Systems and Methods for Measuring the Shape and Location of an object

• US 20090161090A1
• Filed: 12/31/2008
• Published: 06/25/2009
• Est. Priority Date: 06/27/2007
• Status: Active Grant

• Current Assignee: AMO Development LLC (Johnson & Johnson)
• Original Assignee: Advanced Medical Optics Incorporated (Johnson & Johnson)
• Inventors: Farrer, Stephen W., Campbell, Charles E., Raymond, Thomas D., Copland, James, Neal, Daniel R., Powers, William S.
• Granted Patent: US 7,988,290 B2
• Time in Patent Office: Days
• US Class Current: 356/3
• CPC Class Codes: A61B 3/0091 Fixation targets for viewing direction
• CPC Class Codes: A61B 3/107 for determining the shape or measuring the curvature of the cornea
• CPC Class Codes: A61B 3/145 by video means
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G01B 11/255 for measuring radius of curvature measuring diameter G01B11/08

Abstract

A system for determining the shape of an object and/or a distance of the object from the system includes a first plurality of light source, a second plurality of light sources, and a detector or detector array. The first plurality of light sources are disposed about a central axis and are separated from the central axis by radial distances defining an aperture in the first plurality of light sources. The system also includes an optical system adapted to provide light from the second plurality of light sources through the aperture to the object. The system may further include a computer configured to determine the shape of the object and/or the distance of the object from the system using light from the first and second plurality of light sources that is reflected from the object and received by the detector.

Claims

1. A system for determining the shape of a surface of a test object, comprising:

a first plurality of light sources disposed about a central axis, the light sources being separated from the central axis by radial distances defining an aperture in the first plurality;

a second plurality of light sources;

a detector array;

an optical system adapted to provide light from the second plurality of light sources through the aperture to a test object; and

an electronic memory comprising instructions to;

calculate a first plurality of locations on the detector array of light from at least some of the first plurality of light sources when light from the first plurality of light sources is reflected off the test object;

calculate a second plurality of locations on the detector array of light from at least some of the second plurality of light sources when light from the second plurality of light sources is reflected off the test object;

determine a shape of a surface of the test object using the first plurality of locations and the second plurality of locations; and

a processor to perform the instructions.

2. The system of claim 1, wherein the electronic memory further comprise instructions to adjust the first plurality of locations using the second plurality of locations.

3. The system of claim 1, wherein the electronic memory further comprises instructions to:

calculate a distance of the test object from the system using the first plurality of locations and the second plurality of locations; and

determine the shape of the surface of the test object using the distance.

4. The system of claim 1, wherein the electronic memory further comprises instructions to:

calculate a first curvature of the surface using the first plurality of locations;

calculate a second curvature of the surface using the second plurality of locations;

determine the shape of the surface of the test object using the first and second curvatures.

5. The system of claim 1, wherein the electronic memory further comprises instructions to:

calculate a first curvature of the surface using the first plurality of locations;

calculate a second curvature of the surface using the second plurality of locations;

recalculate the first plurality of locations using the first curvature and the second curvature.

6. The system of claim 1, wherein the electronic memory further comprises instructions to:

measure, using the second plurality of light sources, a curvature in an outer portion of a central region of the test object adjacent an outer region of the test object; and

measure reflection locations from the test object of an innermost set of light sources of the first plurality of light sources; and

calculate a distance of the test object from the system using (1) the measured curvature of the outer portion of the central region of the test object and (2) the measured reflection locations of the innermost set of light sources of the first plurality of light sources.

7. The system of claim 1, wherein the optical system comprises an optical element and, when the test object is disposed to reflect light from the first and second light sources, (1) light from the first plurality of light sources reflects off the test object, passes a first time through the optical element, and is received by the detector array, and (2) light from the second plurality of light sources passes a first time through the optical element, reflects off the test object, passes a second time through the optical element, and is received by the detector array.

