Novel Applications of Diffractive Optical Elements for Infrared Seekers

While there has been a great investment by the Government in all types of infrared focal plane arrays (FPAs) over the past several years, there has been little direct investment in innovative imaging systems to mate with these FPAs. For the most part, classical imaging solutions have been applied to this optical imaging problem with a certain level of success. However, the latest generation of focal planes utilize a unit cell size which is driving a demand for very fast (low f/number) imaging objectives. Clearly, more innovative imaging solutions must be found. This proposal demonstrates how advances in optical design, coating, and fabrication technology can be brought together to design hybrid refractive/diffractive systems which can keep pace with both uncooled and cooled focal plane technology. Here two novel objective forms are introduced: (i) the AMOS (Athermal Multiple Order Imaging System) imaging concept and (ii) the ACIS (Athermal Catadioptic Imaging System) imaging concepts. Both concepts utilize hybrid refractive/diffractive components and can be used for either uncooled or cooled focal plane array. Both AMOS and ACIS type systems allow for ultra wideband imaging at very low f/numbers. In addition, the configurations offer a reduced element count making them more manufacturable at a lower cost.