US 2026/0219027 A1Published application

Method for determining a position of a target by optical interferometry and device for doing the same

AssigneeProdrive Technologies Innovation Services B.V.

InventorSybren ZWETSLOOT

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Abstract

Determining a position by differential optical interferometry of a target reflector in a measurement range includes coherent light beams generated at two wavelengths at two instances. First and second reference signals are generated by guiding first and third coherent light beams along first and third optical paths, respectively. A measure signal is generated by guiding a second coherent light beam along a second optical path having a target reflector. A first interference signal is generated from the first and second reference signals at the first and second instance. A second interference signal is generated from the measure signal and the second reference signal at the first and second instance. First and second signals are generated based on the interference signals and their amplitudes. A position of the target is determined as a difference between the first and second optical path lengths based on the first and second signal in both instances.

Claims28

Dependent claims

A method for determining a position by optical interferometry of a target reflector along a measurement range, the method comprising:

generating by modulation a first, a second, and a third coherent light beam at a first single wavelength at a first instance of time and at a second single wavelength different from the first single wavelength at a second instance of time,
generating a first reference signal by guiding the first coherent light beam along a first optical path, wherein the first optical path has a first optical path length,
generating a measure signal by guiding the second coherent light beam along a second optical path comprising the target reflector, wherein the second optical path has a second optical path length,
generating a second reference signal by guiding the third coherent light beam along a third optical path, wherein the third optical path has a third optical path length different from the first optical path length and the second optical path length,
providing a common delay between generating the second reference signal and generating the first reference signal and between generating the second reference signal and generating the measure signal,
generating a first interference signal from the first reference signal and a first portion of the second reference signal at the first instance of time and at the second instance of time,
generating a second interference signal from the measure signal and a second portion of the second reference signal at the first instance of time and the second instance of time,
determining a first amplitude of the first interference signal and a second amplitude of the second interference signal,
generating a first signal based on the first interference signal and the first amplitude,
generating a second signal based on the second interference signal and the second amplitude, and
determining a position of the target reflector by calculating a difference between the first optical path length and the second optical path length based on the first and the second signal both in the first and the second instance of time.

8 more elements

A device for determining by optical interferometry a position of a target reflector along a measurement range, the device comprising:

a light generating means comprising a light source configured to be modulated between a first state and a second state, wherein in the first state the light generating means is configured to generate light at a first single wavelength and in the second state the light generating means is configured to generate light at a second single wavelength different from the first single wavelength,
an optical means downstream of the light generating means configured to generate a first coherent reference signal, a coherent measure signal and a second coherent reference signal, the optical means comprising:
a first optical path configured to generate the first coherent reference signal by guiding light generated by the light source, wherein the first optical path has a first optical path length,
a second optical path comprising a movable target reflector and configured to generate the coherent measure signal by guiding light generated by the light source, wherein the second optical path has a second optical path length,
a third optical path configured to generate the second coherent reference signal by guiding light generated by the light source, wherein the third optical path has a third optical path length different from the first optical path length and the second optical path length,
wherein the optical means further comprises a delay path configured to provide a common delay between generating the second coherent reference signal and generating the first coherent reference signal and between generating the second coherent reference signal and generating the coherent measure signal,
a detecting means downstream of the optical means configured to generate a first interference signal between the first coherent reference signal and a first portion of the second coherent reference signal and to generate a second interference signal between the coherent measure signal and a second portion of the second coherent reference signal, and comprising a first detector, configured to detect the first interference signal and determine a first amplitude of the first interference signal, and a second detector, configured to detect the second interference signal and determine a second amplitude of the second interference signal, and configured to generate a first signal based on the first interference signal and the first amplitude, and to generate a second signal based on the second interference signal and the second amplitude, and
a processing means configured to determine a position of the target reflector by calculating a difference between the first optical path length and the second optical path length based on the first and second signal in both the first and the second state.

5 more elements

Dependencies are inferred from the claim text.