Abstract：Biological aerosols widely spreading in the atmosphere will easily result in various epidemic diseases, meanwhile, biological aerosol weapons pose a severe threat to the safety and security of military forces and civilians. It is critically important to remotely detect biological aerosols at real-time. In this work, a double-wavelength laser induced fluorescence lidar was constructed for atmospheric bacterial spores’ identification and thus the early warning. The device employed a Nd∶YAG laser operating at 1 064 and 266 nm, with a repetition rate of 10 Hz. Based on lidar detection principle, a series of numerical simulations were performed to estimate the measurement range of the elastic scattering signals in the infrared band and the fluorescence signals induced by ultraviolet laser. In the ultraviolet band, the signals were analyzed with a spectrograph to evaluate the minimum concentrations of bacterial spores at different pulses. With a relative error of less than 10%, theoretical analysis shows that, within a range of 1.0 km, the system is capable of identifying a minimum concentration of bacterial spores at about 15 000 and 8 400 particles·L-1 at daytime and nighttime with the single laser pulse excitation. With an integrated pulses of 10 000, the detectable abilities of the fluorescence lidar greatly improves, identifying a minimum concentration of bacterial spores at 144 and 77 particles·L-1 at daytime and nighttime, respectively. In the lidar operation, when bacterial spores are located by the infrared elastic signals, one could actually extend the collected intervals in the fluorescence detection to improve the Signal-to-noise ratio, which may lose acceptable temporal resolution.
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