Active target distance measurement

• US 6,480,265 B2
• Filed: 03/26/2001
• Issued: 11/12/2002
• Est. Priority Date: 03/26/2001
• Status: Expired due to Fees

• Current Assignee: Deep Optic Ltd.
• Original Assignee: Deep Optic Ltd.
• Inventors: Maimon, Shimon, Benoliel, Eli
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/816,736
• Publication Number:
  US 20020135749A1
• Time in Patent Office: 596 Days
• Field of Search: 356/4.07, 356/5-3-, 356/141.1
• 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,

splitting said reflected pulse into two, one part being used for calibration energy retrieval and one part being gated for gated energy retrieval;

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 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, said pulse comprising light, the method further 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.

10. A method according to claim 9, wherein said image information is color information.

11. 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, said pulse beam transmitter being operable to transmit a pulse having a predetermined width, said gatable beam detector being operable to be gated 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, and two sub-detectors, one gated at said at least twice the predetermined width and the other gated at said predetermined width.

12. Apparatus according to claim 11, further comprising a beam splitter for splitting said reflected pulse between said first and said second sub-detectors.

13. Apparatus according to claim 11, 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.

14. Apparatus according to claim 11, wherein said detector is part of an array of detectors.

15. Apparatus according to claim 14, wherein said array is a three-dimensional array.