Intraoral scanning device with extended field of view

Abstract

The present disclosure relates to an intraoral scanning device for scanning a dental subject, the scanning device comprising: an elongate probe defining a longitudinal axis of the scanning device; one or more scanning units, each scanning unit comprising: at least one projector unit configured to project a light pattern onto a surface of a dental object, where the projector unit defines a projector optical axis; and at least one camera comprising an image sensor for acquiring an image, where the at least one camera defines a camera optical axis, where at least one of the scanning units further comprises a reflective element, where each scanning unit defines a field of view (FOV). In particular, the disclosure relates to an intraoral scanning device with an extended field of view.

Description

Technical Field

[0001] The present disclosure relates to an intraoral scanning device for scanning a dental object. The present disclosure also relates to a dental scanning system for acquiring an image of the object and generating a digital representation of the object. Specifically, the present disclosure relates to an intraoral scanning device comprising a plurality of scanning units. Background Art

[0002] Digital dentistry is becoming increasingly popular and offers several advantages over non-digital techniques. Digital dental scanning systems typically utilize a scanning device, such as an intraoral 3D scanner, to generate a three-dimensional digital representation of a three-dimensional object / surface within a subject's mouth. There are a variety of different technologies in scanning devices, such as triangulation-based scanning, confocal scanning, focal scanning, X-ray scanning, and stereo vision.

[0003] An optical scanning device typically has a projector unit for projecting an illumination pattern onto the surface of a 3D object, and an image sensor for acquiring one or more images of the illuminated object. For a scanning device based on triangulation, the projector unit and the camera are offset so that they form a triangle with a given point on the surface of the illuminated object.

[0004] Generally speaking, scanning devices are associated with a field of view (FOV). FOV can be understood as the extent of the observable world that the scanning device sees at any given moment. Typically, FOV is reported as an area measurement at a given distance from a projector or camera, or the area can be measured at a given distance below the end of the scanning device.

[0005] In digital dentistry, a complete digital impression of a patient's teeth is usually obtained. Therefore, during the scanning process, the dentist will maneuver the tip of the scanning device across the patient's dental arch until an image of all teeth is obtained. In some cases, only a portion of the patient's teeth are imaged using the scanning device. However, generally, it is desirable for the digital impression to be obtained quickly and for the scan to be pleasant for the patient. Since the FOV determines how many teeth the scanning device can scan at a given moment, the FOV affects the time required to complete the scan.

[0006] It is often desirable to have a large FOV, thereby covering a larger area, because this allows more data / images to be captured at any given moment, and thus enables faster scanning. In addition, a large FOV can allow for greater overlap in the acquired data, which allows for a more accurate and reliable generation of a digital 3D representation of a patient's teeth. In some cases, it may be difficult to image a patient's teeth if one or more teeth are missing. Therefore, in such cases, using a scanning device with a large FOV is beneficial because it allows images of adjacent teeth to be captured across the missing teeth.

[0007] In addition to a large FOV, it is often desirable that the tip of the scanning device that enters the patient's mouth during the scanning process is fairly compact or small, as a larger scanning tip may be uncomfortable for the patient. Furthermore, if the tip of the scanning device is too large, e.g., the tip height is too large, it may be difficult for it to reach all relevant areas inside the patient's mouth. Therefore, it is desirable to have a smaller scanning device tip height.

[0008] Therefore, it is of interest to provide a scanning device with a reduced tip height and a large field of view. A challenge associated with this is that the field of view generally varies with tip height. For example, a scanning device with a very small tip (e.g., for children) generally has a smaller FOV than a conventionally sized tip (e.g., configured for an adult). Therefore, how to increase the FOV while keeping the tip height of the scanning device to a minimum remains a challenge. Summary of the invention

[0009] There are additional challenges to the above goal of providing a scanning device with a large field of view. Typically, the use of close-focus optics (i.e. optics with high focusing power or short focal length) to provide a large field of view results in large changes in the magnification and illumination of the projected light / acquired image. In addition, this results in a large angle of incidence of the projected light with the front window in the end of the scanning device, which therefore results in undesirable reflections from the front window. In addition, the use of close-focus optics results in a large viewing angle between the camera and the projector unit of the scanning device. Therefore, it is of interest to provide a scanning device with a large field of view, which overcomes the above-mentioned disadvantages of using close-focus optics.

[0010] The present disclosure solves the above challenges by providing a scanning device comprising one or more scanning units, wherein each scanning unit comprises at least one projector unit and at least one camera, wherein at least one of the scanning units further comprises a reflective element. In a preferred embodiment, the scanning device comprises two or more scanning units, which are arranged in series, for example, along a longitudinal axis of the scanning device.

[0011] The inventors have realized how to provide a scanning device in which the end height of the scanning device can be kept relatively low while the field of view is increased. This is achieved by providing a scanning device comprising a plurality of scanning units, each scanning unit comprising at least one projector unit and one or more cameras, wherein at least one scanning unit further comprises a reflective element, such as a mirror, which is configured to redirect light from the projector unit and / or redirect reflected light from an illuminated surface of the scanned object. In particular, the inventors have realized that the field of view can be scaled with the number of scanning units of the scanning device. Therefore, the field of view of the scanning device can be extended by positioning a plurality of scanning units successively (e.g. in series) within the scanning device.

[0012] Therefore, the present disclosure relates to an intraoral scanning device for scanning a dental object, the scanning device comprising: an elongated probe; one or more scanning units, each scanning unit comprising at least one projector unit and at least one camera, which comprises an image sensor for acquiring an image, wherein at least one of the scanning units further comprises a reflective element. In some embodiments, the scanning device comprises at least two scanning units.

[0013] In some embodiments, the scanning device includes: an elongated probe defining a longitudinal axis of the scanning device; at least two scanning units, each scanning unit including: at least one projector unit configured to project a light pattern onto a surface of a dental object, wherein the projector unit defines a projector optical axis; and at least one camera including an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis, wherein at least one of the scanning units further includes a reflective element configured to reflect light from the projector unit(s) of the scanning unit and / or configured to reflect light from the surface of the dental object and reflect it onto an image sensor(s) of each camera of the scanning unit, wherein each scanning unit defines a field of view (FOV).

[0014] In other embodiments, the scanning device comprises: an elongated probe defining a longitudinal axis of the scanning device; at least two scanning units, each scanning unit comprising: at least one projector unit configured to project a light pattern onto a surface of a dental object, wherein the projector unit defines a projector optical axis; and at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis, wherein each scanning unit further comprises a reflective element. The reflective element is configured to reflect light from the projector unit(s) of a given scanning unit associated with the reflective element and / or configured to reflect light from the surface of the dental object and onto the image sensor(s) of each camera of the given scanning unit associated with the reflective element, wherein each scanning unit defines a field of view (FOV).

[0015] The scanning device disclosed herein has several advantages over existing scanning devices. One advantage is that combining multiple scanning units in a scanning device allows the total field of view to be extended, so that the field of view of the intraoral scanning device is larger than the FOV of each scanning unit. Therefore, the FOV of the scanning device can be scaled by the number of scanning units of the device. A large FOV means that the scanning device captures a larger range of the scanned object, such as the teeth / gums of a subject. Therefore, more data / images can be acquired per unit time, which allows a 3D representation of the scanned object to be generated faster. In addition, a large field of view allows for smaller registration errors and thus better global accuracy of the 3D representation. Registration can be understood as the process of determining where scanned data (e.g., a scan block (e.g., a point cloud)) matches in a 3D representation. In other words, registration can be understood as determining the position and orientation of a given scan block so that it can form part of a 3D representation of a dental object.

[0016] Another advantage of the above embodiment, in which each scanning unit comprises a reflective element, is that the scanning device can be made quite compact, since the space in front of one reflective element can be at least partially occupied by another scanning unit. In particular, this is the case if the reflective elements are mirrors, wherein the surface normal of each mirror defines an angle of between 40° and 45°, e.g. approximately 45 degrees, with respect to the projector optical axis of each projector unit. Figure 3 1 shows such an embodiment, in which it can be seen that a first scanning unit overlaps with a reflective element of another scanning unit located behind the first scanning unit. Thus, multiple scanning units can be positioned very close, such as Figure 3 shown.

[0017] Another advantage of the scanning device disclosed herein is that, as disclosed herein, when at least one scanning unit further comprises a reflective element (e.g., a mirror), the camera working distance is increased and the viewing angle is reduced. In particular, this is the case if the projector unit and the camera of at least one scanning unit are "forward-looking" (which can be understood as such that the projector unit projects light toward the distal end of the elongated probe of the scanning device). In other words, the central light beam of the projector unit of at least one scanning unit is preferably substantially parallel to the longitudinal axis of the scanning device. Preferably, the reflective element is then positioned in front of the scanning unit such that the reflective element is configured to direct the light from the projector unit toward the object to be scanned. Alternatively, the scanning unit(s) can be oriented such that the light from the projector unit is projected backwards, i.e., toward the proximal end of the scanning device. In this case, the reflective element can be similarly positioned such that the reflective element is configured to direct the light from the projector unit toward the object to be scanned. In other words, the reflective element is preferably configured to change the direction of the central light beam of the projected light from being substantially parallel to the longitudinal axis of the scanning device to a direction at an angle to said axis, such as a direction substantially perpendicular to the longitudinal axis of the scanning device. Therefore, the camera's working distance is increased and the viewing angle is reduced, which has the following benefits:

[0018] Smaller changes in magnification and lighting;

[0019] Smaller angle of incidence relative to the scanning device front window(s); and

[0020] Smaller viewing angle between camera and projector.

[0021] The relative term "smaller" is to be understood in this context as compared to the case where the scanning unit does not comprise a reflective element to change the direction of the projected light (in order to increase the working distance of the camera(s)). In this case, the scanning unit is oriented so that the projector unit projects the light directly downwards, i.e. so that the central beam of the projected light is substantially orthogonal to the longitudinal direction of the scanning device. This configuration may also be referred to as "looking down". A disadvantage of using a scanning unit configured to "look down" is that, in order to keep the tip height reduced, close-focus optics are required, which means that in order to obtain a suitable field of view at a short focal length, a large angular field of view (e.g. 90°) is required, which in turn results in large variations in magnification and illumination, large angles of incidence with the front window and large viewing angles between the camera(s) and the projector unit(s). All these disadvantages are therefore overcome when the scanning device is provided with a forward-looking scanning unit comprising a reflective element as described above. However, if a longer focal length is feasible, a "looking down" scanning unit may be implemented in the scanning device without the above-mentioned disadvantages becoming a problem.

