Patent ID: 11885607
Assignee: DR. JOHANNES HEIDENHAIN GMBH
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A device for interferometric distance measurement, comprising:
a multi-wavelength light source adapted to emit a beam having at least three different wavelengths;
an interferometer unit adapted to split the beam into a measuring beam that propagates inside a measuring arm in a direction of a measuring reflector movable along a measuring axis and that is back reflected by the measuring reflector and a reference beam that propagates inside a reference arm in a direction of a stationary reference reflector and that is back reflected by the stationary reference reflector and to interferingly superimpose the back-reflected measuring and reference beams in an interference beam;
a detection unit adapted to split the interference beam to produce a plurality of phase-shifted partial interference signals for each wavelength;
a signal processing unit adapted to determine absolute position information relating to the measuring reflector from the partial interference signals for different wavelengths and an additional coarse position signal; and
a modulation unit adapted to impress a phase modulation on at least one wavelength in the emitted beam of the multi-wavelength light source, resulting in a phase-modulated beam propagating toward the interferometer unit and causing a distance-dependent modulation in at least one partial interference signal, for generating the coarse position signal.