Remote photoacoustic detection of liquid contamination of a surface.
A method for the remote detection and identification of liquid chemicals at ranges of tens of meters is presented. The technique uses pulsed indirect photoacoustic spectroscopy in the 10-microm wavelength region. Enhanced sensitivity is brought about by three main system developments: (1) increased laser-pulse energy (150 microJ/pulse), leading to increased strength of the generated photoacoustic signal; (2) increased microphone sensitivity and improved directionality by the use of a 60-cm-diameter parabolic dish; and (3) signal processing that allows improved discrimination of the signal from noise levels through prior knowledge of the pulse shape and pulse-repetition frequency. The practical aspects of applying the technique in a field environment are briefly examined, and possible applications of this technique are discussed.
Perrett
Brian
B
Sensors and Electronics Division, Qinetiq Malvern, Worcestershire, WR14 3PS, UK. bjperrett@qinetiq.com
Harris
Michael
M
Pearson
Guy N
GN
Willetts
David V
DV
Pitter
Mark C
MC