EVALUATION DEVICE, MEASURING ARRANGEMENT AND METHOD FOR PATH LENGTH MEASUREMENT

摘要

An evaluation device (51) for path length measurement is adapted to evaluate a measured signal (15) which represents an intensity of a sequence of pulses of electromagnetic radiation as a function of time. The sequence of pulses has a repetition rate. The evaluation device (51) is adapted to evaluate a phase difference between a component (63) of the measured signal (15), which component oscillates with a first frequency, and a reference signal (67) which oscillates with said frequency. The evaluation device (51) produces, for example by frequency mixing, a first signal (65) and a second signal (69) having a second phase difference (73) in such a manner that the first signal (65) and the second signal (69) each oscillates with another frequency that is different from the frequency, and such that the second phase difference (73) has a predetermined relation to the phase difference (47).