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US 10,852,120 B2Granted
Length metrology apparatus and methods for suppressing phase noise-induced distance measurement errors
AssigneeBridger Photonics, Inc.
InventorsMichael Thorpe, Aaron Kreitinger, Randy Reibel
Life of this patent
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Abstract
Length metrology apparatuses and methods are disclosed for measuring both specular and non-specular surfaces with high accuracy and precision, and with suppressed phase induced distance errors. In one embodiment, a system includes a laser source exhibiting a first and second laser outputs with optical frequencies that are modulated linearly over large frequency ranges. The system further includes calibration and signal processing portions configured to determine a calibrated distance to at least one sample.
Claims24
A method comprising:
- producing a first laser chirp and a second laser chirp, wherein at least one of the first laser chirp and the second laser chirp is an optical frequency sideband;
- directing the first and the second laser chirp towards an object;
- receiving a first interference signal based, at least in part, on the interaction of the first laser chirp with the object;
- receiving a second interference signal based, at least in part, on the interaction of the second laser chirp with the object;
- and
- processing the first interference signal and the second interference signal to determine a range to the object.
3 more elements
A method comprising:
- producing a laser output beam including at least one chirped optical frequency sideband;
- directing the laser output beam including the at least one chirped optical frequency sideband towards an object;
- receiving interference signals using at least one optical detector, wherein each interference signal represents interference between a local oscillator signal and a return signal from the object, the local oscillator signal and the return signal being chirped signals including multiple chirps each having a chirp duration, and wherein the return signal is based on an interaction of the laser output and the object;
- and
- determining a distance to at least a portion of the object, at least in part by calculating a respective phase of the interference signals as a function of time over a respective chirp duration.
2 more elements
A system comprising:
- a laser source configured to produce a laser output including at least one chirped sideband;
- an optical system configured to direct the laser output towards an object and receive light from the object;
- a beam scanner configured to scan the laser output across at least a portion of the object;
- a detector configured to produce a signal based on the received light;
- and
- a processor configured to determine a distance to the object based on the signal.
3 more elements
Dependencies are inferred from the claim text.