A versatile simulation software for performance analysis of DIAL system for the detection of toxic agents

Abstract

Simulation studies have been carried out to analyze the performance of a Differential Absorption Lidar (DIAL) system for the remote detection of a large variety of toxic agents in the 2-5 µm and 9-11 µm spectral bands. Stand-alone Graphical User Interface (GUI) software has been developed in the MATLAB platform to perform the simulation operations. It takes various system inputs from the user and computes the required laser energy to be transmitted, backscattered signal strengths, signal-to-noise ratio and minimum detectable concentrations for various agents from different ranges for the given system parameters. It has the flexibility of varying any of the system parameters for computation in order to provide inputs for the required design of proposed DIAL system. This software has the advantage of optimizing system parameters in the design of Lidar system. As a case study, the DIAL system with specified pulse energy of OPO based laser transmitter (2-5 µm) and a TEA CO 2 laser transmitter (9-11µm) has been considered. The proposed system further consists of a 500-mm diameter Newtonian telescope, 0.5-mm diameter detector and 10-MHz digitizer. A toxic agent cloud with given thickness and concentration has been assumed to be detected in the ambient atmospheric conditions at various ranges between 0.2 and 5 km. For a given set of system parameters, the required energy of laser transmitter, power levels of the return signals, signal-to-noise ratio and minimum detectable concentrations from different ranges have been calculated for each of these toxic agents.