System for dimensioning objects

• US 5,555,090 A
• Filed: 10/24/1994
• Issued: 09/10/1996
• Est. Priority Date: 10/24/1994
• Status: Expired due to Term

• Current Assignee: Ozer M.N. Teitelbaum
• Original Assignee: Adaptive Optics Association Incorporated
• Inventors: Schmutz, Lawrence E.
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US08/327,742
• Time in Patent Office: 687 Days
• Field of Search: 356/376, 356/375, 356/379, 356/381, 356/383, 356/384, 356/385
• US Class Current: 356/601
• CPC Class Codes: G01B 11/0608 Height gauges

Abstract

The present invention teaches a system for measuring the height of an object having an outer surface. The system comprises a system for generating an energy beam along a path, such as light, having a structured pattern, wherein the structured pattern of the energy beam irradiates the outer surface of the object. The structured light pattern comprises a constant dimension. The system further comprises a sensor for sensing the outer surface of the object irradiated by the structured pattern. Moreover, the system comprises a system for calculating the height of the object in response to the constant dimension of the structured pattern irradiating the outer surface of the object and sensed by the sensor. This system for calculating the height of the object preferably comprises a programmed computer containing a series of algorithmic steps for deriving a refined overall height profile of the object.

Claims

1. A system for measuring the height of an object having an outer surface, comprising:

a source, having two or more light sources, including a first light source providing a first light beam having a structured energy pattern for irradiating the outer surface of the object;

said structured energy pattern having a constant dimension, and a second light source providing a second light beam for uniformly illuminating the outer surface of the object;

a sensor, for individually sensing the outer surface of the object as irradiated by said first light beam and said second light beam;

a system for removing interference resulting from unwanted markings on the surface of the object by dividing said first light beam sensed by said sensor with said second light beam sensed by said sensor; and

a system for calculating the height of the object in response to said constant dimension of said structured pattern irradiating said outer surface of the object and sensed by said sensor.

2. The system for measuring the height of an object of claim 1, wherein said structured pattern of said first light beam comprises a light pattern having a number of stripes.

3. The system for measuring the height of an object of claim 2, wherein said source comprises:

a first laser diode for generating said first light beam, and a second laser diode for generating said second light beam;

a focusing lens for generating a focused first light beam;

a collimating lens for generating a collimated focused first light beam; and

a striped binary mask for creating said structured light pattern from said collimated focused first light beam.

4. The system for measuring the height of an object of claim 1, wherein said constant dimension comprises a periodicity, and said system for performing a spatial transform comprises:

a system for measuring said periodicity of said constant dimension of said structured pattern irradiating said outer surface of the object and sensed by said sensor.

5. The system for measuring the height of an object of claim 1, wherein said system for performing a spatial transform comprises:

a system for performing at least one of a Fast Fourier Transform ("FFT"), a Walsh Transform, and a Hadamard Transform.

6. A system for measuring the height and profile of an object having an outer surface, comprising:

a source, having two or more light sources, including a first light source providing a first light beam having a structured energy pattern for irradiating the outer surface of the object;

said structured energy pattern having a constant dimension, and a second light source providing a second light beam for uniformly illuminating the outer surface of the object;

a sensor, for individually sensing the outer surface of the object as irradiated by said first light beam and said second light beam;

said sensor including a first, a second and a third camera system for viewing the object, each said camera having a field of view, said field of views of said second and said third camera overlapping opposite extremes of said field of view of said first camera, such that said first camera field of view comprises a left, a center and a right region;

a system for removing interference resulting from unwanted markings on the surface of the object by dividing said first light beam sensed by said sensor with said second light beam sensed by said sensor; and

a system for performing a spatial transform on said structured pattern energy beam sensed by said sensor in said left, said center, and said right regions of said first camera field of view, thereby calculating the height of the object.

7. The system for measuring the height and profile of an object of claim 6, wherein said system for calculating the height of the object comprises:

a system for inputting said spatial transform for said left region, said center region, and said right region;

a system for locating a peak from each of said spatial transform inputted such that a discrete peak location and a size is determined for each of said spatial transform inputted; and

a system for deriving a peak ratio and an edge estimate of the object in response to said discrete peak location and said size for each spatial transform inputted such that a height profile of the object is calculated for said field of view, and said left, said center, and said right regions.

8. The system for measuring the height and profile of an object of claim 7, wherein said system comprises:

a calculator for calculating an average height profile from the height profiles of said left, center, and right regions, and said field of view of said first camera system;

uniformly illuminated by said light beam;

said sensor further sensing the intensity of said light beam illuminating the outer surface of the object;

a system for enabling said first light source while disabling said second light source, and for enabling said second light source while disabling said first light source; and

a system for determining intensity profiles of the object from said field of view of said first camera, said left, said center, and said right region in response to the intensity of said light beam illuminating the outer surface of the object as sensed by said sensor.

9. The system for measuring the height and profile of an object of claim 8, wherein said system for determining the intensity profile of the object comprises:

a system for subtracting the light intensity profile of at least one of said left region and said right region from the light intensity profile of said field of view of said first camera system such that an overall differential intensity profile is created;

a system for locating an edge of the object in response to said overall differential intensity profile such that an edge location is found from said overall differential intensity profile; and

a system for combining redundant edge location data from said overall differential intensity profile and edge data from said light intensity profile of said at least one of said left region and said right region such that combined redundant edge data is created.

