Proc. SPIE 10705, Modeling, Systems Engineering, and Project Management for Astronomy VIII, 107051K (2018); doi: 10.1117/12.2312487
Fibre fed spectroscopy requires that the output distribution of the optical fibre is as stable as possible. Effects like scrambling and FRD play an important role in any fibre fed instrument design, since they affect directly the output distribution of multi-mode fibres. These effects depend, among other factors, on the excited propagation modes. The propagation modes of different fibre geometries have different spatial distributions, therefore could show different scrambling and FRD characteristics. A model is being developed at the Leibniz-Institute for Astrophysics Potsdam (AIP) that shows the intrinsic effect of scrambling and FRD in optical fibres. The model is based on the Eigenmode Expansion Method (EEM). With this theoretical frame work should be possible to compare the results of mode excitation in different fibre geometries. This work is part of a PhD Thesis involved in the fibre system of MOSAIC, a multi-object spectrograph for the E-ELT.