Surface profile measurement

• US 7,248,344 B2
• Filed: 04/04/2002
• Issued: 07/24/2007
• Est. Priority Date: 04/04/2001
• Status: Expired due to Fees

• Current Assignee: Instro Precision Limited (S. Reisman Ltd.)
• Original Assignee: Instro Precision Limited (S. Reisman Ltd.)
• Inventors: Morcom, Christopher John
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Ratcliffe; Luke D.
• Application Number:
  US10/474,293
• Publication Number:
  US 20050088644A1
• Time in Patent Office: 1,937 Days
• Field of Search: 356/10
• US Class Current: 356/10
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/26 wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G01S 7/51 Display arrangements
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• CPC Class Codes: G05D 1/0248 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes
• CPC Class Codes: G08G 1/167 Driving aids for lane monitoring, lane changing, e.g. blind spot detection

Abstract

An imaging system scans a light source output over an object to be imaged, and receives the reflected signal in a multi-region light detector, wherein different regions of the object to be imaged are imaged onto different regions of the detector by the receiving optics, and wherein different regions of the light detector can be actuated separately. The light source scanning is synchronized with the actuation of the light detector so that a region of the detector imaging the region of object being illuminated by the light source is actuated. The time of flight of light signals from the light source to the actuated portion of the detector is calculated for all scanning directions, to enable a three dimensional image of the object to be constructed.

Claims

1. An imaging system comprising:

a light source arrangement directed to an object to be imaged;

stationary receiving optics for receiving light reflected from the object to be imaged;

a multi-region light detector for detecting light received from the receiving optics, wherein different regions of the light detector can be actuated separately;

control means to synchronise the operation of the light source arrangement and the actuation of the light detector so that a region of the detector imaging the region of the object being illuminated by the light source is actuated synchronously with an allocated operation of the light source; and

processing means for measuring the time of flight of light signals from the light source to the actuated portion of the detector,

wherein the processing means is selectively operable to measure the time of flight from one of;

(i) a signal received by an individual region of the detector, or

(ii) a combined signal received in parallel from a sub-group of regions of the detector.

2. An imaging system as claimed in claim 1, wherein the or each light source is a pulsed laser or light emitting diode or diodes.

3. An imaging system as claimed in claim 1, wherein the light source is a laser or light emitting diode or diodes having a modulated output.

4. An imaging system as claimed in any preceding claim, further comprising:

a reflector for directing the light from a light source of the light source arrangement to an object to be imaged; and

a drive mechanism for controlling movement of the reflector for scanning the light from the light source over the object to be imaged.

5. An imaging system as claimed in claim 1, wherein the light source arrangement comprises:

a plurality of light sources, each light source being directed to an object to be imaged;

wherein each light source is imaged by the receiving optics onto a different region of the light detector, wherein the different regions of the light detector can be actuated separately, and wherein the different light sources are operated in sequence.

6. An imaging system as claimed in claim 5, wherein each light source comprises a pulsed laser or light emitting diode or diodes.

7. An imaging system as claimed in claim 5, wherein the light source is a laser or light emitting diode or diodes having a modulated output.

15. An imaging system as claimed in claim 1, 5 or 8, wherein the light detector comprises a photodiode array.

16. An imaging system as claimed in claim 15, wherein the photodiode array is operable in two modes, a first mode in which light signals from all photodiodes in the array are read out in sequence, and a second mode in which light signals from selected photodiodes or sub-groups of photodiodes in the array are read out in a sequence.

17. An imaging system as claimed in claim 15, wherein the processing means is integrated onto the same substrate as the photodiode array.

18. An imaging system as claimed in claim 15, wherein multiple channels of time of flight measurement circuitry are integrated onto the same substrate as the photodiode array and configured to process signals from different actuated portions of the photodiode array in parallel.

19. An imaging system as claimed in claim 1, 5 or 8, wherein the processing means uses cross-correlation for measuring the time of flight of light signals from the light source to the actuated portion of the detector.

8. An imaging system comprising:

a light source directed to an object to be imaged;

stationary receiving optics for receiving light reflected from the object to be imaged;

a multi-region light detector for detecting light received from the receiving optics;

control means to synchronise the operation of the light source and the operation of the light detector so that a region of the detector is actuated synchronously with an allocated operation of the light source; and

processing means for measuring the time of flight of light signals from the light source to the actuated portion of the detector,

wherein the light detector is operable in two different modes;

a distance measurement mode comprising a direct-read mode of operation for measuring said time of flight of light signals and in which the actuated region of the light detector is connected to the processing means, and an imaging mode comprising an integrating mode of operation in which charges are allowed to build up in the detector without connection to the processing means.

9. An imaging system as claimed in claim 8, wherein all regions of the light detector are actuated in parallel.

10. An imaging system as claimed in claim 8, wherein different regions of the light detector can be actuated separately.

11. An imaging system as claimed in claim 10, wherein different sub-regions of the light detector are actuated in sequence, a different operation of the light source being allocated to each sub-region.

12. An imaging system as claimed in claim 10, wherein each sub region comprises a row or column of detector pixels of a pixel array.

13. An imaging system as claimed in claim 8, wherein the light source comprises a pulsed laser or light emitting diode or diodes.

14. An imaging system as claimed in claim 8, wherein the light source is a laser or light emitting diode or diodes having a modulated output.

20. A method of obtaining an image of an object, comprising:

scanning a light source signal over the object by directing a light source output in a plurality of scanning directions in sequence, and detecting reflected light received from the object using a two dimensional light detector array;

determining the regions of the light detector array which are illuminated for each scanning direction;

scanning the light source signal over the object again, and detecting reflected light received from the object using only the determined regions of the light detector array;

calculating the time of flight of light pulses from the light source to the detector for each scanning direction; and

obtaining a 3D profile from the time of flight calculations.

21. A method as claimed in claim 20, wherein the scanning of the light source is synchronised with the actuation of selected regions of the light detector array.

22. A method as claimed in claim 20 or 21, wherein the light source signal comprises a pulsed laser output or output of a light emitting diode or diodes.

23. A method as claimed in claim 20 or 21, wherein the light source signal comprises a modulated output of a laser or light emitting diode or diodes.

24. A method as claimed in claim 23, wherein calculating the time of flight uses cross-correlation.

25. A method as claimed in claim 20, wherein the determined regions can be selected to comprise a single region or a sub-group of regions of the light detector array with the signals received in parallel.