Aerosol profile measurement by a high-spectral-resolution lidar with a scanning interferometer

A simple high-spectral-resolution lidar (HSRL) is developed for continuous observation of aerosol profile. The second harmonic of an injection-seeding Nd:YAG laser is used for the light source. A scanning interferometer is used to separate the Rayleigh and Mie backscattering components. The interferometer is periodically scanned in the span of one fringe. Lidar signals at the minimum and maximum Mie scattering transmission are obtained. Rayleigh scattering signals are derived by subtracting the bias (cross-talk) component from the lidar signals at the minimum Mie scattering transmission, and the aerosol extinction coefficient is retrieved. The interferometer transmittance and the fringe position are calibrated with the reference signals taken from a portion of the transmitted laser beam. The method is originally developed for an HSRL with a multimode laser, but the measurement sensitivity is higher when using a single-mode laser.