Design and fabrication of optical filters for infrared imaging temperature measurement

Abstract The four kinds of infrared filters for infrared imaging temperature measurement of human body are designed with Ge/ZnS and ZnS/YbF3 film stacks on germanium and zinc selenide substrates, respectively. The characteristics of Ge/ZnS and ZnS/YbF3 film stack on germanium and zinc selenide substrates are discussed based on the analysis and comparison of optical and non-optical properties. The infrared filters designed by Ge/ZnS have fewer film layers, smaller film thickness and lower transmittance in cut-off region than those designed by ZnS/YbF3 film stack. The infrared filters composing of Ge/ZnS film stack on the germanium substrate have been produced. The average transmittance measured in the mid and long-wave infrared (5.5-12 µm) band is about 90%, and the transmittance of the cut-off band is less than 1%. The coating samples can endure the adhesion and environmental tests.