大视场太赫兹光学成像系统设计

Design of Terahertz Optical Imaging System with Large Field-of-View

太赫兹(THz)波具有较高的透过性和时空分辨率等特性,在空间观测领域具有广阔的应用前景.对比于扫描成像,凝视成像具有成像性能高、速度快、结构简单等优点,而大视场成像是凝视型光学系统所必需的.因此,设计大视场凝视型THz光学系统具有重要的工程应用价值.采用反远距结构,利用Zemax设计了一款相对孔径为1、全视场角为60°的大视场THz光学成像系统.该系统采用4片式反远距共轴结构,由2片球面透镜和2片非球面透镜组成,同时透镜材料采用聚甲基戊烯(TPX)材料,整个系统具有结构紧凑、质量轻等优点.优化结果显示,各视场内的弥散斑均方根半径均小于艾里斑半径,在空间频率为12.5 lp/mm处全视场的调制传递函数(MTF)值高于0.3,表明该系统具有良好的成像质量.此外,公差分析结果表明,该系统具有较好的稳健性,加工工艺水准易于实现,符合设计要求.本设计对于THz空间大视场高分辨探测具有重要参考价值.

Terahertz(THz)wave has a potential application prospect in the field of space observation because of its high transmittance and spatial and temporal resolution.Large fieldofview imaging is required for staring optical systems,and compared to scanning imaging,staring imaging has the advantages of high imaging performance,quick speed,and simple structure.As a result,the design of a large fieldofview staring THz optical system has important engineering application value.Zemax and an inverse telephoto structure are used to create a large fieldofview THz optical imaging system with a relative aperture of 1 and a full fieldofview angle of 60°.The system adopts a 4-piece reversetelephoto coaxial structure,consisting of 2 spherical lenses and 2 aspherical lenses,and the lens material is polymethylpentene(TPX)material.Compactness and lightweight are advantages of the entire system.The modulation transfer function(MTF)value of the full fieldofview at the spatial frequency of 12.5 lp/mm is higher than 0.3,and the optimization results demonstrate that the root mean square radius of the diffuse spot in each fieldofview is smaller than the Airy spot radius,demonstrating the system’s high imaging quality.Additionally,the system’s robustness is demonstrated by the results of the tolerance analysis,and it is simple to reach the required processing technology level.This design has significant reference value for THz space large fieldofview highresolution detection.