Anomalous change of Airy disk with changing size of spherical particles-仪器技术资料-珠海真理光学仪器有限公司手机版

Anomalous change of Airy disk with changing size of spherical particles

时间：2019-01-10 阅读：401

提供商
珠海真理光学仪器有限公司
资料大小
1MB
资料图片
下载次数
52次
资料类型
pdf
浏览次数
401次

Use of laser diffraction is considered as a method of reliable principle and mature tech-nique in measurements of particle size distributions. It is generally accepted that for a certain relative refractive index, the size of the scattering pattern (also called Airy disk) of spherical particles monotonically decreases with increasing particle size. This fine struc-ture forms the foundation of the laser diffraction method. Here we show that the Airy disk size of non-absorbing spherical particles becomes larger with increasing particle size in certain size ranges. To learn more about this anomalous change of Airy disk (ACAD), we present images of Airy disk and curves of Airy disk size versus particle size for spherical particles of different relative refractive indices by using Mie theory. These figures reveal that ACAD occurs periodically for non-absorbing particles and will disappear when the absorbing efficiency is higher than certain value. Then by using geometrical optics (GO) approximation, we derive the analytical formulae for the bounds of the size ranges where ACAD occurs. From the formulae, we obtain laws of ACAD as follows: (1) for non-absorbing particles, ACAD occurs periodically, and when the particle size tends to infinity, the period tends to a certain value. As the relative refractive index increases, (2) the particle size ranges where ACAD occurs shift to smaller values, (3) the period of ACAD becomes smaller, and (4) the width of the size ranges where ACAD occurs becomes nar-rower. In addition, we can predict from the formulae that ACAD also exists for particles whose relative refractive index is smaller than 1.

下载此资料需要您留下相关信息