10. The system for measuring the height and profile of an object of claim 9, further comprising:

a system for quantizing a group of coordinated transformed light intensity profiles and a group of coordinated height profiles such that a group of quantized coordinated light intensity profiles and a group of quantized coordinated height profiles are created, wherein;

said system for calculating an average height profile comprises said system for scaling the height profiles of said field of view and said left, said center, and said right regions such that a coordinated height profile is created for each of said height profiles; and

said system for subtracting from the light intensity profile comprises a system for scaling the light intensity profiles of said field of view, and said left, center, and right regions such that a coordinated light intensity profile is created for each of said light intensity profiles.

11. The system for measuring the height and profile of an object of claim 9, further comprising a system for deriving a refined overall height profile for the object in response to said average height profile and said combined redundant edge data.

12. A system for developing a profile of an object having an upper outer surface, a height and an edge, said system comprising:

a first light source for generating a first light beam having a structured light pattern, said structured light pattern having a constant dimension, the outer surface of the object illuminated by said structured light pattern;

a second light source for generating a second light beam having an intensity, the outer surface of the object uniformly illuminated by said second light beam;

a system for enabling said first light source while disabling said second light source, and for enabling said second light source while disabling said first light source;

a sensor for sensing the outer surface illuminated by said first light beam structured light pattern, and for sensing the outer surface illuminated by said second light beam, said sensor comprising a first, a second, and a third camera system, each of said camera systems comprising a field of view, said field of view of said first camera system comprising a left, a center, and a right region, said left region falling within said second camera system'"'"'s field of view and said right region falling within said third camera system'"'"'s field of view; and

a computer for developing a profile of the object comprising;

a system for performing a spatial transform on said structured light pattern illuminating the outer surface of the object sensed by said sensor and falling within said field of view of said first camera system, and said left, said center and said right regions;

a system for calculating the height of the object in response to said spatial transforms for said left, said center and said right regions of said first camera field of view by determining a discrete peak location for each of said transform and calculating a peak ratio and an edge of the object in response to said discrete peak location, to provide a height profile of the object in said left, center, and right regions of said first camera field of view;

said system further calculating average redundant height value therefrom; and

a system for locating the edge of the object in response to the outer surface of the object illuminated by said second light source.

13. The system for developing a profile of an object of claim 12, wherein said system for locating the edge of the object comprises:

a system for determining intensity profiles of the object from said second light beam illuminating the outer surface of the object falling within said field of view of said first camera system, said left, said center, and said right regions, said system for determining intensity profiles comprising;

a system for subtracting from the light intensity profile of said perspective of said first camera system the light intensity profile of at least one of said left overlap area and said right overlap area such that an overall differential intensity profile is created;

a system for locating an edge of the object in response to said overall differential intensity profile such that an edge location is found for overall differential intensity profile; and

a system for combining redundant edge location data from said overall differential intensity profile and edge data from said light intensity profile of said at least one of said left overlap area and said right overlap area such that combined redundant edge data is created.

14. The system for developing a profile of an object of claim 12, wherein said constant dimension comprises a periodicity, and said system for performing a spatial transform comprises a system for measuring said periodicity of said constant dimension of said structured pattern irradiating said outer surface of the object.

15. The system for developing a profile of an object of claim 12, wherein said system for performing a spatial transform comprises at least one of a Fast Fourier Transform ("FFT"), a Walsh Transform, and a Hadamard Transform.

16. A method of developing a profile of an object having an outer surface, a height and an edge, said method comprising the steps of:

irradiating the outer surface of the object with a first light beam having a structured light pattern and a constant dimension;

sensing the outer surface of the object illuminated by said structured light pattern falling within a field of view of a sensor, said field of view having a left, a center, and a right region;

performing a spatial transform on said structured light pattern sensed within said field of view, and said left, center, and right regions;

calculating the height of the object in response to the spatial transforms performed on said structured light pattern sensed within said field of view, and said left, center, and right regions such that a height profile is created for said field of view, and said left, center, and right regions, and calculating an average height profile therefrom;

illuminating the outer surface of the object with a second light beam falling within said field of view of said sensor such that a light intensity profile is created for said field of view, and said left, center, and right regions;

locating the edge of the object in response to the light intensity profile of the outer surface of the object illuminated by said second light beam and sensed by said sensor;

subtracting from the light intensity profile of said field of view the light intensity profile of at least one of said left region and said right region such that a differential light intensity profile is created; and

combining redundant edge location data from said differential light intensity profile and edge data from said light intensity profile of said at least one of

said left region and said right region such that combined redundant edge data is created.

17. The method of developing a profile of an object of claim 16, further comprising the step of:

deriving a refined overall height profile for the object in response to both said average height profile and said combined redundant edge data.

18. The method of developing a profile of an object of claim 16, further comprising the step of:

quantizing a group of coordinated transformed light intensity profiles and a group of coordinated height profiles such that a group of quantized coordinated light intensity profiles and a group of quantized coordinated height profiles are created, wherein;

said step of subtracting from the light intensity profile comprises the step of scaling the light intensity profiles of said field of view, and said left, center, and right regions such that a coordinated light intensity profile is created for each of said light intensity profiles; and

said step of calculating an average height profile comprises the step of scaling the height profiles of said field of view, and said left, center, and right regions such that a coordinated intensity profile is created for each of said height profiles.

19. The method of developing a profile of an object of claim 16, wherein said step of performing a spatial transform comprises the step of;

measuring a periodicity of said constant dimension of said structured pattern irradiating said outer surface of the object and sensed by said sensor.

20. The method of developing a profile of an object of claim 16, wherein said step of performing a spatial transform comprises at least one of performing a Fast Fourier Transform ("FFT"), performing a Walsh Transform, and performing a Hadamard Transform.