Infrared Imaging with COAST John Stephen Young St John's College, Cambridge and Cavendish Astrophysics A dissertation submitted for the degree of Doctor of Philosophy in the University of Cambridge 26 March 1999 iii Preface This dissertation describes work carried out in the Astrophysics Group of the Department of Physics, University of Cambridge, between October 1995 and March 1999. Except where explicit reference is made to the work of others, this dissertation is the result of my own work, and includes