Method of generating digital three-dimensional model using intraoral three-dimensional scanner

Abstract

A method of scanning an oral cavity includes projecting a pattern of discrete unconnected light spots onto an intraoral surface of a patient using one or more light projectors in a probe disposed at a distal end of an intraoral scanner, where the pattern of discrete unconnected light spots is non-coded. The method further includes capturing a plurality of images of the projected pattern of discrete unconnected spots using two or more cameras disposed in the probe; decoding the plurality of images of the projected pattern of discrete unconnected spots in order to determine three-dimensional surface information of the intraoral surface; and generating a digital three-dimensional model of the oral interior surface using the three-dimensional surface information.

Description

[0001] This application is a divisional application of a patent application with an application date of June 24, 2019, application number 2019105506949, and invention name “Method for generating digital three-dimensional models using an intraoral three-dimensional scanner”. Technical Field

[0002] The present invention relates generally to three-dimensional imaging and, more particularly, to intraoral three-dimensional imaging using structured light illumination. Background Art

[0003] A dental impression of the three-dimensional surfaces of the subject's mouth (e.g., teeth and gums) is used to plan dental treatment. A conventional dental impression is made using a dental impression tray filled with an impression material (e.g., PVS or alginate) of the subject's bite. The impression material is then cured into a negative impression of the teeth and gums, from which a three-dimensional model of the teeth and gums can be formed.

[0004] Digital dental impressions utilize intraoral scanning to generate a three-dimensional digital model of the three-dimensional surfaces within a subject's mouth. Digital intraoral scanners typically use structured light three-dimensional imaging. The surfaces of a subject's teeth can be highly reflective and somewhat translucent, which can reduce the contrast in the structured light pattern reflected from the teeth. Therefore, in order to improve the capture of the intraoral scan, when using a digital intraoral scanner that utilizes structured light three-dimensional imaging, the subject's teeth are often coated with an opaque powder prior to scanning so that the contrast of the structured light pattern reaches a usable level, for example, in order to transform the surface into a scattering surface. Although some progress has been made in intraoral scanners that utilize structured light three-dimensional imaging, additional advantages may be possible. Summary of the invention

[0005] The use of structured light 3D imaging can lead to a "correspondence problem" where the correspondence between the light points in the structured light pattern and the light points seen by a camera observing the pattern needs to be determined. One technique to address this problem is based on projecting an "encoded" light pattern and imaging the illuminated scene from one or more viewpoints. The emitted light pattern is encoded so that the various parts of the light pattern are unique and distinguishable when captured by the camera system. Because the pattern is encoded, it is easier to find correspondences between image points and points of the projected pattern. The decoded points can be triangulated and the 3D information recovered.

[0006] Applications of the present invention include systems and methods related to a three-dimensional intraoral scanning device, which includes one or more cameras and one or more pattern projectors. For example, some applications of the present invention may involve an intraoral scanning device with multiple cameras and multiple pattern projectors.

[0007] Other applications of the present invention include methods and systems for decoding structured light patterns.

[0008] Other applications of the present invention may involve systems and methods for three-dimensional intra-oral scanning using non-coded structured light patterns. For example, the non-coded structured light pattern may include a uniform pattern of light spots.

[0009] For example, in some specific applications of the present invention, a device for intraoral scanning is provided, comprising an elongated handheld wand having a probe at a distal end. During scanning, the probe can be configured to enter the oral cavity of a subject. One or more light projectors (e.g., microstructured light projectors) and one or more cameras (e.g., microcameras) are coupled to a rigid structure disposed within the distal end of the probe. Each structured light projector emits light using a light source (e.g., a laser diode). Each light projector can be configured to project a light pattern defined by a plurality of projector lights when the light source is activated. Each camera can be configured to capture a plurality of images depicting at least a portion of the light pattern projected on the surface of the mouth. In some applications, the structured light projector may have an illumination field of at least 45 degrees. Optionally, the illumination field may be less than 120 degrees. Each structured light projector may also include a pattern generating optical element. The pattern generating optical element may generate a light pattern using diffraction and / or refraction. In some applications, the light pattern may be a distribution of discrete, unconnected light spots. Optionally, when a light source (e.g., a laser diode) is activated to emit light through a pattern generating optical element, the light pattern maintains a distribution of discrete, unconnected light spots at all planes between 1 mm and 30 mm from the pattern generating optical element. In some applications, the pattern generating optical element of each structured light projector can have a luminous flux efficiency of at least 80% (e.g., at least 90%), i.e., the proportion of light that falls on the pattern generator that enters the pattern. Each camera includes a camera sensor and an objective optical device including one or more lenses.

[0010] In some applications, a laser diode light source and a diffraction and / or refraction pattern generating optical element may provide certain advantages. For example, the use of a laser diode and a diffraction and / or refraction pattern generating optical element may help maintain an energy efficient structured light projector to prevent the probe from heating up during use. In addition, these components may help reduce costs by not requiring active cooling within the probe. For example, today's laser diodes may use less than 0.6 watts of power while emitting continuously at high brightness (e.g., compared to today's light emitting diodes (LEDs)). When pulsed in accordance with some applications of the present invention, these today's laser diodes may use even less power, e.g., when pulsed at a 10% duty cycle, the laser diode may use less than 0.06 watts (but for some applications, the laser diode may use at least 0.2 watts while emitting continuously at high brightness, and when pulsed, may use even less power, e.g., when pulsed at a 10% duty cycle, the laser diode may use at least 0.02 watts). Furthermore, the diffractive and / or refractive pattern generating optical element may be configured to utilize most, if not all, emitted light (eg, compared to a mask that blocks some light from reaching the object).

[0011] In particular, the diffraction and / or refraction-based pattern generating optical element generates the pattern by diffraction, refraction or interference of light, or any combination thereof, rather than light modulation by a transparent or transmissive mask. In some applications, this may be advantageous because the light flux (throughput) efficiency (the ratio of light entering the pattern to light falling on the pattern generator) is close to 100% (e.g., at least 80%, e.g., at least 90%), regardless of the "area-based duty cycle" mode. In contrast, the light flux efficiency of the transparent mask or transmissive mask pattern generating optical element is directly related to the "area-based duty cycle". For example, for a desired "area-based duty cycle" of 100:1, the throughput efficiency of the mask-based pattern generator would be 1%, while the efficiency of the diffraction and / or refraction-based pattern generating optical element remains close to 100%. In addition, since lasers inherently have a smaller emission area and divergence angle, resulting in brighter output illumination per unit area, the light collection efficiency of lasers is at least 10 times higher than that of LEDs with the same total light output. The high efficiency of the laser and the diffraction and / or refraction pattern generator can help achieve a thermally efficient configuration that limits significant temperature rise of the probe during use, thereby reducing costs by potentially eliminating or limiting the need for active cooling within the probe. Although laser diodes and DOEs may be particularly preferred in some applications, their use alone or in combination is not essential. Other light sources including LEDs and pattern generating elements including transparent and transmissive masks may be used in other applications.

[0012] In some applications, in order to improve image capture of an intraoral scene under structured light illumination without using contrast enhancement methods such as coating teeth with opaque powder, the inventors have realized that a distribution of discrete unconnected light spots (e.g., rather than lines) can provide an improved balance between improving pattern contrast while maintaining the amount of useful information. In some applications, the unconnected light spots have a uniform (e.g., unchanging) pattern. In general, a denser structured light pattern can provide more surface sampling, higher resolution, and better stitching of corresponding surfaces obtained from multiple image frames. However, a structured light pattern that is too dense may lead to a more complex correspondence problem because there are a greater number of light spots to solve the correspondence problem. In addition, a denser structured light pattern may have a lower pattern contrast due to more light in the system, which may be caused by a combination of (a) stray light and (b) percolation, which is reflected from the somewhat smooth surface of the tooth and may be captured by the camera, and percolation is that some light enters the tooth, reflects along multiple paths within the tooth, and then leaves the tooth in many different directions. As further described below, methods and systems are provided for solving the correspondence problem presented by the distribution of discrete unconnected light spots. In some applications, the discrete, unconnected spots of light from each projector may be uncoded.

[0013] In some applications, the field of view of each camera can be at least 45 degrees, for example, at least 80 degrees (e.g., 85 degrees). Optionally, the field of view of each camera can be less than 120 degrees, for example, less than 90 degrees. For some applications, one or more cameras have fisheye lenses or other optical devices that provide up to 180 degrees of viewing.

[0014] In any case, the fields of view of the various cameras may be the same or different. Similarly, the focal lengths of the various cameras may be the same or different. The term "field of view" of each camera used herein refers to the diagonal field of view of each camera. In addition, each camera can be configured to focus on an object focal plane between 1 mm and 30 mm, for example, at least 5 mm and / or less than 11 mm, for example 9 mm-10 mm, from the lens farthest from the corresponding camera sensor. Similarly, in some applications, the illumination field of each structured light projector can be at least 45 degrees and optionally less than 120 degrees. The inventors have recognized that the large field of view achieved by combining the individual fields of view of all cameras can improve accuracy due to the reduced amount of image stitching errors, especially in edentulous areas where the gingival surface is smooth and there may be fewer clear high-resolution three-dimensional features. Having a larger field of view enables large smooth features such as the overall curve of the teeth to appear in each image frame, which improves the accuracy of stitching the individual surfaces obtained from multiple such image frames. In some applications, the field of view of the entire combination of various cameras (e.g., an intraoral scanner) is between about 20 mm and about 50 mm along the longitudinal axis of the elongated handheld wand, and about 20-40 mm along the z-axis, where the z-axis can correspond to depth. In other applications, the field of view can be at least 20 mm, at least 25 mm, at least 30 mm, at least 35 mm, or at least 40 mm along the longitudinal axis. In some embodiments, the combined field of view can vary with depth (e.g., with scanning distance). For example, at a scanning distance of about 4 mm, the field of view can be about 40 mm along the longitudinal axis, and at a scanning distance of about 14 mm, the field of view can be about 45 mm along the longitudinal axis. If most of the movement of the intraoral scanner is done relative to the long axis (e.g., longitudinal axis) of the scanner, the overlap between scans can be substantial. In some applications, the field of view of the combined cameras is discontinuous. For example, an intraoral scanner can have a first field of view separated from a second field of view by a fixed interval. The fixed interval can be, for example, along the longitudinal axis of the elongated handheld wand.

[0015] In some applications, a method is provided for generating a digital three-dimensional image of an intraoral surface. It should be noted that a "three-dimensional image," as the phrase is used in this application, is based on a three-dimensional model (e.g., a point cloud) from which an image of the three-dimensional intraoral surface is constructed. The resulting image, while typically displayed on a two-dimensional screen, contains data related to the three-dimensional structure of the scanned object and can therefore typically be manipulated to display the scanned object from different views and perspectives. Additionally, data from the three-dimensional image can be used to make a physical three-dimensional model of the scanned object.

[0016] For example, one or more structured light projectors may be driven to project a distribution of discrete, unconnected light spots on the surface of the mouth interior, and one or more cameras may be driven to capture the projected images. The images captured by each camera may include at least one light spot.

[0017] Each camera includes a camera sensor having an array of pixels, and for each pixel there is a corresponding ray in three-dimensional space originating from that pixel, the direction of which is toward the object being imaged; when imaged on the sensor, each point along a particular one of these rays will fall on its corresponding corresponding pixel on the sensor. As used throughout this application, the term used for this is "camera ray". Similarly, for each projected light point from each projector, there is a corresponding projector ray. Each projector ray corresponds to a corresponding pixel path on at least one camera sensor, that is, if the camera sees a light point projected by a particular projector ray, then that light point must be detected by a pixel on the particular path of the pixel corresponding to that particular projector ray. (a) The values ​​of the camera ray corresponding to each pixel on the camera sensor of each camera and (b) the values ​​of the projector ray corresponding to each projected light point from each projector can be stored during the calibration process, as described below.

[0018] Based on the stored calibration values, the processor can be used to run a corresponding algorithm to identify the three-dimensional location of each projected light point on the surface. For a given projector ray, the processor "looks" at the corresponding camera sensor path on one of the cameras. Each detected light point along the camera sensor path will have a camera ray that intersects the given projector ray. The intersection defines a three-dimensional point in space. The processor then searches the camera sensor paths corresponding to the given projector ray on the other cameras and identifies how many other cameras have also detected light points on their corresponding camera sensor paths corresponding to the given projector ray, whose camera rays intersect the three-dimensional point in space. As used throughout this application, if two or more cameras detect a light point whose corresponding camera rays intersect the given projector ray at the same three-dimensional point in space, the cameras are considered to "agree" that the light point is at the three-dimensional point. Therefore, the processor can identify the three-dimensional location of the projected light pattern based on the two or more cameras agreeing that there is a light pattern projected by the projector ray at a particular intersection. Repeat this process for additional light points along the camera sensor path, and identify the light points with the maximum number of cameras "agree" as the light points projected onto the surface from the given projector ray. Therefore, the three-dimensional position on the surface is calculated for this light point.

[0019] Once the location of a particular light spot on the surface is determined, the projector ray that projected that light spot and all camera rays corresponding to that light spot can be disregarded, and the corresponding algorithm can be run again for the next projector ray. Ultimately, the identified three-dimensional location can be used to generate a digital three-dimensional model of the intraoral surface.

[0020] In another example, a method for generating a digital three-dimensional model of an intraoral surface may include projecting a pattern of discrete unconnected light spots onto an intraoral surface of a patient using one or more light projectors disposed in a probe at a distal end of an intraoral scanner, wherein the pattern of discrete unconnected light spots is non-encoded. The method may also include capturing multiple images of the projected pattern of unconnected light spots using two or more cameras disposed in the probe, decoding the multiple images of the projected pattern to determine three-dimensional surface information of the intraoral surface, and generating a digital three-dimensional model of the intraoral surface using the three-dimensional surface information. Decoding the multiple images may include accessing calibration data that associates camera rays corresponding to pixels on a camera sensor of each of the two or more cameras with multiple projector rays, wherein each of the multiple projector rays is associated with one of the discrete unconnected light spots. Decoding may also include determining, using the calibration data, an intersection of the projector ray and the camera ray corresponding to the pattern of projected discrete unconnected light spots, wherein the intersection of the projector ray and the camera ray is associated with a three-dimensional point in space. Decoding may also include identifying a three-dimensional position of the pattern of discrete unconnected light spots based on the two or more cameras agreeing that there are discrete unconnected light spots projected by the projector ray at a specific intersection.

[0021] Therefore, according to some applications of the present invention, there is provided a device for intraoral scanning, the device comprising:

[0022] an elongated hand-held wand including a probe at a distal end of the hand-held wand;

[0023] A rigid structure disposed within the distal end of the probe;

[0024] one or more structured light projectors coupled to the rigid structure; and

[0025] One or more cameras are coupled to the rigid structure.

[0026] In some applications, each structured light projector may have an illumination field of 45-120 degrees. Optionally, one or more structured light projectors may use a laser diode light source. In addition, the structured light projector may include a beam shaping optical element. In addition, the structured light projector may include a pattern generating optical element.

[0027] The pattern generating optical element can be configured to generate a distribution of discrete unconnected light spots. When a light source (e.g., a laser diode) is activated to emit light through the pattern generating optical element, a distribution of discrete unconnected light spots can be generated at all planes between 1 mm and 30 mm from the pattern generating optical element. In some applications, the pattern generating optical element (i) generates the distribution using diffraction and / or refraction. Optionally, the pattern generating optical element has a light flux efficiency of at least 90%.

[0028] Additionally, in some applications, each camera may (a) have a field of view of 45-120 degrees. The camera may include a camera sensor and an objective optical device including one or more lenses. In some applications, the camera may be configured to focus at an object focal plane between 1 mm and 30 mm from the lens farthest from the camera sensor.

[0029] For some applications, each of the one or more cameras is configured to focus at an object focal plane between 5 mm and 11 mm from a lens farthest from the camera sensor.

[0030] For some applications, the pattern generating optical element of each of one or more projectors is configured to generate a distribution of discrete, unconnected light spots in all planes between 4 mm and 24 mm from the pattern generating optical element when a light source (e.g., a laser diode) is activated to emit light through the pattern generating optical element.

[0031] For some applications, each of the one or more cameras is configured to focus at an object focal plane between 4 mm and 24 mm from a lens farthest from the camera sensor.

[0032] For some applications, each structured light projector has a field of illumination of 70-100 degrees.

[0033] For some applications, each camera has a field of view of 70-100 degrees.

[0034] For some applications, each camera has a field of view of 80-90 degrees.

[0035] For some applications, the apparatus also includes at least one uniform light projector configured to project white light onto the scanned object, and the at least one camera configured to capture a two-dimensional color image of the object using illumination from the uniform light projector.

[0036] For some applications, the beam shaping optics include a collimating lens.

[0037] For some applications, the structured light projectors and cameras are positioned so that each structured light projector faces an object outside a wand placed in its illumination field. Alternatively, each camera can face an object outside the wand placed in its field of view. Furthermore, in some applications, at least 20% of the discrete unconnected light points are located in the field of view of at least one camera.

[0038] For some applications, the height of the probe is 10-15 mm, where light enters the probe through a lower surface (or sensing surface) of the probe, and the height of the probe is measured from the lower surface of the probe to an upper surface of the probe opposite the lower surface.

[0039] For some applications, the one or more structured light projectors is exactly one structured light projector, and the one or more cameras is exactly one camera.

[0040] For some applications, the pattern generating optical element comprises a diffractive optical element (DOE).

