EP-4740900-A2 - ULTRAMINIATURE PATTERN PROJECTOR

EP4740900A2EP 4740900 A2EP4740900 A2EP 4740900A2EP-4740900-A2

Abstract

An apparatus for intraoral scanning comprises an elongate wand comprising a probe at a distal end of the elongate wand. The apparatus further comprises one or more structured light projectors disposed within the probe, each structured light projector comprising: (a) a housing; (b) a light source disposed within the housing and comprising: a semiconductor laser die; and a beam shaping optical element; and ( c) a pattern generating optical element. A distance D between an emission point of the semiconductor laser die and an input face of the beam shaping optical element is 50-250 microns. Each structured light projector is configured to project a pattern of light onto an intraoral surface when the light source of the structured light projector is activated to emit light through the pattern generating optical element of the structured light projector.

Inventors

ATIYA, Yosef
SAPHIER, OFER
SHEKEL, Noam

Assignees

Align Technology, Inc.

Dates

Publication Date: 20260513
Application Date: 20230727

Claims (15)

An apparatus for intraoral scanning, the apparatus comprising: an elongate wand comprising a probe at a distal end of the elongate wand; and one or more structured light projectors disposed within the probe, each structured light projector comprising: (a) a housing; (b) a light source disposed within the housing and comprising: a semiconductor laser die; and a beam shaping optical element; and (c) a pattern generating optical element, wherein: the semiconductor laser die and the beam shaping optical element are disposed within a common chamber of the housing, and each structured light projector is configured to project a pattern of light onto an intraoral surface when the light source of the structured light projector is activated to emit light through the pattern generating optical element of the structured light projector.
The apparatus according to claim 1, wherein for at least one of the one or more structured light projectors the housing is a sealed housing.
The apparatus according to claim 1 or 2, wherein for at least one of the one or more structured light projectors a height of the housing is 1.6-2.4 mm.
The apparatus according to claim 1 or 2, wherein for at least one of the one or more structured light projectors the longest dimension of the housing is 1.5-2.5 mm.
The apparatus according to any preceding claim, further comprising one or more cameras disposed within the probe, wherein a distance between (i) an optical axis of at least one camera and (ii) an optical axis of at least one structured light projector that is adjacent to the at least one camera is 3-5 mm.
The apparatus according to any preceding claim, wherein for at least one of the one or more structured light projectors the housing comprises a transparent window through which the light exits the housing, and the transparent window comprises the pattern generating optical element.
The apparatus according to any of claims 1-5, wherein for at least one of the one or more structured light projectors: an angle between an optical axis of the beam shaping optical element and an optical axis of the pattern generating optical element is 65-120 degrees or 50-100 degrees, and the apparatus further comprises a mirror disposed within the probe and positioned so as to reflect the light exiting the beam shaping optical element toward the pattern generating optical element.
The apparatus according to any of claims 1-5, wherein for at least one of the one or more structured light projectors the pattern generating optical element is disposed within the probe outside of the housing, and a distance that the light travels from exiting the beam shaping optical element to entering the pattern generating optical element is 2-8 mm or 8-25 mm.
The apparatus according to any preceding claim, wherein for at least one of the one or more structured light projectors: the semiconductor laser die is a first semiconductor laser die and the light source further comprises a second semiconductor laser die, wherein the first semiconductor laser die is optionally axially offset from the second semiconductor laser die.
The apparatus according to any of claims 1-8, wherein for at least one of the one or more structured light projectors: the pattern generating optical element is a first pattern generating optical element and the at least one structured light projector further comprises a second pattern generating optical element, and the first and second pattern generating optical elements are two respective areas on a common substrate that comprises a beam splitter and a reflector disposed within the common substrate.
The apparatus according to claim 10, further comprising: a computer processor configured to activate the semiconductor laser die of the one or more structured light projectors such that: laser light exiting the light source is split by the beam splitter into a first beam and a second beam within the common substrate, and the first beam enters the first pattern generating optical element and the second beam is reflected by the reflector toward the second pattern generating optical element to yield two separate projected patterns that are translationally shifted with respect to each other.
The apparatus according to any preceding claim, wherein for at least one of the one or more structured light projectors the beam shaping optical element comprises a combination of collimating lenses placed in an emission path of the semiconductor laser die to change a shape of a naturally elliptical laser beam output by the semiconductor laser die into a circular beam.
The apparatus according to claim 12, wherein for the at least one of the one or more structured light projectors the combination of collimating lenses comprises a series of two collimating lenses, in particular wherein the series of two collimating lenses comprises a fast axis collimating (FAC) lens and a slow axis collimating (SAC) lens.
The apparatus according to any of claims 1 to 11, wherein for at least one of the one or more structured light projectors the beam shaping optical element comprises a collimating lens placed in an emission path of the semiconductor laser die to change a shape of a naturally elliptical laser beam output by the semiconductor laser die into a circular beam, in particular wherein the collimating lens comprises a fast axis collimating (FAC) lens surface and an opposing slow axis collimating (SAC) lens surface.
The apparatus according to any preceding claim, wherein for at least one of the one or more structured light projectors: the housing comprises metal and the semiconductor laser die is disposed within the housing such that heat is conducted from the semiconductor laser die to the metal of the housing; and the semiconductor laser die is mounted on a submount within the housing such that heat is conducted from the semiconductor laser die to the metal of the housing through the submount, wherein the submount is optionally ceramic.