[0022] Another challenge with respect to the downward-looking scanning unit is that the minimum tip height of the scanning device is limited by the minimum component height, i.e. the longitudinal dimension of the scanning unit, including the projector unit(s) and the camera(s), and possible projector and camera optics, such as collimating lenses and light source(s). The minimum achievable tip height of the scanning device is further limited by the minimum focal length achieved by the scanning unit. Thus, if there is no reflective element, thereby forcing the projector unit(s) and the camera(s) to have a short focal length (close-focus optics), this leads to the above-mentioned disadvantages. In contrast, if the scanning unit is rotated so that it is forward-looking, and combined with a reflective element, the minimum tip height is limited by the size of the reflective element and the lateral dimension(s) of the scanning unit.

[0023] In yet another embodiment, an intraoral scanning device comprises: an elongated probe defining a longitudinal axis of the scanning device; a first scanning unit comprising: at least one projector unit configured to project a light pattern onto a surface of a dental object, wherein the projector unit defines a first projector optical axis; at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis; and a reflective element configured to reflect light from the projector unit(s) and / or reflect light from the surface of the dental object and reflect it onto the image sensor(s) of each camera of the scanning unit. In this embodiment, the scanning device further comprises a second scanning unit comprising: at least one projector unit configured to project a light pattern onto a surface of the dental object, wherein the projector unit defines a second projector optical axis; and at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis, wherein each scanning unit defines a field of view (FOV), and wherein the first projector optical axis and the second projector optical axis define an angle of at least 45°. In some embodiments, the angle is measured on a plane parallel to the longitudinal axis of the scanning device. In other embodiments, the angle is measured in a plane orthogonal to the longitudinal axis of the scanning device.

[0024] In yet another embodiment, an intraoral scanning device comprises: an elongated probe defining a longitudinal axis of the scanning device; a first scanning unit comprising: at least one projector unit configured to project a light pattern onto a surface of a dental object, wherein the projector unit defines a first projector optical axis substantially parallel to the longitudinal axis of the scanning device; at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis; and a reflective element configured to reflect light from the projector unit(s) and / or reflect light from the surface of the dental object and reflect it onto the image sensor(s) of each camera of the scanning unit. In this embodiment, the scanning device further comprises a second scanning unit comprising: at least one projector unit configured to project a light pattern onto a surface of a dental object, wherein the projector unit defines a second projector optical axis substantially orthogonal to the longitudinal axis of the scanning device; and at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis, wherein each scanning unit defines a field of view (FOV).

[0025] This embodiment of the scanning device therefore has two scanning units, each of which comprises a projector unit defining a projector optical axis, wherein the two scanning units are oriented differently. Figure 7 . In other words, one scanning unit is configured to look forward, while the other scanning unit is configured to look downward. Only the first scanning unit comprises a reflective element to change the direction of the projected light, so that both projector units project light onto the surface of the dental object. An advantage of this embodiment is that two different working distances are achieved using similar optics / scanning units. Thereby, two different focal lengths below the probe of the scanning device are effectively achieved. In principle, if the two projector units have approximately similar focal lengths when measured along the optical path, then if one of the optical paths is longer than the other (e.g. for the first scanning unit), the result is that the scanning device has two different scanning unit focal lengths when measured below the window / opening of each scanning unit. An advantage is that typically a user (e.g. a dentist) will hold the scanning device in a slightly tilted position when scanning a subject / patient. Therefore, typically the most distal part of the scanning device / probe will be closer to the dental object than the part located towards the proximal end of the scanning device / probe. This embodiment allows for such use of the scanning device, wherein the scanning device is held in a slightly elevated position.

[0026] In yet another embodiment, an intraoral scanning device comprises: an elongated probe defining a longitudinal axis of the scanning device; a first scanning unit comprising a first projector unit configured to project a light pattern onto a surface of a dental object, wherein the first projector unit defines a first projector optical axis; at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis; and a reflective element configured to reflect light from the first projector unit and / or reflect light from the surface of the dental object and reflect it onto the image sensor(s) of each camera. In this embodiment, the scanning device further comprises: a second projector unit configured to project a light pattern onto a surface of a dental object, wherein the second projector unit defines a second projector optical axis; and at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis, wherein each scanning unit defines a field of view (FOV).

[0027] In yet another embodiment, an intraoral scanning device comprises: an elongated probe defining a longitudinal axis of the scanning device; at least two scanning units, each scanning unit comprising: a projector unit configured to project a light pattern onto a surface of a dental object, wherein the projector unit defines a projector optical axis; at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis; and a reflective element configured to reflect light from the projector unit and / or reflect light from the surface of the dental object and reflect it onto the image sensor (one or more) of each camera; wherein each scanning unit defines a field of view (FOV), and wherein the at least two scanning units are located in the elongated probe and arranged to project the light pattern onto the same side of the probe.

[0028] Thus, the scanning device disclosed herein provides many advantages over existing scanning devices.

[0029] The present disclosure also relates to a method of assembling the intraoral scanning device disclosed herein. The method is particularly relevant to assembling a scanning device, wherein the scanning device includes a first scanning unit and a second scanning unit, and wherein the scanning device also includes a reflective element, such as a reflector, associated with each scanning unit. In other words, each reflective element is preferably positioned and mounted in a frame so that light projected from a given scanning unit is incident on the reflective element associated with the scanning unit. In some embodiments, the method of assembling the scanning device disclosed herein includes the following steps: providing a frame for accommodating the scanning units, wherein the frame includes two or more openings for receiving the scanning units; inserting the first scanning unit into the frame through a first opening located in a first surface of the frame; and inserting the second scanning unit into the frame through a second opening located in a second surface of the frame. The first and second surfaces may be opposite to each other, such that one scanning unit is inserted into the frame from above and the other scanning unit is inserted from below, such as Fig.14 as shown in . BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A side view of a scanning unit comprising a projector unit and four cameras is shown.

[0031] Figure 2 A perspective view of a scanning unit comprising a projector unit and four cameras is shown.

[0032] Figure 3 A side view of two scanning units positioned in tandem along the longitudinal direction of the scanning device is shown.

[0033] Figure 4 A side view of a scanning unit is shown, which comprises a projector unit, four cameras and a reflective element, such as a mirror.

[0034] Figure 5A A scanning device is shown, which comprises two scanning units, so that the scanning device has an extended field of view in the longitudinal direction ("long FOV" configuration).

[0035] Figure 5B Shows the view from the far end of the scanning device Figure 5A scanning device.

[0036] Figure 5C A side view of a scanning device is shown, which comprises two scanning units, so that the scanning device has an extended field of view ("dual scanning" configuration).

[0037] Figure 5D Shows the view from the far end of the scanning device Figure 5C scanning device.

[0038] Figure 5EA side view of a scanning device is shown, which comprises two scanning units, so that the scanning device has an extended field of view ("single scan" configuration).

[0039] Fig. 5F Shows the view from the far end of the scanning device Figure 5E scanning device.

[0040] Figure 6 A dental scanning system is shown, comprising an intraoral scanning device and a computer system, here a laptop computer.

[0041] Figure 7 A side view of a scanning device, in particular an end portion of the scanning device, is shown, wherein the scanning device comprises two scanning units in two different configurations.

[0042] Figures 8A-8D Some examples are shown of how the camera and projector units may be positioned and / or oriented when viewed along the projector optical axis.

[0043] Fig. 9 A perspective view of a scanning unit comprising a projector unit and four cameras is shown, wherein the scanning unit further comprises reflecting elements, here shown as mirrors.

[0044] Fig.10 An embodiment of a scanning device comprising two scanning units is shown, wherein the scanning device further comprises a wireless module configured to wirelessly transmit scanning data, such as images and / or 3D data, to a computer system.

[0045] Fig.11 An embodiment of a scanning device including a scanning unit is shown, wherein the scanning device is configured to transmit scan data using a wired connection.

[0046] Fig.12 An embodiment of a scanning device comprising a first scanning unit and a second scanning unit is shown, wherein each scanning unit further comprises a reflecting element, here a mirror.

[0047] Fig.13 Shows Fig.12 The same embodiment shown in FIG. In this view, a frame of the scanning device is shown. The frame is configured to accommodate a scanning unit.

[0048] Fig.14 Shows Fig.13 The same embodiment shown in FIG. 1 ; shown here in exploded view. In this embodiment, the frame includes a first opening for receiving a first scanning unit and a second opening for receiving a second scanning unit.

[0049] Fig.15 Shows Figure 12-14The same embodiment as shown in , except that in this figure the frame, housing and optical window of the scanning device can be seen.

[0050] Fig.16 A perspective view of an intraoral scanning device according to the present disclosure is shown.

[0051] Fig.17 Shows Fig.16 A perspective view of the same embodiment shown in ; however, in this view, the replaceable component is shown separated from the scanning device.

[0052] Fig.18 A perspective view of an intraoral scanning device according to the present disclosure is shown.

[0053] Fig.19 A cross-sectional view of an embodiment of an intraoral scanning device according to the present disclosure is shown.

[0054] Fig. 20 A perspective view of an intraoral scanning device according to the present disclosure is shown.

[0055] Fig.21 An embodiment of a dental scanning system is shown, which includes an intraoral scanning device and a computer system, here taking a laptop computer as an example.

[0056] FIG. 22 illustrates three different embodiments of how to provide a chairside solution for a dental scanning system according to the present disclosure. DETAILED DESCRIPTION

[0057] 3D Objects

[0058] The three-dimensional (3D) object may be a dental object. Examples of dental objects include one or more of the following: tooth / teeth, gums, implant(s), dental restoration(s), dentures, toothless ridge(s), and / or combinations thereof. Alternatively, the dental object may be a plaster cast or plastic model representing the teeth of a subject. As an example, the three-dimensional (3D) object may include teeth and / or gums of a subject. The dental object may be only a portion of the teeth and / or oral cavity of a subject, as the entire set of teeth of the subject may not necessarily be scanned during the scanning process. The scanning process may be understood herein as a period of time during which data (e.g., images) of a 3D object are acquired.

