Device and method for object illumination and imaging using light pulses

• US 7,045,783 B2
• Filed: 05/28/2003
• Issued: 05/16/2006
• Est. Priority Date: 06/05/2001
• Status: Expired due to Fees

• Current Assignee: University of Florida (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Matveev, Oleg
• Primary Examiner(s): Wells, Nikita
• Assistant Examiner(s): Vanore, David A.
• Application Number:
  US10/448,190
• Publication Number:
  US 20030193981A1
• Time in Patent Office: 1,084 Days
• Field of Search: 356/1, 358/95, 358/211, 358/141, 250/330, 362/464
• US Class Current: 250/330
• CPC Class Codes: B60Q 1/14 having dimming means
• CPC Class Codes: B60Q 1/1415 Dimming circuits
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G01S 7/51 Display arrangements

Abstract

A reduced glare imaging system for motor vehicles which includes at least one light source capable of modulation. The system also includes a synchronization system which has structure for obtaining a time reference, and a trigger for modulating emissions from the light source. The trigger initiates emission of periodic light pulses from the light source at fixed times relative to the time reference. The fixed times can be randomly selected. The light pulses can have a wavelength in the range of 0.19 μm to 5 μm.

Claims

1. A reduced glare imaging system for motor vehicles traveling on roadways, comprising:

at least one pulsed light source;

a synchronization system including structure for obtaining a time reference coupled to said light source;

a trigger for initiating emission of periodic light pulses from said light source during one of a plurality of different fixed time slot intervals relative to said time reference, wherein a first vehicle or first group of vehicles on said roadway is allocated a first of said plurality of fixed time slots and at least a second vehicle or second group of vehicles on said roadway is allocated a second of said plurality of fixed time slots; and

an imaging device for receiving scattered light from objects illuminated by said periodic light pulses, wherein said imaging device is gated to receive said scattered light only during defined gating periods.

2. The system of claim 1, wherein said light pulses have a wavelength in the spectrum range of 0.19 μ

m to 5 μ

m.

3. The system of claim 1, wherein said light pulses have a wavelength in the spectrum range of 400 nm to 750 nm.

4. The system of claim 3, wherein an average power of said light pulses is less than at least one value selected from the group consisting of 10 W, 1 W, 500 mW, 100 mW, 10 mW, 1 mW and 500 μ

W.

5. The system of claim 1, further comprising a display for displaying images contained in said received scattered light.

6. The system of claim 1, wherein said gating periods each have a duration approximately equal to the sum of (2D_S/c)+Δ

T_PULSE, where Δ

T_PULSE is a duration of at least one of said periodic light pulses, D_S is a maximum desired observation range, and c is the speed of light.

7. The system of claim 1, wherein said gating periods each have a duration approximately equal to the sum of 2(D_B−

D_L)/c+Δ

T_PULSE, where Δ

T_PULSE is a duration of at least one of said periodic light pulses, D_L is a distance correlating to a desired observation range minimum, D_B is a distance correlating to a desired observation range maximum, and c is the speed of light.

8. The system of claim 1, wherein each of said gating periods commences when a correlating one of said periodic light pulses begins.

9. The system of claim 1, wherein each of said gating periods commences at a time approximately equal to t_i+2D_L/c and finishes at a time approximately equal to 2D_B/c+Δ

T_PULSE, where t_i=a time when a correlating one of said periodic light pulses begins, D_L is a distance correlating to a desired observation range minimum, D_B is a distance correlating to a desired observation range maximum, and c is the speed of light.

10. The system of claim 1, wherein said imaging detector has a luminosity-resolving power product of at least 10⁴ cm² sr.

11. The system of claim 1, wherein said imaging detector is at least one item selected from the group consisting of an atomic vapor ultranarrowband imaging detector, a molecular vapor ultranarrowband imaging detector, an atomic magnetooptical filter, a molecular magnetooptical filter, a spectral hole burning filter, an image intensifier, an electron bombardment charged coupled device, and a resonance ionization imaging detector.

12. The system of claim 1, further comprising a light filter, wherein said light filter is at least one item selected from the group consisting of colored glass, an acousto-optic filter, a Liot type filter, an atomic resonance fluorescence imaging monochromator, a magneto-optical filter, and an interference filter.

