Interferometric determination of an object position using a low-frequency and / or phase-modulated coherent light beam and a Kalman filter

摘要

For interferometric determination of the position of an object (9) a coherent light beam (4) is divided into two parts (6, 7), a first of the two parts (6) is reflected by the object, a second of the two parts (7) reflected from a reference object (11), the reflected first and second parts (6, 7) are superimposed on a photodetector (12), the light beam (4) with respect to its frequency and / or one of the two parts of the light beam (4) modulates its phase with low modulation frequency (16) and a light intensity on the photodetector (12) indicative signal (13) is evaluated taking into account the low modulation frequency (16) by samples (23) of the signal (13) continuously a Kalman filter (17) indicating the position of the object (9) as an element of a state vector (24 ').