[0059] Scanning device

[0060] The scanning device may be an intraoral scanning device for acquiring an image of the subject's oral cavity. The scanning device may employ a scanning principle such as triangulation-based scanning or stereoscopic vision. In a preferred embodiment, the scanning device employs a triangulation-based scanning principle. The scanning device comprises at least one projector unit and at least one camera. The scanning device may be a handheld scanning device, i.e., a device configured to be held by a human hand.

[0061] The scanning device includes one or more scanning units, for example, at least two scanning units, each of which includes a projector unit and one or more cameras. As an example, the scanning device may include a scanning unit including a projector unit and at least two cameras. As another example, the scanning device may include a scanning unit including a projector unit and four cameras. In yet another example, the scanning device may include at least two scanning units, each of which includes a projector unit and two or more cameras. In yet another example, the scanning device may include at least two scanning units, each of which includes a projector unit and four cameras.

[0062] Any scanning unit may further comprise a reflective element. The reflective element is preferably configured to reflect light from the projector unit(s) of the scanning unit with the reflective element and / or to reflect light from the surface of the dental object and reflect it onto the image sensor(s) of each camera of the scanning unit with the reflective element. In a preferred embodiment, the scanning device comprises an elongated probe defining a longitudinal axis of the scanning device.

[0063] Projector unit

[0064] A projector unit may be understood herein as a device configured to generate an illumination pattern for projection onto a surface, such as the surface of a three-dimensional object. In a preferred embodiment, the projector unit(s) are configured to project a light pattern onto the surface of the dental object. Preferably, the projector unit is configured to project the light pattern such that the light pattern is focused at a predefined focal length measured along the optical axis of the projector. In some embodiments, the predefined focal length differs between the projector units of the respective scanning units. In other embodiments, the focal length of the projector unit is substantially similar along the optical axis of each scanning unit; however, due to different positions and / or orientations of the scanning units within the scanning device, the focal length differs when measured at a certain distance below the end of the scanning device. Figure 7 Such an embodiment is shown.In some embodiments, the projector unit is configured to project the light pattern such that the light pattern is defocused at a probe opening of the scanning device and / or at a surface of an optical window in said probe.

[0065] The projector unit(s) may be a digital light processing (DLP) projector, a diffractive optical element (DOE), a front-illuminated reflective mask projector, a micro-LED projector, a liquid crystal on silicon (LCoS) projector, or a backlit mask projector using a micro-mirror array to generate a time-varying pattern, wherein the light source is located behind a mask having a spatial pattern so that the light projected onto the surface of the dental object is patterned. The pattern may be dynamic: i.e., such that the pattern changes over time, or the pattern may be static over time: i.e., such that the pattern remains unchanged over time. The projector unit(s) may include one or more collimating lenses for collimating light from the light source, the collimating lenses (one or more) being located between the light source and the mask. The collimating lenses (one or more) may include one or more Fresnel lenses. The projector unit(s) may also include one or more focusing lenses configured to focus the light at a predefined focal length or working distance.

[0066] In a preferred embodiment, the projector unit(s) of the scanning device comprises at least one light source and an optical mask having a spatial pattern. Thus, each projector unit may comprise an optical mask configured to define a light pattern. The optical mask may be similar to a small light mask, such as a chrome-on-glass light mask. As an example, the optical mask may define a polygonal pattern comprising a plurality of polygons, such as a checkerboard pattern, such as Figure 2 In other embodiments, the projector unit (one or more) includes at least one light source and a pattern generating element, such as a diffractive optical element (DOE), for defining a spatial pattern. The projector unit (one or more) may also include one or more lenses, such as a collimating lens or a projection lens.

[0067] Preferably, the projector unit(s) are configured to generate a predefined static pattern, which can be projected onto the surface. A first advantage of using a static light pattern is that no moving parts are required in the projector unit to project the static light pattern. Another advantage is that the projector unit can be made very small and thereby, for example, integrated in the tip of an intraoral scanning device, thereby reducing the form factor of the tip and / or the overall size of the intraoral scanning device. Another advantage of projecting a static pattern is that it allows all image data to be captured simultaneously, thereby preventing distortions due to movement between the scanning device and the object.

[0068] Alternatively, the projector unit (one or more) can be configured to generate a dynamic pattern that changes over time. Each projector unit is associated with its own projector plane, which is determined by the projector optical system. For example, if the projector unit is a backlit mask projector, the projector plane can be understood as the plane containing the mask. The projector plane includes multiple pattern features of the projected pattern.

[0069] Preferably, each projector unit defines a projector optical axis. An optical axis may be understood as a line in an optical system (e.g. a camera lens or a projector unit) along which there is a certain degree of rotational symmetry. In some embodiments, the projector optical axis of one or more projector units is substantially parallel to the longitudinal axis of the scanning device. In some embodiments, the projector optical axis of each projector unit is substantially parallel to the longitudinal axis of the scanning device. In other embodiments, a first projector optical axis of a first scanning unit defines an angle with a second projector optical axis of a second scanning unit, e.g. at least 45° or at least 75°. In other embodiments, the projector optical axis of the projector unit of the first scanning unit is substantially parallel to the longitudinal axis of the scanning device, and the projector optical axis of the projector unit of the second scanning unit is substantially orthogonal to the longitudinal axis of the scanning device. Thus, in some embodiments, the first and second projector optical axes define an angle of at least 85°, e.g. approximately 90°. In some embodiments, the angle is measured in a plane parallel to the longitudinal axis of the scanning device, see Figure 6 In other embodiments, the angle is measured in a plane orthogonal to the longitudinal axis of the scanning device, see Figure 5D and Fig. 5F .

[0070] The projector unit can be configured to sequentially turn on and off the light source at a predetermined frequency, wherein the light source is turned on for a predetermined time period. As an example, the time period can be between 3 milliseconds (ms) and 10 milliseconds (ms), such as between 4 milliseconds and 8 milliseconds. Through experiments, the inventors found that the time period between 4 milliseconds and 8 milliseconds is particularly suitable for ensuring a good compromise between pixel exposure and minimizing image blur caused by relative motion between the scanning device and the scanned object. The predetermined frequency of turning on and off the light source can be between 25Hz and 35Hz, such as about 30Hz. In some embodiments, all pixels of the image sensor (one or more) are continuously exposed. In this case, the effective exposure is controlled by the flash cycle of the light source. In some embodiments, the exposure time of the image sensor is less than 15 milliseconds (ms), such as less than 10 milliseconds, such as between 4 and 8 milliseconds. These indicated exposure times preferably correspond to the time period of the light source flash of the projector unit as described above. The advantage of configuring the light source to flash during the time period as described above is that the blur caused by the relative motion between the scanning device and the scanned object is minimized. This blur is also called motion blur. The light source of the projector unit can be configured to generate non-polarized light, such as non-polarized white light. This has the advantage of providing a better signal to noise ratio and therefore a lower noise level in the generated 3D representation.This may be due to the fact that in the case of polarized light more specular light is reflected from the surface.

[0071] The projector unit may be configured to project a plurality of projector rays which are projected onto the surface of the dental object. Solving the correspondence problem may comprise the steps of determining image features in an image within a set of images and further associating the image features with specific projector rays. In a preferred embodiment, the correspondence problem is solved jointly for the group of projector rays, rather than, for example, solving the correspondence problem for each projector ray individually. The group of projector rays considered may form a connected subset within a pattern. The inventors have found that by solving the correspondence problem jointly for a group or set of projector rays, a particularly reliable and robust solution may be obtained, resulting in a more accurate 3D representation. Subsequently, the depth of each projector ray may be calculated, so that a 3D representation of the scanned object may be generated.

[0072] The projector unit may include an aperture of a predetermined size so that it provides a pupil diameter between 0.2 mm and 0.7 mm, for example, between 0.3 mm and 0.6 mm. The pupil diameter may be understood as an entrance pupil or an exit pupil. In some cases, the entrance pupil and the exit pupil have similar sizes. In experiments conducted by the inventors, it was found that the pupil diameter between 0.2 mm and 0.7 mm is particularly useful because it provides a particularly well-focused projection pattern in a larger focus range (e.g., a focus range between 16 mm and 22 mm). Specifically, it was found that the pupil diameter between about 0.3 mm and about 0.5 mm provides a good compromise between imaging resolution (e.g., resolution of the pattern) and depth of focus (i.e., focus range). In some cases, the depth of focus may be understood as the maximum range in which an object appears to be in acceptable focus, for example, within a given predetermined tolerance. Another advantage of the pupil diameter between 0.2 mm and 0.7 mm is that it provides a good ability to gather light, which in turn means that the pixels on the image sensor (one or more) can be exposed over a shorter period of time. Shorter exposures are good for minimizing motion blur.

[0073] light source

[0074] The light source(s) may be configured to generate light of a single wavelength or a combination of wavelengths or a certain wavelength range (monochromatic or polychromatic). The wavelength combination may be generated by a light source configured to generate light containing different wavelengths or light having a certain wavelength range (e.g. white light). In a preferred embodiment, each projector unit comprises a light source for generating white light. A white light source may be used in combination with an optical mask to form a backlit mask projector unit. The advantage of using white light is that it enables the scanning device to simultaneously acquire data related to the surface geometry and to the surface color. Thus, the same set of images may be used to provide both the 3D geometry of the object and the color of the object. Thus, without aligning the recorded surface geometry-related data and the recorded surface color-related data, a digital 3D representation of the object representing both the color and geometry of the object can be generated. Alternatively, the projector unit(s) may comprise a plurality of light sources, such as LEDs, which respectively generate light of different wavelengths (e.g. red, green and blue), which may be combined to form light containing different wavelengths. Thus, the light generated by the light source(s) may be defined by wavelengths defining a particular color or by different wavelength ranges defining a color combination (e.g. white light). In some embodiments, the projector unit comprises a laser, such as a blue or green laser diode generating blue or green light, respectively. This has the advantage that a more efficient projector unit can be achieved, which enables faster exposures than using, for example, a white light diode.

