Imaging apparatus with simplified optical design

• US 10,507,089 B2
• Filed: 04/26/2019
• Issued: 12/17/2019
• Est. Priority Date: 08/15/2014
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Verker, Tal, Levin, Adi, Saphier, Ofer, Moshe, Maayan
• Primary Examiner(s): Ton, Tri T
• Application Number:
  US16/396,484
• Publication Number:
  US 20190247164A1
• Time in Patent Office: 235 Days
• Field of Search: 356600-640
• CPC Class Codes: A61C 9/0066 Depth determination through adaptive focusing
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G02B 21/006 focusing arrangements; selection of the plane to be imaged
• CPC Class Codes: G02B 23/2446 of the image relay G02B23/26 takes precedence
• CPC Class Codes: G02B 23/2461 Illumination
• CPC Class Codes: G02B 23/26 using light guides for illumination G02B23/2469
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration

Abstract

A method of generating a three-dimensional virtual model of an intraoral object includes capturing, by an imaging apparatus for performing intraoral scans, surface scan data of the intraoral object while changing a position of at least one lens of focusing optics of the imaging apparatus, wherein the surface scan data comprises depth data for a plurality of points of the intraoral object. The method further includes adjusting the depth data for one or more of the plurality of points based at least in part on the position of the at least one lens associated with the depth data for the one or more of the plurality of points. The method further includes generating the three-dimensional virtual model of the intraoral object using the adjusted depth data.

Claims

1. A method of generating a three-dimensional virtual model of an intraoral object, comprising:

capturing, by an imaging apparatus for performing intraoral scans, surface scan data of the intraoral object while changing a position of at least one lens of focusing optics of the imaging apparatus, wherein the surface scan data comprises depth data for a plurality of points of the intraoral object;

adjusting the depth data for one or more of the plurality of points based at least in part on the position of the at least one lens associated with the depth data for the one or more of the plurality of points using one or more compensation models, wherein the one or more compensation models compensate for changes in magnification associated with different positions of the at least one lens, and wherein the one or more compensation models provide different adjustments to the depth data for the one or more of the plurality of points for the different positions of the at least one lens; and

generating the three-dimensional virtual model of the intraoral object using the adjusted depth data.

2. The method of claim 1, wherein the focusing optics comprise a non-flat focal surface that distorts the depth data for the one or more of the plurality of points, and wherein the depth data is adjusted to compensate for the non-flat focal surface.

3. The method of claim 2, wherein the non-flat focal surface comprises a curved focal plane and the depth data is adjusted to compensate for a curvature of the curved focal plane.

4. The method of claim 1, wherein the imaging apparatus comprises a non-telecentric optical system, wherein adjustments to the position of the at least one lens cause a change in magnification of a focal surface of the focusing optics, the method further comprising:

adjusting at least one of a position along an x-axis or a position along a y-axis for the one or more of the plurality of points to compensate for the change in magnification of the focal surface for the one or more of the plurality of points.

5. The method of claim 1, wherein a focal surface of the focusing optics changes with changes in temperature, and wherein the depth data is adjusted to compensate for the change in the focal surface caused by the current temperature of the focusing optics for the one or more of the plurality of points.

6. The method of claim 1, wherein an optical system of the imaging apparatus lacks a field lens, wherein the lack of the field lens causes distortion of the depth data for the one or more of the plurality of points, and wherein the depth data is adjusted to compensate for the distortion of the depth data caused by the lack of the field lens.

7. The method of claim 1, wherein:

the imaging apparatus comprises a detector having a plurality of pixels;

each pixel of the plurality of pixels captures the surface scan data for a corresponding point of the plurality of points of the intraoral object; and

capturing the surface scan data comprising the depth data comprises;

determining, for each pixel of the plurality of pixels, a focusing setting of the focusing optics for which a point associated with the pixel is in focus; and

determining, for each pixel of the plurality of pixels, a depth of the point associated with the pixel that corresponds to the determined focusing setting.

8. The method of claim 7, wherein adjusting the depth data for the one or more of the plurality of points comprises applying the determined focusing setting for the pixels associated with the one or more of the plurality of points to at least one of a field curvature model, a thermal state compensation model or a magnification compensation model.

9. An imaging apparatus for performing intraoral scans, comprising:

a light source to provide light;

an optical system comprising a plurality of lenses disposed along an optical path of the light, wherein the optical system comprises focusing optics to perform focusing of the light onto a focal surface and to direct the light toward a three dimensional object to be imaged in an oral cavity;

a translation mechanism to adjust a location of at least one lens of the plurality of lenses to displace the focal surface along an imaging axis defined by the optical path, wherein the at least one lens is a lens of the focusing optics, wherein at least one of a shape or a magnification of the focal surface changes with changes in the location of the at least one lens;

a detector to generate surface scan data by measuring returning light that is reflected off of the three dimensional object and directed back through the focusing optics, wherein the returning light is to be measured for a plurality of locations of the at least one lens for determination of depth data for a plurality of points of the three dimensional object, the surface scan data comprising the depth data; and

one or more processor to;

adjust the depth data for one or more of the plurality of points based at least in part on the location of the at least one lens associated with the depth data using one or more compensation models, wherein the one or more compensation models compensate for changes in magnification associated with different locations of the at least one lens, and wherein the one or more compensation models provide different adjustments to the depth data for the one or more of the plurality of points for the different locations of the at least one lens; and

generate a three-dimensional virtual model using the adjusted depth data.

