Method and system for imaging an object with a plurality of optical beams

• US 6,181,472 B1
• Filed: 06/10/1998
• Issued: 01/30/2001
• Est. Priority Date: 06/10/1998
• Status: Expired due to Term

• Current Assignee: Rudolph Technologies Incorporated (Onto Innovation Inc.)
• Original Assignee: Robotic Vision Systems, Inc. (Acuity Brands, Inc.)
• Inventors: Liu, Kuo-Ching
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): THOMPSON, TIMOTHY J
• Application Number:
  US09/095,367
• Time in Patent Office: 965 Days
• Field of Search: 359/717, 359/718, 359/719, 359/618, 356/376
• US Class Current: 359/618
• CPC Class Codes: G02B 27/106 for splitting or combining a plurality of identical beams or images, e.g. image replication
• CPC Class Codes: G02B 27/1093 for use with monochromatic radiation only, e.g. devices for splitting a single laser source

Abstract

A diffracting beam splitter splits an optical beam. The resulting beams are swept over an object by a beam deflector. The beams are mechanically scanned transverse to the beam deflection direction. A position sensitive device receives light reflected from the incident beams and a three dimensional profile of the object is produced.

Claims

1. An imaging system comprising:

a light source positioned to transmit light along a first path for illuminating an object;

a beam deflector positioned along the first path;

a beam splitter along the first path for splitting the light into a plurality of output paths for illuminating the object at a plurality of X-Y coordinates;

a first photo sensitive device detecting light reflected from the object at the plurality of X-Y coordinates and generating a first at least one signal as a function of the light detected along a first at least one path; and

a processor receiving the first at least one signal and generating an image of at least one portion of the object as a function of the received first at least one signal,

wherein the beam splitter is a diffracting beam splitter.

2. The system of claim 1 wherein the beam deflector and the beam splitter are selected so that the angular separation of adjacent output paths of the beam splitter is substantially at most equal to the beam deflector sweep angle range.

3. The system of claim 2 wherein the beam deflector is an acousto-optical deflector.

4. The system of claim 2 wherein the light source is a diode laser.

5. The system of claim 2 wherein the beam deflector is a rotating polygonal scanner.

6. The system of claim 2 wherein the beam deflector is a galvanometer mirror.

7. The system of claim 2 wherein the first photo sensitive device is a multi-channel position sensitive device.

8. The system of claim 2 wherein the first photo sensitive device is a charge coupled device array.

9. The system of claim 2 wherein the first photo sensitive device is a capacitive metal oxide semiconductor device array.

10. The system of claim 2 further comprising:

a second photo sensitive device detecting light reflected from the object at the plurality of X-Y coordinates and generating a second at least one signal as a function of the light detected along a second at least one path; and

wherein the processor receives the second at least one signal and generates the image of at least a portion of the object as a function of the received first at least one signal and the second at least one signal.

11. The system of claim 10 wherein at least one of the first photo sensitive and the second photo sensitive device is a multi-channel position sensitive device.

12. The system of claim 10 wherein at least one of the first photo sensitive and the second photo sensitive device is a charge coupled device array.

13. The system of claim 10 wherein at least one of the first photo sensitive and the second photo sensitive device is a capacitive metal oxide semiconductor device array.

14. A method for imaging an object, comprising the steps of:

projecting a first light beam from a light source;

directing the first light beam through a beam deflector, the beam deflector deflecting the first light beam at a first selected deflection angle;

directing the deflected first light beam through a beam splitter to produce a plurality of exit beams;

illuminating the object at a plurality of X-Y coordinates with at least two of the plurality of exit beams;

detecting simultaneously light reflected by the object from at least two of the plurality of X-Y coordinates; and

generating a three dimensional image of at least one portion of the object as a function of the detected lights,

wherein the beam splitter is a diffracting beam splitter.

15. The method of claim 14 wherein the beam splitter is selected so that the separation of adjacent exit beams is substantially at most equal to the sweep angle range of the beam deflector.

16. The method of claim 14 wherein the beam deflector is an acousto-optical deflector.

17. The method of claim 16 wherein the beam deflector is a rotating polygonal scanner.

18. The method of claim 14 wherein the beam deflector is a galvanometer mirror.

19. The method of claim 14 further comprising the step of:

scanning the plurality of exit beams across the object in a direction perpendicular to the beam deflector sweep angle at predetermined time intervals.

20. The method of claim 19 wherein the scanning is accomplished by translation of the object.

21. The method of claim 14 further comprising the step of determining the dimensions of selected features from the three dimensional image.

22. The method of claim 14 further comprising the step of determining the relative positions of selected features from the three dimensional image.

23. The method of claim 14 further comprising the step of determining the relative co-planarity of selected features from the three dimensional image.

27. The method of claim 19 wherein the scanning is accomplished by translating the sensor system.

34. The method of claim 19 wherein the scanning is accomplished by translation of the object.

24. A method for scanning optical beams across an object comprising the steps of:

projecting a first light beam from a light source;

directing the first light beam through a beam deflector, the beam deflector deflecting the first light beam at a first selected deflection angle;

directing the deflected first light beam through a beam splitter to produce a plurality of exit beams; and

illuminating the object at a plurality of X-Y coordinates with at least two of the plurality of exit beams,

wherein the sweep angle range is selected so that the separation of adjacent exit beams is substantially at most equal to the sweep angle range.

25. The method of claim 24 wherein the beam splitter is selected so that the separation of adjacent exit beams is substantially at most equal to the preselected sweep angle range of the beam deflector.

26. A method for imaging an object, comprising the steps of:

projecting a first light beam from a light source;

directing the first light beam through a beam deflector, the beam deflector deflecting the first light beam at a first preselected deflection angle;

directing the deflected first light beam through a beam splitter to produce a plurality of exit beams;

illuminating the object at a plurality of X-Y coordinates with at least two of the plurality of exit beams;

detecting simultaneously light reflected by the object from at least two of the plurality of X-Y coordinates; and

generating a three dimensional image of at least one portion of the object as a function of the detected light,

wherein the sweep angle range is selected so that the separation of adjacent exit beams is substantially at most equal to the sweep angle range.

28. The method of claim 26 wherein the beam splitter is a diffracting beam splitter.

29. The method of claim 26 wherein the beam splitter comprises a partially reflective mirror.

30. The method of claim 26 wherein the beam deflector is an acousto-optical deflector.

31. The method of claim 26 wherein the beam deflector is a rotating polygonal scanner.

32. The method of claim 26 wherein the beam defector is a galvanometer mirror.

33. The method of claim 26 further comprising the step of:

scanning the plurality of exit beams across the object in a direction perpendicular to the beam deflector sweep angle at predetermined time intervals.

35. The method of claim 26 further comprising the step of determining the dimensions of selected features from the three dimensional image.

36. The method of claim 26 further comprising the step of determining the relative positions of selected features from the three dimensional image.

37. The method of claim 26 further comprising the step of determining the relative co-planarity of selected features from the three dimensional image.