[0041] For some applications, each DOE is configured to generate a distribution of discrete unconnected light spots such that when the light source is activated to emit light through the DOE, the ratio of illuminated area to non-illuminated area is 1:150-1:16 for each orthogonal plane in the illumination field.

[0042] For some applications, each DOE is configured to generate a distribution of discrete, unconnected light spots such that when the light source is activated to emit light through the DOE, the ratio of illuminated area to non-illuminated area is 1:64-1:36 for each orthogonal plane in the illumination field.

[0043] For some applications, the one or more structured light projectors are a plurality of structured light projectors. In some applications, each light spot generated by a particular DOE has the same shape. Optionally, the shape of the light spot generated by at least one DOE is different from the shape of the light spot generated by at least one other DOE.

[0044] For some applications, each of one or more projectors includes an optical element disposed between the beam shaping optical element and the DOE, the optical element being configured to generate a Bessel beam when the laser diode is activated to emit light through the optical element such that discrete, unconnected spots of light remain less than 0.06 mm in diameter through each inner surface of a sphere centered at the DOE and having a radius between 1 mm and 30 mm.

[0045] For some applications, the optical element is configured to generate a Bessel beam when the laser diode is activated to emit light through the optical element such that discrete, unconnected spots of light remain less than 0.02 mm in diameter through each inner surface of a geometric sphere centered at the DOE and having a radius between 1 mm and 30 mm.

[0046] For some applications, each of the one or more projectors includes an optical element disposed between the beam shaping optical element and the DOE. The optical element can be configured to generate a Bessel beam when the light source is activated to emit light through the optical element such that discrete unconnected light spots maintain a small diameter throughout the depth range. For example, in some applications, the discrete unconnected light spots can maintain a diameter of less than 0.06 mm through each orthogonal plane between 1 mm and 30 mm from the DOE.

[0047] For some applications, the optical element is configured to generate a Bessel beam when the laser diode is activated to emit light through the optical element such that discrete, unconnected light spots maintain a diameter less than 0.02 mm through each orthogonal plane between 1 mm and 30 mm from the DOE.

[0048] For some applications, the optical element is configured to generate a Bessel beam when the laser diode is activated to emit light through the optical element such that discrete, unconnected light spots maintain a diameter less than 0.04 mm through each orthogonal plane between 4 mm and 24 mm from the DOE.

[0049] For some applications, the optical element is an axicon lens.

[0050] For some applications, the axicon lens is a diffractive axicon lens.

[0051] For some applications, the optical element is an annular aperture.

[0052] For some applications, the one or more structured light projectors are a plurality of structured light projectors, and light sources of at least two of the structured light projectors are configured to respectively emit light of two different wavelengths.

[0053] For some applications, the light sources of the at least three structured light projectors are configured to respectively emit light of three different wavelengths.

[0054] For some applications, the light sources of the at least three structured light projectors are configured to emit red light, blue light, and green light, respectively.

[0055] In some applications, the light source includes a laser diode.

[0056] For some applications, the one or more cameras are a plurality of cameras coupled to the rigid structure such that an angle between two respective optical axes of at least two of the cameras is 0-90 degrees.

[0057] For some applications, the angle between two corresponding optical axes of at least two cameras is 0-35 degrees.

[0058] For some applications, the one or more structured light projectors are a plurality of structured light projectors coupled to a rigid structure such that an angle between two respective optical axes of at least two of the structured light projectors is 0-90 degrees.

[0059] For some applications, the angle between two corresponding optical axes of at least two structured light projectors is 0-35 degrees.

[0060] For some applications, each camera has a plurality of discrete preset focus positions, at each focus position the camera is configured to focus at a corresponding object focal plane.

[0061] For some applications, each camera includes an autofocus actuator configured to select a focus position from discrete preset focus positions.

[0062] For some applications, each of the one or more cameras includes an optical aperture phase mask configured to extend the depth of focus of the camera so that an image formed by each camera remains in focus at all object distances between 1 mm and 30 mm from a lens farthest from the camera sensor.

[0063] For some applications, the optical aperture phase mask is configured to extend the depth of focus of the cameras so that the image formed by each camera remains in focus at all object distances between 4 mm and 24 mm from the lens farthest from the camera sensor.

[0064] For some applications, each of the one or more cameras is configured to capture images at a frame rate of 30-200 frames per second.

[0065] For some applications, each of the one or more cameras is configured to capture images at a frame rate of at least 75 frames per second.

[0066] For some applications, each of the one or more cameras is configured to capture images at a frame rate of at least 100 frames per second.

[0067] For some applications, the laser diode of each of the one or more projectors is configured to emit an elliptical beam. The beam shaping optical element of each of the one or more projectors may include a collimating lens. Optionally, the pattern generating optical element includes a diffractive optical element (DOE) that is segmented into a plurality of sub-DOE sheets arranged in an array. Each sub-DOE sheet can generate a corresponding distribution of discrete unconnected light spots in different regions of the illumination field, so that a distribution of discrete unconnected light spots is generated when the light source is activated to emit light through the segmented DOEs.

[0068] For some applications, the collimating lens can be configured to generate an elliptical beam with a major axis of 500-700 microns and a minor axis of 100-200 microns.

[0069] For some applications, when the laser diode is activated to emit light through the segmented DOE, the array of sub-DOE slices can be positioned to be contained within the elliptical beam.

[0070] For some applications, the cross-section of each sub-DOE sheet is a square with sides of 30-75 microns in length, and the cross-section is perpendicular to the optical axis of the DOE.

[0071] For some applications, the plurality of sub-DOE sheets are arranged in a rectangular array comprising 16-72 sub-DOE sheets and having a longest dimension of 500-800 microns.

[0072] For some applications, the collimating lens and the segmented DOE are a single optical element, a first side of the optical element includes the collimating lens, and a second side of the optical element opposite the first side includes the segmented DOE.

[0073] For some applications, at least one light source of each of the one or more projectors is a plurality of laser diodes. In some applications, the plurality of laser diodes may be configured to emit light of the same wavelength.

[0074] For some applications, multiple laser diodes may be configured to emit light at different wavelengths.

[0075] For some applications, the plurality of laser diodes is two laser diodes configured to emit light at two different wavelengths, respectively.

[0076] For some applications, the plurality of laser diodes is three laser diodes configured to emit light at three different wavelengths, respectively.

[0077] For some applications, three laser diodes are configured to emit red, blue, and green light, respectively.

[0078] For some applications:

[0079] The beam shaping optics of each of the one or more projectors include a collimating lens, and

[0080] The pattern generating optical element comprises a complex diffractive periodic structure having a periodic structure feature size of 100-400 nm.

[0081] For some applications, the collimating lens and the complex diffractive periodic structure are a single optical element, a first side of the optical element includes the collimating lens, and a second side of the optical element opposite the first side includes the complex diffractive periodic structure.

[0082] For some applications, the apparatus further includes an axicon lens disposed between the collimating lens and the composite diffractive periodic structure, the axicon lens having an axicon head angle of 0.2-2 degrees.

[0083] For some applications, the collimating lens has a focal length of 1.2-2 mm.

[0084] For some applications:

[0085] The beam shaping optics of each of the one or more projectors include a collimating lens, and

[0086] The pattern generating optical element comprises a microlens array having a numerical aperture of 0.2-0.7.

[0087] For some applications, the microlens array is a hexagonal microlens array.

[0088] For some applications, the microlens array is a rectangular microlens array.

[0089] For some applications, the collimating lens and the microlens array are a single optical element, a first side of the optical element includes the collimating lens, and a second side of the optical element opposite the first side includes the microlens array.

[0090] For some applications, the apparatus further includes an axicon lens disposed between the collimating lens and the microlens array, the axicon lens having an axicon head angle of 0.2-2 degrees.

[0091] For some applications, the collimating lens has a focal length of 1.2-2 mm.

[0092] For some applications:

[0093] The beam shaping optics of each of the one or more projectors include a collimating lens having a focal length of 1.2-2 mm,

[0094] Each of the one or more projectors includes an aperture ring disposed between a collimating lens and a pattern generating optical element, and

[0095] The pattern generating optical element comprises a complex diffractive periodic structure having a periodic structure feature size of 100-400 nm.

[0096] For some applications:

[0097] The beam shaping optical element of each of the one or more projectors includes a lens that (a) is disposed between the laser diode and the pattern generating optical element, and (b) has a planar surface on a first side of the lens and an aspheric surface on a second side of the lens opposite to the first side, the aspheric surface being configured to generate a Bessel beam directly from the divergent beam when the laser diode is activated to emit a divergent beam through the lens and the pattern generating optical element, so that discrete unconnected light spots have substantially uniform sizes at any orthogonal plane between 1 mm and 30 mm from the pattern generating optical element.

[0098] For some applications, the aspheric surface of the lens is configured to generate a Bessel beam directly from the divergent beam when the laser diode is activated to emit a divergent beam through the lens and the pattern generating optical element so that discrete, unconnected light spots have substantially uniform sizes at any orthogonal plane between 4 mm and 24 mm from the pattern generating optical element.

[0099] For some applications, the pattern generating optical element includes a complex diffractive periodic structure having a periodic structure feature size of 100-400 nm.

[0100] For some applications, the pattern generating optical element includes a microlens array having a numerical aperture of 0.2-0.7.

[0101] For some applications:

[0102] (a) the beam shaping optical element comprises an aspheric surface on a first side of the lens, and (b) a planar surface on a second side of the lens opposite the first side is shaped to define a pattern generating optical element, and

[0103] The aspheric surface is configured to generate a Bessel beam directly from the divergent beam when the laser diode is activated to emit a divergent beam through the lens, so that when the laser diode is activated to emit a divergent beam through the lens, the Bessel beam is split into an array of discrete Bessel beams such that the discrete unconnected light spots have substantially uniform sizes at all planes between 1 mm and 30 mm from the lens.

[0104] For some applications, the planar surface of the lens is shaped to define a pattern generating optical element such that when the laser diode is activated to emit a divergent beam through the lens, the Bessel beam is split into an array of discrete Bessel beams such that the discrete, unconnected light spots have substantially uniform sizes at all planes between 4 mm and 24 mm from the pattern generating optical element.

[0105] For some applications, the apparatus and method may further include:

[0106] at least one temperature sensor coupled to the rigid structure and configured to measure a temperature of the rigid structure; and

[0107] Temperature control unit.

[0108] The temperature control circuit can be configured to (a) receive data indicating the temperature of the rigid structure from the temperature sensor, and (b) activate the temperature control unit based on the received data. The temperature control unit and circuit can be configured to maintain the probe and / or the rigid structure at a temperature between 35 and 43 degrees Celsius.

[0109] For some applications, the temperature control unit is configured to maintain the probe at a temperature between 37 and 41 degrees Celsius.

[0110] For some applications, the temperature control unit is configured to prevent a temperature change of the probe from exceeding a threshold temperature change.

[0111] For some applications, the apparatus further includes:

[0112] The target, such as a diffuse reflector, includes a plurality of regions disposed within the probe such that:

[0113] (a) each projector has at least one diffuse reflector area in its field of illumination,

[0114] (b) each camera has at least one diffuse reflector region in its field of view, and

[0115] (c) Multiple diffuse reflector areas are in the field of view of one of the cameras and in the illumination field of one of the projectors.

[0116] In some applications, the temperature control circuit can be configured to (a) receive data from a camera indicating a position of a diffuse reflector relative to a distribution of discrete unconnected light points, (b) compare the received data to a stored calibration position of the diffuse reflector, wherein a difference between (i) the received data indicating the position of the diffuse reflector and (ii) the stored calibration position of the diffuse reflector indicates a temperature change of the probe, and (c) adjust the temperature of the probe based on the comparison of the received data to the stored calibration position of the diffuse reflector.

[0117] According to some applications of the present invention, there is also provided a method for generating a digital three-dimensional image, the method comprising:

[0118] driving each of the one or more structured light projectors to project a distribution of discrete unconnected light spots on a three-dimensional surface within the mouth;

[0119] driving each of the one or more cameras to capture an image, the image comprising at least one light point, each of the one or more cameras comprising a camera sensor, the camera sensor comprising a pixel array;

[0120] Based on stored calibration values ​​indicating (a) a camera ray corresponding to each pixel on a camera sensor of each of the one or more cameras, and (b) a projector ray corresponding to each projected light spot from each of the one or more projectors, such that each projector ray corresponds to a respective pixel path on the at least one camera sensor:

[0121] Use the processor to run the corresponding algorithm:

[0122] (1) for each projector ray i, for each detected light point j on the camera sensor path corresponding to ray i, identifying how many other cameras on their respective camera sensor paths corresponding to ray i detected a corresponding light point k corresponding to the corresponding camera ray that intersects ray i and the camera ray corresponding to the detected light point j, such that ray i is identified as the particular projector ray that generated the detected light point j for which the maximum number of other cameras detected the corresponding light point k; and

[0123] (2) Calculate the corresponding three-dimensional position on the inner surface of the mouth as the intersection point of the projector ray i and the corresponding camera ray corresponding to the detected light point j and the corresponding detected light point k.

[0124] For some applications, using the processor to run the corresponding algorithm further includes, after step (1), using the processor to:

[0125] The projector ray i and each camera ray corresponding to the detected light point j and each detected light point k are no longer considered; and

[0126] The corresponding algorithm is run again for the next caster ray i.

[0127] For some applications, driving each of the one or more structured light projectors to project a distribution of discrete unconnected spots of light includes driving each structured light projector to project 400-3000 discrete unconnected spots of light onto an intra-oral three-dimensional surface.

[0128] For some applications, driving each of the one or more structured light projectors to project a distribution of discrete unconnected spots of light includes driving a plurality of structured light projectors to each project a distribution of discrete unconnected spots of light, wherein:

[0129] (a) at least two structured light projectors are configured to emit light of different wavelengths, and

[0130] (b) For each wavelength, the stored calibration values ​​represent the camera light corresponding to each pixel on the camera sensor.

[0131] For some applications, driving one or more structured light projectors to each project a distribution of discrete unconnected light spots includes driving multiple structured light projectors to each project a distribution of discrete unconnected light spots, wherein each light spot projected from a particular structured light projector has the same shape, and the shape of the light spot projected from at least one structured light projector is different from the shape of the light spot projected from at least one other structured light projector.

[0132] For some applications, the method further includes:

[0133] driving at least one uniform light projector to project white light onto a three-dimensional surface within the mouth; and

[0134] At least one camera is driven to capture a two-dimensional color image of the three-dimensional surface within the mouth using illumination from the uniform light projector.

[0135] For some applications, the method also includes running, using a processor, a surface reconstruction algorithm that combines at least one image captured using illumination from the structured light projector with multiple images captured using illumination from the uniform light projector to generate a three-dimensional image of the intraoral three-dimensional surface.

[0136] For some applications, driving each of the one or more structured light projectors includes driving multiple structured light projectors to simultaneously project a corresponding distribution of discrete, unconnected light spots on a three-dimensional surface within the mouth.

[0137] For some applications, driving each of the one or more structured light projectors includes driving a plurality of structured light projectors to project corresponding discrete unconnected light spots on the intra-oral three-dimensional surface at different respective times.

[0138] For some applications, driving multiple structured light projectors to project corresponding discrete unconnected light spots on the three-dimensional surface inside the mouth at different times includes driving multiple structured light projectors to project corresponding discrete unconnected light spots on the three-dimensional surface inside the mouth in a predetermined order.

[0139] For some applications, driving a plurality of structured light projectors to project corresponding discrete unconnected light spots on a three-dimensional surface within the mouth at different respective times includes:

[0140] driving at least one structured light projector to project a distribution of discrete unconnected light spots on a three-dimensional surface within the mouth; and

[0141] During scanning, it is determined which of a plurality of structured light projectors is driven next to project a distribution of discrete, unconnected light spots.

[0142] For some applications:

[0143] Driving each of the one or more structured light projectors includes driving exactly one structured light projector to project a distribution of discrete unconnected light spots on a three-dimensional surface within the mouth.

[0144] For some applications, driving each of the one or more cameras includes driving the one or more cameras at a frame rate of 30-200 frames per second such that each captures an image.

[0145] For some applications, driving the one or more cameras includes driving the one or more cameras at a frame rate of at least 75 frames per second such that each captures an image.

[0146] For some applications, driving the one or more cameras includes driving the one or more cameras at a frame rate of at least 100 frames per second such that each captures an image.

[0147] For some applications, using the processor includes selecting between multiple sets of stored calibration data corresponding to multiple corresponding temperatures of the structured light projector and the camera based on data received from a temperature sensor indicating the temperature of the structured light projector and the camera, each set of stored calibration data indicating, for a corresponding temperature, (a) projector light corresponding to each projected light point from each of one or more projectors, and (b) camera light corresponding to each pixel on a camera sensor of each of one or more cameras.

[0148] For some applications, using the processor includes interpolating between multiple sets of stored calibration data based on data received from the temperature sensor indicating the temperature of the structured light projector and the camera to obtain calibration data for temperatures between the respective temperatures corresponding to each set of calibration data.

[0149] For some applications:

[0150] Driving each of the one or more cameras includes driving each of the one or more cameras to capture an image, the image also including at least one region of a diffuse reflector having a plurality of regions, such that:

[0151] (a) each projector has at least one diffuse reflector area in its field of illumination,

[0152] (b) each camera has at least one diffuse reflector region in its field of view, and

[0153] (c) Multiple diffuse reflector areas are in the field of view of one of the cameras and in the field of illumination of one of the projectors.