10. The imaging apparatus of claim 9, wherein the optical system comprises a non-flat focal surface that distorts the depth data for the one or more of the plurality of points, and wherein the one or more processor is to adjust the depth data to compensate for the non-flat focal surface.

11. The imaging apparatus of claim 10, wherein the non-flat focal surface comprises a curved focal plane, and wherein the one or more processor is to adjust the depth data to compensate for a curvature of the curved focal plane.

12. The imaging apparatus of claim 10, wherein a shape of the non-flat focal surface changes with changes in the location of the at least one lens.

13. The imaging apparatus of claim 9, wherein the one or more processor is further to:

determine a current temperature of the optical system, wherein the focal surface of the focusing optics changes with changes in temperature; and

adjust the depth data to compensate for the change in the focal surface caused by the current temperature of the optical system for the one or more of the plurality of points.

14. The imaging apparatus of claim 9, wherein the optical system lacks a field lens, wherein the lack of the field lens causes distortion of the depth data for the one or more of the plurality of points, and wherein the one or more processor is further to:

adjust the depth data to compensate for the distortion of the depth data caused by the lack of the field lens.

15. The imaging apparatus of claim 9, wherein:

the detector comprises a plurality of pixels, wherein each pixel of the plurality of pixels is to capture the surface scan data for a corresponding point of the plurality of points of the intraoral object; and

the one or more processor is further to;

determine, for each pixel of the plurality of pixels, a focusing setting of the focusing optics for which a point associated with the pixel is in focus; and

determine, for each pixel of the plurality of pixels, a depth of the point associated with the pixel that corresponds to the determined focusing setting.

16. The imaging apparatus of claim 15, wherein to adjust the depth data for the one or more of the plurality of points the one or more processor applies the determined focusing setting for the pixels associated with the one or more of the plurality of points to at least one of a field curvature model, a thermal state compensation model or a magnification compensation model.

17. The imaging apparatus of claim 9, further comprising:

a beam splitter disposed along the optical path between the light source and the focusing optics, wherein the beam splitter directs the light from the light source towards the focusing optics and directs the returning light from the focusing optics to the detector;

wherein the optical system is characterized in having an absence of a field lens.

18. The imaging apparatus of claim 9, wherein the light source comprises an illumination module configured to generate a pattern of light in an x-y plane.

19. The imaging apparatus of claim 9,

wherein the plurality of lenses comprise:

a first lens;

a second lens, the second lens having a fixed location relative to the first lens; and

a third lens disposed between the first lens and the second lens, the third lens having a variable location that is adjustable by the translation mechanism, wherein the focusing optics comprises the third lens.

20. The imaging apparatus of claim 9, wherein the optical system is a non-telecentric optical system, wherein adjustments to the position of the at least one lens cause a change in magnification of the focal surface of the optical system, and wherein the one or more processor is further to:

adjust at least one of a position along an x-axis or a position along a y-axis for the one or more of the plurality of points to compensate for the change in magnification of the focal surface for the one or more of the plurality of points.

21. The imaging apparatus of claim 9, wherein the imaging apparatus is a confocal imaging apparatus and the focusing optics are confocal focusing optics.

22. An imaging apparatus for performing intraoral scans, comprising:

a light source to provide light;

an optical system comprising a plurality of lenses disposed along an optical path of the light, wherein the optical system comprises focusing optics to perform focusing of the light onto a focal surface and to direct the light toward a three dimensional object to be imaged in an oral cavity, the focusing optics comprising at least one lens of the plurality of lenses;

a translation mechanism to adjust a location of the at least one lens to displace the focal surface along an imaging axis defined by the optical path, wherein adjustments to the location of the at least one lens cause a change in magnification of the focal surface;

a detector to measure returning light that is reflected off of the three dimensional object and directed back through the focusing optics; and

one or more processor to;

determine positions of a plurality of points of the three dimensional object based on the measured returning light; and

adjust the determined positions of one or more of the plurality of points to compensate for respective magnifications of the focal surface associated with respective locations of the at least one lens.

23. The imaging apparatus of claim 22, wherein the focusing optics perform the focusing of the light onto a non-flat focal surface caused by a lack of a field lens in the optical system.

24. The imaging apparatus of claim 23, wherein the non-flat focal surface comprises a curved focal plane, wherein the determined positions for the one or more of the plurality of points are to be adjusted to compensate for a curvature of the curved focal plane, and wherein a shape of the non-flat focal surface changes with changes in the location of the at least one lens.

25. The imaging apparatus of claim 22, wherein the determined positions of the plurality of points comprise determined depths of the plurality of points, and wherein the one or more processor is to adjust the determined depths of the one or more of the plurality of points using one or more compensation models, wherein the one or more compensation models compensate for at least one of a curvature of the focal surface or changes in a position of the focal surface caused by changes in temperature within the imaging apparatus, and wherein the one or more compensation models provide different adjustments to the determined depths of the one or more of the plurality of points for different locations of the at least one lens.

