Lerner Amit, Shashar Nadav, Haspel Carynelisa
Department of Life Sciences, Eilat Campus, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel.
J Opt Soc Am A Opt Image Sci Vis. 2012 Nov 1;29(11):2394-405. doi: 10.1364/JOSAA.29.002394.
A full Mie scattering subroutine is employed to calculate what we call the linear polarization phase function (LPPF; percent polarization and e-vector orientation of radiation as a function of scattering angle) that results from refraction of the direct solar beam from air into water followed by single scattering by spherical hydrosols. The separate effects of refraction at the air-water interface, hydrosol size, the real and imaginary parts of the hydrosol refractive index, and absorption by the surrounding medium (water) on the LPPF are investigated. All of the above factors are found to alter the LPPF, changing the value of the maximum percent polarization (P(max)), the location of P(max), the number of fluctuations in the LPPF, or the location of the neutral points (points of 0 percent polarization), though absorption by the surrounding medium is found to have only a minimal effect. The character and extent of the influence on the LPPF is found to depend on the scattering regime (Rayleigh, Mie, or geometric optics). We conclude that in calculating underwater polarization, it is important to take into consideration Mie scattering even in relatively clear waters. We also find a coupling between the partial polarization and the e-vector orientation, which suggests that for some polarization-based visual tasks, only one of these would suffice. Other implications for aquatic animal polarization vision are discussed.
使用一个完整的米氏散射子程序来计算我们所谓的线性偏振相位函数（LPPF；辐射的偏振百分比和e向量方向作为散射角的函数），该函数是由直射太阳光束从空气折射到水中，然后由球形水溶胶进行单次散射产生的。研究了空气-水界面的折射、水溶胶大小、水溶胶折射率的实部和虚部以及周围介质（水）的吸收对LPPF的单独影响。发现上述所有因素都会改变LPPF，改变最大偏振百分比（P(max)）的值、P(max)的位置、LPPF中的波动数量或中性点（0%偏振点）的位置，不过发现周围介质的吸收只有最小的影响。发现对LPPF的影响特征和程度取决于散射 regime（瑞利、米氏或几何光学）。我们得出结论，在计算水下偏振时，即使在相对清澈的水中，考虑米氏散射也很重要。我们还发现了部分偏振和e向量方向之间的耦合，这表明对于一些基于偏振的视觉任务，其中之一就足够了。讨论了对水生动物偏振视觉的其他影响。
