Electronic Speckle Pattern Interferom-etry for JWVST

Development of many new technologies is required to successfully produce the large, lightweight, deployable, cryogenic telescope with segmented primary mirror for the James Webb Space Telescope (JWST) mission. One of the technologies is interferometry to verify structural deformations in large, deployable, lightweight, cryogenic, precision structures to nanometer level accuracy. An instantaneous acquisition phase shifting speckle interferometer was designed and built to support the development of JWST optical telescope element (OTE) primary mirror backplane. This paper discusses characterization of the electronic speckle pattern interferometer (SPS-DSPI) developed for JWST to verify its capability to measure structural deformations in large composite structures at cryogenic temperature.