LiDAR scanner
A LiDAR sensor can include a laser, a directional sensor, a window, an electromagnetic pulse receiving sensor, and a processor. The laser can be configured to emit a narrow electromagnetic pulse. Further, the directional sensor can be configured to measure the direction of the narrow electromagnetic pulse emitted by the laser. The narrow emitted electromagnetic pulse can pass through the window. The pulse can then be reflected by at least the window and an object external from the LiDAR sensor, creating at least two reflected pulses. The electromagnetic pulse receiving sensor can be configured to measure the two reflected pulses resulting from the narrow pulse emitted by the laser. The processor can be configured to receive information from the sensors, indicating a position of the object relative to the LiDAR sensor. Further, the processor can be configured to measure the intensity of the pulse being reflected by the window.
1. A LiDAR sensor comprising:
a laser configured to emit an electromagnetic pulse;
a window through which the electromagnetic pulse emitted by the laser passes;
an electromagnetic pulse receiving sensor configured to measure at least two reflected pulses resulting from the electromagnetic pulse emitted by the laser, the at least two reflected pulses comprising a first pulse being reflected by the window and a second pulse being reflected by an object external from the LiDAR sensor; and
a processor configured to receive information from the electromagnetic pulse receiving sensor indicating a position of the object relative to the LiDAR sensor, the processor further configured to measure an intensity of the first pulse and estimate a reflectance of the object based at least in part on the intensity of the first pulse.
2. The LiDAR sensor of claim 1 , wherein the processor is further configured to compare the intensity of the first pulse with a reference intensity, the intensity of the first pulse being at least partially indicative of a state of the window.
3. The LiDAR sensor of claim 2 , wherein the processor is further configured to indicate to a user when the intensity of the first pulse exceeds the reference intensity.
4. The LiDAR sensor of claim 1 , wherein the processor is further configured to measure an intensity of the second pulse.
5. The LiDAR sensor of claim 1 , wherein the electromagnetic pulse emitted by the laser is conducted through at least one optical fiber.
6. The LiDAR sensor of claim 5 , wherein the electromagnetic pulse emitted by the laser is split among a plurality of optical fibers with a first optical fiber directing a first split pulse through the window, the first split pulse causing the at least two reflected pulses, and a second optical fiber directing a calibration pulse internally toward the electromagnetic pulse receiving sensor.
7. The LiDAR sensor of claim 6 , wherein the processor is further configured to compare an intensity of the second pulse to an intensity of the calibration pulse.
8. The LiDAR sensor of claim 6 , wherein the processor is further configured to compare the intensity of the first pulse window to an intensity of the calibration pulse.
9. The LiDAR sensor of claim 1 , wherein the window substantially protects one or more internal components of the LiDAR sensor from an external environment.
10. The LiDAR sensor of claim 1 , wherein the second pulse returns to the LiDAR sensor and is measured by the electromagnetic pulse receiving sensor through the window.
11. The LiDAR sensor of claim 1 , wherein the processor is configured to determine when a time derivative or slope of the intensity of the first pulse exceeds a threshold slope.
12. The LiDAR sensor of claim 1 , wherein the electromagnetic pulse comprises a laser pulse having a pulse width between 1 and 10 nanoseconds.
13. A method of accounting for an unclean or damaged window on a LiDAR sensor, the method comprising:
emitting an electromagnetic pulse through a window of the LiDAR sensor;
receiving a first reflected pulse caused by the emitted electromagnetic pulse being reflected from the window;
measuring an intensity of the first reflected pulse;
receiving a second reflected pulse caused by the emitted electromagnetic pulse being reflected from an external object;
measuring a time of receipt of the second reflected pulse from the external object to indicate a distance from the external object; and
based at least in part on the intensity of the first reflected pulse, estimate a reflectance of the external object.
14. The method of claim 13 , further comprising comparing the intensity of the first reflected pulse with a reference intensity, the intensity of the first reflected pulse being at least partially indicative of a state of the window.
15. The method of claim 14 , further comprising indicating to a user when the intensity of the first reflected pulse exceeds the reference intensity.
16. The method of claim 14 , wherein the reference intensity is determined in relation to a baseline intensity representative of a reflected pulse from a clean and undamaged window.
17. The method of claim 14 , further comprising measuring a pulse reflected by a clean and undamaged window to determine a baseline intensity and using the baseline intensity to determine the reference intensity, the reference intensity being greater than the baseline intensity.
18. The method of claim 13 , further comprising measuring an intensity of the second reflected pulse to further estimate the reflectance of the external object.
19. The method of claim 18 , wherein estimating the reflectance of the external object comprises adjusting the estimated reflectance of the external object using the intensity of the first reflected pulse.
20. The method of claim 13 , wherein measuring the time of receipt of the second reflected pulse comprises determining when a time derivative or slope of the intensity of the second reflected pulse exceeds a threshold slope.
21. The method of claim 13 , wherein the electromagnetic pulse comprises a laser pulse having a pulse width between 1 and 10 nanoseconds.
22. A LiDAR sensor comprising:
a laser configured to emit an electromagnetic pulse;
an electromagnetic pulse receiving sensor configured to measure an intensity of a first reflected pulse resulting from the electromagnetic pulse emitted by the laser being reflected from a window, and a second reflected pulse being reflected by an object external from the LiDAR sensor; and
a processor configured to determine a time of receipt of the second reflected pulse according to an estimated time of a peak intensity of the second reflected pulse, the processor being further configured to estimate a reflectance of the object based at least in part on the intensity of the first reflected pulse.
23. The LiDAR sensor of claim 22 , wherein the processor is configured to produce a high intensity signal indicating the estimated time of the peak intensity of the second reflected pulse using only analog elements.
24. The LiDAR sensor of claim 23 , wherein the processor comprises an analog differentiator circuit configured to output a signal indicating a time derivative of an intensity of the second reflected pulse.
25. The LiDAR sensor of claim 24 , wherein the processor comprises an analog comparator circuit configured to receive the signal from the analog differentiator circuit and output the high intensity signal when the signal from the analog differentiator circuit declines below a threshold value.
26. The LiDAR sensor of claim 22 , wherein the processor is configured to determine a time of receipt of a calibration electromagnetic pulse and use the time of receipt of the calibration electromagnetic pulse and the second reflected pulse to estimate a distance from the object.
27. The LiDAR sensor of claim 22 , wherein the processor is configured to determine the estimated time of the peak intensity at sub-nanosecond resolution.
28. The LiDAR sensor of claim 22 , wherein the electromagnetic pulse comprises a laser pulse having a pulse width between 1 and 10 nanoseconds.