[0075] In some embodiments, the scanning device includes a light source configured to excite a fluorescent material to obtain fluorescence data from a dental object (e.g., from a tooth). Such a light source can be configured to produce a narrow range of wavelengths, such as in a range between 380nm and 495nm, such as between 395nm and 435nm. In some embodiments, the scanning device includes an infrared light source configured to produce a wavelength in the infrared range, such as between 700nm and 1.5μm. Infrared light may be able to penetrate tooth tissue to obtain data of a tooth or multiple tooth internal areas. In some embodiments, the scanning device includes a light source selected from the following group of light sources: an infrared (IR) light source, a near infrared (NIR) light source, a blue light source, a violet light source, and / or a combination thereof. The scanning device may also include one or more NIR light sources, such as a plurality of NIR light sources, for emitting near infrared light having a wavelength range of about 750nm to about 1.4μm. Light in the infrared range can be used for diagnostic purposes, such as for detecting caries areas in the oral cavity. Specifically, infrared (IR) light (eg, NIR light) relatively easily penetrates the enamel of teeth and is reflected by porous areas (eg, caries lesions). Therefore, in the IR image captured by the scanning device, the caries area appears bright (brighter).

[0076] Light Pattern

[0077] The terms "light pattern", "illumination pattern", "spatial pattern" and "pattern" are used interchangeably herein. The pattern is preferably defined by a mask having a spatial pattern. The spatial pattern may be a polygonal pattern comprising a plurality of polygons. The polygons may be selected from the following polygon group: triangles, rectangles, squares, pentagons, hexagons and / or combinations thereof. Other polygons may also be conceivable. Typically, polygons consist of sides and angles. In a preferred embodiment, the polygons are repeated in a pattern in a predefined manner. As an example, the pattern may include a plurality of repeating units, wherein each repeating unit includes a predefined number of polygons, wherein the repeating unit is repeated throughout the pattern. Alternatively, the pattern may include a predefined arrangement, including any of stripes, squares, dots, triangles, rectangles and / or combinations thereof. In some embodiments, the pattern is non-coded so that no part of the pattern is unique. In other embodiments, the pattern is a pseudo-random square dot pattern.

[0078] In a preferred embodiment, the generated illumination pattern is a polygonal pattern, such as a checkerboard pattern comprising a plurality of squares. Similar to a normal checkerboard, the squares in the pattern have alternating dark and light areas, corresponding to areas of low light intensity (dark) and areas of high (relatively high) light intensity (bright). Examples of such patterns are shown in FIG. Figure 2 . In some cases, the squares of the checkerboard pattern may be referred to herein as white (bright) and black (dark) squares. In some embodiments, the light pattern is a checkerboard pattern comprising alternating dark and light squares (also referred to as squares). As an example, the checkerboard pattern may include at least 100×100 blocks of alternating dark and light squares, preferably at least 120×120 squares, and further more preferably at least 140×140 squares. In some embodiments, the length of each square in the checkerboard pattern is between 100μm and 200μm. When the pattern is imaged on the image sensor (one or more), this may correspond to a pixel size in the range of 4-16 pixels, for example, 8-12 pixels in some cases. Through experiments, the inventors have realized that at least 4 resolvable pixels per square range are sufficient to obtain reasonable contrast and clearly defined edges of the projected checkerboard pattern.

[0079] The pattern preferably includes a plurality of pattern features. In some embodiments, the light pattern includes at least 1000 pattern features, such as at least 3000 pattern features, or at least 5000 pattern features, or even at least 10000 pattern features. The same applicant further describes a system and method for projecting a high-density pattern in PCT / EP2023 / 058521, which is incorporated herein by reference in its entirety. When a pattern including such pattern features is projected onto the surface of a 3D object, the acquired object image will similarly include a plurality of image features corresponding to the pattern features. Pattern / image features can be understood as a single clearly defined position in a pattern / image. Examples of image / pattern features include angles, edges, vertices, points, transitions, points, stripes, etc. In a preferred embodiment, image / pattern features include the corners of a square in a chessboard pattern. In other embodiments, image / pattern features include angles in a polygonal pattern (e.g., a triangular pattern). The light pattern can be a structured light pattern with distributed discrete unconnected light spots, wherein the light spots correspond to pattern features.

[0080] camera

[0081] A camera may be understood here as a device for capturing an image of an object. Each camera comprises an image sensor for generating an image based on incident light received, for example, from an illuminated 3D object. Each camera may also comprise one or more lenses for focusing light. As an example, the image sensor may be an electronic image sensor, such as a charge coupled device (CCD) or an active pixel sensor (CMOS sensor). The image sensor may comprise a pixel array, such as a two-dimensional pixel array. In some embodiments, the pixel array is square. In some embodiments, the pixel array comprises at least 800x800 pixels, such as at least 1200x1200 pixels. This ensures a good compromise between the size of the image sensor and the image resolution, which directly affects the 3D resolution. In some cases, the projected pattern is a checkerboard pattern, wherein the sides of each square are between 8 pixels and 12 pixels. This has the advantage of improving the certainty of the position of the image feature, and thereby improving the 3D accuracy, because the position of the image feature directly affects the determination of the 3D point. In addition, in some cases, multiple pixels are required to generate a color, such as in the case of a Bayer filter, which means that the color resolution and / or the 3D resolution may be different from the resolution of the image sensor (one or more).

[0082] The image sensor(s) may have a frame rate of at least 30 frames per second, such as at least 60 frames per second, or even at least 75 frames per second. Thus, in some applications, the camera unit may capture an image or a set of images at a frame rate of at least 30 frames per second, such as at least 60 frames per second, or at least 75 frames per second. The number of 3D frames generated per second by the scanner may correspond to or be less than the frame rate of the above-mentioned image sensor.

[0083] The image sensor may be a global shutter sensor or a rolling shutter sensor. An advantage of using a rolling shutter sensor is that the sensor can be made smaller for a given pixel array size compared to, for example, a global shutter sensor, which typically contains more electronics per pixel, resulting in a sensor with a larger area or volume footprint, thereby taking up more space. Rolling shutter sensors are therefore advantageous for space-constrained applications, such as for intraoral scanning devices, in particular for achieving compact intraoral scanning devices. Rolling shutter sensors are particularly advantageous when used in combination with a flash sequence of the light source as described above, because motion blur is limited due to the short flash of, for example, 4 milliseconds to 8 milliseconds, and also because the flash minimizes or completely avoids rolling shutter distortion.

[0084] Each image sensor may define an image plane, which is a plane containing a projected image of an object. Each image obtained by the image sensor (one or more) may include a plurality of image features, wherein each image feature originates from a pattern feature of the projected pattern. In some embodiments, the scanning device includes one or more processors configured to determine image features, such as using a trained neural network. In some cases, the neural network is performed by a neural processing unit (NPU). The training of the neural network is further described in PCT / EP2022 / 086763 of the same applicant, which is incorporated herein by reference in its entirety. In some embodiments, at least one camera in at least one scanning unit is a light field camera. In other embodiments, each scanning unit includes at least one light field camera. Preferably, each camera defines a camera optical axis. In some embodiments, a color filter array, such as a Bayer color filter, is arranged on the image sensor (one or more). The color filter array may include a mosaic of tiny color filters placed on the pixel sensor of each image sensor to capture color information. The image sensor (one or more) may be a color image sensor, or alternatively a monochrome image sensor.

[0085] According to some embodiments, the projector optical axis and the camera optical axis of at least one camera define a camera-projector angle of about 5 to 15 degrees, preferably 5 to 10 degrees, and further more preferably 8 to 10 degrees. In experiments conducted by the inventors, it was found that the camera-projector angle between 5 and 10 degrees is particularly useful because the angle within this range increases the overlap between the camera and the projector unit, which thereby eliminates the need to over-design the field of view (FOV) optical requirements of the scanning device. The term "over-design" can be understood as designing in an overly complex or beyond usual standards. Another advantage is that the camera-projector angle between 5 and 10 degrees significantly improves the ability to scan difficult-to-reach areas, such as cavities within the subject's mouth, such as within the patient's mouth. Therefore, angles within this range are particularly suitable for dental scanning applications using intraoral scanning devices. It was further found that a camera-projector angle less than 5 degrees would introduce more noise in the obtained data, especially in terms of depth determination, which makes it more difficult to determine 3D points by triangulation. It was found that the optimal angle is between 7 and 10 degrees, for example between 8 and 10 degrees. In embodiments employing multiple scanning units (e.g., two or more scanning units) - wherein each scanning unit comprises at least one pair of camera and projector units, the camera-projector angle is preferably substantially the same for both scanning units. In some embodiments, the camera is out of focus at the probe opening of the scanning device and / or at the surface of the optical window in the probe. In a preferred embodiment of the scanning device, the camera and projector unit(s) of a given scanning unit are focused at the same distance.

[0086] The camera can be configured to acquire a set of images, wherein the correspondence problem within the set of images is solved based on triangulation. The images within the set of images can be acquired by different cameras of a given scanning unit of a scanning device. Preferably, the images within the set of images are acquired simultaneously, i.e., at the same time, wherein each camera contributes one image to the set of images. The advantage of doing so is that the budget of light is improved; therefore, the light source and the projector unit consume less power. The images within the set of images preferably capture approximately the same area of ​​the dental object. The image may include a plurality of image features corresponding to pattern features in a structured pattern projected on the surface of the dental object. The correspondence problem may refer to the task of associating each image feature with a projector light from a projector unit. In other words, the problem can also be formulated as the task of associating a point in an image with a point in a projector plane of the projector unit. Systems and methods for solving the correspondence problem are further described in PCT / EP2022 / 086763 from the same applicant, which is incorporated herein by reference in its entirety.

[0087] Scanning unit

[0088] A scanning unit may be understood herein as a unit comprising at least one projector unit and one or more cameras. In some embodiments, each scanning unit comprises at least two cameras having at least partially overlapping fields of view along different camera optical axes. Preferably, each scanning unit comprises at least four cameras having at least partially overlapping fields of view along different camera optical axes. The advantage of having overlapping camera fields of view is that the accuracy is improved due to the reduction in the amount of image stitching errors. Another advantage of using multiple cameras (e.g., two or more cameras) is that the reliability of determining 3D points is improved, thereby improving the accuracy of the generated digital 3D representation. The scanning unit may also include one or more lenses, such as a collimating lens or a projection lens.