[0154] The processor can be used to (a) receive data from a camera indicating the position of a diffuse reflector relative to a distribution of discrete unconnected light points, (b) compare the received data with a stored calibration position of the diffuse reflector, (i) the difference between the received data indicating the position of the diffuse reflector and (ii) the stored calibration position of the diffuse reflector indicates an offset of the projector light and the camera light from their respective stored calibration values, and (c) run a corresponding algorithm based on the offset of the projector light and the camera light from their respective stored calibration values.

[0155] In some embodiments, such as any of those described above or throughout the specification, high dynamic range three-dimensional imaging can be provided using light field imaging in combination with structured illumination. A fringe pattern can be projected onto a scene and modulated by the scene depth. Then, a structured light field can be detected using a light field recording device. The structured light field contains information about the direction of the light rays and the phase-encoded depth, by which the scene depth can be estimated from different directions. Multi-directional depth estimation can effectively achieve high dynamic range three-dimensional imaging.

[0156] Applications of the present invention may also include systems and methods related to a three-dimensional intraoral scanning device, which includes one or more light field cameras and one or more pattern projectors. For example, in some embodiments, an intraoral scanning device is provided. The device may include an elongated handheld stick, which includes a probe located at a distal end. The probe may have a proximal end and a distal end. During intraoral scanning, the probe may be placed in the oral cavity of a subject. According to some applications of the present invention, a structured light projector and a light field camera may be disposed at the proximal end of the probe, and a mirror may be disposed at the distal end of the probe. The structured light projector and the light field camera may be positioned to face the mirror, and the mirror may be positioned to (a) reflect light from the structured light projector directly onto the scanned object, and (b) reflect light from the scanned object to the light field camera.

[0157] The structured light projector in the proximal end of the probe includes a light source. In some applications, the light source can have an illumination field of at least 6 degrees and / or less than 30 degrees. The structured light projector can focus light from the light source at a projector focal plane that is at least 30 mm and / or less than 140 mm from the light source. The structured light projector can also include a pattern generator disposed in an optical path between the light source and the projector focal plane, and when the light source is activated to emit light through the pattern generator, the pattern generator generates a structured light pattern at the projector focal plane.

[0158] In some applications, the light field camera in the proximal end of the probe can have a field of view of at least 6 degrees and / or less than 30 degrees. The light field camera can be focused at a camera focal plane at least 30 mm and / or less than 140 mm from the light field camera. The light field camera can also include a light field camera sensor, the light field camera sensor including (i) an image sensor including an array of sensor pixels, and (ii) a microlens array disposed in front of the image sensor, such that each microlens lens is disposed on a subarray of the sensor pixels. An objective lens disposed in front of the light field camera sensor forms an image of the scanned object onto the light field camera sensor.

[0159] According to some applications of the present invention, one or more structured light projectors and one or more light field cameras are disposed at the distal end of the probe. The structured light projectors and light field cameras are positioned such that each structured light projector directly faces an object outside the rod placed in its illumination field, and each camera directly faces an object outside the rod placed in its field of view. At least 40% of the projected structured light pattern from each projector is in the field of view of at least one camera.

[0160] One or more structured light projectors in the distal end of the probe each include a light source. In some applications, the corresponding structured light projectors can each have an illumination field of at least 60 degrees and / or less than 120 degrees. Each structured light projector can focus light from the light source at a projector focal plane that is at least 30 mm and / or less than 140 mm from the light source. Each structured light projector can also include a pattern generator disposed in the optical path between the light source and the projector focal plane, and when the light source is activated to emit light through the pattern generator, the pattern generator generates a structured light pattern at the projector focal plane.

[0161] In some applications, one or more light field cameras at the distal end of the probe may each have a field of view of at least 60 degrees and / or less than 120 degrees. Each light field camera may be focused at a camera focal plane at least 3 mm and / or less than 40 mm from the light field camera. Each light field camera may also include a light field camera sensor, the light field camera sensor including (i) an image sensor including an array of sensor pixels, and (ii) an array of micro lenses disposed in front of the image sensor, such that each micro lens is disposed on a sub-array of sensor pixels. An objective lens disposed in front of each light field camera sensor forms an image of the scanned object onto the light field camera sensor.

[0162] Therefore, according to some applications of the present invention, there is provided a device for intraoral scanning, the device comprising:

[0163] (A) an elongated handheld stick, comprising a probe located at the distal end of the handheld stick, the probe having a proximal end and a distal end; (B) a structured light projector disposed at the proximal end of the probe, the structured light projector:

[0164] (a) having an illumination field of 6 to 30 degrees,

[0165] (b) including a light source, and

[0166] (c) is configured to focus light from the light source at a focal plane of the projector between 30 mm and 140 mm from the light source, and

[0167] (d) includes a pattern generator disposed in an optical path between the light source and the projector focal plane, the pattern generator being configured to generate a structured light pattern at the projector focal plane when the light source is activated to emit light through the pattern generator.

[0168] (C) A light field camera is disposed at the proximal end of the probe. The light field camera:

[0169] (a) having a field of view of 6 to 30 degrees,

[0170] (b) is configured to focus at a camera focal plane between 30 mm and 140 mm from the light field camera,

[0171] (c) comprising a light field camera sensor comprising (i) an image sensor comprising an array of sensor pixels, and (ii) an array of microlenses disposed in front of the image sensor such that each microlens is disposed over a subarray of the sensor pixels, and

[0172] (d) comprising an objective lens disposed in front of the light field camera sensor and configured to form an image of the scanned object onto the light field camera sensor; and

[0173] (D) A mirror, disposed at the distal end of the hand-held wand,

[0174] The structured light projector and the light field camera are positioned facing the mirror, and the mirror is positioned to (a) reflect light from the structured light projector directly onto the scanned object and (b) reflect light from the scanned object into the light field camera.

[0175] For some applications, the light source includes a light emitting diode (LED), and the pattern generator includes a mask.

[0176] For some applications, the light source includes a laser diode.

[0177] For some applications, the pattern generator includes a diffractive optical element (DOE) configured to generate the structured light pattern as a distribution of discrete unconnected light spots.

[0178] For some applications, the pattern generator includes an array of refractive microlenses.

[0179] For some applications, the height of the probe is 14-17 mm and the width of the probe is 18-22 mm, the height and width defining a plane perpendicular to the longitudinal axis of the rod, the light enters the probe through the lower surface of the probe, and the height of the probe is measured from the lower surface of the probe to the upper surface of the probe opposite the lower surface.

[0180] For some applications, the device is configured for use with an output device, the device further comprising:

[0181] The control circuit is configured as follows:

[0182] (a) driving the structured light projector to project the structured light pattern onto the object outside the rod,

[0183] (b) driving a light field camera to capture a light field generated by a structured light pattern reflected from an object, the light field comprising (i) an intensity of the structured light pattern reflected from the object, and (ii) a direction of the light; and

[0184] At least one computer processor is configured to reconstruct a three-dimensional image of the surface of the scanned object based on the captured light field and output the image to an output device.

[0185] For some applications:

[0186] (a) The objects outside the stick are the teeth in the subject's mouth,

[0187] (b) the control circuit is configured to drive the light field camera to capture a light field generated by the structured light pattern reflected from the teeth in the absence of powder on the teeth, and

[0188] (c) The computer processor is configured to reconstruct a three-dimensional image of the teeth based on the light field captured without powder on the teeth, and output the image to an output device.

[0189] For some applications, each subarray of sensor pixels in a central region of the image sensor includes 10-40% fewer pixels than each subarray of sensor pixels in a peripheral region of the image sensor, the central region of the image sensor including at least 50% of the total number of sensor pixels.

[0190] For some applications, (a) each microlens on a subarray of sensor pixels disposed in a peripheral region of the image sensor is configured to focus at a depth that is 1.1-1.4 times greater than (b) each microlens on a subarray of sensor pixels disposed in a central region of the image sensor is configured to focus.

[0191] According to some applications of the present invention, there is also provided a device, comprising:

[0192] (A) an elongated handheld wand including a probe at a distal end of the handheld wand, the probe having a proximal end and a distal end; (B) one or more structured light projectors disposed at the distal end of the probe, each structured light projector:

[0193] (a) having an illumination field of 60 to 120 degrees,

[0194] (b) including a light source, and

[0195] (c) is configured to focus light from the light source at a focal plane of the projector between 3 mm and 40 mm from the light source, and

[0196] (d) comprising a pattern generator disposed in an optical path between the light source and the focal plane of the projector, the pattern generator being configured to, when the light source is activated to emit light through the pattern generator, emit light in the focal plane of the projector;

[0197] generating a structured light pattern at a focal plane of the detector; and

[0198] (C) one or more light field cameras, disposed at the distal end of the probe, each light field camera:

[0199] (a) have a field of view of 60 to 120 degrees,

[0200] (b) is configured to focus at a camera focal plane between 3 mm and 40 mm from the light field camera,

[0201] (c) comprising a light field camera sensor comprising (i) an image sensor comprising an array of sensor pixels, and (ii) an array of microlenses disposed in front of the image sensor such that each microlens is disposed over a subarray of the sensor pixels, and

[0202] (d) comprising an objective lens disposed in front of the light field camera sensor and configured to form an image of the scanned object onto the light field camera sensor; and

[0203] The structured light projectors and light field cameras are positioned such that (a) each structured light projector faces directly at an object outside the rod placed in its illumination field, (b) each camera faces directly at an object outside the rod placed in its field of view, and (c) at least 40% of the structured light pattern from each projector is within the field of view of at least one camera.

[0204] For some applications, the height of the probe is 10-14 mm and the width of the probe is 18-22 mm, the height and width defining a plane perpendicular to the longitudinal axis of the rod, the light enters the probe through the lower surface of the probe, and the height of the probe is measured from the lower surface of the probe to the upper surface of the probe opposite the lower surface.

[0205] For some applications, one or more structured light projectors is exactly one structured light projector, and one or more structured light field cameras is exactly one light field camera.

[0206] For some applications, the one or more structured light projectors is a plurality of structured light projectors and the one or more light field cameras is a plurality of light field cameras.

[0207] For some applications, the device is configured for use with an output device, the device further comprising:

[0208] The control circuit is configured as:

[0209] (a) driving each of the one or more structured light projectors to project a structured light pattern onto an object outside the wand,

[0210] (b) driving one or more light field cameras to capture a light field generated by a structured light pattern reflected from an object, the light field comprising (i) an intensity of the structured light pattern reflected from the object, and (ii) a direction of the light; and

[0211] At least one computer processor is configured to reconstruct a three-dimensional image of the surface of the scanned object based on the captured light field and output the image to an output device.

[0212] For some applications:

[0213] At least one of the one or more structured light projectors is a monochrome structured light projector configured to project a monochrome structured light pattern onto the scanned object,

[0214] At least one of the one or more light field cameras is a monochrome light field camera configured to capture a light field generated by a monochrome structured light pattern reflected from an object being scanned, and

[0215] The apparatus also includes: (a) a light source configured to emit white light onto the scanned object; and (b) a camera configured to capture a two-dimensional color image of the scanned object.

[0216] For some applications, the monochrome structured light projector is configured to project the structured light pattern at a wavelength of 420-470 nm.

[0217] According to some applications of the present invention, there is also provided a device, comprising:

[0218] (A) an elongated handheld stick, comprising a probe located at the distal end of the handheld stick, the probe having a proximal end and a distal end; (B) a structured light projector disposed at the proximal end of the probe, the structured light projector:

[0219] (a) having an irradiation field,

[0220] (b) including a light source, and

[0221] (c) is configured to focus light from the light source at the projector focal plane, and

[0222] (d) comprising a pattern generator disposed in an optical path between the light source and the projector focal plane, the pattern generator being configured to generate a structured light pattern at the projector focal plane when the light source is activated to emit light through the pattern generator;

[0223] (C) A light field camera is disposed at the proximal end of the probe. The light field camera:

[0224] (a) having a field of view,

[0225] (b) is configured to focus at the camera focal plane,

[0226] (c) comprising a light field camera sensor comprising (i) an image sensor comprising an array of sensor pixels, and (ii) an array of microlenses disposed in front of the image sensor such that each microlens is disposed over a subarray of the sensor pixels, and

[0227] (d) comprising an objective lens disposed in front of the light field camera sensor and configured to form an image of the scanned object onto the light field camera sensor; and

[0228] (D) A mirror, disposed at the distal end of the hand-held wand,

[0229] The structured light projector and the light field camera are positioned facing the mirror, and the mirror is positioned to (a) reflect light from the structured light projector directly onto the scanned object and (b) reflect light from the scanned object into the light field camera.

[0230] According to some applications of the present invention, there is also provided a device, comprising:

[0231] (A) an elongated handheld wand including a probe at a distal end of the handheld wand, the probe having a proximal end and a distal end; (B) one or more structured light projectors disposed at the distal end of the probe, each structured light projector:

[0232] (a) having an irradiation field,

[0233] (b) including a light source, and

[0234] (c) is configured to focus light from the light source at the projector focal plane, and

[0235] (d) comprising a pattern generator disposed in an optical path between the light source and the projector focal plane, the pattern generator being configured to generate a structured light pattern at the projector focal plane when the light source is activated to emit light through the pattern generator; and

[0236] (C) one or more light field cameras, disposed at the distal end of the probe, each light field camera:

[0237] (a) having a field of view,

[0238] (b) is configured to focus at the camera focal plane,

[0239] (c) comprising a light field camera sensor comprising (i) an image sensor comprising an array of sensor pixels, and (ii) an array of microlenses disposed in front of the image sensor such that each microlens is disposed over a subarray of the sensor pixels, and

[0240] (d) comprising an objective lens disposed in front of the light field camera sensor and configured to form an image of the scanned object onto the light field camera sensor; and

[0241] The structured light projectors and light field cameras are positioned such that (a) each structured light projector faces directly at an object outside the rod placed in its illumination field, (b) each camera faces directly at an object outside the rod placed in its field of view, and (c) at least 40% of the structured light pattern from each projector is within the field of view of at least one camera.

[0242] The present invention will be more fully understood from the following detailed description of its application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0243] Figure 1 is a schematic diagram of a handheld wand according to some applications of the present invention, wherein a plurality of structured light projectors and a camera are disposed in a probe at a distal end of the handheld wand;

[0244] Figure 2A -B are schematic diagrams of positioning configurations of cameras and structured light projectors according to some applications of the present invention;

[0245] Figure 2C is a diagram depicting various different configurations of locations of a structured light projector and a camera in a probe according to some applications of the present invention;

[0246] Figure 3 is a schematic diagram of a structured light projector according to some applications of the present invention;

[0247] Figure 4 is a schematic diagram of a structured light projector according to some applications of the present invention, the structured light projector projecting a distribution of discrete unconnected light points onto a plurality of object focal planes;

[0248] Figure 5A -B is a schematic diagram of a structured light projector according to some applications of the present invention, the structured light projector comprising a beam shaping optical element and an additional optical element disposed between the beam shaping optical element and the pattern generating optical element;

[0249] Fig. 6A -B is a schematic diagram of a structured light projector that projects discrete unconnected light spots and a camera sensor that detects the light spots according to some applications of the present invention;

[0250] Figure 7 is a flow chart outlining a method for generating a digital three-dimensional image according to some applications of the present invention;

[0251] Figure 8 is an overview of some applications according to the present invention for performing Figure 7 a flowchart of a method for a particular step in the method;

[0252] Fig. 9 , Fig.10 , Fig.11 and Fig.12 According to some application descriptions of the present invention Figure 8 A schematic diagram of a simplified example of the steps of;

[0253] Fig.13is a flow chart outlining further steps in a method for generating a digital three-dimensional image according to some applications of the present invention;

[0254] Fig.14 , Fig.15 , Fig.16 and Fig.17 According to some application descriptions of the present invention Fig.13 A schematic diagram of a simplified example of the steps of;

[0255] Fig.18 is a schematic diagram of a probe including a diffuse reflector according to some applications of the present invention;

[0256] Fig.19A -B is a schematic diagram of a structured light projector and a cross section of a light beam emitted by a laser diode according to some applications of the present invention, wherein a pattern generating optical element is shown to be arranged in the light path of the light beam;

[0257] Fig. 20A -E is a schematic diagram of a microlens array used as a pattern generating optical element in a structured light projector according to some applications of the present invention;

[0258] Fig.21A -C is a schematic diagram of a compound 2-D diffractive periodic structure used as a pattern generating optical element in a structured light projector according to some applications of the present invention;

[0259] Fig.22A -B is a schematic diagram showing a single optical element and a structured light projector including the optical element according to some applications of the present invention, the single optical element having an aspherical first side and a planar second side opposite the first side;

[0260] Fig.23A -B is a schematic diagram of an axicon lens and a structured light projector including the axicon lens according to some applications of the present invention;

[0261] Fig.24A -B is a schematic diagram showing an optical element and a structured light projector including the optical element according to some applications of the present invention, the optical element having an aspherical surface on a first side and a flat surface on a second side opposite to the first side;

[0262] Fig.25 is a schematic diagram of a single optical element in a structured light projector according to some applications of the present invention;

[0263] Fig.26A -B is a schematic diagram of a structured light projector having more than one laser diode according to some applications of the present invention;

[0264] Fig.27A - B is a schematic diagram of different ways of combining laser diodes of different wavelengths according to some applications of the present invention;

[0265] Fig.28A is a schematic diagram of a handheld wand according to some applications of the present invention, wherein a structured light projector and a light field camera are disposed at a proximal end of the handheld wand, and a mirror is disposed in a probe at a distal end of the handheld wand;

[0266] Fig.28B According to some applications of the present invention Fig.28A A schematic diagram of a hand-held wand showing the probe in the mouth of a subject;

[0267] Fig.29A -B is a schematic diagram of a structured light projector according to some applications of the present invention;

[0268] Fig.30 is a schematic diagram of a light field camera and a captured three-dimensional object according to some applications of the present invention;

[0269] Fig.31 is a schematic diagram of a handheld wand having a structured light projector and a light field camera disposed within a probe at a distal end of the handheld wand according to some applications of the present invention; and

[0270] Fig.32 is a schematic diagram of a handheld wand according to some applications of the present invention, wherein a plurality of structured light projectors and a light field camera are disposed within a probe at a distal end of the handheld wand. DETAILED DESCRIPTION

[0271] Reference now Figure 1 , Figure 1 is a schematic diagram of an elongated handheld wand 20 for intraoral scanning according to some applications of the present invention. A plurality of structured light projectors 22 and a plurality of cameras 24 are coupled to a rigid structure 26 disposed within a probe 28 at a distal end 30 of the handheld wand. In some applications, during intraoral scanning, the probe 28 enters the oral cavity of a subject.

