INTERFEROMETRIC DETERMINATION OF AN OBJECT'S POSITION USING A LOW FREQUENCY AND/OR PHASE-MODULATED COHERENT LIGHT BEAM AND A KALMAN FILTER

摘要

According to the invention, for the purpose of interferometric determination of the position of an object (9), a coherent light beam (4) is split into two parts (6, 7), a first of the two parts (6) is reflected by the object, a second of the two parts (7) is reflected by a reference object (11), the reflected first and second parts (6, 7) are superimposed on a photodetector (12), the light beam (4) is modulated with respect to the frequency thereof and/or one of the two parts of the light beam (4) is modulated with regard to the phase thereof with a low frequency of modulation (16) and a signal (13) indicating a light intensity on the photodetector (12) is evaluated taking into consideration the low frequency of modulation (16), with scanned values (23) of the signal (13) being continuously supplied to a Kalman filter (17) which displays the position of the object (9) as an element of a state vector (24').