Control means and method for optical inspection system

• US 4,878,736 A
• Filed: 12/23/1987
• Issued: 11/07/1989
• Est. Priority Date: 10/17/1986
• Status: Expired due to Fees

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: Global Holonetics Corporation
• Inventors: Hekker, Roeland M. T., Livny, Izhak M.
• Primary Examiner(s): ARNOLD, BRUCE
• Application Number:
  US07/137,464
• Time in Patent Office: 685 Days
• Field of Search: 350/162.13, 356/237, 364/822
• US Class Current: 359/561
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01N 21/95623 using a spatial filtering method per se G02B
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G06E 3/005 using electro-optical or opto-electronic means
• CPC Class Codes: G06V 10/88 Image or video recognition using optical means, e.g. reference filters, holographic masks, frequency domain filters or spatial domain filters
• CPC Class Codes: Y10S 359/90 Methods

Abstract

Operation of system components is automatically monitored, controlled and coordinated. The presence at an inspection station of each successive one of the objects to be inspected is automatically detected. Inspection of each such object commences in response to its detection when the monitoring of other system components indicates that they are ready for commencement of the new inspection cycle. The inspection system includes a rotatable disk having mask apertures that move into the line of sight of a light detector. Signals produced by scanning of timing marks upon the disk reflect which one of the plurality of masks is present in the optical path, and determine the intensity of the transform image sampled by said mask means.

Claims

1. An object inspection system, comprising:

first imaging means for generating electrical signal data representative of the appearance of each inspected object;

second imaging means for receiving said signal data and generating a visual image of the object;

third imaging means for receiving and generating a transform image from said visual image of the object;

signature generating means for sampling light from different spatial domains of said transform image and generating electrical signal data representative thereof and collectively defining a characteristic signature of said transform image and thus of the inspected object;

and control means for automatically controlling and coordinating operation of each of said imaging means and said signature generating means.

2. A system as in claim 1, wherein said control means causes said transform image to be generated for a predetermined time period, and said control means causes operation of said signature generating means during a preselected part of said time period when said transform image is of optimal quality.

3. A system as in claim 1, wherein said first imaging means includes object sensing means for sensing the presence at an inspection location of the object to be inspected, stroboscopic lighting means for illuminating the object at said location, and camera means for generating said electrical signal data.

4. A system as in claim 3, wherein said control means monitors the operating condition of said second imaging means, and initiates operation of said lighting means and transmission of said signal data from said camera means when said object sensing means senses the presence of the object at said inspection location and when said second imaging means is in appropriate condition to receive said signal data from said camera means.

5. A system as in claim 4, wherein said second imaging means includes spatial light modulator means, and frame buffer means for receiving said signal data from said camera means and transmitting said signal data to said spatial light modulator means, and wherein said control means causes said signal data to be transmitted from said frame buffer means to said spatial light modulator means for said preselected time period, said spatial light modulator means generating said visual image in response to receipt of said data.

6. A system as in claim 5, wherein said control means causes said frame buffer means to quench said visual image upon expiration of said preselected time period.

7. A system as in claim 1 wherein said third imaging means includes means for directing a coherent beam of light through said second imaging means, impressing upon the coherent light beam the visual image of the object, and lens means for receiving said light beam and visual image impressed thereon.

8. A system as in claim 6, wherein said third imaging means includes means for directing a coherent beam of light through said spatial light modulator means and said visual image is impressed upon said coherent light beam during its passage through said spatial light modulator means, and lens means for receiving said light beam and said visual image impressed thereon and for converting said visual image into said transform image.

9. A system as in claim 1, wherein said signature generating means includes light detecting and measuring means for generating said last-mentioned electrical signal data from light received thereby during operation thereof, movable mask means for transmitting light from different spatial domains of said transform image to said light detecting and measuring means, and wherein said control means coordinates operation of said light detecting and measuring means and movement of said mask means.

10. A system as in claim 9, wherein said mask means is a rotatable disk member having a plurality of mask apertures extending therethrough, and wherein said control means includes means for monitoring the rotative position of said disk means and coordinating the operation of said light detecting and sensing means therewith.

11. An object inspection system, comprising:

object sensing means for sensing the presence of an object at a predetermined location, and for generating first signal data indicative thereof;

stroboscopic lighting means for illuminating the object at said location;

camera means for generating second electrical signal data representative of the appearance of the object at said location;

means for generating a coherent beam of light;

imaging means for receiving said second electrical signal data and utilizing the same to produce a visual image of said object, said light beam extending through said visual image and having said visual image impressed thereon;

lens means for generating a transform image of said object from said visual image thereof;

signature generating means for sampling light from different spatial domains of said transform image, and for generating third electrical signal data representative of each domain thereof and collectively defining a characteristic signature of said transform image;

and control means for initiating operation of said stroboscopic lighting means and the transfer of said second-mentioned signal data from said camera means to said imaging means in response to said first signal data generated by said object sensing means.

