紫外像增强器的调制传递函数测试系统设计

Design of Modulation Transfer Function Test System for Ultraviolet Image Intensifiers

紫外像增强器是紫外成像系统的核心器件,其成像质量决定了对紫外光学信号的探测和成像能力。调制传递函数(Modulation Transfer Function,MTF)反映了系统对图像不同频率信息的传递能力,是像质评定的一种客观指标。本文基于狭缝成像和傅里叶分析的调制传递函数测试原理,设计了一套紫外像增强器的调制传递函数测试系统。然后对3支紫外像增强器进行了调制传递函数测试实验,得到3支紫外像增强器的MTF曲线截止频率均在32~34lp/mm之间,并根据MTF曲线对3支紫外像增强器成像质量进行对比分析。最后经过重复测试得到几个重要频率点MTF测试值的标准差均低于0.02。

The ultraviolet(UV) image intensifier is the core device of an UV imaging system. Its imaging quality determines its ability to detect and image UV optical signals. The modulation transfer function(MTF)represents the system’s ability to transfer information at different frequencies and is an objective indicator of image quality assessment. Based on the MTF test principle of slit imaging and the Fourier analysis method, a set of MTF test systems for UV image intensifiers is established in this study. MTF test experiments were performed on three UV image intensifiers. The MTF curve cutoff frequencies of the three UV image intensifiers were between 32 and 34 lp/mm, and the imaging quality of the three UV image intensifiers was compared based on the MTF curves. Finally, the standard deviations of the MTF values of several important frequency points obtained from repeated tests were lower than 0.02.