High-performance real-time heterodyne interferometry

A novel system for real-time heterodyne interferometry of extended objects is demonstrated. Featured in this system is the direct measurement of the optical path difference, eliminating the sometimes troublesome interpretation of the fringe patterns of traditional interferometry. High spatial and temporal resolutions are available in real time for a properly instrumented system. The concept, its performance, and applications are presented along with results from a breadboard system, where phase accuracy of better than lambda/100 is demonstrated.