Ultraviolet laser-induced fluorescence lidar for pollen detection

Abstract

Pollen is one of the important allergens in allergic diseases. The objective of this research effort is to investigate the use of a fluorescence lidar to measure concentrations of pollens in the atmosphere. The fluorescence lidar was constructed with a pulsed Nd:YAG laser, employing at fourth harmonic and second harmonic. A 250mm diameter custom telescope was used to receive optical spectra from 260 nm–560nm excited by 266nm, and R7506 Photomultiplier tubes for two linear orthogonal polarization applications at 532nm. Range-resolved fluorescence signals are collected in 32 channels of compound PMT sensor coupled with Czerny–Turner spectrograph. Based on the current configurations, we performed a series of simulations to estimate the measurement range and the concentration resolutions of pollens. With a relative error of less than 10%, theoretical analysis shows that the system is capable of identify a minimum concentration of pollen grains at 19 particlesL−1 and 1 particlesL−1 at daytime and nighttime within a range of 1.0km, which is capable of identify a minimum concentration of pollen grains at 903 particlesL−1 and 10 particlesL−1 at daytime and nighttime within a range of 5.0km.