Coupled lasers for coherent distance and velocity measurements
AssigneeWaymo LLC
InventorsMichael R. Matthews, Bryce Remesch, John Lam
Life of this patent
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Abstract
The subject matter of this specification can be implemented in, among other things, systems and methods that enable lidar channel multiplexing using optical locking of separate lasers while simultaneously imparting different frequency offsets to beams output by different lasers. As a result, received beams reflected from various objects, which are present in an outside environment, can have Doppler-shifted frequencies that do not overlap, facilitating concurrent identification of distances to and velocities of multiple objects.
Claims20
A system comprising:
- a first light source configured to produce a first beam having a first frequency;
- a second light source configured to produce a second beam;
- a first optical feedback loop configured to set a frequency of the second beam to a second frequency, wherein the second frequency is different from the first frequency by a first offset frequency;
- and
- an optical detection subsystem configured to:
- receive a reflected beam produced upon interaction of the second beam with an object in an outside environment;
- and
- determine, based on a phase difference between the reflected beam and a copy of the first beam, at least one of a velocity of the object or a distance to the object.
A sensing system of an autonomous vehicle (AV), comprising:
- a first light source configured to produce a first beam having a first frequency;
- a second light source configured to produce a second beam;
- a first optical feedback loop configured to lock a frequency of the second beam to a second frequency, wherein the second frequency is different from the first frequency by a first offset frequency;
- a third light source configured to produce a third beam;
- a second optical feedback loop configured to lock a frequency of the third beam to a third frequency, wherein the third frequency is different from the first frequency by a second offset frequency;
- an optical interface configured to output the second beam and the third beam to a driving environment of the AV;
- and
- an optical detection subsystem configured to:
- receive a first reflected beam, wherein the first reflected beam is produced upon interaction of the second beam with a first object in the driving environment of the AV, and wherein the first reflected beam is time-delayed and Doppler-shifted relative to the second beam;
- and
- determine, based on a first time delay and a first Doppler shift of the first reflected beam relative to the second beam, a velocity of the first object and a distance to the first object.
A method comprising:
- producing a first beam having a first frequency;
- producing a second beam;
- setting, using a first optical feedback loop, a frequency of the second beam to a second frequency, wherein the second frequency is different from the first frequency by a first offset frequency;
- receiving a reflected beam produced upon interaction of the second beam with an object in an outside environment;
- and
- determining, based on a phase difference between the reflected beam and a copy of the first beam, at least one of a velocity of the object or a distance to the object.
Dependencies are inferred from the claim text.