Chromatic confocal system

• US 9,752,867 B2
• Filed: 12/28/2015
• Issued: 09/05/2017
• Est. Priority Date: 07/03/2014
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Atiya, Yossef, Verker, Tal
• Primary Examiner(s): Punnoose, Roy M
• Application Number:
  US14/980,337
• Publication Number:
  US 20160109226A1
• Time in Patent Office: 617 Days
• Field of Search: 356601
• CPC Class Codes: A61B 1/00009 of image signals during a use of endoscope
• CPC Class Codes: A61B 1/00194 adapted for three-dimensional imaging
• CPC Class Codes: A61B 1/04 combined with photographic or television appliances
• CPC Class Codes: A61B 1/06 with illuminating arrangements
• CPC Class Codes: A61B 1/0605 for spatially modulated illumination
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• CPC Class Codes: A61B 1/24 for the mouth, i.e. stomatoscopes, e.g. with tongue depressors tongue depressors per se A61B13/00; Instruments for opening or keeping open the mouth combined with saliva removers A61C17/00; mouth openers for animals A61D15/00
• CPC Class Codes: A61B 5/0088 for oral or dental tissue
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: A61B 5/1079 using optical or photographic means
• CPC Class Codes: A61B 5/4547 Evaluating teeth
• CPC Class Codes: A61C 1/088 Illuminating devices or attachments for examination of the mouth A61B1/24 and A61B1/06
• CPC Class Codes: A61C 9/006 projecting one or more stripes or patterns on the teeth
• 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: 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 2210/50 Using chromatic effects to achieve wavelength-dependent depth resolution

Abstract

A system for determining surface topography of a three-dimensional structure is provided. The system can include an illumination unit configured to output a two-dimensional array of light beams each comprising a plurality of wavelengths. An optical assembly can focus the plurality of wavelengths of each light beam to a plurality of focal lengths so as to simultaneously illuminate the structure over a two-dimensional field of view. A detector and a processor are used to generate data representative of the surface topography of the three-dimensional structure based on the measured characteristics of the light reflected from the structure.

Claims

1. A system for measuring surface topography of a three-dimensional structure, the system comprising:

an illumination unit configured to output a two-dimensional array of light beams each comprising a plurality of wavelengths;

an optical assembly operatively coupled to the illumination unit and configured to focus the plurality of wavelengths of each light beam to a plurality of focal lengths relative to the optical assembly so as to simultaneously illuminate the three-dimensional structure over a two-dimensional field of view, wherein the plurality of focal lengths is fixed relative to the optical assembly during the measuring of the surface topography; and

a detector configured to measure a characteristic of light reflected from the three-dimensional structure for each of a plurality of locations distributed in two dimensions over the two-dimensional field of view.

2. The system of claim 1, wherein the characteristic comprises an intensity.

3. The system of claim 1, wherein the plurality of wavelengths comprises wavelengths from 400 nm to 800 nm.

4. The system of claim 1, wherein the plurality of wavelengths comprises at least three spectral bands, and wherein the at least three spectral bands comprise overlapping wavelengths of light.

5. The system of claim 1, wherein the plurality of wavelengths comprises a continuous spectrum of wavelengths.

6. The system of claim 1, wherein the two-dimensional array of light beams forms a two-dimensional array of spots on the three-dimensional structure over the two-dimensional field of view, and wherein a ratio of pitch to spot size for the two-dimensional array of spots is configured to inhibit cross-talk between the two-dimensional array of spots.

7. The system of claim 1, wherein the optical assembly is configured to focus the light beams of the two-dimensional array to the plurality of focal lengths using at least one optical component with longitudinal chromatic aberration.

8. The system of claim 1, wherein the plurality of focal lengths covers a depth of at least 20 mm.

9. The system of claim 2, wherein the detector comprises a plurality of sensor elements distributed over a surface area configured to receive the light reflected from the three-dimensional structure over the two-dimensional field of view.

10. The system of claim 9, wherein each sensor element of the plurality of sensor elements is configured to measure the intensity of at least one wavelength of the light reflected from the three-dimensional structure.

11. The system of claim 10, wherein the plurality of sensor elements comprises a plurality of red sensor elements, a plurality of green sensor elements, and a plurality of blue sensor elements;

each of the plurality of red sensor elements being configured to measure the intensity of a red light wavelength, each of the plurality of green sensor elements being configured to measure the intensity of a green light wavelength, and each of the plurality of blue sensor elements being configured to measure the intensity of a blue light wavelength.

12. The system of claim 11, wherein the plurality of sensor elements are arranged in a Bayer pattern or in a plurality of layers.

13. The system of claim 1, wherein the optical assembly is configured to focus the plurality of wavelengths to the plurality of focal lengths to a depth within a range from 10 mm to 30 mm relative to the optical assembly without relative movement of components of the optical assembly and components of the illumination unit.

14. A method for measuring surface topography of a three-dimensional structure, the method comprising:

generating a two-dimensional array of light beams each comprising a plurality of wavelengths;

focusing the plurality of wavelengths of each light beam to a plurality of focal lengths relative to the three-dimensional structure so as to simultaneously illuminate the three-dimensional structure over a two-dimensional field of view, wherein the plurality of focal lengths is fixed relative to the optical assembly during the measuring of the surface topography; and

measuring a characteristic of light reflected from the three-dimensional structure for each of a plurality of locations distributed in two dimensions over the two-dimensional field of view.

15. The method of claim 14, wherein the characteristic comprises an intensity.

16. The method of claim 14, wherein the plurality of wavelengths comprises wavelengths from 400 nm to 800 nm.

17. The method of claim 14, wherein the plurality of wavelengths comprises at least three spectral bands, and wherein the at least three spectral bands comprise overlapping wavelengths of light.

18. The method of claim 14, wherein the plurality of wavelengths comprises a continuous spectrum of wavelengths.

19. The method of claim 14, wherein the two-dimensional array of light beams forms a two-dimensional array of spots on the structure over the two-dimensional field of view, and wherein a ratio of pitch to spot size for the two-dimensional array of spots is selected to inhibit cross-talk between the two-dimensional array of spots.

20. The method of claim 14, wherein the light beams of the two-dimensional array are focused to the plurality of focal lengths using at least one optical component with longitudinal chromatic aberration.

21. The method of claim 14, wherein the plurality of focal lengths covers a depth of at least 20 mm.

22. The method of claim 15, wherein the intensity of the light reflected from the three-dimensional structure is measured using a detector comprising a plurality of sensor elements distributed over a surface area configured to receive the light reflected from the three-dimensional structure over the two-dimensional field of view.

23. The method of claim 22, wherein each sensor element of the plurality of sensor elements is configured to measure the intensity of at least one wavelength of the light reflected from the three-dimensional structure.

24. The method of claim 23, wherein the plurality of sensor elements comprises a plurality of red sensor elements, a plurality of green sensor elements, and a plurality of blue sensor elements;

each of the plurality of red sensor elements being configured to measure the intensity of a red light wavelength, each of the plurality of green sensor elements being configured to measure the intensity of a green light wavelenath, and each of the plurality of blue sensor elements being configured to measure the intensity of a blue light wavelength.

25. The method of claim 24, wherein the plurality of sensor elements are arranged in a Bayer pattern or in a plurality of layers.

26. The method of claim 14, wherein the focusing of the plurality of wavelengths to the plurality of focal lengths to a depth within a range from 10 mm to 30 mm is performed without relative movement of components of an optical assembly and components of an illumination unit.