Focus scanning apparatus

• US 11,076,146 B1
• Filed: 03/19/2021
• Issued: 07/27/2021
• Est. Priority Date: 06/17/2009
• Status: Active Grant

• Current Assignee: 3shape A/S
• Original Assignee: 3shape A/S
• Inventors: Fisker, Rune, Ojelund, Henrik, Kjaer, Rasmus, van der Poel, Mike, Qazi, Arish A., Hollenbeck, Karl-Josef
• Primary Examiner(s): Tran, Thai Q
• Assistant Examiner(s): Mesa, Jose M
• Application Number:
  US17/206,581
• Publication Number:
  US 20210211638A1
• Time in Patent Office: 130 Days
• CPC Class Codes: A61B 5/0068 Confocal scanning
• CPC Class Codes: A61B 5/1075 for measuring dimensions by non-invasive methods, e.g. for determining thickness of tissue layer A61B8/0858 takes precedence
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: A61B 5/1077 Measuring of profiles
• CPC Class Codes: A61B 5/4547 Evaluating teeth
• 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 2210/58 Wireless transmission of information between a sensor or probe and a control or evaluation unit
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof

Abstract

A scanner includes a camera, a light source for generating a probe light incorporating a spatial pattern, an optical system for transmitting the probe light towards the object and for transmitting at least a part of the light returned from the object to the camera, a focus element within the optical system for varying a position of a focus plane of the spatial pattern on the object, unit for obtaining at least one image from said array of sensor elements, unit for evaluating a correlation measure at each focus plane position between at least one image pixel and a weight function, a processor for determining the in-focus position(s) of each of a plurality of image pixels for a range of focus plane positions, or each of a plurality of groups of image pixels for a range of focus plane positions, and transforming in-focus data into 3D real world coordinates.

Claims

1. An intraoral scanner for determining the 3D geometry and color of at least a part of the surface of an object in an oral cavity, the intraoral scanner comprising:

at least one camera accommodating an array of sensor elements;

a pattern generator configured to generate, using a light source, a probe light with a plurality of configurations in the form of a time-varying illumination pattern;

an optical system for transmitting the probe light towards the object along an optical path thereby illuminating at least a part of the object with the time-varying illumination pattern, and for transmitting at least a part of the light returned from the object to the at least one camera to form a plurality of 2D images, wherein the 3D geometry is determined based on the plurality of 2D images and the time-varying illumination pattern;

a tip configured to be inserted into the oral cavity; and

a hardware processor configured to;

selectively switch a color of the probe light, thereby illuminating the object with different colors at different times;

record different images by the at least one camera at the different times, thereby recording images of the object with the different colors; and

combine the different colors from the different images, thereby obtaining the color of the surface of the object,

wherein the intraoral scanner is wireless, and wherein the at least one camera is a high-speed camera.

2. The intraoral scanner according to claim 1, wherein the pattern generator includes at least one translucent and/or transparent pattern element.

3. The intraoral scanner according to claim 1, wherein the pattern generator is based on a projector such as a liquid crystal display (LCD) projector or a digital light processing (DLP) projector.

4. The intraoral scanner according to claim 1, wherein the different colors are provided by at least three monochromatic light sources of the light source.

5. The intraoral scanner according to claim 4, wherein the at least three monochromatic light sources are light-emitting diodes (LEDs) or a segmented LED.

6. The intraoral scanner according to claim 4, wherein the hardware processor is configured to selectively switch the color of the probe light by switching on and off the at least three monochromatic light sources.

7. The intraoral scanner according to claim 1, wherein the optical system is substantially achromatic.

8. The intraoral scanner according to claim 1, wherein the probe light is directed towards the object in a direction substantially parallel with the longitudinal axis of the tip, and wherein the probe light is further reflected towards the object by a single reflective mirror located in the tip.

9. The intraoral scanner according to claim 1, wherein the hardware processor is further configured to locally process raw 3D data into data for the 3D geometry, such that the data for the 3D geometry is wirelessly transmitted instead of the raw 3D data, and wherein the raw 3D data is based on the plurality of 2D images.