26. The imaging apparatus of claim 22, wherein the one or more processor is to adjust at least one of a position along an x-axis or a position along a y-axis for the one or more of the plurality of points to compensate for the change in magnification of the focal surface for the one or more of the plurality of points.

27. The imaging apparatus of claim 22, wherein the light source comprises an illumination module configured to generate a pattern of light in an x-y plane.

28. The imaging apparatus of claim 22, wherein the imaging apparatus is a confocal imaging apparatus and the focusing optics are confocal focusing optics.

29. The imaging apparatus of claim 22, wherein the one or more processor is further to:

determine a current temperature of the optical system, wherein the focal surface of the optical system changes with changes in temperature; and

adjust the determined positions of the one or more of the plurality of points to compensate for the change in the focal surface caused by the current temperature of the optical system for the one or more of the plurality of points.

30. A method of generating a three-dimensional virtual model of an intraoral object, comprising:

capturing, by an imaging apparatus for performing intraoral scans, surface scan data of the intraoral object while changing a position of at least one lens of focusing optics of the imaging apparatus, wherein the surface scan data comprises depth data for a plurality of points of the intraoral object;

adjusting the depth data for one or more of the plurality of points based at least in part on the position of the at least one lens associated with the depth data for the one or more of the plurality of points using one or more compensation models, wherein the one or more compensation models compensate for a curvature of a focal surface of the focusing optics, and wherein the one or more compensation models provide different adjustments to the depth data for the one or more of the plurality of points for the different positions of the at least one lens; and

generating the three-dimensional virtual model of the intraoral object using the adjusted depth data.

31. A method of generating a three-dimensional virtual model of an intraoral object, comprising:

capturing, by an imaging apparatus for performing intraoral scans, surface scan data of the intraoral object while changing a position of at least one lens of focusing optics of the imaging apparatus, wherein the surface scan data comprises depth data for a plurality of points of the intraoral object;

adjusting the depth data for one or more of the plurality of points based at least in part on the position of the at least one lens associated with the depth data for the one or more of the plurality of points using one or more compensation models, wherein the one or more compensation models compensate for changes in a position of a focal surface caused by changes in temperature within the imaging apparatus, and wherein the one or more compensation models provide different adjustments to the depth data for the one or more of the plurality of points for the different positions of the at least one lens; and

generating the three-dimensional virtual model of the intraoral object using the adjusted depth data.

32. An imaging apparatus for performing intraoral scans, comprising:

a light source to provide light;

an optical system comprising a plurality of lenses disposed along an optical path of the light, wherein the optical system comprises focusing optics to perform focusing of the light onto a focal surface and to direct the light toward a three dimensional object to be imaged in an oral cavity;

a translation mechanism to adjust a location of at least one lens of the plurality of lenses to displace the focal surface along an imaging axis defined by the optical path, wherein the at least one lens is a lens of the focusing optics, wherein at least one of a shape or a magnification of the focal surface changes with changes in the location of the at least one lens;

a detector to generate surface scan data by measuring returning light that is reflected off of the three dimensional object and directed back through the focusing optics, wherein the returning light is to be measured for a plurality of locations of the at least one lens for determination of depth data for a plurality of points of the three dimensional object, the surface scan data comprising the depth data; and

one or more processor to;

adjust the depth data for one or more of the plurality of points based at least in part on the location of the at least one lens associated with the depth data using one or more compensation models, wherein the one or more compensation models compensate for a curvature of the focal surface, and wherein the one or more compensation models provide different adjustments to the depth data for the one or more of the plurality of points for the different locations of the at least one lens; and

generate a three-dimensional virtual model using the adjusted depth data.

33. An imaging apparatus for performing intraoral scans, comprising:

a light source to provide light;

an optical system comprising a plurality of lenses disposed along an optical path of the light, wherein the optical system comprises focusing optics to perform focusing of the light onto a focal surface and to direct the light toward a three dimensional object to be imaged in an oral cavity;

a translation mechanism to adjust a location of at least one lens of the plurality of lenses to displace the focal surface along an imaging axis defined by the optical path, wherein the at least one lens is a lens of the focusing optics, wherein at least one of a shape or a magnification of the focal surface changes with changes in the location of the at least one lens;

a detector to generate surface scan data by measuring returning light that is reflected off of the three dimensional object and directed back through the focusing optics, wherein the returning light is to be measured for a plurality of locations of the at least one lens for determination of depth data for a plurality of points of the three dimensional object, the surface scan data comprising the depth data; and

one or more processor to;

adjust the depth data for one or more of the plurality of points based at least in part on the location of the at least one lens associated with the depth data using one or more compensation models, wherein the one or more compensation models compensate for changes in a position of the focal surface caused by changes in temperature within the imaging apparatus, and wherein the one or more compensation models provide different adjustments to the depth data for the one or more of the plurality of points for the different locations of the at least one lens; and

generate a three-dimensional virtual model using the adjusted depth data.