Simulation of All-Day Lidar Detection Technology Based on Photon Sieve
Objective Currently,there is a pressing for high temporal and spatial resolution atmospheric observation data in meteorological forecasting,meteorological services,climate change,atmospheric environment,and others.However,during daytime lidar detection,the solar background light is the most important interference noise,and the strong sky background light and ground radiance will pollute or even flood the lidar returns,and thus directly affects and greatly restricts the effective detection distance and detection accuracy.Mitigating the influence of strong solar background light remains the foremost challenge in achieving all-day lidar detection.Methods Drawing upon the diffraction theory of photon sieves and leveraging the optical field properties of vortex lasers,we propose a photon sieve-based all-day lidar detection technique aimed at filtering out solar background light.Initially,using vector diffraction theory,we conduct numerical simulations to analyze the diffraction patterns of photon sieves under various incident beams including Gaussian,parallel,and vortex beams.Subsequently,based on the numerical simulation,we develop a photon sieve-based solar background light filtering technique for filtering solar background light and design an optical system dedicated to this purpose.This system facilitates absolute spatial separation between the atmospheric lidar returns and the solar background light in two independent channels.In addition,the signal-to-noise ratio curves of lidar are simulated under clear and cloudy weather conditions,to demonstrate the all-day performance of a photon sieve-based lidar system.Results and Discussions The numerical simulations of the photon sieve present significant differences in the shape and position of focused spots for Gaussian,parallel,and vortex beams.While parallel and Gaussian beams exhibit similar focused spot shapes but differ in size(Fig.2),vortex beams produce focused spots characterized by a dark center and a bright ring whose radius increases with the topological charge L(Fig.3).Investigation into the diffraction patterns of mixed light(parallel and vortex)passing through the photon sieve shows that vortex and parallel beams with a topological charge of L=7 are focused o bright rings and centers with radii of 35 and 18 μm,respectively,and the absolute spatial separation of the parallel beam and the vortex light can be obtained theoretically(Fig.4).Additionally,we present the design of a photon sieve-based solar background light filtering optical system featuring a core configuration of photon sieves and a plane reflector with a hole,enabling the extraction of pure lidar returns in the reflection channel(Fig.6).Conclusions Taking atmospheric water vapor as an example,we simulate the signal-to-noise ratio of water vapor detection under clear and cloudy weather conditions.The simulation results show that the photon sieve-based lidar system achieves a water vapor detection range that can reach up to 4 km during the daytime.By comparison,the detection range is less than 2 km due to the effect of the solar background light for the traditional lidar system.These findings validate the feasibility of the photon sieve-based all-day lidar detection technique and underscore its significant advantages in this regard.Our study provides a robust theoretical foundation and technical framework for advancing all-day lidar technology.
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