A mathematical model for computation of parameters of eyesafe lidar for detection of forest fire smoke has been developed. It is assumed that the lidar uses a wavelength of 1.54 micrometer. This wavelength can be obtained from Er:glass lasers, from Nd:YAG lasers with an optical parametric oscillator, or from Nd:YAG lasers with a Raman cell. It is assumed that receiver optics of 20 cm diameter and an avalanche photodiode are used. Particle size distributions in the smoke from experiments in the literature are utilized for calculation of backscattering efficiency. The backscattering cross section is calculated on the basis of Mie formulae. Diffusion of the smoke plume is estimated on the basis of an analytical solution of the relevant hydrodynamics equations. Results of the calculations show that for detection of forest fires with fuel mass burned in unit time 2 kg/s at a distance of 10 km it is necessary to have a laser pulse energy of 120 mJ.
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