Optimized signal to noise ratio of a PMT based detector system in Mie-Lidar

Signal to noise ratio calculations are made for a Mie-Lidar system which uses photomultiplier tube (PMT) as a detector. Power received by the Lidar system from different altitudes is calculated considering four different model vertical profiles of aerosols representing urban and background continent conditions, with and without stratospheric volcanic aerosol layer. The minimum detectable energy of the backscattered laser pulse by the photomultiplier is derived using optimum spectral response of the amplifier-filter. In this article we report the signal to noise ratio obtained in terms of power received, detector efficiency, background radiation, pulse width of the laser etc. Calculations specific to our currently operational Mie-Lidar system at Mount Abu (Lat. 24°36′N, Long. 72°42′E) operating at second harmonic of Nd:YAG, at 532 nm and uses photomultiplier tube as a detector, are made. Parameter sensitivity study shows that signal to noise ratio is more sensitive to changes in transmission factor than the energy, volume backscattering coefficient and less to background radiation level and detector efficiency.