[0272] For some applications, the structured light projectors 22 are located within the probe 28 so that each structured light projector 22 faces an object 32 placed in its illumination field outside the handheld wand 20, rather than positioning the structured light projector in the proximal end of the handheld wand and illuminating the object by reflecting light through a mirror and then onto the object. Similarly, for some applications, the cameras 24 are located within the probe 28 so that each camera 24 faces an object 32 placed in its field of view outside the handheld wand 20, rather than positioning the camera in the proximal end of the handheld wand and observing the object by reflecting light into the camera through a mirror. This positioning of the projectors and cameras within the probe 28 enables the scanner to have an overall large field of view while maintaining a low profile probe.

[0273] In some applications, the height H1 of the probe 28 is less than 15 mm, and the height H1 of the probe 28 is measured from the lower surface 176 (sensing surface) to the upper surface 178 opposite the lower surface 176, through which reflected light from the scanned object 32 enters the probe 28. In some applications, the height H1 is between 10-15 mm.

[0274] In some applications, the cameras 24 each have a large field of view β (beta) of at least 45 degrees, for example, at least 70 degrees, for example, at least 80 degrees, for example, 85 degrees. In some applications, the field of view can be less than 120 degrees, for example, less than 100 degrees, for example, less than 90 degrees. In experiments conducted by the inventors, it was found that a field of view β (beta) of each camera between 80 and 90 degrees was particularly useful because it provided a good balance between pixel size, field of view and camera overlap, optical quality and cost. The camera 24 may include a camera sensor 58 and an objective optical device 60 including one or more lenses. In order to enable close focus imaging, the camera 24 may be focused at an object focal plane 50, which is between 1 mm and 30 mm from the lens farthest from the camera sensor, for example, between 4 mm and 24 mm, for example, between 5 mm and 11 mm, for example, 9 mm-10 mm. In experiments performed by the inventors, it was found that an object focal plane 50 between 5 mm and 11 mm from the lens farthest from the camera sensor is particularly useful because it is easy to scan the teeth at this distance and because most of the tooth surface is in good focus. In some applications, the camera 24 can capture images at a frame rate of at least 30 frames per second, for example, at a frame rate of at least 75 frames per second, for example, at a frame rate of at least 100 frames per second. In some applications, the frame rate can be less than 200 frames per second.

[0275] As described above, the large field of view achieved by combining the respective fields of view of all cameras can improve accuracy due to the reduced amount of image stitching errors, especially in edentulous areas where the gingival surface is smooth and fewer clear high-resolution three-dimensional features may be present. Having a larger field of view enables large smooth features such as the overall curve of a tooth to appear in each image frame, which improves the accuracy of stitching individual surfaces obtained from multiple such image frames.

[0276] Similarly, each of the structured light projectors 22 can have a large illumination field α(alpha) of at least 45 degrees, for example, at least 70 degrees. In some applications, the illumination field α(alpha) can be less than 120 degrees, for example, less than 100 degrees. Other features of the structured light projectors 22 are described below.

[0277] For some applications, to improve image capture, each camera 24 has a plurality of discrete preset focus positions, at each focus position, the camera focuses at a corresponding object focal plane 50. Each camera 24 may include an autofocus actuator that selects a focus position from the discrete preset focus positions to improve a given image capture. Additionally or alternatively, each camera 24 includes an optical aperture phase mask that extends the depth of focus of the camera so that the image formed by each camera remains in focus at all object distances between 1 mm and 30 mm, e.g., between 4 mm and 24 mm, e.g., between 5 mm and 11 mm, e.g., 9 mm to 10 mm, from the lens farthest from the camera sensor.

[0278] In some applications, the structured light projectors 22 and cameras 24 are coupled to the rigid structure 26 in a closely packed and / or alternating manner such that (a) a major portion of each camera's field of view overlaps with an adjacent camera's field of view, and (b) a major portion of each camera's field of view overlaps with an adjacent projector's illumination field. Optionally, at least 20%, e.g., at least 50%, e.g., at least 75%, of the projected light pattern is in the field of view of at least one camera at an object focal plane 50 that is at least 4 mm from a lens that is farthest from the camera sensor. Due to the different possible configurations of the projectors and cameras, some projected patterns may never be seen in the field of view of any camera, and some projected patterns may be blocked from view by the object 32 as the scanner is moved during scanning.

[0279] The rigid structure 26 may be a non-flexible structure to which the structured light projectors 22 and cameras 24 are bonded to provide structural stability for the optics within the probe 28. Bonding all of the projectors and all of the cameras to a common rigid structure helps maintain the geometric integrity of the optics of each structured light projector 22 and each camera 24 under varying environmental conditions (e.g., conditions of mechanical stress that may be induced by the mouth of a subject). Additionally, the rigid structure 26 helps maintain the stable structural integrity and positioning of the structured light projectors 22 and cameras 24 relative to each other. As further described below, controlling the temperature of the rigid structure 26 helps maintain the geometric integrity of the optics over a wide range of ambient temperatures as the probe 28 enters and exits the mouth of the subject or as the subject breathes during scanning.

[0280] Reference now Figure 2A -B, Figure 2A -B are schematic diagrams of positioning configurations of the camera 24 and the structured light projector 22 according to some applications of the present invention. For some applications, in order to improve the overall field of view and illumination field of the intraoral scanner, the camera 24 and the structured light projector 22 are positioned so that they do not all face the same direction. For some applications, such as Figure 2A As shown in , the plurality of cameras 24 are coupled to the rigid structure 26 such that the angle θ (theta) between the two corresponding optical axes 46 of at least two cameras 24 is 90 degrees or less, for example, 35 degrees or less. Similarly, for some applications, such as Figure 2B As shown in FIG. 1 , a plurality of structured light projectors 22 are coupled to a rigid structure 26 such that an angle between two corresponding optical axes 48 of at least two structured light projectors 22 is (phi) is 90 degrees or less, for example 35 degrees or less.

[0281] Reference now Figure 2C , Figure 2C FIG. 2 is a diagram depicting various different configurations of the positions of the structured light projector 22 and the camera 24 in the probe 28 according to some applications of the present invention. Figure 2C Indicated by a circle in the figure, the camera 24 is Figure 2C Note that rectangles are used to represent cameras because, typically, the field of view β (beta) of each camera sensor 58 and each camera 24 has an aspect ratio of 1:2. Figure 2C Column (a) shows a bird's eye view of various configurations of the structured light projector 22 and the camera 24. The x-axis labeled in the first row of column (a) corresponds to the central longitudinal axis of the probe 28. Column (b) shows a side view of the camera 24 of various configurations observed from a line of sight coaxial with the central longitudinal axis of the probe 28. Figure 2A , Figure 2CColumn (b) shows the cameras 24 positioned so that the optical axes 46 are at an angle of 90 degrees or less relative to each other, such as 35 degrees or less. Column (c) shows side views of the cameras 24 in various configurations as viewed from a line of sight perpendicular to the central longitudinal axis of the probe 28.

[0282] Typically, the farthest side (towards Figure 2C in the positive x direction) and the closest side (towards Figure 2C The cameras 24 (negative x-direction in the probe 28) are positioned so that their optical axes 46 are slightly rotated inwardly relative to the adjacent closest camera 24, for example, at an angle of 90 degrees or less, such as 35 degrees or less. The cameras 24 located more centrally, i.e., neither the farthest camera 24 nor the closest camera 24, are positioned so that they face directly outwardly of the probe, with their optical axes 46 being substantially perpendicular to the central longitudinal axis of the probe 28. It should be noted that in row (xi), the projector 22 is located at the farthest position of the probe 28, so the optical axis 48 of the projector 22 points inwardly, allowing a greater number of light spots 33 projected from this particular projector 22 to be seen by more cameras 24.

[0283] Typically, the number of structured light projectors 22 in a probe 28 can range from two (e.g., Figure 2C Typically, the number of cameras 24 in the probe 28 can range from four (e.g., as shown in rows (iv) and (v)) to seven (e.g., as shown in row (ix)). Note that Figure 2C The various configurations shown in are for example only and are not limiting, and the scope of the present invention includes additional configurations not shown. For example, the scope of the present invention includes more than five projectors 22 located in the probe 28 and more than seven cameras located in the probe 28.

[0284] In an exemplary application, a device for intraoral scanning (e.g., an intraoral scanner) includes an elongated handheld wand including: a probe located at a distal end of the elongated handheld wand; at least two light projectors disposed in the probe; and at least four cameras disposed in the probe. Each light projector may include: at least one light source configured to generate light when activated; and a pattern generating optical element configured to generate a light pattern when emitting light passing through the pattern generating optical element. Each of the at least four cameras may include a camera sensor and one or more lenses, wherein each of the at least four cameras is configured to capture a plurality of images depicting at least a portion of the light pattern projected on an intraoral surface. A majority of the at least two light projectors and the at least four cameras may be arranged in at least two rows, each of which is substantially parallel to a longitudinal axis of the probe, the at least two rows including at least a first row and a second row.

[0285] In a further application, the farthest camera along the longitudinal axis and the closest camera along the longitudinal axis of at least four cameras are positioned so that their optical axes are at an angle of 90 degrees or less relative to each other from a line of sight perpendicular to the longitudinal axis. The cameras in the first row and the cameras in the second row can be positioned so that from a line of sight coaxial with the longitudinal axis of the probe, the optical axes of the cameras in the first row are at an angle of 90 degrees or less relative to the optical axes of the cameras in the second row. The remainder of the at least four cameras other than the farthest camera and the closest camera have optical axes substantially parallel to the longitudinal axis of the probe. Each of the at least two rows can include an alternating sequence of light projectors and cameras.

[0286] In a further application, the at least four cameras include at least five cameras, the at least two light projectors include at least five light projectors, the closest components in the first row are the light projectors, and the closest components in the second row are the cameras.

[0287] In further applications, the farthest camera along the longitudinal axis and the closest camera along the longitudinal axis are positioned such that their optical axes are at an angle of 35 degrees or less relative to each other from a line of sight perpendicular to the longitudinal axis. The cameras in the first row and the cameras in the second row can be positioned such that the optical axes of the cameras in the first row are at an angle of 35 degrees or less relative to the optical axes of the cameras in the second row from a line of sight coaxial with the longitudinal axis of the probe.

[0288] In a further application, at least four cameras may have a combined field of view of 25-45 mm along the longitudinal axis and 20-40 mm along the z-axis, corresponding to the distance from the probe.

[0289] Reference now Figure 3 , Figure 3 2 is a schematic diagram of a structured light projector 22 according to some applications of the present invention. In some applications, the structured light projector 22 includes a laser diode 36, a beam shaping optical element 40, and a pattern generating optical element 38, which generates a distribution 34 of discrete unconnected light spots (hereinafter referred to as Figure 4Further discussion). In some applications, the structured light projector 22 can be configured to generate a distribution 34 of discrete, unconnected light spots at all planes between 1 mm and 30 mm, such as between 4 mm and 24 mm, from the pattern generating optical element 38 when the laser diode 36 emits light through the pattern generating optical element 38. For some applications, the distribution 34 of discrete, unconnected light spots is focused on one plane between 1 mm and 30 mm, such as between 4 mm and 24 mm, while all other planes between 1 mm and 30 mm, such as between 4 mm and 24 mm, still contain discrete, unconnected light spots. Although described above as using a laser diode, it should be understood that this is an exemplary and non-limiting application. Other light sources may be used in other applications. In addition, although described as projecting a pattern of discrete, unconnected light spots, it should be understood that this is an exemplary and non-limiting application. Other light patterns or arrays, including but not limited to lines, grids, checkerboards, and other arrays, may be used in other applications.

[0290] The pattern generating optical element 38 may be configured to have a light throughput efficiency (ie, the ratio of light entering the pattern to the total light falling on the pattern generating optical element 38) of at least 80%, for example, at least 90%.

[0291] For some applications, the corresponding laser diodes 36 of each structured light projector 22 emit light of different wavelengths, that is, the corresponding laser diodes 36 of at least two structured light projectors 22 respectively emit light of two different wavelengths. For some applications, the corresponding laser diodes 36 of at least three structured light projectors 22 respectively emit light of three different wavelengths. For example, red, blue, and green laser diodes can be used. For some applications, the corresponding laser diodes 36 of at least two structured light projectors 22 respectively emit light of two different wavelengths. For example, in some applications, there are six structured light projectors 22 disposed in the probe 28, three of which contain blue laser diodes and three of which contain green laser diodes.

[0292] Reference now Figure 4 , Figure 4is a schematic diagram of a structured light projector 22 according to some applications of the present invention, which projects a distribution of discrete unconnected light spots onto multiple object focal planes. The scanned object 32 can be one or more teeth or other intraoral objects / tissues in the mouth of a subject. The somewhat translucent and smooth nature of the teeth may affect the contrast of the projected structured light pattern. For example, (a) some of the light hitting the teeth may be scattered to other areas within the intraoral scene, resulting in a certain amount of stray light, and (b) some of the light may penetrate the teeth and then exit the teeth at any other point. Therefore, in order to improve image capture of the intraoral scene under structured light illumination without using contrast enhancement devices such as coating the teeth with opaque powder, the inventors have recognized that a sparse distribution 34 of discrete unconnected light spots can provide an improved balance between reducing the amount of projected light while maintaining a useful amount of information. The sparsity of the distribution 34 can be characterized by the ratio of (a) to (b) as follows:

[0293] (a) The irradiated area on the orthogonal plane 44 in the irradiated field α (alpha), i.e., the irradiated field α (alpha)

[0294] The sum of the areas of all projected light spots 33 on the orthogonal plane 44 in

[0295] (b) Non-irradiated area on orthogonal plane 44 in illumination field α (alpha). In some applications, the sparsity ratio can be at least 1:150 and / or less than 1:16 (eg, at least 1:64 and / or less than 1:36).

[0296] In some applications, during scanning, each structured light projector 22 projects at least 400 discrete, unconnected light spots 33 onto the intraoral three-dimensional surface. In some applications, during scanning, each structured light projector 22 projects less than 3,000 discrete, unconnected light spots 33 onto the intraoral surface. In order to reconstruct the three-dimensional surface from the projected sparse distribution 34, the correspondence between each projected light spot 33 and the light spot detected by the camera 24 must be determined, as described below with reference to Figure 7 to Figure 1 9 further described.

[0297] For some applications, the pattern generating optical element 38 is a diffractive optical element (DOE) 39 ( Figure 3), when the laser diode 36 emits light through the DOE and onto the object 32, the DOE generates a distribution 34 of discrete, unconnected light spots 33. As used herein throughout this application, including in the claims, a light spot is defined as a small area of ​​light having any shape. For some applications, corresponding DOEs 39 of different structured light projectors 22 generate light spots having different corresponding shapes, i.e., each light spot 33 generated by a particular DOE 39 has the same shape, and the shape of the light spot 33 generated by at least one DOE 39 is different from the shape of the light spot 33 generated by at least one other DOE 39. For example, some of the DOEs 39 may generate circular light spots 33 (e.g., Figure 4 ), some of the DOEs 39 may generate square light spots, and some of the DOEs 39 may generate elliptical light spots. Alternatively, some of the DOEs 39 may generate connected or unconnected line patterns.

[0298] Reference now Figure 5A -B, Figure 5A -B is a schematic diagram of a structured light projector 22 according to some applications of the present invention, the structured light projector 22 including a beam shaping optical element 40 and an additional optical element disposed between the beam shaping optical element 40 and the pattern generating optical element 38 (e.g., DOE 39). Optionally, the beam shaping optical element 40 is a collimating lens 130. The collimating lens 130 can be configured to have a focal length of less than 2 mm. Optionally, the focal length can be at least 1.2 mm. For some applications, when the laser diode 36 emits light through the optical element 42, the additional optical element 42 disposed between the beam shaping optical element 40 and the pattern generating optical element 38 (e.g., DOE 39) generates a Bessel beam. In some applications, the Bessel beam is transmitted through the DOE 39 so that all discrete unconnected light spots 33 maintain a small diameter (e.g., less than 0.06 mm, such as less than 0.04 mm, such as less than 0.02 mm) through a series of orthogonal planes 44 (e.g., each orthogonal plane is located between 1 mm and 30 mm from the DOE 39, such as between 4 mm and 24 mm from the DOE 39, etc.). In the context of the present patent application, the diameter of the light spot 33 is defined as the full width at half maximum (FWHM) of the light spot intensity.