[0089] Figure 4 An embodiment of a scanning unit in a cross-sectional view viewed from the side is shown, wherein the scanning unit comprises a projector unit, at least two cameras and a reflective element (here a mirror as an example). The figure defines a number of dimensions of the scanning unit.

[0090] exist Figure 4 In , "a" represents the baseline, which can be understood as the center-to-center distance between a given camera and the projector unit. As an example, the baseline can be less than 5 mm, such as less than 4 mm, such as about 3 mm. Therefore, in some embodiments, for a given scanning unit, the center-to-center distance between the projector unit of the scanning unit and a given camera is between 2 and 5 mm, preferably between 3 and 4 mm. In these examples, the working distance of the scanning unit is about 24 mm.

[0091] exist Figure 4 In , "b" represents the distance from the projector optical axis to the outer edge of the scanning unit, as shown in the figure. Preferably, the top of the scanning unit does not extend beyond a horizontal line drawn from the top of the reflective element. In other words, in a preferred embodiment, the value of "b" is selected so that the scanning unit does not extend beyond the top of the reflective element.

[0092] exist Figure 4 In , "c" represents the distance between the projector unit and the reflective element, the distance being measured along the projector optical axis. Preferably, the distance is as small as possible to minimize the size of the reflective element. In some embodiments, the distance "c" is selected so that the bottom corners and / or edges of the scanning unit do not cut off the light projected by the projector unit and / or do not cut off the light reflected from the scanned object. The angle is Figure 4In some embodiments, the scanning device comprises a first scanning unit and a second scanning unit, wherein the first scanning unit is positioned as close as possible to the second scanning unit without cutting off the light reflected by the reflective element of the first scanning unit. In some embodiments, the second scanning unit further comprises a reflective element configured to reflect light from the second projector unit and / or light reflected from the surface of the dental object and reflect it onto an image sensor (one or more) of each camera of the second scanning unit.

[0093] exist Figure 4 In , "d" represents the length of the scanning unit. Usually, this length is measured along the optical axis of the projector. Preferably, this length is relatively short so that the second scanning unit including the reflector can be positioned "behind" the first scanning unit, such as Figure 3 As shown. This allows increasing the total field of view of the scanning device while keeping the end height of the scanning device low compared to a scanning device with only one scanning unit. Specifically, the short distance "d" allows the individual scanning units to be positioned together, thereby allowing the FOV of the scanning device to be spatially continuous, i.e., such that the FOVs of adjacent scanning units are aligned to form a combined FOV, and ideally there is no uncovered area between the individual FOVs of the individual scanning units.

[0094] exist Figure 4 In , "e" represents the camera-projector angle, which is the angle between the optical axis of a given camera and the optical axis of the projector. In a preferred embodiment, the angle is between 5-25 degrees, such as between 5-15 degrees, such as between 8-10 degrees.

[0095] In a preferred embodiment, the scanning device comprises a plurality of scanning units positioned along a longitudinal axis of the scanning device. Figure 3 An embodiment is shown in which two scanning units are positioned in tandem along the longitudinal axis of the scanning device. For simplicity, only the scanning unit including the reflective element is shown in the figure, rather than the entire scanning device and its components. Preferably, the scanning unit is located at the distal end of the elongated probe, for example at the end of the scanning device.

[0096] The scanning unit may have a predefined field of view (FOV) and / or a predefined angular field of view (AFOV). The field of view (FOV) of a scanning unit / scanning device may be understood as the extent of the observable environment that the scanning unit / scanning device sees at any given moment. The FOV may be reported as an area measurement, such as the area at a given distance from the scanning unit or at a given distance below the probe of the scanning device. Preferably, the FOV of each scanning unit is at least 300 mm 2 , preferably at least 400 mm 2 , preferably at least 500 mm 2 , preferably at least 550 mm2 , wherein the area is measured for a given predefined focal length or working distance. For example, the field of view of the scanning device may be at least 20x20 mm 2 , for example at least 23x23mm 2 , the working distance is between 18 mm and 36 mm, for example about 20 mm to 24 mm. For some applications, for example for dental scanning applications, it is preferred that the scanning device has a working distance between 10 mm and 100 mm. In experiments performed by the inventors, it has been found that a working distance of the projector unit between 10 mm and 70 mm, for example between 15 mm and 50 mm, is particularly useful because the optical device, such as the scanning unit (one or more), takes up less space in the scanning device, and also because it is desirable to be able to scan objects very close to the scanning device. Since the scanning unit (one or more) takes up less space in the scanning device, it also allows a plurality of scanning units to be placed in a row in the scanning device. In a preferred embodiment, the scanning device is capable of projecting a focused pattern at the outlet of the end of the scanning device (for example, at the optical window of the scanning device or at an opening on the surface of the scanning device). The working distance can be understood as the distance from the object to the lens when the image is in the sharpest focus. The working distance can also or alternatively be understood as the distance from the object to the front lens (for example, the front lens of the projector unit). The front lens can be one or more focusing lenses of the projector unit.

[0097] In a preferred embodiment, the elongated probe comprises one or more openings and / or one or more optical windows at the distal end of the elongated probe. Preferably, there are openings and / or optical windows in the elongated probe, wherein the openings / windows are associated with each scanning unit, so that each scanning unit is configured to project a light pattern through the openings or optical windows. Therefore, the elongated probe may include openings and / or optical windows for each scanning unit of the scanning device. The optical window may be made of a polymer material, such as polymethyl methacrylate (PMMA), or of a ceramic or glass material, such as sapphire glass. The optical window may be made of a transparent crystalline ceramic material, such as aluminum oxide (Al2O3). The advantage is that the optical window is strong and scratch-resistant. Alternatively, the optical window may be made of mineral glass. The advantage is that it provides a good compromise between transparency, durability and cost. Preferably, the predefined distance mentioned in relation to the FOV of a given scanning unit is measured below the opening / window. In a preferred embodiment, the FOV of at least one scanning unit is at least 500mm 2 , for example about 23×23mm 2 , a distance of about 0-15 mm, such as 4-7 mm, below the opening / window. This may correspond to a working distance between 15 mm and 50 mm, such as between 15 mm and 36 mm.

[0098] The angular field of view (AFOV) of the scanning unit / scanning device is related to the FOV. However, AFOV is expressed as an angle herein and FOV is expressed as an area. According to some embodiments, each scanning unit defines an angular field of view (AFOV) between 50° and 80°, preferably between 60° and 75°. According to some embodiments, the projector optical axis and the camera optical axis of at least one camera define a camera-projector angle of approximately 5 to 25 degrees, preferably 5 to 15 degrees, preferably 5 to 10 degrees, and further more preferably 8 to 10 degrees. Preferably, the scanning unit(s) are rotationally symmetric such that each camera optical axis defines a substantially similar camera-projector angle with the projector unit of the scanning unit.

[0099] Through experiments conducted by the inventors, it has been determined that a numerical aperture of the projector unit (one or more) and / or the camera (one or more) between 0.0035 and 0.015 enables very fine details with a size between 50-200 μm to be resolved within a focal length range between 10 mm and 50 mm, for example between 12 mm and 36 mm. In some applications, the scanning unit is configured to have a working distance between 15 mm and 50 mm, for example the working distance of the projector unit (one or more) and / or the camera (one or more). In some cases, the working distance may be longer than 50 mm, for example in the case where the scanning device includes a reflector arranged at the far end of the scanning device. In contrast, if the scanning unit is not provided with a reflector in the scanning device, the working distance may be shorter than 15 mm in some cases. A numerical aperture between 0.0035 and 0.015 may correspond to an aperture providing a pupil diameter between 0.2 mm and 0.7 mm. Thus, a technical effect of this numerical aperture range is that it provides the ability to project a high density pattern, wherein the pattern is focused within a relatively wide focus range close to the scanning device, and wherein the blurriness of the features of the pattern is below a given tolerance. Thus, a more accurate 3D representation can be generated because the positions of the 3D points can be determined more accurately, i.e. with less uncertainty, and also because smaller features allow more features to be present in the pattern, resulting in a 3D representation containing more 3D points.

[0100] In an embodiment where the scanning device comprises at least two scanning units, the scanning device has a FOV that is larger than the FOV of each scanning unit. For example, if the scanning device comprises two scanning units, each scanning unit having a predefined FOV, the scanning device will have a FOV that is twice as large as that of each scanning unit, provided that the FOVs of the scanning units do not overlap. In some cases, there may be a small overlap in the FOV, but in general, the scanning device will have a larger field of view, or in other words, an extended field of view, compared to a single scanning unit. Therefore, the FOV of the scanning device can be increased / scaled by the number of scanning units in the scanning device. In some embodiments, the scanning device comprises at least three scanning units. Therefore, the scanning device may also include a third scanning unit, which includes a third projector unit, and the projector unit is preferably configured to project a light pattern with a predefined third focal length.

[0101] The scanning unit may further comprise at least one reflective element, such as a mirror or a prism, wherein the reflective element is configured to change the direction of light projected by a projector unit of the scanning unit. In general, the scanning unit may be oriented in many different ways, wherein the orientation is defined according to a projector optical axis of the scanning unit. As an example, the scanning unit may be oriented such that the projector optical axis of the scanning unit is substantially parallel to the longitudinal axis of the scanning device. Additionally, the scanning unit may be oriented such that the light from the projector unit is projected in a forward direction, i.e. towards the distal end of the scanning device. If the scanning unit is oriented in this manner, the scanning unit is also referred to as being in a forward viewing configuration. In some embodiments, each scanning unit comprises a reflective element. Such an embodiment in Figure 3 In other embodiments, at least one scanning unit comprises a reflective element.

[0102] As another example, the scanning unit can be oriented such that a projector optical axis of the scanning unit is at an angle relative to the longitudinal axis of the scanning device or relative to a projector optical axis of another scanning unit. In some embodiments, at least one projector optical axis is substantially orthogonal to the longitudinal axis of the scanning device. Additionally, such a scanning unit can be oriented such that light from the projector unit is projected in a downward direction, i.e. directly towards the dental object to be scanned / being scanned. When the scanning unit is oriented in this manner, the scanning unit is also referred to as being in a downward-looking configuration. If the scanning device comprises a plurality of scanning units, such as at least two scanning units, the scanning units may be in different configurations, such as a first scanning unit in a forward-looking configuration and a second scanning unit in a downward-looking configuration. Such an embodiment is shown in Figure 7In this embodiment, the first projector optical axis is substantially parallel to the longitudinal axis of the scanning device, and the second projector optical axis is substantially orthogonal to the longitudinal axis of the scanning device. In other words, the first projector optical axis of the first projector unit of the first scanning unit is at an angle relative to the second projector optical axis of the second projector unit of the second scanning unit. The angle is preferably at least 45°, such as at least 75°, and further more preferably at least 85°, such as about 90°.

