Identification and correction of cyclic errors in the interferometry for distance measurement and dispersion measurement

摘要

The invention features interferometry systems that characterize cyclic errors. In many embodiments, the systems include a phase-shifting component (81), such as a phase shifter or frequency shifter, for introducing a variable and controlled phase between the reference and measurement beams of an interferometer (69). By analyzing the distance measurements of the interferometer (69) as a function of the introduced phase, an analyzer (27, 29) in the interferometry system can characterize the cyclic errors in the interferometer. Once the cyclic errors are characterized, the analyzer (27, 29) can directly correct the distance measurements to remove contributions from cyclic errors.