Simulations of multimode bolometric interferometers

摘要

We describe a modal theory of interferometry, suitable for the modelling of multimode bolonietric interferometers, and present the first simulations of such an interferometer. The motivation for the work is the wish to combine the low noise properties of bolometers with aperture synthesis techniques to design far-infrared and sub-mm interferometers, without the need for single-mode components that restrict the power throughput and therefore reduce the signal to noise ratio. The analysis of such interferometers has proved impossible in the past because optical systems at sub-mm wavelengths are partially coherent, and bolometers respond not only to the intensity but also to the correlations in the field. In order to assess the viability of bolometric interferometers, we therefore require a multimode theory of interferometry. We show that the appropriate modes for describing an interferometer are the Hilbert-Schmidt decompositions of the kernels of the integral operators describing the individual telescopes, and demonstrate that these modes provide both a clear conceptual understanding of the operation of an interferometer and an extremely fast method of computation. We present simulations of idealized Michelson and Fizeau interferometers, and show that the normal behaviour of such interferometers is recovered. We show simulated sources, and dirty maps obtained from uv data for a simulated Michelson interferometer. We discuss the application of the theory to real instrument design