[0103] In some embodiments, each scanning unit comprises a projector unit and a plurality of cameras, wherein, for each scanning unit, the cameras are located substantially in the same plane.The cameras and projector units of each scanning unit may be positioned and / or oriented in said plane in a variety of ways. Figures 8A-8D Some examples of how the camera and projector units are positioned / oriented in the plane are shown. It should be noted that this plane represents a cross section of the scanning unit. Therefore, in reality the components are not completely contained in the same plane, as the components have physical dimensions that extend outside of this plane / cross section.

[0104] In some embodiments, each scanning unit comprises a projector unit and a plurality of cameras, for example four cameras, wherein the cameras are arranged on two axes to form a cross in a plane, wherein the projector unit is located at the center of the cross when viewed along the projector optical axis. This embodiment is shown in Fig. 8A In this embodiment, the first camera is located above the projector unit in the plane, the second camera is located below the projector in the plane, the third camera is located to the left of the projector in the plane, and the fourth camera is located to the right of the projector in the plane. Preferably, the two axes of the cross are substantially parallel to at least two edges of the reflective element.

[0105] Specifically, in Figures 8A-8D In the illustrated embodiment, each of the image sensor, the optical mask, and the reflective element includes four edges that form a rectangle. Some corners of the rectangle (one or more) may be rounded. In addition, in this embodiment, for each scanning unit, one or more edges of the image sensor, the optical mask, and the reflective element are substantially aligned so that the corresponding edges are substantially parallel.

[0106] As from Fig. 8A As can be seen in the cross-section, the edges of the image sensor are substantially parallel to the edges of the reflective element. The inventors have found that this particular arrangement has some advantages over other arrangements of the camera and projector unit relative to the reflective element in a plane. One advantage is good tracking uniformity, i.e. more uniform tracking performance between each image sensor. Tracking can be understood as the task of solving the correspondence problem, i.e. the problem of determining which parts of one image correspond to which parts of another image. In particular, Fig. 8AThe arrangement of the image sensors and optical masks in ensures a more uniform depth resolution for a given image sensor range. This is due to the fact that the epipolar lines on a given image sensor are associated with a larger depth range because the epipolar lines are substantially aligned with the edges of the given image sensor and optical mask. In other words, ideally all areas of the image sensor(s) cover a similar depth range. Thus, compared to, for example Fig.8D Compared to the arrangement shown, Fig. 8A The image sensor(s) in FIG. capture more depth information, especially in the corners of the image sensor(s). Fig.8D In the arrangement of , the epipolar lines are on the diagonals of the image sensor, which means that certain corners of a given image sensor will capture less depth information than, for example, the center of the image sensor. Fig.8D In the arrangement, the depth resolution is not as large between the image sensor(s). Fig. 8A The arrangement in the .

[0107] Fig. 8A Another advantage of the device shown in is that it allows the size of the reflective element (one or more) to be kept to a minimum without cutting off the light. Therefore, the height of the end of the scanning device can be made quite small because the reflective element affects the minimum size of the end.

[0108] Figure 8B The embodiments shown in Fig. 8A , however, in this embodiment the cross is rotated 45 degrees relative to the edge / side of the reflective element. In other words, the diagonal of the optical mask / image sensor is aligned with the vertical axis of the reflective element. As the angular field of view increases along the mask / sensor diagonal, the height of the reflective element (here the mirror) must be increased to avoid cutting off the light. The mirror height corresponds to the height of the mirror as seen from the side, as Figure 4 In some embodiments, the projector is viewed along the optical axis (or from the side, such as Figure 4 The height of the reflector, as seen in the figure (shown in FIG. 1 ), is between about 13 mm and about 20 mm. This has the advantage that the height of the tip of the scanning device is kept to a minimum, in particular for working distances above 15 mm. The reflector thus allows a part of the optical path to be folded or redirected inside the scanning device, so that the scanning device can accommodate an optical system (e.g. a scanning unit) whose working distance is longer than the expected height of the probe or tip of the scanning device. As a result, the tip or probe can be made smaller, in particular the height of the probe, so that it can easily enter, for example, the oral cavity of a patient. A smaller probe also makes it easier to acquire data in the back of the patient's mouth.

[0109] The scanning unit may include a fixing unit configured to receive and mount the projector unit and the camera unit. The fixing unit is preferably further configured so that each camera optical axis forms a predefined angle with the projector axis when mounted in the fixing unit. In a preferred embodiment, the fixing unit is configured to accommodate at least one projector unit and two or more camera units, such as four camera units. The fixing unit may be rigid and made in one piece. The advantage is that the geometric relationship between the projector unit and the camera unit (one or more) is fixed. In some embodiments, the fixing unit is made of stainless steel, which has the advantage of being a good thermal conductor and therefore has a good ability to remove heat from, for example, the projector unit.

[0110] Reflective element

[0111] A reflective element is understood herein to be an element configured to change the direction of light passing through or incident on the surface of the reflective element. In particular, the reflective element is preferably configured to change the direction of a central beam of projection light from the projector unit from a direction substantially parallel to the longitudinal axis of the scanning device to a direction substantially orthogonal to the longitudinal axis. In some embodiments, the surface normal of each reflective element defines an angle of approximately 40-50 degrees, preferably approximately 45 degrees, relative to the projector optical axis. This is particularly useful in Figure 3 and Figure 4 In other embodiments, each scanning unit defines an angle relative to the longitudinal axis of the scanning device. As an example, the surface of the reflective element may define an angle between 40° and 45° relative to the longitudinal axis, such as approximately 41°. This has the advantage of enabling a smaller tip height to be achieved, for example, compared to using 45°. Fig.19 Shown in.

[0112] As an example, the reflective element may be selected from the following reflective element group: a reflector, a prism and / or a combination thereof. In a preferred embodiment, the reflective element is configured to reflect light from the projector unit (one or more) of at least one scanning unit and / or reflect light from the surface of the scanned object and reflect it onto the image sensor (one or more) of at least one scanning unit. In some embodiments, at least one of the scanning units includes a reflector as a reflective element. In other embodiments, at least one of the scanning units includes a prism as a reflective element. Some embodiments are characterized by a combination of a reflector (one or more) and a prism (one or more). In the case of a prism as a reflective element of at least one scanning unit, the prism is preferably configured to change the direction of the central beam of the projected light pattern from substantially parallel to the longitudinal axis of the scanning device to a direction having an angle of at least 45 degrees relative to the longitudinal axis. Further more preferably, the prism is configured to change the direction of the central beam of the projected light pattern from substantially parallel to the longitudinal axis of the scanning device to a direction having an angle of approximately 90 degrees relative to the longitudinal axis.

[0113] In some embodiments, the scanning device includes a forward-looking scanning unit, wherein the scanning device also includes a reflective element located on the projector optical axis of the projector unit of the scanning unit. In other embodiments, the scanning device includes at least two scanning units, wherein each scanning unit is configured to be forward-looking, wherein each scanning unit also includes at least one reflective element, which is configured to reflect light from the projector unit (one or more) and / or reflect light from the scanned object and reflect it to the image sensor (one or more) of each camera of the scanning unit. Therefore, in some embodiments, each scanning unit includes a reflective element. In some embodiments, the reflective element (one or more) of the scanning unit is located on the projector optical axis. In some embodiments, the projector optical axis can coincide with the longitudinal axis of the scanning device. The reflective element (one or more) can be shaped in a variety of ways. As an example, each reflective element can be substantially rectangular. In some embodiments, the reflective element (one or more) includes multiple corners, at least some of which are rounded.

[0114] Flexible cable

[0115] In some embodiments, the scanning device includes one or more flexible cables, such as flexible printed circuits or flexible printed circuit boards (PCBs). Each flexible cable can connect one of the cameras to a main printed circuit board (PCB). Preferably, a flexible cable is connected to each camera, wherein each cable includes multiple wires or circuits connected to the image sensor of a given camera. In some embodiments, each flexible cable is bent at a first radius of curvature, wherein the first radius of curvature lies in a first plane. Each cable can be further bent at a second radius of curvature, wherein the second radius of curvature lies in a second plane. Alternatively, each cable is a flexible PCB that is manufactured in a predetermined shape such that each flexible PCB includes a straight first portion and a second portion having one or more turns. Preferably, the second portion includes three turns, which may be right-angle turns; however, the turns may have rounded corners. This is Fig.12 As shown in . The first plane can be substantially parallel to the longitudinal axis of the scanning device, and the second plane can be perpendicular to the first plane. Therefore, the manufactured flexible PCB can be bent only along the first radius of curvature so that the entire second portion is located in the second plane. The first radius of curvature is selected to be about 0.5 mm to about 5 mm. The first portion of each cable can be substantially parallel to the longitudinal axis of the scanning device, and the second portion of each cable can be located in the second plane. In addition, in the portion where the cable is bent with the first radius of curvature, the cables can overlap with each other. In the above and in Figure 12-13 An advantage of providing flexible cables in the arrangement shown in is that it ensures low stress in each cable. In particular, this is the case if each flexible cable is bent along a first radius of curvature, wherein the radius is selected from about 0.5 mm to about 5 mm. Such a large radius of curvature ensures that the stress in each cable is minimized.

[0116] processor

[0117] According to some embodiments, the scanning device includes one or more processors. The scanning device may include a first processor configured to determine image features in the acquired image. As an example, the first processor may be a field programmable gate array (FPGA). The scanning device may also include a computer memory for storing instructions, which, when executed, causes the first processor to perform the steps of determining image features in the acquired image. The scanning device may also include a second processor configured to perform the following steps: executing a computer-implemented method to generate a digital representation of a three-dimensional (3D) object. The digital representation may be generated continuously during the scanning process, and it may be generated in real time. As an example, the second processor may be configured to run a tracking algorithm to solve the corresponding problem, i.e., determine the corresponding image features in the acquired image.

