Operation conditions of eyesafe lidar at 1.54 /spl mu/m for detection of smoke plumes

Summary form only given. Detection of smoke was one of the first practical applications of lidar. Smoke contains a large number of small particles, leading to a large backscattering efficiency. The first lidars used ruby or Nd:YAG lasers, which are dangerous to the eye. However the modern tendency in lidar is to use lasers with eyesafe wavelengths at /spl ap/1.54 or /spl ap/2.1 or /spl ap/10.6 /spl mu/m. In particular, lidars with a wavelength within the range /spl ap/1.54 /spl mu/m are increasingly being used. In the study we perform computations for a lidar with direct detection mode, at a wavelength at 1.54 /spl mu/m which is intended for the detection of smoke plumes originating from burning wood or oil. It is assumed that the fuel (wood or oil) is situated at ground level and is in the form of a circle with diameter varying in the range 1.3-3.5 m and burning rate in the range 0.3-4 kg/s. To find parameters burning thermodynamic calculations was performed. The buoyant plume of burning products was described by slender flow equations. An approximate numerical solution of these equations was found on the assumption that the velocity and temperature profiles are Gaussian. The particle emission factor for the burning of wood is within the range 1% and the average density of ash is equal to 1.0 g/cm/sup 3/. These values correspond to a concentration of ash in the gas products of burning C/sub pb/=0 3 g/m/sup 3/.