基于波前编码的红外光学系统消热差设计研究

Research on Athermalization Design of Infrared Optical System Based on Wavefront Coding

消热差是红外光学系统设计的重要环节之一,本文介绍使用波前编码技术进行红外光学系统消热差设计的原理及方法,分析波前编码的基本原理,给出波前编码光学系统调制传递函数(Modulation Transfer Function,MTF)的表达式。在此基础上,以三片式长波红外光学系统为例,利用ZEMAX光学设计软件分析其在常温(+20℃)、-40℃和+60℃下的成像质量。分析结果表明,该系统在常温下的成像质量接近衍射极限,但是当温度在-40~+60℃之间变化时,MTF值迅速下降且出现零点,说明系统的成像质量急剧恶化,不再满足使用要求。加入波前编码相位版进行消热差设计后,MTF值对温度不再敏感,在不同温度下可以得到较为清晰的目标图像,表明波前编码技术可以实现红外光学系统的消热差设计。

Athermalization is one of the important aspects of infrared optical system design.This article introduces the principle and method of athermalization design of infrared optical system using wavefront coding technology,analyzes the basic principles of wavefront coding,and gives the expression of modulation transfer function(MTF)of wavefront coding optical system.On this basis,the image quality of the three-plate long-wave infrared optical system at room temperature(+20℃),-40℃and+60℃is analyzed by using ZEMAX optical design software.The analysis results show that the imaging quality of the system is close to the diffraction limit at room temperature,but when the temperature changes between-40℃and+60℃,the MTF value decreases rapidly and appears zero,indicating that the imaging quality of the system deteriorates sharply and no longer meets the requirements of use.The MTF value is no longer sensitive to temperature when the wavefront coding phase plate is added to the design of dethermal error,and a clearer target image can be obtained at different temperatures,indicating that the wavefront coding technology can realize the athermalization design of the infrared optical system.