A synchronous measurement technique for the evaluation of atmospheric extinction coefficient and refractive index structure constant

Atmospheric extinction coefficient and refractive index structure constant (Cn2) are important parameters to represent laser beam propagation in the atmosphere. However, to best of our knowledge, the typical measurement methods for these two parameters have not been integrated into a system. Therefore, a synchronous measurement technique for the evaluation of atmospheric extinction coefficient and Cn2 is proposed, which is applicable from weak to strong fluctuation. This technique employs projector image optics with larger aperture Fresnel lens to receive atmosphere modulated speckle. The extinction coefficient is evaluated by speckle irradiance and Cn2 is evaluated by speckle wander effect. The receiving aperture constrain condition is also discussed to ensure the speckle can be received in the long term beam wander effect under the strong fluctuation. The theory and experiment demonstration indicate that this technique provides a feasible way to simultaneously measurement extinction coefficient and Cn2.