Multiple pixel scanning lidar
Methods and systems for performing three-dimensional (3-D) LIDAR measurements with multiple illumination beams scanned over a 3-D environment are described herein. In one aspect, illumination light from each LIDAR measurement channel is emitted to the surrounding environment in a different direction by a beam scanning device. The beam scanning device also directs each amount of return measurement light onto a corresponding photodetector. In some embodiments, a beam scanning device includes a scanning mirror rotated in an oscillatory manner about an axis of rotation by an actuator in accordance with command signals generated by a master controller. In some embodiments, the light source and photodetector associated with each LIDAR measurement channel are moved in two dimensions relative to beam shaping optics employed to collimate light emitted from the light source. The relative motion causes the illumination beams to sweep over a range of the 3-D environment under measurement.
1. A computer system, comprising:
a processor; and
a memory communicatively coupled to the processor, the memory having instructions stored thereon, which when executed by the processor, cause the computer system to:
generate a first signal configured to cause at least one illumination source to emit illumination light into a three-dimensional (3-D) environment;
generate a second signal configured to cause an actuator to move a beam scanning device to redirect the illumination light from the at least one illumination source to the 3-D environment, wherein the beam scanning device is disposed in an optical path between the at least one illumination source and at least one photo detector;
receive, from the at least one photo detector, a third signal indicative of a detected amount of return light reflected from the 3-D environment illuminated by the illumination light, wherein the return light enters a receiving end of the at least one photo detector from a beam shaping element interposed between the at least one photo detector and the beam scanning device;
before receiving the third signal, receive a fourth signal indicative of a detected amount of light due to internal cross talk when the at least one illumination source emits the illumination light;
measure a difference between a first time when the fourth signal is received and a second time when the third signal is received;
determine a distance between the at least one illumination source and an object in the 3-D environment based on the measured difference; and
generate an output based on the distance.
2. The computer system of claim 1 , wherein the beam scanning device is configured to redirect the return light to the at least one photo detector, the at least one photo detector being configured to generate the third signal in response to detecting the amount of return light.
3. The computer system of claim 1 , wherein the beam scanning device is a single mirror apparatus, and wherein causing the actuator to move the beam scanning device includes rotating the single mirror apparatus about a rotation axis.
4. The computer system of claim 1 , wherein the emitted illumination light passes through the beam shaping element prior to being redirected by the beam scanning device so that a direction of the redirected illumination light is perpendicular with respect to a direction of the emitted illumination light passing through the beam shaping element.
5. The computer system of claim 1 , wherein the output is indicative of the distance between the at least one illumination source and the object in the 3-D environment.
6. The computer system of claim 1 , wherein the memory has further instructions stored thereon, which when executed by the processor, cause the computer system to further:
measure another difference between a first time when the first signal was generated and a second time when the third signal was received; and
the determined distance between the at least one illumination source and the object in the 3-D environment is further based on the other measured difference.
7. The computer system of claim 1 , wherein the internal cross talk occurs between the at least one illumination source and the at least one photo detector.
8. A method, comprising:
generating a first signal configured to cause at least one illumination source to emit illumination light into a three-dimensional (3-D) environment;
generating a second signal configured to cause an actuator to move a beam scanning device to redirect the illumination light from the at least one illumination source to the 3-D environment, wherein the beam scanning device is disposed in an optical path between the at least one illumination source and at least one photo detector;
receiving, from the at least one photo detector, a third signal indicative of a detected amount of return light reflected from the 3-D environment illuminated by the illumination light, wherein the return light enters a receiving end of the at least one photo detector from a beam shaping element interposed between the at least one photo detector and the beam scanning device;
before receiving the third signal, receiving a fourth signal indicative of a detected amount of light due to internal cross talk when the plurality of illumination sources emit the illumination light;
measuring a difference between a first time when the fourth signal is received and a second time when the third signal is received;
determining a distance between the plurality of illumination sources and an object in the 3-D environment based on the measured difference; and
generating an output based on the distance.
9. The method of claim 8 , wherein the beam scanning device redirects the return light to the at least one photo detector, the at least one photo detector being configured to generate the third signal in response to detecting the amount of return light.
10. The method of claim 8 , wherein the beam scanning device is a single mirror apparatus, and wherein causing the actuator to move the beam scanning device includes rotating the single mirror apparatus about a rotation axis.
11. The method of claim 8 , wherein the emitted illumination light passes through the beam shaping element prior to being redirected by the beam scanning device so that a direction of the redirected illumination light is perpendicular with respect to a direction of the emitted illumination light passing through the beam shaping element.
12. The method of claim 8 , wherein the output is indicative of the distance between the at least one illumination source and the object in the 3-D environment.
13. The method of claim 8 , further comprising:
measuring another difference between a first time when the first signal was generated and a second time when the third signal was received; and
the determined distance between the at least one illumination source and the object in the 3-D environment is further based on the other measured difference.
14. The method of claim 8 , wherein the internal cross talk occurs between the at least one illumination source and the at least one photo detector.
15. A non-transitory computer readable storage medium having instructions stored thereon, the instructions, when executed by one or more processors of a computer system, cause the computer system to perform acts comprising:
generating a first signal configured to cause at least one illumination source to emit illumination light into a three-dimensional (3-D) environment;
generating a second signal configured to cause an actuator to move a beam scanning device to redirect the illumination light from the at least one illumination source to the 3-D environment, wherein the beam scanning device is disposed in an optical path between the at least one illumination source and at least one photo detector;
receiving, from the at least one photo detector, a third signal indicative of a detected amount of return light reflected from the 3-D environment illuminated by the illumination light, wherein the return light enters a receiving end of the at least one photo detector from a beam shaping element interposed between the at least one photo detector and the beam scanning device;
before receiving the third signal, receiving a fourth signal indicative of a detected amount of light due to internal cross talk when the plurality of illumination sources emit the illumination light;
measuring a difference between a first time when the fourth signal is received and a second time when the third signal is received;
determining a distance between the plurality of illumination sources and an object in the 3-D environment based on the measured difference; and
generating an output based on the third signal.