LiDAR safety systems and methods
Embodiments discussed herein refer to LiDAR systems and methods that monitor for fault conditions that could potentially result in unsafe operation of a laser. The systems and methods can monitor for faulty conditions involving a transmitter system and movement of mirrors in a scanning system. When a fault condition is monitored, a shutdown command is sent to the transmitter system to cease laser transmission. The timing by which the laser should cease transmission is critical in preventing unsafe laser exposure, and embodiments discussed herein enable fault detection and laser shutoff to comply with laser safety standards.
1. A light detection and ranging (LiDAR) system, comprising:
a transmitter system comprising a fiber laser;
a scanning system comprising:
at least a first mirror operative to move according to a first motor motion, wherein the at least the first mirror at least partially controls directionality of laser pulses originating from the fiber laser; and
monitoring circuitry operative to:
monitor the first motor motion and the transmitter system for a fault condition;
detect occurrence of the fault condition; and
instruct the fiber laser to shut down in response to a detected fault condition.
2. The LiDAR system of claim 1 , wherein the scanning system further comprises a second mirror operative to move according to a second motor motion, wherein the first and second mirrors control directionality of laser pulses originating from the fiber laser, and where the monitoring circuitry is further operative to:
monitor the first motor motion, the second motor motion, and the transmitter system for a fault condition.
3. The LiDAR system of claim 2 , wherein a first fault condition is improper operation of the first mirror, and, wherein a second fault condition is improper operation of the second mirror.
4. The LiDAR system of claim 3 , wherein a third fault condition is improper operation of the transmitter system.
5. The LiDAR system of claim 1 , wherein the transmitter system comprises:
a fiber optic cable; and
a detector for observing reflectance in the fiber optic cable, and wherein the monitoring circuitry is operative to monitor observed reflectance to detect occurrence of the fault condition.
6. The LiDAR system of claim 5 , wherein the fault condition occurs when the observed reflectance passes a threshold.
7. The LiDAR system of claim 1 , wherein the transmitter system comprises:
a fiber optic cable; and
a detector for observing laser pulses in the fiber optic cable, and wherein the monitoring circuitry is operative to monitor observed laser pulses to detect occurrence of the fault condition.
8. The LiDAR system of claim 7 , wherein the fault condition occurs when a laser pulse is not observed within an expected laser pulse period.
9. The LiDAR system of claim 1 , wherein the transmitter system comprises a seed laser, at least one amplifier, and an amplified spontaneous emission (ASE) filter.
10. The LiDAR system of claim 9 wherein the ASE filter is operative to filter out out-of-band spontaneous emissions having wavelengths that cannot pass through the ASE filter.
11. The LiDAR system of claim 10 , wherein in response to a shutdown instruction, the seed laser is substantially immediately deactivated and wherein the ASE filter reduces energy output of the fiber laser to a safe emission level within a fixed time period.
12. A method for operating a light detection and ranging (LiDAR) system, comprising:
controlling movement of a first mirror according to a first motion;
activating a laser transmitter system comprising a fiber laser, wherein the fiber laser transmits light pulses that are projected according to a field of view defined by the controlled movements of at least the first mirror;
monitoring movement of the first mirror and operation of the transmitter system for a fault condition;
detecting occurrence of the fault condition; and
turning the fiber laser off in response to a detected fault condition.
13. The method of claim 12 , further comprising:
controlling movement of a second mirror according to a second motion;
wherein the monitoring comprises monitoring movement of the first mirror, movement of the second mirror, and operation of the transmitter system for a fault condition.
14. The method of claim 12 , wherein a first fault condition is improper movement of the first mirror, and wherein a second fault condition is improper movement of the second mirror.
15. The method of claim 14 , wherein a third fault condition is improper operation of the transmitter system.
16. The method of claim 12 , wherein the transmitter system comprises:
a fiber optic cable; and
a detector for observing reflectance in the fiber optic cable, and the method further comprising monitoring observed reflectance to detect occurrence of the fault condition.
17. The method of claim 16 , wherein the fault condition occurs when the observed reflectance passes a threshold.
18. The method of claim 12 , wherein the transmitter system comprises:
a fiber optic cable; and
a detector for observing laser pulses in the fiber optic cable, and the method further comprising monitoring observed laser pulses to detect occurrence of the fault condition.
19. The method of claim 18 , wherein the fault condition occurs when a laser pulse is not observed within an expected laser pulse period.
20. The method of claim 12 , wherein the transmitter system comprises a seed laser, at least one amplifier, and an amplified spontaneous emission (ASE) filter.
21. The method of claim 20 , further comprising filtering out, using the ASE filter, out-of-band spontaneous emissions having wavelengths that cannot pass through the ASE filter.