Measurement of atmospheric turbulence strength by vortex beam

The behavior of spatial correlation singularities suggests a possible method for measuring atmospheric turbulence strength with a vortex beam. The refractive index structure constant Cn2 can be obtained by measuring the radius of a ring dislocation of a vortex beam which has passed through atmospheric turbulence. An approximate analytic expression for the radius of a ring dislocation as a function of Cn2 has been derived, and its accuracy is verified by numerical examples.