13. The system of claim 1, wherein said fixed times are defined by time slots, each time slot having a duration equal to at least an amount of time selected from the group consisting of a gating period and a period between light pulses.

14. The system of claim 1, wherein said fixed times are a arbitrarily selected.

15. The system of claim 1, wherein said fixed times are predetermined.

16. The system of claim 1, wherein a period between said light pulses is constant for all vehicles having said system while traveling on said roadway.

17. The system of claim 1, wherein a period between said light pulses is constant for all vehicles having imaging systems which are tuned to a light frequency which is common to all of said vehicles.

18. The system of claim 1, wherein a duration of said gating period is constant for a plurality of vehicles.

19. The system of claim 1, wherein said time reference is a wirelessly transmitted timing signal.

20. The system of claim 1, wherein said time reference is a signal transmitted from at least one of a global positioning satellite system, a global navigation satellite system and an earth based time station.

21. The system of claim 1, wherein said light source is configured as at least one device selected from the group consisting of a vehicle headlight and a head-mounted pulsed illuminator.

22. A motor vehicle, comprising:

an illumination system mounted to said vehicle, said illumination system including;

at least one light source capable of modulation;

a synchronizing system including structure for obtaining a time reference coupled to said light source;

a trigger for initiating emission of periodic light pulses from said light source during one of a plurality of different fixed time slot intervals relative to said time reference, wherein on a roadway said vehicle is allocated a first of said plurality of fixed time slots, wherein another vehicle on said roadway is allocated a second of said plurality of fixed time slots; and

an imaging device for receiving scattered light from objects illuminated by said periodic light pulses, wherein said imaging device is gated to receive said scattered light only during defined gating periods.

23. A method of providing reduced glare imaging for motor vehicles sharing roadways, comprising the steps:

receiving a time reference;

triggering a light source to initiate emission of periodic light pulses from said light source during one of a plurality of different fixed time slot intervals relative to said time reference, wherein on a roadway a first vehicle or first group of vehicles is allocated a first of said plurality of fixed time slots and at least a second vehicle or second group of vehicles on said roadway is allocated a second of said plurality of fixed time slots;

exclusively during gating periods correlating to said light pulses, receiving light scattered from objects illuminated by said periodic light pulses; and

displaying images based on said scattered light.

24. The method of claim 23, wherein said light pulses have a wavelength in at least one of the ranges of 0.19 μ

m to 5 μ

m.

25. The method of claim 23, wherein said light pulses have a wavelength in the spectrum range of 400 nm to 750 nm.

26. The method of claim 25, wherein an average power of said light pulses is less than at least one value selected from the group consisting of 1 W, 500 mW, 100 mW, 10 mW, 1 mW and 500 μ

W.

27. The method of claim 23, further comprising the step of defining said gating periods to be approximately equal to the sum of (2D_S/c)+Δ

T_PULSE, where Δ

T_PULSE is a duration of at least one of said periodic light pulses, D_S is a desired illumination distance for the imaging system'"'"'s field of observation, and c is the speed of light.

28. The method of claim 23, wherein said gating periods each have a duration approximately equal to the sum of [2(D_B−

D_L)/c+Δ

T_PULSE], where Δ

T_PULSE is a duration of at least one of said periodic light pulses, D_L is a distance correlating to a desired observation range minimum, D_B is a distance correlating to a desired observation range maximum, and c is the speed of light.

29. The method of claim 23, wherein each of said gating periods commences when a correlating one of said periodic light pulses begins.

30. The method of claim 23, wherein each of said gating periods commences at a time approximately equal to t_i+2D_L/c and finishes at a time approximately equal to 2D_B/c+Δ

T_PULSE, where t_i=a time when a correlating one of said periodic light pulses begins, D_L is a distance correlating to a desired observation range minimum, D_B is a distance correlating to a desired observation range maximum, and c is the speed of light.

31. The method of claim 23, wherein said fixed times are defined by time slots, each time slot having a duration equal to at least an amount of time selected from the group consisting of a gating period and a period between light pulses.

32. The method of claim 23, wherein said fixed times are arbitrarily selected.

33. The method of claim 23, wherein said fixed times are predetermined.

34. The method of claim 23, wherein said time reference is a wirelessly transmitted timing signal.

35. The method of claim 23, wherein said time reference is a signal transmitted from at least one of a global positioning satellite system, a global navigation satellite system and an earth based time station.