The JWST Mid-Infrared Instrument (MIRI) is designed to meet the JWST science requirements for mid-IR capabilities
and includes an Imager MIRIM provided by CEA (France). A double-prism assembly (DPA) allows MIRIM to perform
low-resolution spectroscopy. The MIRIM DPA shall meet a number of challenging requirements in terms of optical and
mechanical constraints, especially severe optical tolerances, limited envelope and very high vibration loads.
The University of Cologne (Germany) and the Centre Spatial de Liege (Belgium) are responsible for design,
manufacturing, integration, and testing of the prism assembly. A companion paper (Fischer et al. 2008) is presenting the
science drivers and mechanical design of the DPA, while this paper is focusing on optical manufacturing and overall
The first part of this paper describes the manufacturing of Zinc-sulphide and Germanium prisms and techniques to ensure
an accurate positioning of the prisms in their holder. (1) The delicate manufacturing of Ge and ZnS materials and (2) the
severe specifications on the bearing and optical surfaces flatness and the tolerance on the prism optical angles make this
process innovating. The specifications verification is carried out using mechanical and optical measurements; the
implemented techniques are described in this paper.
The second part concerns the qualification program of the double-prism assembly, including the prisms, the holder and
the prisms anti-reflective coatings qualification. Both predictions and actual test results are shown.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.