Interferometric determination of distance change with laser diode, high bandwidth detection and fast signal processing

摘要

Method and systems for determining a change of distance to an object by interferometry with emitting measurement laser light from a laser diode are disclosed. The method may include receiving at least a part of the measurement laser light, superimposing the reflected measurement laser light with a reference laser light and thereby providing at an interferometric phase and determining the change of distance to the object depending on the superimposition. In some embodiments, the measurement laser light may be emitted with low coherence and broad spectral bandwidth. An emitting wavelength of the measurement laser light may be fluctuating hop-freely within the spectral bandwidth causing interferometric phase fluctuations.

主权项

1. A method for determining a change of distance to an object by interferometry with emitting measurement laser light from a laser diode,
receiving at least a part of the measurement laser light reflected from the object, superimposing the reflected measurement laser light with a reference laser light and thereby providing an interferometric phase and determining the change of distance to the object depending on the superimposition, wherein the measurement laser light being emitted with low coherence and broad spectral bandwidth, wherein an emitting wavelength of the measurement laser light is fluctuating hop-freely within the spectral bandwidth causing interferometric phase fluctuations, wherein the measurement laser light is emitted with a coherence length between one and three meters, continuously detecting the interferometric phase with a first detection rate, the detection rate and a rate for processing of the detected interferometric phase being high enough that the interferometric phase fluctuations are continuously incrementally tracked so that successive interferometric phase states provided by successive detections of the interferometric phase differ by a phase shift of less than π, averaging the detected phase fluctuations for a defined averaging time period and deriving an averaged phase, and determining the change of distance to the object with a second detection rate in dependency on the averaged phase, the second detection rate being correlated with the averaging time period.