Abstract
A high PRF (8 KHz), 266 nm Laser Induced Fluorescence (LIF) system has been modified using a multi-beam geometry to enhance its sensitivity. The system uses a gated PMT and 13 channel interference filter for the collection of the fluorescence emission. The system has been shown to have a sensitivity for the detection of quinine sulfate at a level of 1 ppt. This represents an improvement of a factor of 1000 compared to previous instruments for detection of trace organics in water. The portable LIF system consisted of a (4×) Nd-.YAG microchip laser source (5 mW, 8 kHz) operating at 266 nm, 13 optical filter channels ranging from 239 nm to 685 nm in combination with absorption filters with cutoff at 280 nm and 295 nm, and a PMT detector and a boxcar integrator averager system. A laptop computer was used for data acquisition (via GPIB interface) and controlling the filter wheels. A software program was written in Ijbview to acquire, store and monitor the optical channels in real-time. The emission channels were switched every few seconds, resulting in a complete scan in about one minute. Figure 1 shows the schematic of the LIF system.
© 2002 Optical Society of America
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