Hollow Gaussian beam-based experimental investigation on echo measurements under atmospheric turbulence and central obstruction.

Despite their potential, Cassegrain systems face challenges due to central obstruction, resulting in reduced emitting efficiency. Optical vortex (OV) beams, known for their unique orbital angular momentum (OAM) characteristics, show promise in enhancing transmission efficiency. However, the existence of central phase singularity in OV beams may limits their effectiveness in laser ranging. In this work, a solid 532 nm laser and a spatial light modulator (SLM) are used to produce the OV and hollow Gaussian beam (HGB). Per the requirements of our experiments, the transmission characteristics of OVs in the Fresnel region have been thoroughly investigated. Based on the healing properties of HGBs, Experimental validation is conducted using HGBs and OV beams under varying atmospheric turbulence levels, and stronger echo signals with HGBs are realized. Additionally, a simplified model simulating central obstruction challenges in Cassegrain systems is developed, HGB shows the superior performance of HGBs in improving transmission efficiency and enhancing echo signals. This research provides valuable insights for optimizing Cassegrain antenna systems and advancing laser ranging technology and highlighting the potential of HGBs as a promising solution for overcoming central obstruction challenges and improving overall system performance.