[0118] The computer memory may also store instructions that, when executed, cause the second processor to perform a method for generating a digital representation of a three-dimensional (3D) object. As an example, the second processor may be a central processing unit (CPU), such as an ARM processor or another suitable microprocessor. The second processor may include a computer memory. Both the first and second processors may be located on a scanning device, and they may be operably connected so that the first processor provides input to the second processor. Alternatively, the first processor may be located on a scanning device and the second processor may be located on a computer system described herein. As an example, the first processor may be configured to determine image features in an image and then provide data associated with the determined image features to a second processor. The data may include image feature coordinates and other attributes, such as a camera index or predefined attributes (e.g., phase) of the image feature (one or more).

[0119] The second processor may then be configured to generate a digital representation of the 3D object, for example in the form of a point cloud. The scanning device may further be configured to provide the digital representation to a computer system for rendering the representation. The computer system may further process the digital representation, for example by stitching the point cloud received from the scanning device and / or by fitting one or more surfaces to the stitched point cloud. Such further processing by the computer system may also be referred to herein as reconstruction. The output of the reconstruction is a digital 3D model of the scanned object. The digital 3D model may be rendered and displayed on a display (e.g., a display connected to the computer system).

[0120] Module for transferring data

[0121] The scanning device preferably includes a module for transmitting data (e.g., an image or a point cloud) to one or more external devices (e.g., a computer system). The module may be a wireless module configured to transmit data wirelessly from the scanning device to the computer system. The wireless module may be configured to perform various functions required for the scanning device to wirelessly communicate with a computer network. The wireless module may utilize one or more IEEE 802.11 Wi-Fi protocols / integrated TCP / IP protocol stacks, which allow the scanning device to access a computer network. It may also use other networks. The wireless module may include a system-on-chip with different types of built-in network connection technologies. These may include commonly used wireless protocols, such as Bluetooth, ZigBee, Wi-Fi, WiGig (also known as 60GHz Wi-Fi), etc. The scanning device may be further (or alternatively) configured to transmit data using a wired connection (e.g., an Ethernet cable or a USB cable). In some embodiments, the scanning device includes a wireless module configured to transmit data wirelessly from the scanning device to the computer system.

[0122] Computer Systems

[0123] A computer system can be understood as an electronic processing device for performing a series of arithmetic or logical operations. In this context, a computer system refers to one or more devices, including at least one processor (such as a central processing unit (CPU)) and some type of computer memory. Examples of computer systems that fall within this definition include desktop computers, laptops, computer clusters, servers, cloud computers, quantum computers, mobile devices (such as smartphones and tablets), and / or combinations thereof.

[0124] The computer system may include hardware, such as one or more central processing units (CPUs), graphics processing units (GPUs), neural processing units (NPUs), and computer memory, such as random access memory (RAM) or read-only memory (ROM). The computer system may include a CPU configured to read and execute instructions stored in a computer memory, such as in the form of a random access memory. The computer memory is configured to store instructions executed by the CPU and data used by these instructions. As an example, the memory may store instructions that, when executed by the CPU, cause the computer system to perform, in whole or in part, any computer-implemented method disclosed herein. The computer system may also include a graphics processing unit (GPU). The GPU may be configured to perform various tasks, such as video decoding and encoding, rendering of digital representations, and other image processing tasks.

[0125] The computer system may also include a non-volatile memory in the form of a hard drive. The computer system preferably also includes an I / O interface configured to connect peripheral devices connected to the computer system. More specifically, a display may be connected and configured to display output from the computer system. The display may, for example, display a 2D rendering of a generated digital 3D representation. 2D renderings may be continuously generated during the scanning process and displayed in the display. An input device may also be connected to the I / O interface. Examples of such input devices include a keyboard and a mouse, which allow a user to interact with the computer system. A network interface may also be a part of the computer system to allow it to be connected to an appropriate computer network to receive data (e.g., scanned data and / or images) from other computing devices, and to transfer data (e.g., scanned data and / or images) to other computing devices. The CPU, volatile memory, hard drive, I / O interface, and network interface may be connected together by a bus.

[0126] The computer system is preferably configured to receive data from the scanning device, either directly from the scanning device, or through a computer network (e.g., a wireless network). The data may include images, processed images, point clouds, data point sets, or other types of data. Wireless connections, wired connections, and / or combinations thereof may be used to transmit / receive data. The computer system may be configured to perform any computer-implemented method disclosed herein in whole or in part. In some embodiments, the computer system is configured to perform a computer-implemented method for generating a digital representation of a three-dimensional (3D) object as described herein. In some embodiments, the computer system is configured to receive data (e.g., a point cloud) from a scanning device, and then subsequently perform steps of reconstructing and rendering a digital representation of a three-dimensional (3D) object. Rendering may be understood as a process of generating one or more images from three-dimensional data. The computer system may include a computer memory for storing a computer program, the computer program including computer executable instructions, which, when executed, cause the computer system to perform a method for generating a digital representation of a three-dimensional (3D) object.

[0127] Image acquisition

[0128] According to a preferred embodiment, the scanning device is configured to acquire an image of a three-dimensional (3D) object. Preferably, the image is acquired using a scanning device comprising one or more scanning units, wherein each scanning unit comprises a projector unit and one or more cameras. The scanning device may be an intraoral scanning device for acquiring images of the oral cavity of a subject. The projector unit (one or more) of the scanning device is configured to project a predefined illumination pattern (e.g., a static pattern) onto a surface, such as onto a surface of a three-dimensional object. Once projected onto the surface, some light will be reflected from the surface, which can then enter the camera (one or more) of the scanning device, so that an image of the 3D object can be acquired.

[0129] Preferably, each projector unit uses one or more cameras to acquire images, for example at least two cameras or at least four cameras per projector unit. In a preferred embodiment, each scanning unit of the scanning device includes a projector unit and four cameras. The image can be processed by a processor located on the scanning device and then subsequently transmitted to the computer system. The image can also be transmitted to the computer system without any processing. In some embodiments, both the original image and the processed image are transmitted to the computer system by the scanning device. In some embodiments, the processor located on the scanning device receives the image as input and provides one or more point clouds as output by performing one or more steps of the disclosed computer-implemented method.

[0130] Example

[0131] According to one embodiment, the scanning device comprises two scanning units, wherein the scanning units are positioned in series along the longitudinal axis of the scanning device, preferably at the ends of the scanning device. Figure 3 Note that although Figure 3 Only two scanning units are shown, but the scanning device may include other components disclosed herein. In this embodiment, each scanning unit is configured in a forward-looking configuration, i.e., wherein the projector unit of each scanning unit projects light toward the distal end of the elongated probe of the scanning device. In other words, in the forward-looking configuration, the projector optical axis of each projector unit is substantially parallel to the longitudinal axis of the elongated probe. In this embodiment, each scanning unit includes one or more cameras, such as four cameras, each camera including an image sensor for acquiring an image, wherein at least one camera defines a camera optical axis. In this embodiment, each scanning unit also includes a reflective element, such as a reflector, which is configured to reflect light from the projector unit of a given scanning unit and / or reflect light from the scanned object and reflect it onto the image sensor (one or more) of each camera of the scanning unit. According to this embodiment, the scanning device includes a first scanning unit and a second scanning unit, wherein the first scanning unit is positioned further toward the distal end of the probe than the second scanning unit. The two scanning units can be configured to project light patterns at two different focal lengths, such that the first scanning unit is configured to project light patterns at a predefined first focal length, and the second scanning unit is configured to project light patterns at a predefined second focal length. In some embodiments, the second focal length is greater than the first focal length.

[0132] Preferably, the two scanning units are positioned as close to each other as possible without any light projected by the first scanning unit being cut off by the reflective elements of the second scanning unit. As an example of how to describe the compactness of the scanning units, the minimum bounding box of the first scanning unit may overlap with the minimum bounding box of the second scanning unit. A bounding box may be understood as a virtual bounding box into which the entire scanning unit may be placed. A minimum bounding box may be understood as a virtual bounding box having a minimum area and / or minimum volume into which the entire scanning unit may be placed. Therefore, a bounding box may be understood as a virtual tool for describing the periphery of a scanning unit, which is a rectangular cuboid when the scanning unit is enclosed in a box. Therefore, in some embodiments, the bounding box of the first scanning unit overlaps with the bounding box of the second scanning unit.

[0133] According to another embodiment, the scanning device comprises two scanning units, namely a first and a second scanning unit, the first scanning unit comprising a first projector unit, which is configured to project a light pattern with a predefined first focal length, and the second scanning unit comprising a second projector unit, which is configured to project a light pattern with a predefined second focal length, wherein the scanning units are positioned in series along the longitudinal axis of the scanning device, preferably located in the ends of the scanning device, and wherein the first scanning unit is configured in a forward viewing configuration and the second scanning unit is configured in a downward viewing configuration. Therefore, the projector optical axis of the first projector unit is substantially parallel to the longitudinal axis of the scanning device, and the projector optical axis of the second projector unit is substantially orthogonal to the longitudinal axis of the scanning device. This embodiment is Figure 7 In this embodiment, each scanning unit comprises one or more cameras, for example four cameras, each camera comprising an image sensor for acquiring an image, wherein at least one camera defines a camera optical axis. In this embodiment, the first scanning unit further comprises a reflective element, such as a mirror or a prism, which is configured to reflect light from the first projector unit and / or reflect light from the surface of the scanned object and reflect it onto the image sensor(s) of the first scanning unit.

[0134] Figure 7 The two annular sectors shown below the scanning device in the figure represent the scanning volume, i.e. the volume observable by the scanning device. Thus, a first scanning volume is associated with the first scanning unit and a second scanning volume is associated with the second scanning unit. The first and second scanning volumes may overlap in time and / or space. This has the advantage that the accuracy of the generated 3D representation may be increased. In addition, as Figure 7 As shown, two scanning volumes can be projected at two different distances below the end of the scanning device. This can be achieved in at least two different ways. If the same optical elements are used, that is, if the configuration of the first and second projector units is similar, the first and second focal lengths will be similar when measured along each projector optical axis. However, since the first and second scanning units (including the projector units) are oriented differently, the two scanning units will project light patterns at two different distances below the end of the scanning device. In particular, this is the case if more of the light path is located within the housing of the scanning device, such as shown for the first (farthest) scanning unit, while for the second scanning unit, since the light is projected directly downwards, the light path within the housing is shorter. Alternatively, if different optical elements are used, the two different distances below the scanning device can be achieved by having the first and second projector units have different focal lengths, i.e., making the second focal length greater than the first focal length.

