Exploration of coherent backscattering mechanisms for nonspherical particles in geometric optics regime

作者：Masanori Saito, Ping Yang, Leung Tsang, Hajime Okamoto, Jiachen Ding · 发表于：Journal of Quantitative Spectroscopy and Radiative Transfer · 年份：2025 · DOI：10.1016/j.jqsrt.2025.109805 · 被引用次数：2 · 研究领域：Random lasers and scattering media、Atmospheric aerosols and clouds、Orbital Angular Momentum in Optics

ABSTRACT Coherent backscattering enhancement (CBE) is critical to the quasi-backscattering (i.e., close to 180° scattering angle) properties of a nonspherical particle. However, the conventional geometric optics method (GOM) does not account for CBE in computing the single-scattering properties of nonspherical particles, leading to systematic biases in the phase function at quasi-backscattering angles. To mitigate the biases, this study explores the mechanisms of CBE in the geometric optics regime and derives a correction formula to approximately account for the CBE effect in the phase functions computed with the principles of geometric optics. In particular, the enhancement of the scattering intensity at quasi-backscattering angles can be explained by the CBE mechanisms associated with constructive interference due to mutual pairs of transmitted rays going through internal reflection-refraction events within a particle. The present CBE correction is obtained based on physical rationales about the CBE mechanisms and substantially improves the consistency of the computed phase functions of an ensemble of randomly oriented nonspherical particles, including droxtals and conical hydrometeors, between numerically rigorous methods and GOMs with the CBE correction. The applicability and limitations of the present CBE correction formula are also discussed.