Adrian R J, Orloff K L
Appl Opt. 1977 Mar 1;16(3):677-84. doi: 10.1364/AO.16.000677.
The signal visibility characteristics of a dual beam laser anemometer operated in a backscatter mode have been investigated both experimentally and analytically. The analysis is based on Mie's electromagnetic scattering theory for spherical particles and is exact within the limitations of the scattering theory. It is shown that the signal visibility is a function of the ratio of the particle diameter to the fringe spacing in a certain, restricted case; but more generally it also depends on the Mie scattering size parameter, refractive index, the illuminating beam polarization, and the size, shape, and location of the light collecting aperture. The character of backscatter signal visibility differs significantly from the forward scatter case, and it is concluded that backscatter measurements of particle diameters using the visibility sizing technique may not always be possible. Restrictions on the forward scatter application of the visibility sizing method are also discussed.
对在反向散射模式下运行的双光束激光风速仪的信号可见度特性进行了实验和分析研究。该分析基于米氏电磁散射理论对球形粒子的描述，并且在散射理论的限制范围内是精确的。结果表明，在特定的、受限的情况下，信号可见度是粒子直径与条纹间距之比的函数；但更一般地说，它还取决于米氏散射尺寸参数、折射率、照明光束偏振以及光收集孔径的尺寸、形状和位置。反向散射信号可见度的特性与前向散射情况有显著不同，得出的结论是，使用可见度测量技术对粒子直径进行反向散射测量可能并不总是可行的。还讨论了可见度测量方法在前向散射应用中的限制。
