. H. ; Kolb, C. E. ; Zayhowski, J. J. ; Johnson, B.

PDF Url : ADA321087

Report Date : 09 JAN 1997

Pagination or Media Count : 25

Abstract : Site characterization using cone penetrometers is required for efficient and thorough screening of explosives contaminated soils at Army facilities. This report documents a Phase 1 SSTR investigation into a novel class of miniature laser devices for sensitive detection of pyrolysis products of explosives and other nitrogen-containing soil contaminants. The major products, nitric oxide (NO) and nitrogen dioxide (NO2), are detectable by laser-induced fluorescence (LIF) in the ultraviolet (UV) and visible spectral regions. Previous optical fiber-based systems cannot be applied to NO LIF due to poor fiber transmission in the UV. We investigated a detection system based on a diode-pumped microchip laser. This has the advantage that a near-infrared pump laser can be located on the surface, and efficiently transmitted over a fiber to crystals in the penetrometer probe which generate the Nd:YAG laser wavelength (1064 nm) and its harmonics. In Phase 1 we generated fifth harmonic UV light, and demonstrated detection of NO2 fluorescence excited by 532 nm (second harmonic) light. We calculate that coatings can be fabricated which suppress laser oscillation at 1064 nm and allow operation at 1074 nm, whose fifth harmonic at 214.8 nm will overlap the NO absorption band. In Phase 2 we will fabricate this laser and develop and demonstrate a detection system.

Descriptors :   *SOIL POLLUTION, *EXPLOSIVES DETECTION, *CONE PENETRATION TESTS, *DIODE LASERS, LASER PUMPING, YAG LASERS, CHEMICAL CONTAMINATION, TOXIC HAZARDS, LASER INDUCED FLUORESCENCE, PENETROMETERS, LASER APPLICATIONS, VISIBLE SPECTRA, ABSORPTION SPECTRA, NITROGEN OXIDES, MINIATURE ELECTRONIC EQUIPMENT, BAND SPECTRA, PYROLYSIS, ULTRAVIOLET SPECTRA, HARMONIC GENERATORS.

Subject Categories : Lasers and Masers
      Solid Wastes Pollution and Control

Distribution Statement : APPROVED FOR PUBLIC RELEASE