10. The intraoral scanner according to claim 1, wherein the hardware processor is further configured to locally process raw 3D data into data for the 3D geometry, such that the data for the 3D geometry is wirelessly transmitted at a reduced data rate in comparison with transmission of raw 3D data, and wherein the raw 3D data is based on the plurality of 2D images.

11. The intraoral scanner according to claim 9, wherein the data for the 3D geometry is wirelessly transmitted to a workstation.

12. The intraoral scanner according to claim 9, wherein the hardware processor processes the raw 3D data into data for the 3D geometry in real time.

13. The intraoral scanner according to claim 1, wherein a temporal correlation measure is computed with sensor signals, in the at least one camera, recorded at different times while the plurality of configurations in the form of a time-varying illumination pattern are changed.

14. The intraoral scanner according to claim 13, wherein the temporal correlation measure is computed for each individual sensing element.

15. The intraoral scanner according to claim 13, wherein the temporal correlation measure is based on a reference signal that is based on knowledge or on calibration of the plurality of configurations of the time-varying illumination pattern.

16. The intraoral scanner according to claim 1, wherein the high-speed camera records images at a frame rate of at least 500 frames per second or at a frame rate of at least 2000 frames per second.

17. The intraoral scanner according to claim 1, wherein the intraoral scanner comprises at least two light sources, each of the light sources configured to operate with the pattern generator.

18. The intraoral scanner according to claim 17, wherein the at least two light sources are configured to operate with different wavelengths.

19. The intraoral scanner according to claim 18, wherein the intraoral oral scanner is configured such that the different wavelengths can be manually selected, whereby the 3D geometry is dependent on which light source is being manually selected.

20. The intraoral scanner according to claim 1, wherein the intraoral scanner further comprises polarization optics.

21. A method for determining the 3D geometry and color of at least a part of the surface of an object in an oral cavity, said method comprising the steps of:

using a light source and a pattern generator to generate a probe light with a plurality of configurations in the form of a time-varying illumination pattern;

transmitting the probe light, through a tip of intraoral scanner inserted into the oral cavity, towards the object along an optical path, thereby illuminating at least a part of the object with the time-varying illumination pattern;

transmitting at least a part of the light returned from the object to at least one camera accommodating an array of sensor elements to form a plurality of 2D images,

wherein the 3D geometry is determined based on the plurality of 2D images and the time-varying illumination pattern;

selectively switching a color of the probe light, thereby illuminating the object with different colors at different times;

recording different images by the at least one camera at the different times, thereby recording images of the object with the different colors;

combining the different colors from the different images to obtain the color of the surface of the object; and

wirelessly transmitting the data for the 3D geometry.

22. The method according to claim 21, wherein the plurality of 2D images is recorded using a high-speed camera.

23. The method according to claim 21, wherein the method further comprises a step of locally processing, on the intraoral scanner, raw 3D data into data for the 3D geometry, such that the data for the 3D geometry is wirelessly transmitted instead of the raw 3D data, and wherein the raw 3D data is based on the plurality of 2D images.

24. The method according to claim 21, wherein the method further comprises a step of locally processing, on the intraoral scanner, raw 3D data into data for the 3D geometry, such that the data for the 3D geometry is wirelessly transmitted at a reduced data rate in comparison with transmission of raw 3D data, and wherein the raw 3D data is based on the plurality of 2D images.

25. The method according to claim 23, wherein the step of wirelessly transmitting the data for the 3D geometry is to a workstation.

26. The method according to claim 23, wherein the step of locally processing is in real time.

27. The method according to claim 21, where the method further comprises a step of computing a temporal correlation measure with sensor signals, in the at least one camera, recorded at different times while the plurality of configurations in the form of a time-varying illumination pattern are changed.

28. The method according to claim 27, wherein the temporal correlation measure is computed for each individual sensing element.

29. The method according to claim 27, wherein the temporal correlation measure is based on a reference signal that is based on knowledge or on calibration of the plurality of configurations of the time-varying illumination pattern.

30. The method according to claim 21, wherein method further comprises a step of manually selecting a wavelength for which the intraoral scanner obtains the 3D geometry.