This report documents activities carried in support of the design and construction of an ultra-high precision measuring machine intended for the support of Extreme Ultraviolet Lithography development (for semiconductor fabrication). At the outset, this project was aimed at the overall fabrication of such a measuring machine. Shortly after initiation, however, the scope of activities was reduced and effort was concentrated on the key technical advances necessary to support such machine development: high accuracy surface sensing and highly linear distance interferometry.