Saarela Jaakko, Sorvajärvi Tapio, Laurila Toni, Toivonen Juha
Optics Laboratory, Department of Physics, Tampere University of Technology, PO Box 692, FI-33101 Tampere, Finland.
Opt Express. 2011 Jul 4;19 Suppl 4:A725-32. doi: 10.1364/OE.19.00A725.
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).
已开发出一种用于检测二氧化氮（NO₂）的光声（PA）传感器。十个振幅调制的高功率发光二极管（LED），在453nm处发射的总光功率为9W，用于激发NO₂中的光声信号。这些LED附着在圆柱形光声池的圆周上。使用位于光声池两端的两个机电薄膜叠层来检测感应的纵向声波。通过对两个压力传感器的差分信号进行相敏检测来实现背景信号消除。相敏方法可提高动态范围和灵敏度。对于流动的NO₂气体样品，在2.1s的采集时间内实现了体积分数为十亿分之十的检测限，对应于最小可检测吸收系数为1.6×10⁻⁷cm⁻¹Hz⁻¹/²。所开发的传感器具有对NO₂进行紧凑、轻便且低成本测量的潜力。
