Evolution study of smoke backscattering coefficients in a cell by means of a compact mobile Nd:YAG lidar system

Detection of smoke from forest fire is one of the practical applications of lidar. As it is well known, smoke contains a large number of small particles of ash or soot, leading to a large backscattering efficiency and consequently favourable conditions for lidar application. We have developed a compact mobile lidar system based on Nd:YAG Q-Switched laser source, operating at three wavelengths: 1064 nm, 532 nm and 355 nm, with emission rate of 10 Hz and pulse duration equal to 5 ns when the laser operate at the fundamental harmonic and 4 ns for the second and the third ones. The system has been tested by experimental measurements of the smoke backscattering coefficients carried out in an ad hoc cell. Since the spatial resolution of laser pulse is smaller than the cell length it has been possible to evaluate the profile of the smoke backscattering coefficients inside the cell itself. Moreover it has been developed a computational model for simulating the temporal and spatial evolution of smoke within the cell. These experimental and theoretical data have been used to optimize the theoretical already developed to study the smoke evolution into the atmosphere. In this paper measurements of smoke backscattering coefficients into a cell and simulations of smoke evolution will be presented.