Confocal surface topography measurement with fixed focal positions

• US 10,281,266 B2
• Filed: 02/27/2018
• Issued: 05/07/2019
• Est. Priority Date: 07/03/2014
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Lampert, Erez, Levin, Adi, Verker, Tal
• Primary Examiner(s): Punnoose, Roy M
• Application Number:
  US15/906,616
• Publication Number:
  US 20180266814A1
• Time in Patent Office: 434 Days
• Field of Search: 356601, 356603, 356609
• CPC Class Codes: A61C 9/0053 Optical means or methods, e.g. scanning the teeth by a laser or light beam
• CPC Class Codes: A61C 9/006 projecting one or more stripes or patterns on the teeth
• 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 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 11/2518 Projection by scanning of the object
• CPC Class Codes: G01B 11/303 using photoelectric detection means
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G02B 21/0028 specially adapted for specific applications, e.g. for endoscopes, ophthalmoscopes, attachments to conventional microscopes
• CPC Class Codes: G02B 21/006 focusing arrangements; selection of the plane to be imaged
• CPC Class Codes: G02B 23/2461 Illumination
• CPC Class Codes: G02B 23/26 using light guides for illumination G02B23/2469
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085

Abstract

An apparatus is described for measuring surface topography of a three-dimensional structure. In many embodiments, the apparatus is configured to focus each of a plurality of light beams to a respective fixed focal position relative to the apparatus. The apparatus measures a characteristic of each of a plurality of returned light beams that are generated by illuminating the three-dimensional structure with the light beams. The characteristic is measured for a plurality of different positions and/or orientations between the apparatus and the three-dimensional structure. Surface topography of the three-dimensional structure is determined based at least in part on the measured characteristic of the returned light beams for the plurality of different positions and/or orientations between the apparatus and the three-dimensional structure.

Claims

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

a hand-held optical probe;

an illumination unit configured to generate a plurality of incident light beams;

an optical system configured to focus each of incident light beams to respective focal planes relative to the hand-held optical probe, the focal lengths being fixed during surface topology measurement;

a motion tracking device configured to collect motion data during surface topology measurement;

a detector unit configured to measure a characteristic of each of a plurality of returned light beams that are generated by illuminating the three-dimensional structure with the plurality of incident light beams in order to measure the surface topography of the three-dimensional structure; and

a processing unit comprising one or more processors and a tangible non-transitory storage medium storing instructions executable by the one or more processors to cause the one or more processors to process the motion data to determine relative position and orientation of the hand-held optical probe with respect to the three-dimensional structure and determine surface topography of the three-dimensional structure based on the measured characteristic of each of the plurality of returned light beams and the motion data.

2. The apparatus of claim 1, wherein the measured characteristic is intensity.

3. The apparatus of claim 1, wherein the detector unit comprises a two-dimensional array of sensor elements, each sensor element of the two-dimensional array of sensor elements being configured to measure the characteristic from a corresponding returned light beam of the plurality of returned light beams.

4. The apparatus of claim 3, wherein the optical system is configured to form a two-dimensional pattern of the plurality of incident light beams from light generated by the illumination unit, the two-dimensional pattern of the plurality of incident light beams corresponding to the plurality of returned light beams measured by the two-dimensional array of sensor elements.

5. The apparatus of claim 4, wherein the optical system comprises an optics expander unit configured to expand light generated by the illumination unit to form the two-dimensional pattern of the plurality of incident light beams.

6. The apparatus of claim 3, wherein the illumination unit is configured to produce a two-dimensional pattern of the plurality of incident light beams corresponding to the plurality of returned light beams measured by the two-dimensional array of sensor elements.

7. The apparatus of claim 1, wherein the motion tracking device generates a motion tracking signal in response to movement of the hand-held optical probe.

8. The apparatus of claim 1, wherein the fixed focal lengths are focused between 5 mm and 25 mm from the hand-held optical probe.

9. The apparatus of claim 3, wherein the two-dimensional array of sensor elements is arranged in a plane that is oriented for confocal sensing of the plurality of returned light beams relative to focal lengths of the plurality of incident light beams.

10. The apparatus of claim 9, wherein the plane of the two-dimensional array of sensor elements is non-orthogonal to the plurality of returned light beams.

11. A method for measuring surface topography of a three-dimensional structure with a hand-held probe, the method comprising:

generating a plurality of incident light beams;

focusing each of the plurality of light beams to respective fixed focal lengths relative to the hand-held probe;

measuring a characteristic of each of a plurality of returned light beams that are generated by illuminating the three-dimensional structure with the plurality of incident light beams;

collecting motion data corresponding to movement of the hand-held probe during surface topology measurement;

determining relative position and orientation of the hand-held optical probe with respect to the three-dimensional structure based on the motion data; and

determining surface topography of the three-dimensional structure based on the measured characteristic of each of the plurality of returned light beams and the determined relative position and orientation of the hand-held optical probe.

12. The method of claim 11, wherein the measured characteristic is intensity.

13. The method of claim 11, comprising generating a motion tracking signal in response to movement of the hand-held probe.

14. The method of claim 11, wherein the fixed focal lengths are at a location between 5 mm and 25 mm from the hand-held probe.

15. The method of claim 11, wherein the measuring is performed using a two-dimensional array of sensor elements, each sensor element of the two-dimensional array of sensor elements being configured to measure the characteristic from a corresponding returned light beam of the plurality of returned light beams.

16. The method of claim 15, wherein the plurality of incident light beams are generated as a two-dimensional pattern, and the two-dimensional pattern of the plurality of incident light beams corresponds to the plurality of returned light beams measured by the two-dimensional array of sensor elements.

17. The method of claim 11, wherein the motion data is inertial measurement data.

18. The method of claim 11, wherein the motion data includes three degrees of translation and three degrees of rotation.

19. The method of claim 11, further comprising generating a virtual model of the three-dimensional structure based on the surface topography of the three-dimensional structure.

20. The method of claim 11, wherein the characteristic further comprises wavelength.