Open AccessPhase-sensitive method for background-compensated photoacoustic detection of NO_2 using high-power LEDs
Author(s) -
Jaakko Saarela,
Tapio Sorvajärvi,
Toni Laurila,
Juha Toivonen
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.00a725
Subject(s) - light emitting diode , materials science , optics , signal (programming language) , photoacoustic effect , phase (matter) , optical power , transducer , diode , optoelectronics , dynamic range , detection limit , photoacoustic spectroscopy , absorption (acoustics) , amplitude , photoacoustic imaging in biomedicine , laser , acoustics , physics , chemistry , chromatography , quantum mechanics , computer science , programming language
A photoacoustic (PA) sensor has been developed for the detection of nitrogen dioxide (NO(2)). Ten amplitude-modulated high-power light emitting diodes (LEDs), emitting a total optical power of 9 W at 453 nm, are used to excite the photoacoustic signal in NO(2). The LEDs are attached to the circumference of a cylindrical PA cell. The induced longitudinal acoustics waves are detected using two electromechanical film stacks, located at the ends of the cell. Background signal cancelation is achieved by using phase-sensitive detection of the difference signal of the two pressure transducers. The phase-sensitive approach allows for improved dynamic range and sensitivity. A detection limit of 10 parts per billion by volume was achieved for flowing NO(2) gas sample in an acquisition time of 2.1 s, corresponding to a minimum detectable absorption coefficient of 1.6 × 10(-7) cm(-1) Hz(-1/2). The developed sensor has potential for compact, light-weight, and low-cost measurement of NO(2).