EXTREMELY ACHROMATIC F 1.0 ALL-SPHERICAL CAMERA CONSTRUCTED FOR THE HIGH-RESOLUTION ECHELLE SPECTROMETER OF THE KECK TELESCOPE/

We present a very large f/1.0 prime focus, all-spherical, all-fused-si lica catadioptric camera. It contains a two-element airspaced correcto r, an f/0.76 primary mirror, and a singlet final element. It accommoda tes a chromatic range from 0.3 to 1.1 mum or more without refocus. It is optimized with an external entrance pupil but can be reoptimized fo r other pupil distances. In spite of its 30-in. (76.2-cm) focal length , it delivers 12.6-mum (rms) average image diameters to a 3.6-in.-(9.1 -cm-) diameter flat focal surface. It is thus well matched to the (7-1 5-mum) pixels and to the size of a (2 x 2) mosaic of today's largest a vailable CCD's.