High Spectral Resolution Scheimpflug Lidar for Atmospheric Aerosol Sensing

Abstract

High spectral resolution lidar (HSRL) can accurately retrieve aerosol optical properties by separating aerosol Mie‐scattering signal from molecular Rayleigh‐scattering signal, but primarily confined to UV–vis region, limiting reliable derivation of aerosol microphysical properties across broader spectral ranges. This paper demonstrates a novel continuous‐wave near‐infrared high spectral resolution Scheimpflug lidar (HSR‐SLidar) for atmospheric aerosol sensing. The lidar system employs a 780‐nm laser diode and a tapered semiconductor optical amplifier to build up a tunable laser with a frequency stability of ±72 MHz (±0.15 pm), allowing real‐time switching between on‐resonance and off‐resonance wavelengths. A temperature‐stabilized rubidium cell is utilized as the discriminator with a spectral discrimination ratio up to 104. Atmospheric echoes of the molecular channel and the combined channel are detected by a 45° tilted image sensor with a time‐multiplexing scheme. Validation measurements are carried out in comparison with a collocated Raman lidar, and a good agreement between aerosol backscattering coefficients measured by the two lidar systems is achieved. The proposed HSR‐SLidar, featuring low cost and low maintenance, extends the HSRL scheme to the near infrared region with a short blind‐range down to 30 m and overcomes the ill‐conditioned lidar‐equation challenge of the Mie‐scattering Scheimpflug lidar.