Millimetre-wave optics design and verification

Microwave background astronomy requires very high performance millimetre-wave optical systems. However, compact quasi-optics are difficult to design with any confidence using techniques developed for visible wavelengths. In this paper we investigate the performance of existing software design tools (ASAP, CODE V, GLAD) as well as a Gaussian beam mode analysis technique not yet available as commercial software. We have devised a set of test cases and used these to study the underlying methodologies and physics of these packages and we look at their ability to analyse millimetre systems and components. We have used GRASP as our benchmark software