Interferometric dual-comb distance measuring device and measuring method
AssigneeHexagon Technology Center GmbH
InventorsThomas Jensen, Frank Pryzgodda
Life of this patent
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Abstract
An opto-electronic dual-comb interferometric distance measuring method and device wherein a signal comb is chromatically divided into a target signal comb and a non-target signal comb at a emission position, preferably by an optical interleaver in a measurement probe of the device. Only the target signal comb serves as a free beam emitted to the target. The non-target signal comb serves for generation of additional or compensation internal phase differences. Thus, the distance to the target is based on first, target related phase differences and on the second, internal compensation phase differences.
Claims16
An opto-electronic dual-comb interferometric distance measuring method for measuring a distance to a target comprising:
- generating first frequency comb radiation—denoted local comb—and
- generating second frequency comb radiation—denoted signal comb—
- generating of first beat frequencies—denoted reference beat frequencies—by superposing of a local comb and signal comb having travelled along defined optical paths,
- generating of second beat frequencies—denoted measurement beat frequencies—by superposing of local comb having travelled along a defined optical path and signal comb having travelled to and back from the target as a free beam from an emission position,
- determining of first phase differences, in particular in form of a first gradient of phase difference, between the reference beat frequencies and the measurement beat frequencies,
- chromatically dividing signal comb into a target signal comb and a non-target signal comb at the emission position, only the target signal comb serving as said free beam emitted to the target,
- generating of third beat frequencies—denoted compensation beat frequencies—by superposing of local comb having travelled along a defined optical path and the non-target signal comb,
- determining of second phase differences, in particular in form of a second gradient of phase difference, between the reference beat frequencies and the compensation beat frequencies, and
- determining the distance to the target based on the first and the second phase difference.
An opto-electronic dual-comb interferometric distance measuring device for measuring a distance to a target, the device comprising
- a first frequency comb source for providing a first frequency comb radiation—denoted local comb—and
- a second frequency comb source for providing a second frequency comb radiation,—denoted signal comb—and
- an electronic analyzing unit,
- the electronic analyzing unit being designed for determination of a distance to a target based on first phase differences, in particular in form of a first gradient of phase difference, between:
- first beat frequencies—denoted reference beat frequencies—generated by superposition of first internally travelling local comb and internally travelling signal comb, and
- second beat frequencies—denoted measurement beat frequencies—generated by superposition of second internally travelling local comb and signal comb travelling to and back from the target as a free beam by emission by a measurement probe,
- wherein the device is configured to determinate a distance to a target based on the first phase differences and on second phase differences, in particular in form of a second gradient of phase difference, of third beat frequencies—denoted compensation beat frequencies—and the reference beat frequencies and
- wherefore:
- the measurement probe comprises a first frequency comb separation element for chromatic division of signal comb before emitting into non-target signal comb and target signal comb, only the target signal comb serving as said free beam, and the compensation beat frequencies being generated by superposition of second internally travelling local comb and the internally travelling non-target signal comb.
Dependencies are inferred from the claim text.