The bench is under cryogenic temperatures and support the 8 mirrors, the detector, the filter wheel and the focal plane mechanisms. The minimum enveloppe is given by the size of the optical design. The general picture of the bench is a flat rectangular plate with a structure in the bottom to support the liquid nitrogen can in the bottom without perturbations of the flatness by the gas pressure. A unique and specialized solution to optical testing surfaced in our discussion with Janos Technology.
Instead of testing each optic separately to ensure that it is within specification, the entire system is tested as a whole. This novel technique encompasses the bench, bracket, and mirrors, and allows for immediate correction of alignment problems in situ. However, this method requires to define perfectly all the elements in the bench before start polishing mirrors. Although this delays the beginning of manufacturing until the design is totally defined the step of aligment and testing is considerably faster. We show the global design of the bench with the holes for all the systems and attachments.
In order to manufacture ourself the bench reducing the cost and the manufacturing time we decided to split the bench into three pieces. One piece for the camera, one for the collimator and a piece for the filter box. Because of the method to polish mirrors small misalignement between pieces will be compensated at the optical testing by Janos. Flexures will not either be affected since most of the stiffness is given by the semicylindrical structure of the can on the bottom of the bench. In addition, a structure supports the flat plates of the bench as shown in the following diagram.