[0299] Although all of the spots described above are less than 0.06 mm, some spots having diameters near the upper ends of these ranges (e.g., only slightly less than 0.06 mm or 0.02 mm) and also near the edge of the illumination field of projector 22 may be elongated when they intersect a geometric plane orthogonal to DOE 39. For such cases, it is useful to measure their diameters as they intersect the inner surface of a geometric sphere centered on DOE 39 and having a radius between 1 mm and 30 mm, which corresponds to a distance from the DOE 39 of the corresponding orthogonal plane between 1 mm and 30 mm. As used throughout this application, including in the claims, the word "geometric" is used in relation to theoretical geometric constructions (e.g., a plane or a sphere), and is not part of any physical device.

[0300] For some applications, when the Bessel beam is transmitted through DOE 39, a light spot 33 having a diameter greater than 0.06 mm is generated in addition to light spots having a diameter less than 0.06 mm.

[0301] For some applications, optical element 42 is an axicon lens 45, e.g. Figure 5A As shown in and as hereinafter referred to Fig.23A Alternatively, the optical element 42 may be an annular aperture ring 47, such as Figure 5B Maintaining a small diameter spot improves three-dimensional resolution and accuracy throughout the focal depth. In the absence of optical element 42 (e.g., axicon lens 45 or annular aperture ring 47), the size of spot 33 can change, e.g., become larger, as you move away from the plane of best focus due to diffraction and defocusing.

[0302] Reference now Fig. 6A -B, Fig. 6A -B is a schematic diagram of a structured light projector 22 that projects discrete, unconnected light spots 33 and a camera sensor 58 that detects the light spots 33' according to some applications of the present invention. For some applications, a method is provided for determining a correspondence between projected light spots 33 on an intraoral surface and detected light spots 33' on corresponding camera sensors 58. Once the correspondence is determined, a three-dimensional image of the surface is reconstructed. Each camera sensor 58 has an array of pixels, and for each pixel there is a corresponding camera ray 86. Similarly, for each projected light spot 33 from each projector 22, there is a corresponding projector ray 88. Each projector ray 88 corresponds to a corresponding path 92 of a pixel on at least one camera sensor 58. Therefore, if the camera sees a light spot 33' projected by a particular projector ray 88, then that light spot 33' must be detected by a pixel on a particular path 92 of a pixel corresponding to that particular projector ray 88. Specific reference is made to Figure 6B , shows the correspondence between each projector light 88 and the corresponding camera sensor path 92. Projector light 88' corresponds to camera sensor path 92', projector light 88" corresponds to camera sensor path 92", and projector light 88"' corresponds to camera sensor path 92"'. For example, if a particular projector light 88 projects a light spot into a dusty space, the dust line in the air will be illuminated. This dust line detected by the camera sensor 58 will follow the same path on the camera sensor 58 as the camera sensor path 92 corresponding to the particular projector light ray 88.

[0303] During the calibration process, calibration values ​​are stored based on the camera rays 86 corresponding to the pixels on the camera sensor 58 of each camera 24 and the projector rays 88 corresponding to the projected light spots 33 from each structured light projector 22. For example, calibration values ​​are stored for (a) a plurality of camera rays 86 corresponding to a corresponding plurality of pixels on the camera sensor 58 of each camera 24, and (b) a plurality of projector rays 88 corresponding to a corresponding plurality of projected light spots 33 from each structured light projector 22.

[0304] By way of example, the following calibration process may be used. A high precision point target, such as a black dot on a white background, is illuminated from below and an image of the target is captured with all cameras. The point target is then moved vertically toward the camera, i.e., along the z-axis to the target plane. The dot centers of all points in all corresponding z-axis positions are calculated to create a three-dimensional grid of points in space. The distortion and camera pinhole models are then used to find the pixel coordinates of each three-dimensional position of the corresponding dot center, so that for each pixel the camera ray is defined as the ray originating from the pixel whose direction is toward the corresponding dot center in the three-dimensional grid. The camera rays corresponding to the pixels between the grid points may be interpolated. The above camera calibration process is repeated for all corresponding wavelengths of the respective laser diodes 36, so that for each wavelength, included in the stored calibration values ​​is the camera ray 86 corresponding to each pixel on each camera sensor 58.

[0305] After the cameras 24 have been calibrated and all camera light ray 86 values ​​have been stored, the structured light projectors 22 may be calibrated as follows. A flat featureless target is used and one structured light projector 22 is turned on at a time. Each light point is located on at least one camera sensor 58. Since the cameras 24 are now calibrated, the three-dimensional light point position of each light point is calculated by triangulation based on the images of the light point in multiple different cameras. The above process is repeated using a featureless target at multiple different z-axis locations. Each projected light point on the featureless target will define a projector ray originating from the projector in space.

[0306] Reference now Figure 7 , Figure 7 is a flow chart outlining a method for generating a digital three-dimensional image according to some applications of the present invention. Figure 7 In steps 62 and 64 of the method outlined, each structured light projector 22 is driven to project a distribution 34 of discrete unconnected light spots 33 on an intraoral three-dimensional surface, and each camera 24 is driven to capture an image including at least one light spot 33. Based on stored calibration values ​​indicating (a) camera rays 86 corresponding to each pixel on the camera sensor 58 of each camera 24, and (b) projector rays 88 corresponding to each projected light spot 33 from each structured light projector 22, a processor 96 ( Figure 1 ) Run the corresponding algorithm, which will be referenced below Figures 8 to 12 Once the correspondence is resolved, the three-dimensional position on the intraoral surface is calculated in step 68 and used to generate a digital three-dimensional image of the intraoral surface. In addition, using multiple cameras 24 to capture the intraoral scene provides a signal to noise improvement in the capture by a factor of the square root of the number of cameras.

[0307] Reference now Figure 8 , Figure 8 is an overview of some applications according to the present invention Figure 7 Based on the stored calibration values, all projector rays 88 and all camera rays 86 corresponding to all detected light spots 33' are mapped (step 70), and all intersection points 98 of at least one camera ray 86 and at least one projector ray 88 are identified (step 71). Fig.10 )(Step 72). Fig. 9 and Fig.10 They are Figure 8 A schematic diagram of a simplified example of steps 70 and 72 of FIG. Fig. 9 As shown, three projector rays 88 are mapped together with eight camera rays 86 corresponding to a total of eight detected light points 33' on the camera sensor 58 of the camera 24. Fig.10 As shown, sixteen intersection points 98 are identified.

[0308] exist Figure 8 In steps 74 and 76, the processor 96 determines the correspondence between the projected light spots 33 and the detected light spots 33' so as to identify the three-dimensional position of each projected light spot 33 on the surface. Fig.11 is depicted using the simplified example described in the previous paragraph Figure 8Schematic diagram of steps 74 and 76 of . For a given projector ray i, the processor 96 "looks" at the corresponding camera sensor path 90 on the camera sensor 58 of one of the cameras 24. Each detected light point j along the camera sensor path 90 will have a camera ray 86 that intersects the given projector ray i at an intersection 98. The intersection 98 defines a three-dimensional point in space. The processor 96 then "looks" at the camera sensor paths 90' corresponding to the given projector ray i on the corresponding camera sensors 58' of the other cameras 24, and identifies how many other cameras 24 have also detected corresponding light points k on their corresponding camera sensor paths 90' corresponding to the given projector ray i, whose camera rays 86' intersect the same three-dimensional point in space defined by the intersection 98. The process is repeated for all detected light points j along the camera sensor paths 90, and the light point j that has the greatest number of cameras 24 "agrees" to be identified as the light point 33 ( Fig.12 ). That is, the projector ray i is identified as the specific projector ray 88 that generated the detected light point j for which the highest number of other cameras detected the corresponding light point k. Thus, the three-dimensional position of the light point 33 on the surface is calculated.

[0309] For example, Fig.11 As shown, all four cameras detect corresponding light spots on respective camera sensor paths corresponding to projector ray i, and their corresponding camera rays intersect projector ray i at intersection point 98, which is defined as the intersection of camera ray 86 corresponding to detected light spot j and projector ray i. Therefore, all four cameras are said to "agree" that there is a light spot 33 projected by projector ray i at intersection point 98. However, when the process is repeated for the next light point j', none of the other cameras detects a corresponding light point on their respective camera sensor paths corresponding to projector ray i whose corresponding camera rays intersect with projector ray i at intersection 98', which intersection 98' is defined as the intersection of camera ray 86" (corresponding to detected light point j') and projector ray i. Therefore, only one camera is said to "agree" that there is a light point 33 projected by projector ray i at intersection 98', while four cameras "agree" that there is a light point 33 projected by projector ray i at intersection 98. Therefore, projector ray i is identified as the specific projector ray 88 (which generated the detected light point j by projecting light point 33 onto the surface at intersection 98). Fig.12 ).according to Figure 8 Step 78, and as Fig.12 As shown, the three-dimensional position 35 on the inner surface of the outlet is calculated at the intersection point 98.

[0310] Reference now Fig.13 , Fig.13 is a flow chart outlining the other steps in the correspondence algorithm according to some applications of the invention. Once the position 35 on the surface is determined, the projector ray i that projects the light point j, as well as all camera rays 86 and 86' corresponding to the light point j and the corresponding light point k are removed from consideration (step 80), and the correspondence algorithm is run again for the next projector ray i (step 82). Fig.14 Depicted is a simplified example of the above description after removal of the particular projector ray i that projects the light spot 33 at position 35. Fig.13 Step 82 in the flowchart of , and then run the corresponding algorithm again for the next projector ray i. Fig.14 As shown, the remaining data shows that the three cameras "agree" that light spot 33 exists at intersection point 98, which is defined by the intersection of camera ray 86 corresponding to detected light spot j and projector ray i. Fig.15 As shown, the three-dimensional position 37 is calculated at the intersection point 98 .

[0311] like Fig.16 As shown, once the three-dimensional position 37 on the surface is determined, the projected ray i projecting the light point j, as well as all camera rays 86 and 86' corresponding to the light point j and the corresponding light point k are not considered. The remaining data shows that there is a light point 33 projected by the projector ray i at the intersection 98 and the three-dimensional position 41 on the surface is calculated at the intersection 98. Fig.17 As shown, according to a simplified example, three projected light spots 33 of three projector rays 88 of the structured light projector 22 are now located at three-dimensional positions 35, 37 and 41 on the surface. In some applications, each structured light projector 22 projects 400-3000 light spots 33. Once the correspondence of all projector rays 88 is resolved, a reconstruction algorithm can be used to reconstruct a digital image of the surface using the calculated three-dimensional positions of the projected light spots 33.

[0312] Reference again Figure 1. For some applications, there is at least one uniform light projector 118 coupled to the rigid structure 26. The uniform light projector 118 emits white light onto the object 32 being scanned. At least one camera (e.g., one of the cameras 24) is configured to capture a two-dimensional color image of the object 32 using illumination from the uniform light projector 118. The processor 96 can run a surface reconstruction algorithm that combines at least one image captured using illumination from the structured light projector 22 with multiple images captured using illumination from the uniform light projector 118 to generate a three-dimensional image of the intraoral three-dimensional surface. Using a combination of structured light and uniform illumination enhances the overall capture of the intraoral scanner and can help reduce the number of options that the processor 96 needs to consider when running the corresponding algorithm.

[0313] For some applications, multiple structured light projectors 22 are driven simultaneously to project their respective distributions 34 of discrete, unconnected light spots 33 on the three-dimensional surface within the mouth. Alternatively, multiple structured light projectors 22 may be driven to project their respective distributions 34 of discrete, unconnected light spots 33 on the three-dimensional surface within the mouth at different individual times, for example, in a predetermined order, or in an order dynamically determined during scanning. Alternatively, for some applications, a single structured light projector 22 may be driven to project distribution 34.

[0314] Dynamically determining which structured light projector 22 to activate during a scan can improve the overall signal quality of the scan because some structured light projectors may have better signal quality in some areas within the oral cavity relative to other areas. For example, when scanning the palate (maxillary area) of a subject, a red projector tends to have better signal quality than a blue projector. Additionally, difficult to see areas within the oral cavity may be encountered during a scan, such as areas with missing teeth or narrow crevices between large teeth. In these types of situations, dynamically determining which structured light projector 22 to activate during a scan allows for activation of a specific projector that may have a better line of sight.

[0315] For some applications, different structured light projectors 22 may be configured to focus at different object focal planes. Dynamically determining which structured light projector 22 to activate during scanning allows for activation of specific structured light projectors 22 according to their respective object focal planes depending on the distance from the area currently being scanned.

[0316] For some applications, all data points collected at a particular time are used as a rigid point cloud, and multiple such point clouds are captured at a frame rate of more than 10 captures per second. Multiple point clouds are then stitched together using a registration algorithm (e.g., iterative closest point (ICP)) to create a dense point cloud. A surface reconstruction algorithm can then be used to generate a representation of the surface of object 32.

[0317] For some applications, at least one temperature sensor 52 is coupled to the rigid structure 26 and measures the temperature of the rigid structure 26. A temperature control circuit 54 disposed within the hand-held wand 20 (a) receives data indicating the temperature of the rigid structure 26 from the temperature sensor 52, and (b) activates a temperature control unit 56 in response to the received data. The temperature control unit 56 (e.g., a PID controller) maintains the probe 28 at a desired temperature (e.g., between 35 and 43 degrees Celsius, between 37 and 41 degrees Celsius, etc.). Maintaining the probe 28 above 35 degrees Celsius, such as above 37 degrees Celsius, reduces fogging of the glass surface of the hand-held wand 20, through which the structured light projector 22 projects and the camera 2 observes when the probe 28 enters the oral cavity, which is typically around or above 37 degrees Celsius. Maintaining the probe 28 below 43 degrees, such as below 41 degrees Celsius, prevents discomfort or pain.

[0318] In addition, in order to use the stored calibration values ​​of the camera light and the projector light during scanning, the temperature changes of the camera 24 and the structured light projector 22 can be prevented, thereby maintaining the geometric integrity of the optical devices. Changes in temperature may cause the length of the probe 28 to change due to thermal expansion, which in turn may cause the corresponding camera and projector positions to shift. Due to different types of stresses that may accumulate in the probe 28 during such thermal expansion, distortions may also be generated, causing the angles of the corresponding camera light and projector light to shift. Geometric changes may also be generated in the camera and projector due to temperature changes. For example, the DOE 39 may expand and change the projected pattern, the temperature change may affect the refractive index of the camera lens, or the temperature change may change the wavelength emitted by the laser diode 36. Therefore, in addition to maintaining the probe 28 at a temperature within the above-mentioned range, the temperature control unit 56 can also prevent the temperature of the probe 28 from changing by more than 1 degree when the hand-held wand 20 is used, thereby maintaining the geometric integrity of the optical devices disposed in the probe 28. For example, if the temperature control unit 56 maintains the probe 28 at a temperature of 39 degrees Celsius, the temperature control unit 56 will further ensure that the temperature of the probe 28 does not drop below 38 degrees Celsius or rise above 40 degrees Celsius during use.

[0319] For some applications, probe 28 may be maintained at its controlled temperature by using a combination of heating and cooling. For example, temperature control unit 56 may include a heater, such as a plurality of heaters, and a cooler, such as a thermoelectric cooler. If the temperature of probe 28 drops below 38 degrees Celsius, a heater may be used to raise the temperature of probe 28, and if the temperature of probe 28 is above 40 degrees Celsius, a thermoelectric cooler may be used to lower the temperature of probe 28.

[0320] Alternatively, for some applications, the probe 28 is maintained at its controlled temperature by using only heating without using cooling. The use of the laser diode 36 and the diffractive and / or refractive pattern generating optical element helps maintain an energy efficient structured light projector, thereby limiting the probe 28 from heating up during use; the laser diode 36 can use less than 0.2 watts of power while emitting at high brightness, and the diffractive and / or refractive pattern generating optical element utilizes all emitted light (e.g., as opposed to a mask that blocks some light from striking the subject). However, external ambient temperatures, such as those encountered within the oral cavity of a subject, may cause heating of the probe 28. To overcome this, heat can be drawn out of the probe 28 by a thermally conductive element 94 (e.g., a heat pipe) disposed within the hand-held wand 20, such that the distal end 95 of the thermally conductive element 94 is in contact with the rigid structure 26, and the proximal end 99 is in contact with the proximal end 100 of the hand-held wand 20. As a result, heat is transferred from the rigid structure 26 to the proximal end 100 of the hand-held wand 20. Alternatively or additionally, a fan disposed in the handle region 174 of the handheld wand 20 may be used to draw heat away from the probe 28 .

[0321] For some applications, alternatively or additionally, in order to maintain the geometric integrity of the optical device by preventing the temperature of the probe 28 from changing beyond a threshold change in temperature, the processor 96 may select between multiple sets of calibration data corresponding to different temperatures, respectively. For example, the threshold change may be 1 degree Celsius. Based on data received from the temperature sensor 52 indicating the temperature of the structured light projector 22 and the camera 24, the processor 96 may select between multiple sets of stored calibration data corresponding to multiple corresponding temperatures of the structured light projector 22 and the camera 24, each set of stored calibration data indicating (a) projector light corresponding to each projected light point from each of the one or more projectors, and (b) camera light corresponding to each pixel on the camera sensor of each of the one or more cameras for a corresponding temperature. If the processor 96 only has access to stored calibration data for a specific plurality of temperatures, the processor 96 may interpolate between the multiple sets of stored calibration data based on the data received from the temperature sensor 52 to obtain calibration data corresponding to temperatures between the corresponding temperatures of each set of calibration data.

