Optical setup for evaluating image quality of thermal imaging lenses working in the spectral region of 8÷12 µm

Abstract

In this paper, we demonstrate a homemade setup and an image processing algorithm to evaluate the image quality of optical systems working in the spectral region of 8-12 µm. The working principle of our approach relies on measuring the line spread function (LSF) and the modulation transfer function (MTF). All components in the setup are carefully designed and manufactured, and we strictly follow quality control to limit measurement errors. The setup can determine the LSF and MTF of a thermal imaging lens with a focal length of f' ≤ 500 mm and pupil diameter D ≤ 100 mm. A number of objective samples have been studied using our setup, and the experimental results indicate that our setup can work reliably with high accuracy.