Method and device for optimizing the use of emitter and detector in an active remote sensing application

1. A method for remote sensing by at least one laser emitter and at least one detector, comprising:

providing a laser emitter having a laser class and a nominal ocular hazard distance (NOHD);

setting a target time unit integration time t p ;

translating said time unit integration time into a reduced time τ p and its corresponding power increase factor η −1 , and so that the energy of the resulting pulse of duration τ p =η*t p remains below the acceptable eye-safe emission power of said laser emitter at said NOHD without increasing the NOHD;

activating both the laser emitter, with a power output corrected by η −1 , and the detector for a duration of τ p ;

deactivating the emitter and detector after duration τ p ; and

keep emitter and detector off for the subsequent duration t off =t p −τ p .

2. The method according to claim 1 , in which said target integration time unit results from a target frame rate.

3. The method according to claim 1 , wherein during the off-time t off =t p −τ p communication is exchanged with an external device.

4. The method according to claim 3 , wherein said communication updates configurations.

5. The method according to claim 1 , wherein the translation of said time unit integration time into a reduced time τ p is obtained by a look-up-table (LUT) listing pre-calculated values.

6. The method according to claim 1 , wherein the translation of said time unit integration time into a reduced time τ p is obtained by calculating the translation continuously according to the time domain and/or the spectral region.

7. The method according to claim 1 , wherein the translation of said time unit integration time into a reduced time τ p is obtained by providing coarse steps from a look-up-table (LUT) listing pre-calculated values and by calculating interpolated value.

8. The method according to claim 1 , further comprising operating in a continuous acquisition mode set up to acquire frames of t p integration time each in order to obtain a frame rate 1/t p .

9. The method according to claim 1 , further comprising operating in such a way to acquire a single acquisition following a trigger signal and then wait for a subsequent trigger signal.

10. The method according to claim 1 , further comprising delaying the activation of the laser emitter and photo-sensitive detector by an additional amount of t delay =max[(η preceding −η)t p , 0], with η preceding being the inverse of the power increase factor of the preceding acquisition.

11. The method according to claim 9 , wherein, if the trigger signal arrives during the idle mode duration t off , said trigger signal is ignored or delayed until said duration has timed out.

12. A device for remote sensing by at least one laser emitter and at least one detector, comprising at least a laser emitter having a laser class and a nominal ocular hazard distance (NOHD), a photo-sensitive detector and a logic circuit controlling the laser emitter and the photo-sensitive detector and a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon executable by a processor to perform actions comprising:

setting a target time unit integration time t p ;

translating said time unit integration time into a reduced time τ p and its corresponding power increase factor η −1 , and so that the energy of the resulting pulse of duration τ p =η*t p remains below the acceptable eye-safe emission power of said single laser emitter at said NOHD without increasing the NOHD;

activating both the laser emitter, with a power output corrected by η −1 , and the detector for a duration of τ p ;

deactivating the emitter and detector after duration τ p ; and

keep emitter and detector off for the subsequent duration t off =t p −τ p .

13. A device according to claim 12 wherein said target integration time unit results from a target frame rate.

14. A device according to claim 12 wherein during the off-time t off =t p −τ p communication is exchanged with an external device.

15. A device according to claim 14 wherein said communication updates configurations.

16. A device according to claim 12 wherein the translation of said time unit integration time into a reduced time τ p is obtained by means of a look-up-table (LUT) listing pre-calculated values.

17. A device according to claim 12 wherein the translation of said time unit integration time into a reduced time τ p is obtained by calculating it continuously according to the time domain and/or the spectral region.

18. A device according to claim 12 wherein the translation of said time unit integration time into a reduced time τ p is obtained by providing coarse steps from a look-up-table (LUT) listing pre-calculated values and by calculating interpolated value.

19. A device according to claim 12 wherein the device is configured to operate in a continuous acquisition mode set up to acquire frames of t p integration time each in order to obtain a frame rate 1/t p .

20. A device according to claim 12 wherein the device is configured to operate in such a way that the device acquires a single acquisition following a trigger signal and then wait for a subsequent trigger signal.

21. A device according to claim 12 further comprising means for delaying the activation of the laser emitter and photo-sensitive detector by an additional amount of t delay =max[(η preceding −η)t p , 0], with η preceding being the inverse of the power increase factor of the preceding acquisition.

22. A device according to claim 20 wherein, if the trigger signal arrives during the idle mode duration t off , said trigger signal is ignored or delayed until said duration has timed out.

23. A device according to claim 20 further comprising an external device ( 14 ) sending said trigger signal.

24. A device according to claim 23 wherein said external device is a screen, a projector, a computer, or a server.