12. A system as in claim 11, wherein said signature generating means includes light detecting means for generating said third electrical signal data from light received during operation thereof, and rotatable mask means for controlling transmission of light from said spatial domains of said transform image to said light detecting means, and said control means also coordinates operation of said light detecting means with rotation of said mask means.

13. A system as in claim 12, wherein said control means delays operation of said light detecting means until said transform image is in an optimal condition.

14. A system as in claim 12, wherein said control means effects operation of said light detecting means during a time period beginning a preselected time interval after generation of said visual image is commenced.

15. A system as in claim 12, wherein said mask means and said control means include cooperating means for identifying the rotative positions of said mask means.

16. A system as in claim 15, wherein said mask means has a plurality of masks thereon, said masks being sequentially moved by rotation of said mask means into alignment with said light detecting means, and said control means permitting operation of said light detecting means at those times when successive ones of said masks are aligned with said light detecting means.

17. A system as in claim 11, wherein said imaging means includes a liquid crystal display device upon which said visual image is incrementally generated, and further including means associated with said display device for at times refreshing and at other times quenching said visual image.

18. A system as in claim 17, wherein said means associated with said display device includes frame buffer means for acquiring and storing complete frames of said second signal data from said camera means, and said control means also controls the timing of the acquisition by said frame buffer means of each of said frames.

19. A system as in claim 11, wherein said control means also monitors transfer of said second signal data from said camera means.

20. An object inspection system, comprising:

camera means for generating electrical signal data representative of an image of the object;

means for generating a coherent beam of light;

spatial light modulator means for utilizing said electrical signal data to produce a visual image of said object, and for impressing said image upon said coherent beam of light;

transform imaging means for generating a transform image of said object from said first-mentioned image thereof;

signature generating means for sampling light from different spatial domains of said transform image, and for generating electrical signal data representative of each domain thereof and collectively defining a characteristic signature of said transform image;

and control means for coordinating operation of said light modulator means and said signature generating means.

21. A method of object inspection, comprising:

generating electrical signal data representative of the appearance of an object to be inspected;

utilizing the signal data to generate a visual image of the object;

generating a transform image from the visual image of the object;

sampling light from different spatial domains of the transform image and generating electrical signal data representative of different domains thereof and collectively defining a characteristic signature of the transform image and thus of the object;

and automatically controlling and coordinating the steps of generating the visual image of the object sampling light from different spatial domains of the transform image and generating electrical signal data representative thereof.

22. The method of claim 21 wherein the step of automatically controlling and coordinating comprises generating said transform image for a predetermined time period when said transform image is of optimal quality.

23. The method of claim 21 wherein the step of generating electrical signal data representative of the appearance of a object to be inspected comprises sensing the presence at an inspection location of the object to be inspected, illuminating the object at said location using stroboscopic lighting means, and generating electrical signal data from the reflected image of the object.

24. The method of claim 23 wherein the step of automatically controlling and coordinating comprises initiating operation of said lighting means and generating said electrical signal data when said object sensing means senses the presence of the object at said inspection location and when said second imaging means is in appropriate condition to receive said electrical signal data.

25. The method of claim 21 wherein the step of utilizing the signal data to generate a visual image comprises transmitting the signal data to a frame buffer for temporary storage followed by transmission from said frame buffer to a spatial light modulator means for a preselected time period, said spatial light modulator means generating said visual image in response to receipt of said data.

26. The method of claim 21 wherein the step of automatically controlling and coordinating the steps of generating the visual image of the object further comprises quenching the generated visual image of the preceding object.

27. The method of claim 21 wherein the step of utilizing signal data to generate a visual image comprises directing a coherent beam of light through a spatial light modulator means to generate a visual image and define an optical path, and the step of generating a transform image comprises passing said visual image through lens means for converting said visual image into a transform image.

28. The method of claim 27 wherein the step of sampling light from different spatial domains of the transform image comprises rotating a plurality of movable masks means representing different domains of the generated transform image into add out of the optical path, detecting which one of the plurality of masks is present in the optical path, and determining the intensity of the domain of the transform image sampled by said mask means.

29. The method of claim 28 wherein the step of automatic controlling and coordinating further comprises monitoring the rotative position of said disk means and coordinating the operation of said light detecting and sensing means therewith.