用Mie氏散射理论测量聚苯乙烯微球的折射率

采用全Mie氏散射理论，计算单色平行光被该球粒散射后的光强图案分布.在实验上，把聚苯乙烯小球分散在纯净水中，使其浓度满足光的透过率为70%左右的条件，然后测量单色平行光通过该样品比色皿后的远场衍射图样的第一暗环角半径的数值大小.将该测得的角半径大小同上述采用全Mie氏散射理论计算的不同折射率下的散射光强角分布曲线图相比较，选出与测得的第一暗环角半径大小符合最好者，从而得到国家标准物质聚苯乙烯小球相对于分散剂纯净水的折射率大小，最后得到聚苯乙烯小球的折射率为1.6.本研究为该标准样品提供了一个重要光学参数.

Measurement of Refractive Index of Polystyrene Beads by Using Mie Scattering Theory

The present paper exploits a full Mie theory, in theory, to study the scattered pattern of parallel monochromatic light passing through the bead-water-aerosol cuvette. In experiment, the bead concentration was adjusted to make the transmission of the light through the cuvette to be about 70%, and the scattering pattern in far field was measured for the angular radius of its first dark ring. The measured angular radius value was compared with those computed theoretically for varying indices of refraction. The best comparison gave the value of the relative index of refraction with respect to that of the pure water. From the refractive index of water, a value of n = 1.6 of the refractive index for these plastic particles were inferred, thereby providing a key optical parameter for these Standard-Matter beads.