Fibre developments at the Anglo-Australian Observatory for SPIRAL and AUSTRALIS.

In this paper we discuss some of the recent developments with optical fibres at the Angle-Australian Observatory. Firstly we will describe the upgrade to the SPIRAL integral field spectrograph for the Angle-Australian Telescope. SPIRAL-B uses a crossed cylindrical microlens array to feed 512 optical fibres at F/5.5 providing a field of view of 22 by 11 arcseconds with 0.7 arcsecond spatial sampling. The performance of the fibre bundle, microlens array, and construction techniques will be described. We will also discuss the development of prototype optical fibre switchyard as part of the AUSTRALIS concept study. The switchyard provides an "optical break" in the fibre, between the telescope and spectrograph, which allows coupling between fibres of different diameters and focal ratios. A dichroic can also be incorporated into the switchyard to allow both optical and IR spectrographs to be fed simultaneously. Switchyards therefore provide much greater observing flexibility by increasing the number of possible instrument configurations. We will briefly discuss the merits of fibre switchyards and present the results of FRD and transmission tests performed in the laboratory.