Assembly and testing of the ESI camera

The Echellette Spectrograph and Imager (ESI), currently being delivered for use at the Cassegrain focus of the Keck II telescope employs an all-spherical, 308 mm focal length f/1.07 Epps camera. The camera consists of 10 lens elements in 5 groups: an oil-coupled doublet; a singlet, an oil- coupled triplet; a grease-coupled triplet; and a field flattener, which also serves as the vacuum-dewar window. A sensitivity analysis suggested that mechanical manufacturing tolerances of order +/- 25 microns were appropriate. In this paper we discuss the sensitivity analysis, the assembly and the testing of this camera.