Description

FIELD OF THE INVENTION The present invention relates generally to three-dimensional imaging, and more particularly to intraoral three-dimensional imaging using structured light illumination. BACKGROUND Dental impressions of a subject's intraoral three-dimensional surface, e.g., teeth and gingiva, are used for planning dental procedures. Traditional dental impressions are made using a dental impression tray filled with an impression material, e.g., PVS or alginate, into which the subject bites. The impression material then solidifies into a negative imprint of the teeth and gingiva, from which a three-dimensional model of the teeth and gingiva can be formed. Digital dental impressions utilize intraoral scanning to generate three-dimensional digital models of an intraoral three-dimensional surface of a subject. Digital intraoral scanners often use structured light three-dimensional imaging. The surface of a subject's teeth may be highly reflective and somewhat translucent, which may reduce the contrast in the structured light pattern reflecting off the teeth. Therefore, in order to improve the capture of an intraoral scan, when using a digital intraoral scanner that utilizes structured light three-dimensional imaging, a subject's teeth may be coated with an opaque powder prior to scanning in order to facilitate a usable level of contrast of the structured light pattern, e.g., in order to turn the surface into a scattering surface. While intraoral scanners utilizing structured light three-dimensional imaging have made some progress, additional advantages may be had. International Patent Application No. PCT/US2019/038510 to Saphier et al., which published as WO 2019/246542 to Saphier et al., is assigned to the assignee of the present application, and is incorporated herein by reference, describes an apparatus for intraoral scanning including an elongate handheld wand that has a probe. One or more light projectors and two or more cameras are disposed within the probe. The light projectors each have a pattern generating optical element, which may use diffraction or refraction to form a light pattern. Each camera may be configured to focus between 1 mm and 30 mm from a lens that is farthest from the camera sensor. Other applications are also described. International Patent Application No. PCT/US2020/039438 to Saphier et al., which published as WO 2020/264035 to Saphier et al., is assigned to the assignee of the present application, and is incorporated herein by reference, describes a method for generating a 3D image, including driving structured light projector(s) to project a pattern of light on an intraoral 3D surface, and driving camera(s) to capture images, each image including at least a portion of the projected pattern, each one of the camera(s) comprising an array of pixels. A processor compares a series of images captured by each camera and determines which of the portions of the projected pattern can be tracked across the images. The processor constructs a three-dimensional model of the intraoral three-dimensional surface based at least in part on the comparison of the series of images. Other embodiments are also described. SUMMARY OF THE INVENTION Applications of the present invention include systems and methods related to a three-dimensional intraoral scanning device that includes one or more cameras, and one or more light projectors, e.g., structured light projectors. For example, certain applications of the present invention may be related to an intraoral scanning device having a plurality of cameras and a plurality of structured light projectors. For example, in some particular applications of the present invention, an apparatus is provided for intraoral scanning, the apparatus including an elongate handheld wand with a probe at the distal end of the handheld handle. Typically, the one or more structured light projectors are disposed within the probe. In accordance with some applications of the present invention, each structured light projector includes a housing, within which is disposed a light source. In some embodiments the housing is a sealed housing (e.g., is hermetically sealed). Each light source includes at least one semiconductor laser die and at least one beam shaping optical element. Typically, the semiconductor laser die and the beam shaping optical element are disposed within a common chamber of the housing. The inventors have realized that placing the beam shaping optical element and the semiconductor laser die of the structured light projector within the same chamber of the housing enables a distance between an emission point of the semiconductor laser die and an input face of the beam shaping optical element to be shorter than conventional laser diodes permit. Typically, a distance D between an emission point of the semiconductor laser diode and an input face of the beam shaping optical element is at least 50 microns and/or less than 250 microns. This in turn results in a number of a