[0322] Reference now Fig.18 , Fig.18 28 according to some applications of the present invention. For some applications, the probe 28 also includes a target, such as a diffuse reflector 170, which has a diffuse reflector 170 disposed in the probe 28 (or, as Fig.1828). In some applications, (a) each structured light projector 22 may have at least one region 172 of diffuse reflector 170 in its illumination field, (b) each camera 24 may have at least one region 172 of diffuse reflector 170 in its field of view, and (c) multiple regions 172 of diffuse reflector 170 are in the field of view of the camera 24 and in the illumination field of the structured light projector 22. Alternatively or additionally, in order to maintain the geometric integrity of the optical device by preventing the temperature change of the probe 28 from exceeding a threshold temperature change, the processor 96 may (a) receive data from the camera 24 indicating the position of the diffuse reflector relative to the distribution 34 of discrete unconnected light spots 33, (b) compare the received data with a stored calibration position of the diffuse reflector 170, wherein the difference between (i) the received data indicating the position of the diffuse reflector 170 and (ii) the stored calibration position of the diffuse reflector 170 indicates an offset of the projector light 88 and the camera light 86 from their respective stored calibration values, and (c) run a corresponding algorithm based on the offset of the projector light 88 and the camera light 86.

[0323] Alternatively or additionally, a difference between (i) the received data indicating the position of the diffuse reflector 170 and (ii) the stored calibration position of the diffuse reflector 170 may indicate a change in temperature of the probe 28. In this case, the temperature of the probe 28 may be adjusted based on a comparison of the received data of the diffuse reflector 170 to the stored calibration position.

[0324] Several applications of structured light projector 22 are described below.

[0325] Reference now Fig.19A -B, Fig.19A -B is a schematic diagram of a structured light projector 22 and a cross section of a light beam 120 emitted by a laser diode 36 according to some applications of the present invention, wherein a pattern generating optical element 38 is shown disposed in the optical path of the light beam. In some applications, each laser diode 36 emits an elliptical light beam 120, whose elliptical cross-section has (a) a major axis of at least 500 microns and / or less than 700 microns and (b) a minor axis of at least 100 microns and / or less than 200 microns. For some applications, a small area beam splitter can be used to generate a tightly focused array of light spots, for example, a DOE with a side length of less than 100 microns can be used to keep the projected light spot 33 tightly focused throughout the focal range of interest. However, such a small DOE will only utilize a portion of the light emitted by the elliptical laser beam 120.

[0326] Thus, for some applications, the pattern generating optical element 38 is a segmented DOE 122 that is segmented into a plurality of sub-DOE pieces 124 arranged in an array. The array of sub-DOE pieces 124 is positioned so as to (a) be contained within the elliptical beam 120 and (b) utilize a high percentage, for example at least 50%, of the light emitted by the elliptical laser beam 120. In some applications, the array is a rectangular array comprising at least 16 and / or less than 72 sub-DOE pieces 124 and having a longest dimension of at least 500 microns and / or less than 800 microns. Each sub-DOE piece 124 can have a square cross-section having a side of a length of at least 30 microns and / or less than 75 microns, the cross-section being taken perpendicular to the optical axis of the DOE.

[0327] Each sub-DOE sheet 124 generates a corresponding distribution 126 of discrete, unconnected light spots 33 in a different region 128 of the illumination field. For this application of the structured light projector 22, as described above with reference to Figure 4 The distribution 34 of discrete unconnected light spots 33 is a combination of the corresponding distributions 126 generated by the corresponding sub-DOE slices 124. Fig.19B An orthogonal plane 44 is shown on which respective distributions 126 of discrete unconnected light spots 33 are shown, each respective distribution 126 being located in a different region 128 of the illumination field. Since each sub-DOE slice 124 is responsible for a different region 128 of the illumination field, each sub-DOE slice 124 has a different design in order to direct its respective distribution 126 in a different direction and avoid beam crossing to avoid overlap between the projected light spots 33.

[0328] Reference now Fig. 20A -E, Fig. 20A -E is a schematic diagram of a microlens array 132 as a pattern generating optical element 38 according to some applications of the present invention. The microlens array can be used as a light spot generator because it is periodic and the profile variation of each lens in the array is wavelength-scaled. The spacing of the microlens array 132 is adjusted to obtain the desired angular pitch between the light spots. As described above, the numerical aperture (NA) of the microlens array 132 is adjusted to provide an illumination field at a desired angle. In some applications, the NA of the microlens array 132 is at least 0.2 and / or less than 0.7. The microlens array 132 can be, for example, a hexagonal microlens array, such as Fig. 20C As shown, or a rectangular microlens array, such as Fig.20E shown.

[0329] The structured light projector 22 having a microlens array 132 as a pattern generating optical element 38 may include a laser diode 36, a collimating lens 130, an aperture, and the microlens array 132. The aperture defines a smaller input beam diameter in order to maintain a tightly focused spot at a close focal distance from the microlens array 132, e.g., at least 1 mm and / or less than 30 mm, e.g., at least 4 mm and / or less than 24 mm. Fig. 20B A collimated laser beam is shown illuminating a microlens array 132, which then generates divergent light beams 134, the interference of which generates an array of light spots 33, such as a distribution 34 ( Fig.20D ). For some applications, the aperture is a chrome film applied to the laser diode side of collimating lens 130. Alternatively, for some applications, the aperture is a chrome film disposed on the collimating lens side of microlens array 132. In some applications, the aperture can span a distance of at least 10 times the pitch of microlens array 132 and have a diameter of at least 50 microns and / or less than 200 microns.

[0330] Reference now Fig.21A -C, Fig.21A -C is a schematic diagram of a composite two-dimensional diffractive periodic structure 136 (e.g., a diffraction grating such as a Dammann grating) as a pattern generating optical element 38 according to some applications of the present invention. The composite diffractive periodic structure 136 can have a periodic structure feature size 137 of at least 100 nm and / or less than 400 nm. A large illumination field as described above can be obtained with a small sub-feature of about 300 nm. The period of the composite diffractive periodic structure 136 can be adjusted to provide the desired angular spacing of the projected light beams.

[0331] The structured light projector 22 having a compound diffraction periodic structure 136 as a pattern generating optical element 38 may include a laser diode 36, a collimating lens 130, an aperture, and a compound diffraction periodic structure 136. The aperture defines a smaller input beam diameter so as to maintain a tightly focused light spot at a close focal distance from the compound diffraction periodic structure 136, for example, at least 1 mm and / or less than 30 mm, for example, at least 4 mm and / or less than 24 mm. For some applications, the aperture is a chrome film located on the periodic structural features of the compound diffraction periodic structure 136. In some applications, the aperture may span a distance of at least 10 periods of the compound diffraction periodic structure 136 and have a diameter of at least 50 microns and / or less than 200 microns.

[0332] For some applications, the beam shaping optical element 40 (e.g. Figure 3 ) is a collimating lens 130 disposed between the laser diode 36 and the pattern generating optical element 38. Fig.19A-B, 20A-E and 21A-C, the collimating lens 130 can be disposed between the laser diode 36 and the segmented DOE 122 ( Fig.19A ), disposed between the laser diode 36 and the microlens array 132 ( Fig. 20A ), and disposed between the laser diode 36 and the composite diffraction periodic structure 136 ( Fig.21A ).

[0333] Reference now Fig.22A -B, Fig.22A -B is a schematic diagram of a single optical element 138 and a structured light projector 22 including the optical element 138 according to some applications of the present invention, the single optical element 138 having an aspheric first side and a planar second side opposite the first side. For some applications, the collimating lens 130 and the pattern generating optical element 38 can be manufactured as a single optical element 138, whose first aspheric side 140 collimates the light emitted from the laser diode 36 and whose second planar side 142 generates a distribution 34 of discrete unconnected light spots 33. The planar side 142 of the single optical element 138 can be shaped to define a DOE 39, a segmented DOE 122, a microlens array 132, or a complex diffractive periodic structure 136.

[0334] Reference now Fig.23A -B, Fig.23A -B is a schematic diagram of an axicon lens 144 and a structured light projector 22 including the axicon lens 144 according to some applications of the present invention. Axicon lenses are known to generate Bessel beams, which are beams focused within a desired depth range based on an input beam diameter and an axicon head angle. For some applications, an axicon lens 144 having a head angle γ (gamma) of at least 0.2 degrees and / or less than 2 degrees is disposed between the collimating lens 130 and the pattern generating optical element 38. When the laser diode 36 emits light through the axicon lens 144, the axicon lens 144 generates a focused Bessel beam 146. The focused Bessel beam 146 is split into a plurality of beams 148 by the pattern generating optical element 38, each beam 148 being an exact copy of the Bessel beam 146 generated by the axicon lens 144. The pattern generating optical element 38 may be a DOE 39, a microlens array 132, or a compound diffraction periodic structure 136.

[0335] Reference now Fig.24A -B, Fig.24A-B is a schematic diagram of an optical element 150 and a structured light projector 22 including the optical element 150 according to some applications of the present invention, the optical element 150 having an aspheric surface 152 on a first side and a planar surface on a second side opposite the first side. For some applications, the collimating lens 130 and the axicon lens 144 can be manufactured as a single optical element 150. When the laser diode 36 emits light through the optical element 150, the aspheric surface 152 of the single optical element 150 directly generates a Bessel beam from the divergent beam. Then when the light travels through the pattern generating optical element 38, a distribution 34 of discrete unconnected light spots 33 is generated, so that the discrete unconnected light spots 33 have a substantially uniform size at any orthogonal plane between 1 mm and 30 mm, for example, between 4 mm and 24 mm from the pattern generating optical element 38. The pattern generating optical element 38 can be a DOE 39, a microlens array 132, or a complex diffraction periodic structure 136. As used throughout this application, including in the claims, a light spot having a "substantially uniform size" means that the size of the light spot does not vary by more than 40%.

[0336] Reference now Fig.25 , Fig.25 1 is a schematic diagram of a single optical element 154 in a structured light projector 22 according to some applications of the present invention. For some applications, the single optical element 154 can perform the functions of a collimating lens, an axicon lens, and a pattern generating optical element. The single optical element 154 includes an aspheric surface 156 on a first side and a planar surface 158 on a second side opposite to the first side. When the laser diode 36 emits a divergent beam through the single optical element 154, the aspheric surface 156 generates a Bessel beam directly from the divergent beam. The planar surface 158 is shaped to define the pattern generating optical element 38, and thus divides the Bessel beam into an array of discrete Bessel beams 160, so as to generate a distribution 34 of discrete unconnected light spots 33, so that the discrete unconnected light spots 33 have a substantially uniform size at any orthogonal plane between 1 mm and 30 mm, such as between 4 mm and 24 mm from the single pattern optical element 154. The planar surface 158 can be shaped to define a DOE 39, a microlens array 132, or a complex diffractive periodic structure 136.

[0337] Reference now Fig.26A -B, Fig.26A-B is a schematic diagram of a structured light projector 22 with more than one light source (e.g., laser diodes 36) according to some applications of the present invention. When laser diodes are used, laser speckle may generate spatial noise. The speckle effect is the result of the interference of many waves of the same frequency but different phases and amplitudes. When all the waves are superimposed together, the composite wave is a wave whose amplitude varies randomly over the beam profile. For some applications, the speckle effect can be reduced by combining multiple laser diodes 36 of the same wavelength. Different lasers with the same wavelength are incoherent with each other, so combining them into the same space or the same diffraction beam splitter 162 will reduce the speckle by at least a factor of the square root of the number of different laser diodes 36.

[0338] The beam splitter 162 may be a standard 50 / 50 splitter that reduces the efficiency of the two beams to less than 50%, or a polarization beam splitter (PBS) that maintains greater than 90% efficiency. For some applications, each laser diode 36 may have its own collimating lens 130, such as Fig.26A Alternatively, a plurality of laser diodes 36 may share a collimating lens 130, which is disposed between the beam splitter 162 and the pattern generating optical element 38, as shown in FIG. Fig.26B The pattern generating optical element 38 may be a DOE 39 , a segmented DOE 122 , a microlens array 132 , or a complex diffractive periodic structure 136 .

[0339] As described above, the sparse distribution 34 improves capture by providing an improved balance between reducing the amount of projected light while maintaining the amount of useful information. For some applications, in order to provide a higher density pattern without reducing capture, multiple laser diodes 36 with different wavelengths can be combined. For example, each structured light projector 22 may include at least two, such as at least three, laser diodes 36 that emit light of different corresponding wavelengths. Although the projected light spots 33 may almost overlap in some cases, the color differentiation capabilities of the camera sensor can be used to distinguish light spots of different colors in space. Optionally, red, blue, and green laser diodes can be used. All of the structured light projector configurations described above can be implemented using multiple laser diodes 36 in each structured light projector 22.

[0340] Reference now Fig.27A -B, Fig.27A -B is a schematic diagram of different ways to combine laser diodes of different wavelengths according to some applications of the present invention. Fiber coupler 164 ( Fig.27A ) or laser combiner 166 ( Fig.27B) combines two or more lasers of different wavelengths into the same diffraction element. For the laser combiner 166, the combining element can be a dichroic two-way or three-way dichroic combiner. Within each structured light projector 22, all laser diodes 36 emit light through a common pattern generating optical element 38 simultaneously or at different times. Each laser beam can hit slightly different locations in the pattern generating optical element 38 and generate different patterns. These patterns do not interfere with each other due to different colors, different pulse times or different angles. The use of a fiber optic coupler 164 or a laser combiner 166 allows the laser diode 36 to be set in a remote enclosure 168. The remote enclosure 168 can be set at the proximal end of the handheld wand 20, allowing a smaller probe 28.

[0341] For some applications, structured light projector 22 and camera 24 may be disposed in proximal end 100 of probe 28 .

[0342] The following description mainly relates to applications of the invention involving a light field camera.

[0343] Reference now Fig.28A , Fig.28A is a schematic diagram of an intraoral scanner 1020 according to some applications of the present invention. The intraoral scanner 1020 includes an elongated hand-held wand 1022 having a probe 1028 at a distal end 1026 of the hand-held wand 1022. The probe 1028 has a distal end 1027 and a proximal end 1024. As used throughout this application, including in the claims, the proximal end of the hand-held wand is defined as the end of the hand-held wand closest to the user's hand when the user holds the hand-held wand in a position ready for use, and the distal end of the hand-held wand is defined as the end of the hand-held wand farthest from the user's hand when the user holds the hand-held wand in a position ready for use.

[0344] For some applications, a single structured light projector 1030 is disposed in the proximal end 1024 of the probe 1028, a single light field camera 1032 is disposed in the proximal end 1024 of the probe 1028, and a mirror 1034 is disposed in the distal end 1027 of the probe 1028. The structured light projector 1030 and the light field camera 1032 are positioned to face the mirror 1034, and the mirror 1034 is positioned to reflect light from the structured light projector 1030 directly onto the scanned object 1036 and reflect light from the scanned object 1036 into the light field camera 1032.

[0345] The structured light projector 1030 includes a light source 1040. In some applications, the structured light projector 1030 can have an illumination field ψ (psi) of at least 6 degrees and / or less than 30 degrees. In some applications, the structured light projector 1030 focuses light from the light source 1040 at a projector focal plane 1038 (e.g., at least 30 mm and / or less than 140 mm) from the light source 1040. Fig.29A -B). The structured light projector 1030 may have a pattern generator 1042 disposed in the light path between the light source 1040 and the projector focal plane 1038. When the light source 1040 is activated to emit light through the pattern generator 1042, the pattern generator 1042 generates a structured light pattern at the projector focal plane 1038.

[0346] The light field camera 1032 may have a field of view ω (omega) of at least 6 degrees and / or less than 30 degrees. The light field camera 1032 may focus on a camera focal plane 1039 (e.g., Fig.30 ). The light field camera 1032 has a light field camera sensor 1046, which includes an image sensor 1048 and a micro lens array 1050 arranged in front of the image sensor 1048. The image sensor 1048 includes a pixel array, such as a CMOS image sensor, and the micro lens array 1050 is such that each micro lens 1050 is arranged on a sub array 1052 of sensor pixels. In addition, the light field camera 1032 has an objective lens 1054 arranged in front of the light field camera sensor 1048, and the objective lens 1054 forms an image of the scanned object 1036 onto the light field camera sensor 1046.

[0347] The intraoral scanner 1020 may include control circuitry 1056 that (a) drives the structured light projector 1030 to project a structured light pattern onto an object 1036 outside the handheld wand 1022, and (b) drives the light field camera 1032 to capture a light field generated by the structured light pattern reflected from the object 1036. The structured light field contains information about the intensity and direction of light rays of the structured light pattern reflected from the object 1036. The light field also contains information about phase-encoded depth, which can be used to estimate the depth of the scene from different directions. Using information from the captured light field, the computer processor 1058 can reconstruct a three-dimensional image of the surface of the object 1036, and can output the image to an output device 1060, such as a monitor. Note that in Fig.28A , Fig.31 and Fig.321058 is shown as being external to the handheld stick 1022 by way of illustration and not limitation. For other applications, the computer processor 1058 may be disposed within the handheld stick 1022.

[0348] In some applications, the scanned object 1036 is at least one tooth in the mouth of a subject. As described above, dentists often coat the subject's teeth with an opaque powder to improve image capture when using a digital intraoral scanner. The light field camera 1032 in the intraoral scanner 1020 can capture the light field from the structured light pattern reflected from the tooth in the absence of such powder on the tooth, thereby enabling a simpler digital intraoral scanning experience.

