Multi-static coherent LiDAR

Patent metadata

Field	Value
Publication number	US-11525915-B2
Application number	US-202016825556-A
Country	US
Kind code	B2
Filing date	Mar 20, 2020
Priority date	May 3, 2018
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

At least one beam of an optical wave is transmitted along a transmission angle toward a target location from a send aperture of a transmitter. The optical wave comprises at least a first portion, and a second portion having a different characteristic from a characteristic of the first portion. Two or more receivers include at least one receiver comprising: a receive aperture arranged in proximity to at least one of the send aperture or a receive aperture of a different receiver, an optical phased array within the receive aperture, the optical phased array being configured to receive at least a portion of a collected optical wave arriving at the receive aperture along a respective collection angle, and a filter configured to filter the received portion of the collected optical wave according to the characteristic of the first portion of the optical wave.

First claim

What is claimed is:

1. An apparatus, comprising:
at least one transmitter comprising a send aperture configured to provide at least one beam of a transmitted optical wave along a transmission angle toward a target location, the optical wave comprising at least a first portion of the optical wave, and a second portion of the optical wave having a different characteristic from a characteristic of the first portion of the optical wave; and
two or more receivers, at least one receiver comprising:
a receive aperture arranged in proximity to at least one of the send aperture or a receive aperture of a different receiver,
an optical phased array within the receive aperture, the optical phased array being configured to receive at least a portion of a collected optical wave arriving at the receive aperture along a respective collection angle,
a filter configured to filter the received portion of the collected optical wave according to the characteristic of the first portion of the optical wave, and
a detector configured to provide a signal based on the filtered portion of the collected optical wave.

2. The apparatus of claim 1 , wherein each detector comprises a coherent detector configured to optically combine the received portion of the collected optical wave with a local oscillator optical wave to provide a combined optical wave and to detect the combined optical wave to provide the signal.

3. The apparatus of claim 2 , wherein there is a frequency shift between the local oscillator and the transmitted optical wave to enable heterodyne detection in coherent detectors.

4. The apparatus of claim 2 , wherein each signal comprises an amplitude and a phase angle, and the respective component corresponding to that signal comprises a quantity that is based on the amplitude and is independent from the phase angle.

5. The apparatus of claim 4 , wherein the circuitry is configured to convert each signal to digital form and to process the signals in digital form to remove dependence on the phase angles.

6. The apparatus of claim 4 , wherein at least one coherent detector is configured to use a first local oscillator optical wave to provide an in-phase combined optical wave and to use a second local oscillator optical wave shifted relative to the first local oscillator wave to provide a quadrature combined optical wave, and to provide the amplitude and phase angle in an In-phase/Quadrature (I/Q) space.

7. The apparatus of claim 4 , wherein the circuitry is configured to perform a transform on a real-valued signal provided from one of the detectors to provide the amplitude and phase angle in a complex space of a resulting complex transform of the real-valued signal.

8. The apparatus of claim 2 , wherein each detector is configured to generate a current that represents a difference between photocurrents generated by a pair of balanced photodetectors.

9. The apparatus of claim 1 , wherein a total quantity of the receive apertures is between 3 and 20.

10. The apparatus of claim 9 , wherein a total quantity of the receive apertures is between 4 and 10.

11. The apparatus of claim 9 , wherein a total quantity of send apertures is 1.

12. The apparatus of claim 1 , wherein an area of each receive apertures is equal to an area of the send aperture within a factor of between 4/9 to 9/4.

13. The apparatus of claim 1 , wherein the receive apertures are arranged along an axis in a plane in which the optical phased arrays are configured to provide steering of the respective collection angles using phases of elements of the optical phased arrays.

14. The apparatus of claim 1 , wherein each of the optical phased arrays of the receivers is configured to align the respective collection angle with the target location.

15. The apparatus of claim 1 , wherein the transmitter comprises an optical phased array within the send aperture.

16. The apparatus of claim 15 , wherein an area of each optical phased array within the receive apertures is equal to an area of the optical phased array with the send aperture within a factor between 4/9 to 9/4.

17. The apparatus of claim 15 , wherein at least one optical phased array within the send aperture or at least one of the receive apertures is configured to steer a first angle using phases of elements of the optical phased array and to steer a second angle using wavelength.

18. The apparatus of claim 1 , wherein the receiver is a first receiver, the receive aperture is a first receive aperture, the optical phased array is a first optical phased array, the filter is a first filter, the detector is a first detector, and the two or more receivers include a second receiver comprising:
the send aperture configured as a second receive aperture,
a second optical phased array within the send aperture, the second optical phased array being configured to receive at least a portion of a collected optical wave arriving at the send aperture along a respective collection angle,
a second filter configured to filter the received portion of the collected optical wave according to a characteristic different from the characteristic of the first portion of the optical wave and different from the characteristic of the second portion of the optical wave, and
a second detector configured to provide a signal based on the filtered portion of the collected optical wave filtered by the second filter.

19. The apparatus of claim 1 , further comprising circuitry configured to determine an estimated distance associated with the collected optical wave based at least in part on a combination that includes a respective component corresponding to each of two or more of the signals provided from the detectors of the two or more receivers.

20. The apparatus of claim 19 , wherein the transmitter applies linear frequency modulation to the transmitted optical wave to enable the circuitry to determine the estimated distance.

21. The apparatus of claim 1 , wherein the send aperture is further configured as a receive aperture in which an optical phased array is used to receive at least a portion of an optical wave having a different characteristic from a characteristic of the transmitted optical wave, and at least one of the receive apertures is used as a send aperture for providing a beam of an optical wave having the different characteristic.

22. The apparatus of claim 1 , wherein the characteristics comprise at least one of: a particular wavelength, a particular time slot, or a particular polarization.

23. The apparatus of claim 22 , wherein the characteristics comprise a particular wavelength.

24. The apparatus of claim 23 , wherein one or more optical sources provide a plurality of spectral components tunable over different respective spectral bands, and the first portion of the optical wave comprises a first spectral component and the second portion of the optical wave comprises a second spectral component different from the first spectral component.

25. The apparatus of claim 24 , further comprising the one or more optical sources.

26. The apparatus of claim 24 , wherein the send aperture is further configured as a receive aperture in which an optical phased array is used to receive a third spectral component different from the first spectral component and different from the second spectral component.

27. The apparatus of claim 26 , wherein the third spectral component has a wavelength between a wavelength of the

Assignees

• Analog Photonics LLC

Inventors

• Russo Peter Nicholas
• Poulton Christopher Vincent
• Byrd Matthew
• Su Zhan
• Hosseini Ehsan
• Watts Michael Robert

Classifications

• G01S7/4816

  of receivers alone · CPC title

• G01S17/32 Primary

  using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated · CPC title

• G01S7/4911

  Transmitters · CPC title

• G01S7/4918

  Controlling received signal intensity, gain or exposure of sensor · CPC title

• G01S7/4815

  using multiple transmitters · CPC title