HARMONI Pre-Optics Design at PDR

HARMONI is a visible and near-infrared (0.5 to 2.45 mu m) integral field spectrograph, providing the E-ELT's core spectroscopic capability, over a range of resolving powers from R (lambda/Delta lambda) similar to 3500 to similar to 18000. The instrument provides simultaneous spectra of similar to 32000 spaxels arranged in a sqrt(2): 1 aspect ratio contiguous field. The pre-optics take light entering the science cryostat (from the telescope or calibration system), reformatting and conditioning to be suitable for input for the rest of the instrument. This involves many functions, mainly relaying the light from the telescope focal plane to the integral field unit (IFU) focal plane via a set of interchangeable scale changing optics. The pre-optics also provides components including a focal plane mask wheel, cold pupil masks, spectral order sorting filters, a fast shutter, and a pupil imaging capability to check telescope/instrument pupil alignment. In this paper, we present the optical design of the HARMONI pre-optics at Preliminary Design Review and, in particular, we detail the differences with the previous design and the difficulties salved to the Preliminary Design Review.