ZnSe-material phase mask applied to athermalization of infrared imaging systems

Abstract

This paper reports a ZnSe-material phase mask that is applied to athermalization of a conventional infrared imaging system. Its principle, design, manufacture, measurement, and performance validation are successively discussed. This paper concludes that a ZnSe-material phase mask has a permissible manufacturing error 2.14 times as large as a Ge-material phase mask. By constructing and solving an optimization problem, the ZnSematerial phase mask is optimally designed. The optimal phase mask is manufactured and measured with a form manufacturing error of 1.370 μm and a surface roughness value of 9.926 nm. Experiments prove that the wavefront coding athermalized longwave infrared (LWIR) imaging system works well over the temperature range from −40°C to 60°C.

110 °C range athermalization of wavefront coding infrared imaging systems

“…This experiment with athermalization range of 100°C is only target observation in laboratory and its decoded images at high-low temperature are serious in artefacts. Our previous works report thermal effect [8], design and manufacture of optical phase masks [2,9], a proposed decoding method based on shrinkage function [10], and a developed wavevfront coding athermalized infrared imaging [9]. This paper will further make a quantitative validation of our wavefront coding athermalized infrared imaging system in three aspects of athermalization temperature range, extension of focal depth, approximation to with in-focus image.…”

“…An experimental setup previously reported [2] is constructed to verify the athermalization of infrared imaging systems. An infrared imaging system is placed in the high-low temperature test chamber for around one hour at the preset temperature.…”

“…It outperforms a visible camera in term of night-vision ability, but tends to cause significant thermal defocus aberration. In order to keep good imaging quality over a wide range of environmental temperatures, athermalization should be considered at stages of designing, manufacturing and validating infrared imaging systems [1,2].…”

A Wide-FoV Athermalized Infrared Imaging System with a Two-Piece Lens

“…For a wide-FoV infrared imaging system to work over a wide range temperature, athermalization should be taken into account. As a classic computational imaging technique, wavefront coding is a powerful hybrid optical-digital technique for extending an operating temperature range of an infrared imaging system [1,2] .…”

“…We further developed wavefront coding athermalized infrared imaging systems with a narrow-medium FoV [1,5] .…”