Equipment requirements No Title No Title

Introduction

The WYFFOS spectrograph, based on a Baranne white pupil design, was installed on its own optical table in the GHRIL room on one of the Nasmyth platforms of the WHT during March 1995. This document describes the alignment procedure as determined at the initial assembly at RGO, Cambridge, through 1994, and modified in 1995. Effectively, WYFFOS is a kit of optical components which have to be placed to a high tolerance at certain positions on the optical table. WYFFOS works in two modes - reflection and transmission. Some components are common to both modes. Light is fed into WYFFOS via optical fibres of either 2.5 arcsecs or 1.5 arcsecs diameter, the output from the fibres into WYFFOS being slowed to f/8.2. In both modes, light from the curved slit is directed towards collimator one, where it is ... collimated onto the grating or grism. In reflection mode, the light is then reflected back through the collimator towards a concave relay mirror, where an image is formed close to the mirror. The relay mirror directs this image towards the camera, where it is re-imaged onto the internal CCD. In transmission mode, the light passes through the grism, then a second collimator, where it forms an image close to another concave relay mirror, which directs the image towards the turned round camera.