Broadband Antireflection Coatings for Infrared Windows
Recent advances in infrared instrumentation for application in many fields ranging from astronomy to military, have increased the performance requirements of infrared components and devices. Perhaps the most important coating is for antireflection purpose since most of the useful infrared materials reflect strongly in the infrared band of interest. The objective of this work is to develop designs to produce superior performance antireflection coatings (ARC) for infrared transmitting windows such as germanium and silicon. Germanium is considered as the workhorse material since it is one of the better materials available for windows and domes. Its transparency is excellent from 1 μm to 23 μm region without substantial absorption. It meets the requirements of this research for designing a broadband ARC for 3-5 μm and 8-12 μm regions. At these spectral bands, high index materials with great transparency and low absorption are scarce. Therefore, it is necessary to use equivalent layers, where a period of three layers of thin films of realizable materials are synthesized to produce one single layer film of not realizable material. Also, the methods for controlling layers' parameters such as indices and phase thicknesses are discussed. These methods are used to improve the performance of designs at high oblique incidence also.
Master of Science (M.S.)
College of Engineering
Length of Campus-only Access
Masters Thesis (Open Access)
Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic
Le, Tam Van Thanh, "Broadband Antireflection Coatings for Infrared Windows" (1990). Retrospective Theses and Dissertations. 4025.