US 12,708,494 B2Granted

Intraoral 3D scanner with inaccurate focus lens

AssigneeAlign Technology, Inc.

InventorOfer Saphier

Life of this patent

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Abstract

An intraoral scanner includes one or more structured light projectors, a camera, and control circuitry. The structured light projector(s) are to project a pattern of light onto an intraoral 3D surface. The camera comprises a focusing lens configured to focus at a plurality of different focal depths, each associated with a distinct optical distortion. The camera captures of at least a portion of the pattern of light projected onto the intraoral 3D surface at one or more of the different focal depths. The control circuitry is to change a focus position of the focusing lens to cause the camera to capture the images of the intraoral three-dimensional surface at the one or more different focal depths, wherein the change in the focus position causes a change in optical distortion for the camera and a corresponding change in a calibration of the camera associated with the change in the optical distortion.

Claims27

Dependent claims

An apparatus for intraoral scanning, comprising:

one or more structured light projectors configured to project a pattern of light onto an intraoral three-dimensional surface;
a camera comprising a focusing lens configured to focus at a plurality of different focal depths, wherein each of the plurality of different focal depths is associated with a distinct optical distortion, and wherein the camera is to capture images of at least a portion of the pattern of light projected onto the intraoral three-dimensional surface at one or more of the plurality of different focal depths;
control circuitry to change a focus position of the focusing lens to cause the camera to capture the images of the intraoral three-dimensional surface at the one or more of the plurality of different focal depths, wherein the change in the focus position causes a change in optical distortion for the camera and a corresponding change in a calibration of the camera associated with the change in the optical distortion;
and
a processor to determine depths of at least some of a plurality of detected features by solving a correspondence algorithm that relates projector rays to pixels of the camera, taking into consideration the distinct optical distortions of the plurality of different focal depths.

2 more elements

An apparatus for intraoral scanning, the apparatus comprising:

one or more structured light projectors, each structured light projector configured to project a pattern of light defined by a plurality of projector rays, each projector ray projecting a feature of the pattern, when the structured light projector is activated;
a camera comprising a camera sensor having an array of pixels, wherein:
(a) the camera is configured to capture an image that depicts at least a plurality of detected features of the projected pattern of light on an intraoral three-dimensional surface, and
(b) the camera comprises a lens that is configured to focus at a plurality of different focal depths, and
a computer processor configured to:
(A) store calibration values for the one or more structured light projectors,
(B) store calibration values for the camera determined for each of a plurality of discrete states Sn of the lens, each discrete state Sn of the lens having a distinct focal depth and distinct optical magnification, and
(C) for a between-state image captured by the camera when the lens is in an intermediate state Si between two discrete states Sn and Sn+1, the focal depth of the lens in intermediate state Si being between the distinct focal depths of the lens in states Sn and Sn+1, compute respective three-dimensional positions on the intraoral three-dimensional surface of a plurality of features of the pattern of light detected in the between-state image based on (i) the stored calibration values for the camera determined for each of a plurality of discrete states Sn of the lens, and (ii) the stored calibration values for the one or more structured light projectors.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/414,289Filed 16 Jan 2024 · us provisional application
Priority: 15 Feb 2023
Published: US 2024/0268936 A115 Aug 2024
Granted: 18 Aug 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

A61C 9/0066
Optical means or methods, e.g. scanning the teeth by a laser or light beam: depth determination through adaptive focusing
A61C 9/006
Optical means or methods, e.g. scanning the teeth by a laser or light beam: projecting one or more stripes or patterns on the teeth
G06T 7/00
Image analysis
G06T 2200/04
Indexing scheme for image data processing or generation, in general: involving 3D image data