We are setting up a new scattering laboratory, the Optical Lab for Lidar Applications (OLALA) to measure the particle depolarization ratio of irregularly shaped mineral dust particles in the exact backscatter direction. For that, we will use size-segregated natural dust samples which will be observed at three wavelengths (355, 532 and 1064 nm) in order to assess the particle's size effect on the spectral slope of the depolarization ratio. The gained knowledge will be applied to a better understanding of particle's size in lidar field observations of mineral dust and to improve optical scattering models dealing with non-spherical particles at a scattering angle of 180°.
Haarig et al. (Thu,) studied this question.