[0349] When the structured light projector 1030 and the light field camera 1032 are disposed in the proximal end 1024 of the probe 1028, the size of the probe 1028 is limited by the angle at which the mirror 1034 is placed. In some applications, the height H2 of the probe 1028 is less than 17 mm, and the width W1 of the probe 1028 is less than 22 mm, and the height H2 and the width W1 define a plane perpendicular to the longitudinal axis 1067 of the hand-held wand 1022. In addition, the height H2 of the probe 1028 is measured from a lower surface 1070 (scanning surface) to an upper surface 1072 opposite the lower surface 1070, through which reflected light from the scanned object 1036 enters the probe 1028. In some applications, the height H2 is between 14-17 mm. In some applications, the width W1 is between 18-22 mm.

[0350] Reference now Fig.29A , Fig.29A is a schematic diagram of a structured light projector 1030 having a laser diode 1041 as a light source 1040 according to some applications of the present invention. For some applications, the pattern generator 1042 may be a diffractive optical element (DOE) 1043. The laser diode 1041 may emit light through a collimator 1062, and the collimated light is then transmitted through the DOE 1043 to generate a structured light pattern as a distribution of discrete, unconnected light spots. As an alternative to the DOE 1043, the pattern generator 1042 may be an array of refractive microlenses disposed in the optical path (configuration not shown) between the laser diode 1041 and the projector focal plane.

[0351] Reference now Fig.29B , Fig.29B is a schematic diagram of a structured light projector 1030 having a light emitting diode (LED) 1064 as a light source 1040 and a mask 1066 as a pattern generator 1042 .

[0352] Reference now Fig.30 , Fig.301 is a schematic diagram of a light field camera 1032 according to some applications of the present invention, showing a light field camera sensor 1046 and a captured three-dimensional object 1036. For some applications, optical parameters of the light field camera 1032 may be selected so that (a) light reflected from a foreground 1075 of the object 1036 is focused onto a central region 1074 of the light field camera sensor, and (b) light reflected from a background 1077 of the object 1036 is focused onto a peripheral region 1076 of the light field camera sensor 1046. In some applications, when scanning an intraoral scene, the peripheral region 1076 may be directed more frequently toward more distant objects, such as gums, than toward closer objects, such as teeth.

[0353] The central region 1074 of the light field camera sensor 1046 can have a higher spatial resolution than the peripheral region 1076 of the light field camera sensor 1046. For example, each sub-array 1052 in the central region 1074 of the image sensor 1048 can have 10-40% fewer pixels than each sub-array 1052 in the peripheral region 1076, i.e., the micro-lenses in the central region 1074 can be smaller than the micro-lenses in the peripheral region 1076. Smaller micro-lenses allow for more micro-lenses per unit area in the central region 1074. Therefore, the central region 1074 of the light field camera sensor 1046 can have a higher spatial resolution due to the increased ratio of micro-lenses per unit area. In some applications, the central region 1074 can include at least 50% of the total number of sensor pixels.

[0354] While the central region 1074 has a higher spatial resolution than the peripheral region 1076, the peripheral region 1076 may have a higher depth resolution than the central region 1074 and may be configured to focus at a greater object distance than the central region 1074. The larger microlenses in the peripheral region 1076 of the light field camera sensor 1046 are configured to focus at a greater depth than the smaller microlenses in the central region 1074. For example, each microlens 1050 disposed on the subarray 1052 of sensor pixels disposed in the peripheral region 1076 of the image sensor 1048 may be configured to focus at a depth that is 1.1-1.4 times greater than the depth at which each microlens 1050 disposed on the subarray 1052 of sensor pixels disposed in the central region 1074 of the image sensor 1048 is configured to focus.

[0355] Thus, the higher spatial resolution of the central region 1074 can allow the foreground 1075 of the object 1036 to be captured with a higher spatial resolution than the background 1077 of the object 1036, for example, when scanning an intraoral scene of a subject, the teeth can be captured with a higher spatial resolution than the area surrounding the teeth, while the farther focus and greater depth resolution of the peripheral region 1076 can allow the background 1077, such as the edentulous areas and gums surrounding the teeth in the foreground 1075, to be captured.

[0356] Reference now Fig.31 , Fig.31 1 is a schematic diagram of an intraoral scanner 1020 having a light field camera 1032 and a structured light projector 1030 disposed in a distal end 1027 of a probe 1028 according to some applications of the present invention. For some applications, exactly one structured light projector 1030 and exactly one light field camera 1032 are disposed in the distal end 1027 of the probe 1028. The structured light projector 1030 can be positioned to directly face an object 1036 that is located outside the handheld wand 1022 and is placed in its illumination field. Thus, the light projected from the structured light projector 1030 will fall on the object 1036 without any optical redirection, such as reflection from a mirror to redirect the light, as described above with reference to Fig.28A Similarly, the light field camera 1032 can be positioned to directly face an object 1036 placed in its field of view that is outside of the handheld wand 1022. Thus, light reflected from the object 1036 will enter the light field camera 1032 without any optical redirection, such as reflecting from a mirror to redirect the light, as described above with reference to Fig.28A described.

[0357] Positioning the structured light projector 1030 in the distal end 1027 of the probe 1028 can allow the illumination field ψ (psi) of the structured light projector 1030 to be wider, for example, at least 60 degrees and / or less than 120 degrees. Positioning the structured light projector 1030 in the distal end 1027 of the probe 1028 can also allow the structured light projector 1030 to focus light from the light source 1040 at a projector focal plane that is at least 3 mm and / or less than 40 mm from the light source 1040.

[0358] Positioning the light field camera 1032 in the distal end 1027 of the probe 1028 can allow the field of view ω(omega) of the light field camera 1032 to be wider, for example, at least 60 degrees and / or less than 120 degrees. Positioning the light field camera 1032 in the distal end 1027 of the probe 1028 can also allow the light field camera 1032 to focus at a camera focal plane that is at least 3 mm and / or less than 40 mm from the light source 1040. In some applications, the illumination field ψ(psi) of the structured light projector 1030 and the field of view ω(omega) of the light field camera 1032 overlap, such that at least 40% of the projected structured light pattern from the structured light projector 1030 is within the field of view ω(omega) of the light field camera 1032. Similar to the above reference Fig.30 As described above, when the intraoral scanner 1020 has a single light field camera 1032 disposed in the distal end 1027 of the probe 1028 , the optical parameters of the light field camera sensor 1046 can be selected so that a central area of ​​the light field camera sensor 1090 has a higher resolution than a peripheral area of ​​the light field camera sensor 1046 .

[0359] Positioning the structured light projector 1030 and the light field camera 1032 in the distal end 1027 of the probe 1028 can make the probe 1028 smaller because the mirror 1034 is not used in this configuration. In some applications, the height H3 of the probe 1028 is less than 14 mm and the width W2 of the probe 1028 is less than 22 mm, and the height H3 and the width W2 define a plane perpendicular to the longitudinal axis 1067 of the handheld wand 1022. In some applications, the height H3 is between 10-14 mm. In some applications, the width W2 is between 18-22 mm. As described above, the height H2 of the probe 1028 is measured from (a) the lower surface 1070 (scanning surface) to (b) the upper surface 1072 opposite the lower surface 1070, through which reflected light from the scanned object 1036 enters the probe 1028. The control circuit 1056 may (a) drive the structured light projector 1030 to project a structured light pattern onto an object 1036 outside the handheld wand 1022, and (b) drive the light field camera 1032 to capture a light field generated by the structured light pattern reflected from the object 1036. Using information from the captured light field, the computer processor 1058 may reconstruct a three-dimensional image of the surface of the object 1036 and output the image to an output device 1060, such as a monitor.

[0360] Reference now Fig.32 , Fig.321 is a schematic diagram of an intraoral scanner 1020 having a plurality of structured light projectors 1030 and a plurality of light field cameras 1032 disposed in a distal end 1027 of a probe 1028 according to some applications of the present invention. Having a plurality of structured light projectors and a plurality of light field cameras can increase the overall field of view of the intraoral scanner 1020, which can enable the capture of a plurality of objects 1036, for example, the capture of a plurality of teeth and areas surrounding the teeth, for example, edentulous areas in the mouth of a subject. In some applications, a plurality of illumination fields ψ(psi) overlap with a corresponding plurality of fields of view ω(omega) such that at least 40% of the projected structured light pattern from each structured light projector 1030 is within the field of view ω(omega) of at least one light field camera 1032. The control circuit 1056 can (a) drive the plurality of structured light projectors 1030 to project the structured light pattern onto an object 1036 outside the handheld wand 1022, and (b) drive the plurality of light field cameras 1032 to capture a light field generated by the plurality of structured light patterns reflected from the object 1036. Using information from the captured light field, computer processor 1058 may reconstruct a three-dimensional image of the surface of object 1036 and output the image to an output device 1060, such as a monitor.

[0361] For some applications, at least one of the structured light projectors 1030 may be a monochrome structured light projector that projects a monochrome structured light pattern onto the scanned object 1036. For example, the monochrome structured light projector may project a blue structured light pattern at a wavelength of 420-470 nm. At least one of the light field cameras 1032 may be a monochrome light field camera that captures a light field generated by the monochrome structured light pattern reflected from the scanned object 1036. The intraoral scanner 1020 may also include a light source that emits white light onto the object 1036 and a camera that captures a two-dimensional color image of the object 1036 under illumination with the white light. The computer processor 1058 may combine (a) the information captured from the monochrome light field with (b) at least one two-dimensional color image of the object 1036 to reconstruct a three-dimensional image of the surface of the object 1036. The computer processor 1058 may then output the image to an output device 1060, such as a monitor.

[0362] Any of the above-described devices may be used to perform a method of generating image data (e.g., image data of an intraoral surface). In an example embodiment, the method includes generating a corresponding light pattern by one or more light projectors disposed in a probe of an intraoral scanner. Generating the light pattern by the light projectors of the one or more light projectors may include generating light by the light projectors, focusing the light at a projector focal plane, and generating a light pattern from the light at the projector focal plane by a pattern generator. The method may also include projecting the corresponding light pattern of the one or more light projectors toward an intraoral surface disposed within an illumination field of the one or more light projectors. The method may also include receiving, by one or more light field cameras disposed in the probe, a light field generated by at least a portion of the corresponding light pattern reflected from the intraoral surface. The method may also include generating, by the one or more light field cameras, a plurality of images depicting the light field, and sending the plurality of images to a data processing system.

[0363] In some embodiments, one or more light projectors and one or more light field cameras are disposed at a distal end of the probe, and the one or more light projectors and the one or more light field cameras are positioned such that (a) each light projector directly faces the intraoral surface, (b) each light field camera directly faces the intraoral surface, and (c) at least 40% of the light pattern from each light projector is within the field of view of at least one light field camera.

[0364] In some embodiments, one or more light projectors and light field cameras are disposed at the proximal end of the probe. For such embodiments, the method may further include using a mirror to reflect the corresponding light pattern onto an inner surface of the mouth, and using a mirror to reflect the light field reflected from the inner surface of the mouth into one or more light field cameras.

[0365] In some applications of the present invention, a method may be performed by any described device for intraoral scanning (e.g., an intraoral scanner and / or a data processing system such as computer processor 1058) to generate a digital three-dimensional model of an intraoral surface. In one embodiment, the method includes driving one or more light projectors of the intraoral scanner to project a light pattern onto the intraoral surface. The method also includes driving one or more light field cameras of the intraoral scanner to capture multiple images depicting a light field generated by at least a portion of the projected light pattern reflected from the intraoral surface, wherein the light field contains information about the intensity of the light pattern reflected from the intraoral surface and the direction of the light. The method also includes receiving multiple images depicting at least a portion of the light pattern projected onto the intraoral surface, and using information from the captured light field depicted in the multiple images to generate a digital three-dimensional model of the intraoral surface.

[0366] In one application, at least 40% of the light pattern from each light projector is in the field of view of at least one of the one or more light field cameras. In one application, each light projector is a structured light projector having a 60-120 degree illumination field and wherein the projector focal plane is between 3 mm and 40 mm from the light source. In one application, each light field camera has a 60-120 degree field of view and is configured to focus at a camera focal plane between 3 mm and 40 mm from the light field camera. In one application, the plurality of images include images from a plurality of light field cameras. In one application, the light field also includes information about phase encoded depth, from which depth can be estimated from different directions. In one application, the method further includes receiving a plurality of two-dimensional color images of the intraoral surface and determining color data for a digital three-dimensional model of the intraoral surface based on the plurality of two-dimensional color images.

[0367] Applications of the invention described herein may take the form of a computer program product accessible from a computer-usable or computer-readable medium (e.g., a non-transitory computer-readable medium) that provides program code for use by or in conjunction with a computer or any instruction execution system (e.g., processor 96 or processor 1058). For purposes of this description, a computer-usable or computer-readable medium may be any device that may contain, store, communicate, propagate, or transmit a program for use by or in conjunction with an instruction execution system, device, or apparatus. The medium may be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or device or apparatus) or a propagation medium. In some applications, a computer-usable or computer-readable medium is a non-transitory computer-usable or computer-readable medium.

[0368] Examples of computer readable media include semiconductor or solid-state memory, magnetic tape, removable computer disk, random access memory (RAM), read-only memory (ROM), rigid disks, and optical disks. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read / write (CD-R / W), and DVD. For some applications, cloud storage and / or storage in remote servers is used.

[0369] A data processing system suitable for storing and / or executing program code will include at least one processor (e.g., processor 96 or processor 1058) directly or indirectly coupled to a memory element via a system bus. The memory element may include a local memory, a bulk memory, and a cache memory used during the actual execution of the program code, which provides temporary storage of at least some program codes to reduce the number of times that code must be retrieved from the bulk memory during execution. The system may read instructions of the present invention on a program storage device and follow these instructions to perform the method of the application program of the present invention.

[0370] A network adapter may be coupled to a processor to enable the processor to couple to other processors or remote printers or storage devices through an intervening private or public network. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters.

[0371] Computer program code for carrying out operations of the present invention may be written in any combination of one or more programming languages ​​including object oriented programming languages ​​such as Java, Smalltalk, C++ and traditional procedural programming languages ​​such as the C programming language or similar programming languages.

[0372] It should be understood that the methods described herein can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer (e.g., processor 96 or processor 1058) or other programmable data processing device create a device for implementing the function / action specified in the method described in this application. These computer program instructions can also be stored in a computer-readable medium (e.g., a non-transitory computer-readable medium), which can instruct a computer or other programmable data processing device to act in a particular manner, so that the instructions stored in the computer-readable medium generate an article including an instruction device, which implements the function / action specified in the method described in this application. The computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are performed on a computer or other programmable device to generate a computer-implemented process, so that the instructions executed on a computer or other programmable device provide a process for implementing the function / action specified in the method described in this application.

[0373] Processor 96 and processor 1058 are typically hardware devices programmed with computer program instructions to generate corresponding special-purpose computers. For example, when programmed to perform the methods described herein, the computer processor is typically used as a special-purpose three-dimensional surface reconstruction computer processor. Typically, the operations described herein performed by the computer processor transform the physical state of the memory as a real physical item into a memory with different magnetic polarity, charge, etc. according to the technology of the memory used.

[0374] Alternatively, processor 96 may take the form of a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a neural network implemented on a dedicated chip.

[0375] Those skilled in the art will appreciate that the present invention is not limited to what is particularly shown and described above. On the contrary, the scope of the present invention includes the combination and sub-combination of the various features described above, as well as changes and modifications that do not exist in the prior art that those skilled in the art will think of when reading the foregoing description.

Claims

1. An intraoral scanning system, comprising: an elongated handheld wand having a probe at a distal end; a structured light projector configured to project a uniform structured light pattern onto an object, the structured light projector comprising a light source configured to emit light and a pattern generating optical element configured to generate the uniform structured light pattern when light is emitted from the light source and passes through the pattern generating optical element; a plurality of cameras configured to capture points of the uniform structured light pattern projected onto the object by the structured light projector; as well as One or more processors configured to: determining a correspondence between projection points in the uniform structured light pattern generated by the structured light projector and capture points of the uniform structured light pattern captured by the plurality of cameras observing the uniform structured light pattern projected onto the object; and A three-dimensional point in space is determined using triangulation and the determined correspondences, wherein the three-dimensional point in space is associated with a capture point of the uniform structured light pattern captured by the plurality of cameras observing the uniform structured light pattern projected onto the object.

