Transmitted Wavefront Metrology on Large Domes and Windows

The economical fabrication of hemispherical missile domes is a key driver for the Joint Common Missile program. An essential, and unsolved, part of the fabrication process is the fast and accurate measurement of the transmitted-wavefront error of the hemispherical dome over its full aperture. In the proposal we describe the development of a prototype interferometer for solving this measurement problem. The interferometer that is proposed is insensitive to alignment yet provides to measure the entire aperture in double-pass without stitching and is configured in a manner that is relatively insensitive to alignment of the dome to the instrument. The measurement data provided by this instrument is essential to providing feedback to a deterministic final figuring process, most likely a magnetorheological based technology. The effort is divided into two major phases: a breadboard and a prototype instrument. The breadboard will be based almost entirely on catalog components to allow for rapid implementation so that software can be developed and tested quickly. The distinction between the breadboard and prototype will allow for incorporation of performance and ease-of-use features to support low-rate initial dome production.