The development of CVD infrared optics from planar windows to missile domes

摘要

Chemical Vapour Deposited (CVD) diamond can now be fabricated in the form of large planar windows (up to 120mm in diameter and 2mm thick) and hemispherical domes (up to 70mm in diameter) suitable for operation as ultra-robust, external optical elements on air-based infrared (IR) system. This paper describes the optical properties of such components. Many of the optical properties of large area CVD diamond windows are governed by its polycrystalline structure. In this paper its fracture strength properties are related to its structure. It is shown that 3-point bend techniques are an appropriate method for evaluating the strength of CVD diamond under specific conditions and that its strength is dictated by internal bulk flaws that are similar in size to the grains in the polycrystalline material. Its unsurpassed rain and sand erosion properties are briefly discussed and it is shown that its solid particle erosion properties are also related to its microstructure.