8. The system of claim 7, wherein the optical element is a lens that is disposed to collimate light from the second plurality of light sources.

9. The system of claim 1, wherein the test object is a reference object having a know shape.

10. The system of claim 9, wherein the shape is a spherical shape with a constant radius of curvature.

11. The system of claim 1, wherein the test object is a spectacle lens, a contact lens, an intraocular lens, or a mold for forming a contact lens or intraocular lens.

12. The system of claim 1, wherein the test surface is a cornea of an eye.

13. The system of claim 1, wherein the first plurality of light sources forms a Placido-like light source and the second plurality of light sources forms a Helmholtz source.

14. A system for measuring a distance of a test object from the system, comprising:

a first light source and a second light source;

a detector array configured to receive light from the first and second light sources;

wherein, when a test object is disposed to reflect light from the first and second light sources, (1) light from the first light source reflects off the test object, passes a first time through the optical element, and is received by the detector array, and (2) light from the second light source passes a first time through the optical element, reflects off the test object, passes a second time through the optical element, and is received by the detector array;

wherein the first light source, second light source, and the detector array are disposed for calculating a distance of the test object from the system.

15. The system of claim 14, further comprising:

an electronic memory comprising instructions to;

measure one or more first locations on the detector array of light from the first light source;

measure one or more first locations on the detector array of light from the second light source;

calculate the distance of the test object from the system using the measured first and second locations of light from the first and second light sources; and

a processor to perform the instructions.

16. The system of claim 14, wherein the optical element is a lens having a focal length configured to collimate light from the second light source.

17. The system of claim 14, wherein the distance of the test object from the system is a vertex error of the test object from a reference plane of the system.

18. The system of claim 14, wherein the distance of the test object from the system is a distance from a reference location of the system to the test object.

19. The system of claim 18, wherein the reference location is a location of the first light source.

20. The system of claim 18, wherein the reference location is a principal plane of the optical element or a distance one focal length of the optical element away from the optical element.

21. The system of claim 14, wherein the first light source comprises a first plurality of individual light sources and the second light source comprises a second plurality of individual light sources, the system further comprising an electronic memory comprising instructions to:

measure, using the second plurality of individual light sources, a curvature in an outer portion of a central region of the test object, adjacent an outer region of the test object; and

measure one or more reflection locations from the test object of an innermost set of individual light sources of the first plurality of individual light sources; and

calculate a distance of the test object from the system using (1) the measured curvature of the outer portion of the central region of the test object and (2) the measured reflection locations of the innermost set of individual light sources.

22. The system of claim 14, wherein the test surface is a cornea of an eye.

23. The system of claim 14, wherein the test object is a spectacle lens, a contact lens, or an intraocular lens, or a mold for forming a contact lens or intraocular lens.

24. A method of determining a distance of a test object from the system, comprising:

providing a system including a first light source, a second light source, an optical element, and a detector array;

disposing a test object so that light from the first and second light sources is reflected off the test object;

passing light from the second light source a first time through the optical element, reflecting light off the test object, and passing the reflected light a second time through the optical element;

reflecting light from the first light source off the test object, passing the reflected light from the first light source a first time through the optical element;

receiving light from the first and second light sources at the detector array;

calculating a distance of the test object from the system using the received light from the first and second light sources at the detector array.

25. A system for measuring a distance of a test object from the system, comprising:

a first light source and a second light source;

a detector array configured to receive light from the first and second light sources;

wherein, when a surface of a test object is illuminated by light from the first and second light sources, (1) the first light source produces a signal at the detector array that depends on a shape of the surface of the test object and on a distance of the test object from the system, and (2) the second light source produces a signal at the detector array that depends on a shape of the surface of the test object and that does not depend on a distance of the test object from the system;

wherein the first light source, second light source, and the detector array are disposed for calculating a distance of the test object from the system.

26. The system of claim 25 wherein the first light source, second light source, and the detector array are disposed for calculating a shape of the surface of the test object.

27-35. -35. (canceled)