A general methodology for rating both performance and potential of lidar systems used for detection of atmospheric trace constituents including pollutants and gas leaks is developed. By individually examining and decomposing the contribution of both lidar system parameters and atmospheric operating conditions on signal-to-noise-ratio, a generalized figure of merit, V , for lidar quality is introduced and evolved. Computer simulations based on V and atmospheric parameters are carried out to determine achievable lidar performance. A simple design procedure is outlined for determination of lidar instrumentation parameters to ensure the best monitoring efficiency for a given set of initial parameters/requirements, including operation range, minimum detectable gas concentration, and so on.PACS 42.68.Wt; 42.79.Qx; 92.60.Sz; 42.62.Fi
IntroductionLidar designs vary widely dependent on measurement application, available components and financial constraints, and design capability [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. For example, Zuev et al. [4] presented data on over a hundred differential absorption lidars (DIALs) from scientific groups all over the world. On the basis of the data assembled by that paper [4], it is possible to get a general view of operational ranges and measurement capabilities achieved for a wide variety of lidar transmitting and receiving subsystems parameters. There is, however, no straightforward way for evaluating and selecting amongst these many systems the optimum one for a particular lidar application. To carry out a quantitative analysis of efficiency and potential capabilities of a lidar system, in each case a significant number of instrumental and environmental factors must be taken into account. While it is obvious that the use of a more powerful laser transmitter, a larger-aperture receiving telescope, and/or more sensitive photodetectors will allow achievement of a greater operation range, financial considerations often limit such design considerations.The traditional approach to the analysis of lidar capabilities, discussed, for example, in [1-3, 5, 6, 8, 10-12] as well u Fax: +1-212/650-5491, E-mail: ravil_agishev@mail.ru as in many other works, is based largely on examination of the signal-to-noise ratio (SNR) at the photodetector output. This frequently used criterion for lidar instrument efficiency is a comprehensive one, since it incorporates system parameters, the medium through which signals propagate, the external background radiation, the range factor, etc. The inclusive nature of the SNR criterion makes it convenient [6,12].However, the all-inclusive nature of the SNR criterion is also its weak point [8,13], because it is difficult sometimes to separate the impact of the different components mentioned above, which is desirable to a system developer or user. For example, an increase or reduction of SNR can be caused not only by a change in a constituent component but also by changes of optical 'weather' conditions for signal propagation [5,6,[9][10][11], b...