中文摘要：

为研究闪电特性,设计了用于闪电实验室场景模拟的大变倍比近红外无焦激光扩束光学系统,用于模拟不同光斑尺寸的闪电单元。根据高斯光学几何法计算系统外形尺寸,合理确定了各组份的口径及光焦度;由ZEMAX软件包优化设计得到系统的光学结构参数,并对系统整体性能进行了分析评价。该系统变倍比为13,出射光束光斑均匀、无衍射环,满足研究闪电信号特性的需求。激光扩束系统的中心工作波长为777.4nm,入射光束直径为1.0mm,入射激光光束在步进电机驱动下连续可调,使得出射光束可从φ0.8mm变化到φ10.6mm。系统具有镜片少,结构简单,变焦轨迹平滑无卡滞等优点,可用于模拟不同尺寸的闪电单元。

英文摘要：

To explore lightning properties,a near-infrared afocal continuous zoom laser beam expanding system with large zoom ratio was designed to simulate lightning spot elements with different sizes for the lightning scene in a laboratory.On the basis of Gaussian geometric method,the overall dimensions of the system was calculated and the diameters and focal powers of lenses were determined reasonably.By using ZEMAX optical design software,optical structural parameters of the system were optimized,then total performance of the system was analyzed and evaluated.As the results,the system shows a 13X beam expansion ratio and excellent emitting beams with higher energies,uniform spots,and diffraction-free rings,which meets the requirements for simulating lightning properties.Furthermore,the central wavelength of the afocal laser beam expanding system is 777.4 nm,the incident laser beam with a diameter of 1.0 mm is continuously adjustable by a stepper motor and the emitted beam diameter ranges from φ0.8 mm to φ10.6 mm.The beam expanding system has some advantages of fewer lenses,simple structures and smoothly zoom trajectory,and it is suitable for simulating lighting elements with different sizes.