Optical scanning for line-of-sight communications to optical tags
An optical communication device can address these and other issues by utilizing a system and method in which an optical device emits a series of laser pulses that trace a spiral path over a coverage area. Each laser pulse containing a packet of information modulated at a relatively rate to help mitigate adverse effects from device movements, scintillation, and the like. The beam width of the laser, speed of the scan (along the spiral path), and number of laser pulses can be configured such that corresponding response pulses (e.g., retro-modulated pulses) received from an illuminated tag within the coverage may have a variety of different amplitudes, increasing the likelihood that at least one of the response pulses will have power characteristics that facilitate a proper decoding of the response pulse.
1. An optical device comprising:
a laser;
a laser-steering unit configured to direct laser light generated by the laser;
a receiver unit; and
a processing unit communicatively coupled with the laser, laser-steering unit, and receiver unit, the processing unit configured to:
cause the optical device to execute a scanning process in which:
the laser generates a plurality of pulses of laser light, and
the laser steering unit illuminates a coverage area with the plurality of pulses of laser light by directing the plurality of pulses of laser light such that:
each pulse of the plurality of pulses of laser light illuminates a respective portion of the coverage area along a spiral scan pattern within the coverage area,
each portion of the coverage area illuminated by a respective pulse of the plurality of pulses of laser light overlaps with at least one or more other portions of the coverage area illuminated by respective one or more other pulses of the plurality of pulses of laser light,
the laser steering unit traces the entire spiral scan pattern during the scanning process, and
the scanning process is completed in less than 1 s; and
for each of one or more pulses of received laser light detected with the receiver unit corresponding to respective one or more pulses of the plurality of pulses of laser light, determine whether the pulse of received laser light has been modulated to include predetermined information.
2. The optical device of claim 1 , wherein the laser, the laser-steering unit, the receiver unit, and the processing unit are at least partially housed in a mountable body configured to be mounted to another apparatus.
3. The optical device of claim 1 , wherein the processing unit is configured to cause the optical device to execute the scanning process, wherein a length of time each pulse of the plurality of pulses is generated is 1/1000 the length of the scanning process or less.
4. The optical device of claim 3 , wherein the length of time each pulse of the plurality of pulses is generated is 100 μs or less.
5. The optical device of claim 3 , wherein the processing unit is configured to cause the laser to modulate each pulse of the plurality of pulses of laser light with data.
6. The optical device of claim 5 , wherein the processing unit is configured to cause the laser to modulate each pulse of the plurality of pulses of laser light at a data rate of at least 1 MHz.
7. The optical device of claim 1 , wherein the portion of the coverage area illuminated by at least one pulse of the plurality of pulses overlaps with at least 20 other portions of the coverage area illuminated by respective at least 20 other pulses of the plurality of pulses.
8. The optical device of claim 1 , wherein the coverage area scanned during the scanning process is at least 5 milliradians (mrad).
9. The optical device of claim 1 , wherein the laser-steering unit comprises a microelectromechanical systems (MEMS) mirror.
10. The optical device of claim 1 , wherein the laser comprises a laser diode.
11. A method of optical laser communication, the method comprising:
executing a scanning process in which:
a plurality of pulses of laser light is generated,
the plurality of pulses of laser light are directed to illuminate a coverage area with the plurality of pulses of laser light such that:
each pulse of the plurality of pulses of laser light illuminates a respective portion of the coverage area along a spiral & scan pattern within the coverage area,
each portion of the coverage area illuminated by a respective pulse of the plurality of pulses of laser light overlaps with at least one or more other portions of the coverage area illuminated by respective one or more other pulses of the plurality of pulses of laser light,
the plurality of pulses of laser light are directed to illuminate the coverage area along the entire spiral scan pattern during the scanning process, and
the scanning process is completed in less than 1 s;
detecting one or more pulses of received laser light corresponding to respective one or more pulses of the plurality of pulses of laser light; and
for each of the detected one or more pulses of received laser light, determining whether the pulse of received laser light has been modulated to include predetermined information.
12. The method of claim 11 , wherein:
the plurality of pulses of laser light are generated over of a period of time, and
a length of time each pulse of the plurality of pulses is generated is 1/1000 the length of the period of time or less.
13. The method of claim 12 , wherein the length of time each pulse of the plurality of pulses is generated is 100 μs or less.
14. The method of claim 12 , wherein generating the plurality of pulses of laser light further comprises modulating each pulse of the plurality of pulses of laser light with data.
15. The method of claim 14 , wherein the modulating comprises modulating each pulse of the plurality of pulses of laser light at a data rate of at least 1 MHz.
16. The method of claim 11 , wherein the coverage area scanned during the scanning process is at least 5 milliradians (mrad).
17. The method of claim 11 , wherein directing the plurality of pulses of laser light comprises using a microelectromechanical systems (MEMS) mirror to direct the plurality of pulses of laser light.
18. The method of claim 11 , wherein generating the plurality of pulses of laser light comprises using a laser diode.