Cryogenic High Accuracy Refraction Measurements Capabilities and New FUV Coating Mirror Technology Developments

This talk will emphasize the basic principles of refractive materials used in an optical telescope. In particular, the presentation will describe refractive index measurements that were performed for one of the instruments on the James Webb Space Telescope (JWST). A refractive system design was implemented in the Near-Infrared Camera (NIRCam) which is one of the main instruments on the JWST observatory. This camera was designed to make observations in the infrared part of the optical spectrum, and it is required to operate in a space environment at temperatures as low as 25K. Therefore, it was imperative to know the refractive index at those low cryogenic temperatures for the various glass substrates (ZnSe, LiF and BaF2) used in the system design of NIRCam. These cryogenic index of refraction measurements were carried out by using the world-class refractometer called the Cryogenic High Accuracy Refraction Measuring System (CHARMS) facility that was designed and built at the Goddard Space Flight Center (GSFC) in Greenbelt, MD.

In the second part, there will be a discussion of the recent advances on the research and development activities of advanced and new mirror coating technologies that provide high reflectance performance in the far-ultraviolet (FUV) part of the optical spectrum. These new mirror coatings are envisioned for use on the reflecting mirrors of the next mission (beyond JWST) that will focus on astronomical observations in the FUV spectral range to deliver new and exciting discoveries about the origin of the cosmos.