2. An intraoral scanning system, comprising: Intraoral scanner, including: an elongated wand having a probe at a distal end of the elongated wand, the probe being configured to enter an oral cavity of a patient during a scanning procedure and defining a longitudinal axis of the intraoral scanner; a first structured light projector disposed within the probe and positioned on the longitudinal axis defined by the probe, the first structured light projector comprising a first light source configured to emit a first light and a first pattern generating optical element, the first pattern generating optical element configured to generate a first uniform structured light pattern when the first light is emitted from the first light source and passes through the first pattern generating optical element; a second structured light projector disposed within the probe and positioned proximally relative to the first structured light projector along the longitudinal axis, the second structured light projector comprising a second light source configured to emit a second light and a second pattern generating optical element, the second pattern generating optical element configured to generate the first uniform structured light pattern or the second uniform structured light pattern when the second light is emitted from the second light source and passes through the second pattern generating optical element; a first camera disposed within the probe and positioned proximally along the longitudinal axis relative to the first structured light projector, the first camera configured to capture points of at least one of the first uniform structured light pattern or the second uniform structured light pattern; a second camera disposed within the probe and positioned distally along the longitudinal axis relative to the first structured light projector, the second camera configured to capture points of at least one of the first uniform structured light pattern or the second uniform structured light pattern; a third camera disposed in the probe and disposed on a first side of the longitudinal axis relative to the first structured light projector, the third camera being configured to capture a point of at least one of the first uniform structured light pattern or the second uniform structured light pattern; and a fourth camera disposed in the probe and disposed on a second side of the longitudinal axis relative to the first structured light projector, the fourth camera being configured to capture a point of at least one of the first uniform structured light pattern or the second uniform structured light pattern, wherein the first camera and the second camera are positioned such that their optical axes are at an angle of 90 degrees or less to each other from a line of sight perpendicular to the longitudinal axis, and Wherein, the third camera and the fourth camera are positioned so that their optical axes are at an angle of 90 degrees or less to each other from a line of sight coaxial with the longitudinal axis.

3. An intraoral scanning system, comprising: an elongated handheld wand having a probe at a distal end; a structured light projector configured to project one or more structured light patterns onto an object, the structured light projector comprising one or more light sources configured to emit light and a pattern generating optical element, the pattern generating optical element configured to generate the one or more structured light patterns when light is emitted from the one or more light sources and passes through the pattern generating optical element, wherein the one or more structured light patterns include a first type of pattern dots and a second type of pattern dots; a plurality of cameras configured to capture the first type of pattern points and the second type of pattern points of the one or more structured light patterns; and One or more processors configured to: detecting the first type of pattern points and the second type of pattern points, wherein the first type of pattern points and the second type of pattern points are distinguished; processing the first type of pattern points using a correspondence algorithm to determine a first correspondence between projected first type of pattern points in the one or more structured light patterns generated by the structured light projector and captured first type of pattern points in the one or more structured light patterns captured by the plurality of cameras observing the one or more structured light patterns projected onto the object; processing the second type of pattern points using the correspondence algorithm to determine a second correspondence between projected second type of pattern points in the one or more structured light patterns generated by the structured light pattern and captured second type of pattern points in the one or more structured light patterns captured by the plurality of cameras observing the one or more structured light patterns projected onto the object; determining, using triangulation and the determined first correspondence, a three-dimensional point in space associated with a pattern point of the first type in the one or more structured light patterns captured by the plurality of cameras observing the one or more structured light patterns projected onto the object; and Using triangulation and the determined second correspondence, a three-dimensional point in space is determined, the three-dimensional point in space being associated with a pattern point of the second type in the one or more structured light patterns captured by the multiple cameras observing the one or more structured light patterns projected onto the object.

4. An intraoral scanning system, comprising: an elongated handheld wand having a probe at a distal end; means for projecting a uniform structured light pattern onto an object; as well as Devices for: determining a correspondence between projected points in the uniform structured light pattern generated by the device for projecting the uniform structured light pattern onto the object and captured points of the uniform structured light pattern captured by a plurality of devices for capturing points of the uniform structured light pattern projected onto the object that observe the uniform structured light pattern projected onto the object relationship; and Using triangulation and the determined correspondences, a three-dimensional point in space is determined, wherein the three-dimensional point in space is associated with a capture point of the uniform structured light pattern captured by the plurality of devices for capturing points of the uniform structured light pattern projected onto the object that observe the uniform structured light pattern projected onto the object.

5. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising: Intraoral scanning device, comprising: an elongated handheld wand including a probe at a distal end of the elongated handheld wand; one or more light projectors disposed at a distal end of the probe and configured to project a non-coded structured light pattern onto a surface of the dental object, wherein the non-coded structured light pattern includes a plurality of pattern features; and two or more cameras disposed at a distal end of the probe and configured to acquire one or more sets of images, wherein each set of images includes at least one image from each camera, wherein each image includes one or more image features of at least a portion of the projected non-coded structured light pattern, and wherein images in a set of images are acquired simultaneously; and One or more processors configured to: solving a correspondence problem in each set of images such that a point in 3D space is determined based on the one or more image features, wherein the point forms a solution to the correspondence problem, and wherein the correspondence problem is solved for one or more pattern features; and The digital 3D representation of the dental object is generated, wherein a solution to the correspondence problem is used to generate the digital 3D representation of the dental object.

6. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising: Handheld intraoral scanner, including: one or more light projectors configured to project a uniform light pattern onto a surface of the dental object, wherein the uniform light pattern comprises a plurality of pattern features, and wherein each pattern feature of the plurality of pattern features is defined by one or more projector rays; and two or more cameras configured to acquire one or more sets of images, each of the two or more cameras comprising a camera sensor having an array of pixels, wherein each set of images comprises at least one image from each camera, wherein each image comprises one or more image features of at least a portion of the projected uniform light pattern; and one or more processors configured to: For each set of images, determining a correspondence between pattern features of the projected uniform light pattern and image features in the set of images by determining, in 3D space, intersections of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features based on calibration data associating camera rays corresponding to pixels on a camera sensor of each of the two or more cameras with the projector rays, wherein determining the correspondence comprises: For a first subset of the pattern features associated with a maximum number of image features, determining a first correspondence between a first image feature in the 3D space and the first subset of the pattern features; and Then, for a second subset of the pattern features associated with the next largest number of image features, determining a second correspondence between a second image feature in the 3D space and the second subset of the pattern features; and The digital 3D representation is generated based on the determined correspondence between the image features and the pattern features in the one or more sets of images.

7. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising: Handheld intraoral scanner, including: one or more light projectors configured to project a light pattern onto a surface of the dental object, wherein the light pattern comprises a plurality of pattern features, and wherein each pattern feature of the plurality of pattern features is defined by one or more projector rays; and two or more cameras configured to acquire one or more sets of images, each of the two or more cameras comprising a camera sensor having a pixel array, wherein each set of images comprises at least one image from each camera, wherein each image comprises one or more image features of at least a portion of the projected light pattern; and one or more processors configured to: For each set of images, determining a correspondence between pattern features in the light pattern and image features in the set of images by determining, in 3D space, intersections of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features based on calibration data associating camera rays corresponding to pixels on a camera sensor of each of the two or more cameras with the projector rays, wherein determining the correspondence comprises: detecting the one or more image features in the one or more sets of images using a neural network, and determining, for a first subset of the pattern features associated with a maximum number of image features, a first correspondence between a first image feature in the 3D space and the first subset of the pattern features; and Then, for a second subset of the pattern features associated with the next largest number of image features, determining a second correspondence between a second image feature in the 3D space and the second subset of the pattern features; and The digital 3D representation of the dental object is generated based on the determined correspondence between the image features and the pattern features in the one or more sets of images.

8. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising: Handheld intraoral scanner, including: one or more light projectors configured to project a light pattern onto a surface of the dental object, wherein the light pattern comprises a plurality of pattern features, and wherein each pattern feature of the plurality of pattern features is defined by one or more projector rays; and one or more cameras configured to acquire one or more sets of images, each of the one or more cameras comprising a camera sensor having an array of pixels, wherein each set of images comprises at least one image from each camera, wherein each image comprises one or more image features of at least a portion of the projected light pattern, and wherein images in a set of images are acquired simultaneously; a mirror at a distal end of a probe of the intraoral scanning device, wherein a light projector of the one or more light projectors and a camera of the one or more cameras are positioned to face the mirror, and wherein the mirror is positioned to reflect the light pattern onto the dental object and reflect the light pattern from the dental object into the camera; and One or more processors configured to: For each set of images, a correspondence between pattern features in the light pattern and image features in the set of images is determined by determining, in a three-dimensional 3D space, intersections of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features based on calibration data associating camera rays corresponding to pixels on a camera sensor of each of the one or more cameras with the projector rays, wherein determining the correspondence comprises: For a first subset of the pattern features associated with a maximum number of image features, determining a first correspondence between a first image feature in the 3D space and the first subset of the pattern features; and Then, for a second subset of the pattern features associated with the next largest number of image features, determining a second correspondence between a second image feature in the 3D space and the second subset of the pattern features; and The digital 3D representation of the dental object is generated based on the determined correspondence between the image features and the pattern features in the one or more sets of images.

9. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising: Handheld intraoral scanner, including: one or more light projectors configured to project a checkerboard light pattern onto a surface of the dental object, wherein each light projector comprises at least one light source configured to generate non-patterned light and a pattern generating optical element configured to receive the non-patterned light and generate the checkerboard light pattern based on propagation of the non-patterned light through the pattern generating optical element, wherein the pattern generating optical element comprises a transmissive mask, wherein the at least one light source comprises at least one light emitting diode, wherein the checkerboard light pattern comprises a plurality of pattern features, and wherein each of the plurality of pattern features is defined by one or more projector rays; and two or more cameras configured to acquire one or more sets of images, each of the two or more cameras comprising a camera sensor having an array of pixels, wherein each set of images comprises at least one image from each camera, wherein each image comprises one or more image features of at least a portion of the projected checkerboard light pattern; and One or more processors configured to: For each set of images, determining a correspondence between pattern features in the checkerboard light pattern and image features in the set of images by determining, in 3D space, intersections of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features based on calibration data associating camera rays corresponding to pixels on a camera sensor of each of the two or more cameras with the projector rays, wherein determining the correspondence comprises: For a first subset of the pattern features associated with a maximum number of image features, determining a first correspondence between a first image feature in the 3D space and the first subset of the pattern features; and Then, for a second subset of the pattern features associated with the next largest number of image features, determining a second correspondence between a second image feature in the 3D space and the second subset of the pattern features; and The digital 3D representation of the dental object is generated based on the determined correspondence between the image features and the pattern features in the one or more sets of images.

10. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising: Handheld intraoral scanner, including: one or more light projectors configured to project a light pattern onto a surface of the dental object, wherein the light pattern comprises a plurality of pattern features, and wherein each pattern feature of the plurality of pattern features is defined by one or more projector rays; and two or more cameras configured to acquire one or more sets of images, each of the two or more cameras comprising a camera sensor having an array of pixels, wherein each set of images comprises at least one image from each camera, wherein each image comprises one or more image features of at least a portion of the projected light pattern, and wherein images in a set of images are acquired simultaneously; and One or more processors configured to: For each set of images, a correspondence between pattern features in the light pattern and image features in the set of images is determined by determining, in 3D space, intersection points of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features based on calibration data associating camera rays corresponding to pixels on a camera sensor of each of the two or more cameras with the projector rays, wherein each projector ray corresponds to a corresponding path of pixels on a camera sensor of a corresponding camera of the two or more cameras, and wherein, in order to determine the intersection points between the camera rays and the projector rays in three-dimensional 3D space, the one or more processors further run a corresponding algorithm, thereby: for each projector ray i, for each detected image feature j on the camera sensor path corresponding to projector ray i, identifying how many other cameras on their respective camera sensor paths corresponding to projector ray i detected a corresponding image feature k corresponding to the corresponding camera ray that intersected projector ray i and the camera ray corresponding to detected image feature j, wherein projector ray i is identified as the particular projector ray that generated detected image feature j for which a maximum number of other cameras detected the corresponding image feature k; and calculating a corresponding three-dimensional position on the tooth object as an intersection of the projector ray i with the corresponding camera ray corresponding to the detected image feature j and the corresponding detected image feature k; and The digital 3D representation of the dental object is generated based on the determined correspondence between the image features and the pattern features in the one or more sets of images.

11. An intraoral scanner, comprising: an elongated wand including a probe at a distal end of the elongated wand, the probe defining a longitudinal axis of the intraoral scanner; A plurality of component groups are arranged continuously along the longitudinal axis of the probe, and the plurality of component groups include: A first component group, including one or more first structured light projectors and one or more first cameras; and a second component group, including one or more second structured light projectors and one or more second cameras; and One or more processors configured to: driving the one or more first structured light projectors and the one or more second structured light projectors to project a light pattern onto an intraoral three-dimensional 3D surface; and The one or more first cameras and the one or more second cameras are driven to capture a plurality of images depicting at least a portion of the projected light pattern on the intra-oral 3D surface.

12. A device for intraoral scanning, the device comprising: an elongated rod including a probe at a distal end of the elongated rod; One or more light projectors, each light projector comprising: at least one light source configured to generate light when activated; and a pattern generating optical element, wherein the pattern generating optical element is configured to generate a light pattern when light passes through the pattern generating optical element; and Two or more cameras, each of the two or more cameras comprising a camera sensor and one or more lenses, wherein each of the two or more cameras is configured to capture multiple images depicting at least a portion of the light pattern projected onto the intraoral surface, wherein each camera is configured to focus at an object focal plane between about 1 mm and about 30 mm from a lens of the one or more lenses that is farthest from the camera sensor.

13. A device for intraoral scanning, the device comprising: an elongated rod including a probe at a distal end of the elongated rod; One or more light projectors, each light projector comprising: at least one light source configured to generate light when activated; and a pattern generating optical element, wherein the pattern generating optical element comprises a diffractive optical element (DOE) configured to generate a light pattern when light passes through the pattern generating optical element, wherein the DOE is segmented into a plurality of sub-DOE slices arranged in an array, wherein each sub-DOE slice generates a respective distribution of discrete unconnected light spots in a different region of an illumination field, such that the distribution of discrete unconnected light spots is generated when the light source is activated; and Two or more cameras, each of the two or more cameras comprising a camera sensor and one or more lenses, wherein each of the two or more cameras is configured to capture multiple images depicting at least a portion of the light pattern projected onto the intraoral surface, wherein each camera is configured to focus at an object focal plane between about 1 mm and about 30 mm from a lens of the one or more lenses that is farthest from the camera sensor.

14. A device for intraoral scanning, the device comprising: an elongated rod including a probe at a distal end of the elongated rod; One or more light projectors, each light projector comprising: at least one light source configured to generate light when activated; a pattern generating optical element, wherein the pattern generating optical element is configured to generate a light pattern when light passes through the pattern generating optical element, wherein the light pattern comprises a pattern of discrete unconnected light points that maintain a diameter of less than 0.06 mm through each inner surface of a geometric sphere centered at the pattern generating optical element and having a radius between 1 mm and 30 mm; and an additional optical element disposed between the light source and the pattern generating optical element, the additional optical element being configured to generate a Bessel beam from light passing through the additional optical element; and Two or more cameras, each of the two or more cameras comprising a camera sensor and one or more lenses, wherein each of the two or more cameras is configured to capture multiple images depicting at least a portion of the light pattern projected onto the intraoral surface, wherein each camera is configured to focus at an object focal plane between about 1 mm and about 30 mm from a lens of the one or more lenses that is farthest from the camera sensor.

15. A device comprising: an elongated rod including a probe at a distal end of the elongated rod; At least two light projectors, each light projector comprising: at least one light source configured to generate light when activated; a pattern generating optical element, wherein the pattern generating optical element is configured to generate a light pattern when light passes through the pattern generating optical element; and an additional optical element disposed between the light source and the pattern generating optical element, the additional optical element being configured to generate a Bessel beam from light passing through the additional optical element; and at least four cameras, each of the at least four cameras comprising a camera sensor and one or more lenses, wherein each of the at least four cameras is configured to capture a plurality of images depicting at least a portion of the light pattern projected onto an intraoral surface, wherein each camera is configured to focus at an object focal plane between about 1 mm and about 30 mm from a lens of the one or more lenses that is farthest from the camera sensor, wherein the at least two light projectors and the majority of the at least four cameras are arranged in at least two rows, each of the at least two rows is parallel to the longitudinal axis of the probe, and the at least two rows include at least a first row and a second row, wherein the farthest camera along the longitudinal axis and the closest camera along the longitudinal axis of the at least four cameras are positioned such that their optical axes are at an angle of 90 degrees or less relative to each other from a line of sight perpendicular to the longitudinal axis, and Wherein, the cameras in the first row and the cameras in the second row are positioned so that from a line of sight coaxial with the longitudinal axis of the probe, the optical axes of the cameras in the first row are at an angle of 90 degrees or less relative to the optical axes of the cameras in the second row.

16. A device comprising: an elongated rod including a probe at a distal end of the elongated rod; One or more light projectors, each light projector comprising: at least one light source configured to generate light when activated; a pattern generating optical element, wherein the pattern generating optical element is configured to generate a light pattern when light passes through the pattern generating optical element, wherein the light pattern is defined by the plurality of projector lights; and an additional optical element disposed between the light source and the pattern generating optical element, the additional optical element being configured to generate a Bessel beam from light passing through the additional optical element; two or more cameras, each of the two or more cameras comprising a camera sensor and one or more lenses, wherein each of the two or more cameras is configured to capture a plurality of images depicting at least a portion of the light pattern projected onto an intraoral surface, wherein each camera is configured to focus at an object focal plane between about 1 mm and about 30 mm from a lens of the one or more lenses that is farthest from the camera sensor; and One or more processors configured to: accessing calibration data that associates camera rays corresponding to pixels on the camera sensor of each of the two or more cameras with projector rays of the plurality of projector rays; determining, using the calibration data, an intersection point of a projector ray and a camera ray corresponding to a portion of the projected light pattern, wherein the intersection point of the projector ray and the camera ray is associated with a three-dimensional point in space; identifying a three-dimensional location of the projected light pattern based on the two or more cameras agreeing that there is a light pattern projected by the projector rays at certain intersections; and The identified three-dimensional locations are used to generate a digital three-dimensional model of the intraoral surface.

Images