Ultra-stable wide field of regard electronic autocollimator (UWFOREA) and its applications

Recent advances in a unique, pattern-recognition, electronic autocollimator called the Ultra-stable Wide Field of Regard Electronic Autocollimator (UWFOREA, pronounced “euphoria”) engineered at Leviton Metrology Solutions (LMS) in Boulder, CO are presented. A measurement system using this autocollimator called the Inter-target Differential Electronic Autocollimator (IDEA) is capable of making differential angular measurements between a target flat and a flat base reference mirror with 30 nrad accuracy. This measurement approach largely nullifies environmental influences on angle measurements and makes it possible to test payloads at extreme temperatures in thermal vacuum environments with exquisite accuracy. For shorter focal length versions of UWFOREA, the system can measure over an astounding and unprecedented +/-10° angular range with 1 μrad rms calibrated accuracy. The internal stability of UWFOREA has been demonstrated to be as low as 5 nrad rms with only modest temperature control of about 1 C. Select UWFOREA and IDEA data for critical calibrations for a number of space-flight missions and GSE systems are presented.