ACTIVE TARGET DISTANCE MEASUREMENT

• US 20020135749A1
• Filed: 03/26/2001
• Published: 09/26/2002
• Est. Priority Date: 03/26/2001
• Status: Active Grant

• Current Assignee: Deep Optic Ltd.
• Original Assignee: Deep Optic Ltd.
• Inventors: Benoliel, Eli, Maimon, Shimon
• Granted Patent: US 6,480,265 B2
• Time in Patent Office: Days
• US Class Current: 356/4.07
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

Apparatus for determining a distance of a target, the apparatus comprising a pulse transmitter, a gatable beam detector, and a comparator, the gatable beam detector being operable to obtain gated and calibration beam energy information of a pulse transmitted by the beam pulse transmitter for reflection from the target, and to pass the beam energy information to the comparator, thereby to obtain a ratio between the gated and the calibration beam energy, the ratio being inversely proportional to the distance. Also an array thereof for simultaneously obtaining distances of a multiplicity of points of a three-dimensional object in real time, in particular to obtain movement information of the target.

Claims

1. A method of measuring distance to a target comprising

reflecting a pulse off a target,

retrieving energy from said reflected pulse over a predetermined gating period and measuring a level of said retrieved energy,

determining a distance of said target by comparing said measured retrieved energy level from said target over said predetermined gating period with a calibration energy level.

2. A method according to claim 1 comprising carrying out said step of retrieving at each one of a plurality of sensors.

3. A method according to claim 1 wherein said step of retrieving energy comprises detecting a brightness of said reflection and integrating said brightness over said predetermined gating period.

4. A method according to claim 1 wherein said predetermined gating period is a length of said pulse.

5. A method according to claim 4 wherein said step of determining comprises forming a ratio between said calibration energy level and said gated energy, which ratio is inversely proportional to said distance.

6. A method according to claim 5, comprising setting a width of said pulse as a time taken by light to travel to a maximum distance to be measured.

7. A method according to claim 6, wherein said calibration is carried out by measuring a total energy of a pulse reflected from said object.

8. A method according to claim 7, wherein said calibration and said gated energy retrieval are carried out on a single reflected pulse.

9. A method according to claim 1, comprising a step of splitting said reflected pulse into two, one part being used for calibration energy retrieval and one part being gated for gated energy retrieval.

10. A method according to claim 1, wherein two successive pulses are reflected one after the other, a first beam being used for calibration energy retrieval and the second being gated for gated energy retrieval.

11. A method according to claim 1, comprising splitting incoming light into two parts, one part for analysis of said reflected pulse to determine distance information and a second part being used to obtain image information.

12. A method according to claim 11, wherein said image information is color information.

13. A method according to claim 1, wherein said pulse is any one of a group comprising a light beam, an ultra-violet beam, an infra-red beam, a microwave beam and an ultra-sound beam.

15. Apparatus according to claim 14 wherein said pulse beam transmitter is operable to transmit a pulse having a predetermined width and wherein said gatable beam detector is operable to be gated at at least twice the predetermined width and at the predetermined width, thereby to produce a total reflected energy of said pulse for said calibration energy, and said gated pulse energy.

16. Apparatus according to claim 15, wherein said detector comprises two sub-detectors, one gated at said at least twice the predetermined width and the other gated at said predetermined width.

17. Apparatus according to claim 16, further comprising a beam splitter for splitting said reflected pulse between said first and said second sub-detectors.

18. Apparatus according to claim 14, further comprising a beam splitter for splitting light incoming to said apparatus between a first sub-detector gated to obtain distance information and a second sub-detector for obtaining general image information.

19. Apparatus according to claim 14, further having compensation factors to correct for built-in errors.

20. Apparatus according to claim 14, wherein said detector is part of an array of detectors.

21. Apparatus according to claim 20, wherein said array is a three-dimensional array.

14. Apparatus for determining a distance of a target, said apparatus comprising a pulse transmitter, a gatable beam detector, and a comparator, said gatable beam detector being operable to obtain gated and calibration beam energy information of a pulse transmitted by said beam pulse transmitter for reflection from said target, and to pass said beam energy information to said comparator, thereby to obtain a ratio between said gated and said calibration beam energy, said ratio being inversely proportional to said distance.

22. An array of distance sensors for sensing distance to multiple points of a target object by detecting pulses reflected off a target object, each sensor comprising a gatable detector for detecting incident energy levels of said pulses to produce an output indicative of the distance of a respective point.

23. An array according to claim 22, wherein said sensor is gatable to a time delay equaling at least twice of a length of said pulse to obtain a calibration energy, and wherein said sensor is further gatable to a time delay equaling a length of said pulse to obtain an energy level indicative of said distance.

24. An array according to claim 22, operable to detect using pulses having a duration equal to the time taken by light to travel to a maximum distance to be measured.