Rytov number

The Rytov number, often denoted as \( R \), is a dimensionless parameter that characterizes the strength of fluctuations in the refractive index of a medium through which light propagates. It is commonly used in the field of optics, especially in atmospheric optics and free-space communication systems. Mathematically, the Rytov number is defined in relation to the refractive index structure constant \( C_n^2 \) and the spatial or temporal scale of the propagation path.