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Semiconductor photon counter and microlaser based system for water pollution remote sensing by laser induced fluorescence

The Laser Induced Fluorescence is a well-known and established analytical technique. We are reporting on the research and development of the remote sensing technique for water pollution of the organic pollutants dissolved in the water or flowing on the water level. The recent development in diode pumped compact micro lasers, solid state photon counters and fast timing electronics opens quite new application possibilities. We are relying on the diode pumped Nd:YAG microlaser, passively Q-switched and frequency doubled. It provides pulse energy exceeding 100 nJ in 600 ps long pulses at 532 nm with the repetition rate of 10 kHz within a compact, small and low power package. The fluorescence signal is detected by the customized silicon photon counting detector. The compact time-to-digital converter with 20 ps timing resolution and a personal computer interface has been constructed for the device. The small receiving optics apertures together with advanced time gating of the detected signal permits to operate in an outdoor environment in daylight background conditions with acceptable signal to noise ratio. The first measurement results. the capabilities of the technique in the environmental monitoring along with the device construction will be presented.