[0135] Figure 7An advantage of the illustrated embodiment is that two scanning volumes are projected at two different distances, such that the first scanning unit projects light at a first distance below the end of the scanning device, and the second scanning unit projects light at a second distance below the end of the scanning device, wherein the second distance is greater than the first distance. This is particularly useful because some users hold the scanning device at an angle during scanning, wherein the most distal portion of the scanning device is closer to the dental object being scanned than the less distal portion of the scanning device.

[0136] Detailed description with drawings

[0137] Figure 1 A side view (section view) of a scanning unit 5 comprising a projector unit 6 and four cameras 9 is shown, wherein the scanning unit is configured to project light directly onto the dental object 2. This configuration of the scanning unit is also referred to herein as "looking down". The longitudinal axis 4 of the scanning device 1 is horizontal in this figure.

[0138] Figure 2 A perspective view of a scanning unit 5 comprising a projector unit 6 and four cameras 9 is shown, wherein the projector unit is configured to project a light pattern 13, here a chessboard pattern, onto the surface of the dental object. The light pattern may be a pattern that is static over time.

[0139] Figure 3 A side view (cross-section) of two scanning units 5 placed in series along the longitudinal axis 4 of the scanning device 1 is shown. In this embodiment, both scanning units comprise a projector unit 6, four cameras 9 and a reflective element 12 (e.g. a mirror) configured to direct (a central beam of) light from a substantially horizontal direction to a substantially orthogonal direction relative to the longitudinal axis 4 of the scanning device. Many thin lines represent projected light rays / light rays reflected from a surface.

[0140] Figure 4 A side view (cross-section) of a scanning unit 5 comprising a projector unit 6, four cameras 9 and a reflective element 12 (e.g., a mirror) is shown, wherein some dimensions are included in the figure. In the figure, "a" represents the baseline, which can be understood as the center-to-center distance between a given camera 9 and the projector unit 6, "b" represents the distance from the projector optical axis 8 to the outer edge of the scanning unit 5, as shown in the figure, "c" represents the distance between the projector unit 6 and the reflective element 12, the distance being measured along the projector optical axis 8, "d" represents the length of the scanning unit 5, and "e" represents the camera-projector angle, i.e., the angle between the given camera optical axis 11 and the projector optical axis 8. In general, the intersection of two straight lines (e.g., two of the axes) can produce two angles. The camera-projector angle can be understood as the smallest of the angles.

[0141] Figure 5A A side view of a scanning device 1 is shown, which comprises two scanning units 5, so that the scanning device has an extended field of view ("long FOV" configuration) along the longitudinal axis 4 compared to a scanning device comprising one scanning unit. The advantage is that the field of view is larger (compared to one scanning unit), which enables more data / images to be captured per unit time, which allows a faster generation of a 3D representation of the scanned object. Furthermore, a large field of view allows smaller registration errors and therefore a higher overall accuracy of the 3D representation. Cones 34 show projected light from the scanning units.

[0142] Figure 5B Shows the view from the far end of the scanning device Figure 5A scanning device.

[0143] Figure 5C A side view of a scanning device 1 is shown, which comprises two scanning units 5, so that the scanning device has an extended field of view ("dual scanning" configuration) compared to a scanning device comprising one scanning unit. In this embodiment, the two scanning units are angled relative to each other so that they illuminate different parts of the dental object 2 from different angles, see Figure 5D This has the advantage that more surface area of ​​the dental object is illuminated per unit time, thereby enabling faster scanning of the entire dental object with fewer scanning device movements during the scanning process. Another advantage is that parts / areas of the dental object are illuminated from different angles, thereby improving the accuracy of generating a 3D representation based on the acquired dental object images. Cone 34 shows the projected light from the scanning unit.

[0144] Figure 5D shows the view from the far end of the scanning device Figure 5C . Cone 34 shows the projected light from the scanning unit, which projects light with a predefined angular field of view. Note that in this configuration, the scanning unit 5 is tilted so that the projector optical axes 8 of the two scanning units are at an angle relative to each other, so that the two scanning units illuminate the dental object 2 from different angles.

[0145] Figure 5E A side view of a scanning device 1 is shown, which comprises two scanning units 5, so that the scanning device has an extended field of view ("single scan" configuration) compared to a scanning device comprising one scanning unit. In this embodiment, the two scanning units 5 are angled relative to each other so that they illuminate different parts of the dental object 2 from different angles, see Fig. 5F In this embodiment, the angle is measured in a plane perpendicular to the longitudinal axis of the scanning device. Cone 34 shows the projected light from the scanning unit.

[0146] Fig. 5Fshows the view from the far end of the scanning device Figure 5E The scanning device 1 in this embodiment Figure 5C-5D The embodiment shown in is generally similar to that shown in Figure 5D Compared to the embodiment of the embodiment of the present invention, the angle between the projector optical axes 8 of the two scanning units 5 is larger. In this embodiment, the angle is measured in a plane perpendicular to the longitudinal axis of the scanning device. The angle may be greater than 45°, such as greater than 75°, such as greater than 85°. As an example, the angle may be about 90°, such as Fig. 5F The advantage of a large angle between the projector optical axes is that the scanning device 1 can illuminate the dental object 2 from different angles, preferably so that the entire tooth is within the field of view of the scanning device. Therefore, during the scanning process, the scanning device needs to be moved less because a larger surface area of ​​the dental object is covered / captured per unit time.

[0147] Figure 6 A dental scanning system is shown, which includes an intraoral scanning device 1 and a computer system 26 (here a laptop). In a preferred embodiment, the scanning device 1 is configured to wirelessly transmit scan data (e.g., images or 3D data) to the computer 26. The scan data may include image(s), processed image(s), 2D data, 3D data, processed 3D data, 3D representation(s), fluorescence data, infrared (IR) data, near infrared (N IR) data, and / or combinations thereof. The scan data may be transmitted by a wireless module 31, which is configured to wirelessly transmit data from the scanning device to the computer system. Alternatively, the scanning device may be configured to transmit the scan data using a wired connection 32. The computer system 26 may include a display for displaying a 3D representation 27 or a 3D model based on the 3D representation. The scanning device may be configured to transmit the scan data in real time to an external processing unit, such as a computer system disclosed herein.

[0148] Figure 7A side view of a scanning device 1 is shown, in particular an end 25 of the scanning device, wherein the scanning device comprises two scanning units 5 in two different configurations. In this embodiment, a first scanning unit 14 is configured in a forward viewing configuration, i.e. such that the projector unit projects light forward along an optical path substantially parallel to the longitudinal axis of the scanning device. The first scanning unit further comprises a reflector 12, which is configured to direct (the central beam of) light from a substantially horizontal direction to a direction substantially orthogonal with respect to the longitudinal direction of the scanning device. A second scanning unit 15 is configured in a downward viewing configuration, i.e. such that the projector unit of the scanning unit projects light in a downward direction, i.e. substantially orthogonal to the longitudinal axis of the scanning device. An advantage of this embodiment is that the first scanning unit can project light at a predefined first distance below the end of the scanning device, and the second scanning unit can project light at a predefined second distance below the end of the scanning device, wherein the second distance is greater than the first distance. This is particularly useful because some users hold the scanning device at an angle during scanning. Thus, the first scanning unit 14 may be configured to project a first scanning volume 16 at a first distance below the end 25 of the scanning device 1, and the second scanning unit 15 may be configured to project a second scanning volume 17 at a second distance below the end 25 of the scanning device 1. The first scanning volume 16 and the second scanning volume 17 may overlap in time and / or space.

[0149] Figures 8A-8D Four different ways of positioning / orienting the projector unit 6 and the camera 9 of the scanning unit 5 are shown. In these embodiments, the image sensor 10, the optical mask 18 and the reflective element 12 each include four edges, which form a rectangle. Some corners of the rectangle (one or more) may be rounded. In some embodiments, the reflective element 12 has a rectangular shape, wherein some corners of the rectangle are rounded. Furthermore, in this embodiment, for each scanning unit 5, one or more edges of the image sensor 10, the optical mask 18 and the reflective element 12 are substantially aligned, such that the corresponding edges are substantially parallel. As can be seen from Fig. 8A As can be seen in FIG. 1 , the edge of the image sensor 10 is parallel to the edge of the reflective element 12 when viewed in this cross section.

[0150] exist Fig. 8A In the embodiment, the cameras 9 are arranged on two axes to form a cross in the plane, wherein the projector unit 6 is located at the center of the cross when viewed along the projector optical axis 8. Thus, the first camera 9 is located above the projector unit 6 in the plane, the second camera 9 is located below the projector unit 6 in the plane, the third camera 9 is located to the left of the projector unit 6 in the plane, and the fourth camera 9 is located to the right of the projector unit 6 in the plane. The two axes of the cross are substantially parallel to at least two edges of the reflective element 12. Figure 8B, the cross is rotated 45 degrees relative to the edge / side of the reflective element 12. In other words, the diagonal of the optical mask 18 / image sensor 10 is aligned with the vertical axis of the reflective element 12. Figure 8C An example is shown in which the camera 9 and the projector unit 6 are as shown in FIG. Figure 8B The projector unit 6 is arranged in a cross shape as in FIG. 1 , but the edge of the projector unit 6 is substantially aligned with the edge of the reflective element 12. Fig.8D An example is shown, which is similar to Figure 8C but in which the camera 9 is rotated so that an edge of the image sensor 10 is substantially aligned with an edge of the reflective element 12.

[0151] Fig. 9 A perspective view of a scanning unit 5 is shown, which includes a projector unit 6 and four cameras 9, wherein the scanning unit also includes a reflective element 12, shown here as a mirror. The projector unit 6 may include a light source 22, an optical mask 18 for defining a pattern, one or more optical lenses (19, 21). Each camera includes an image sensor 10 and may also include one or more camera lenses 20.

[0152] Fig.10 An embodiment of a scanning device 1 is shown, which includes two scanning units 5, wherein each scanning unit 5 includes a reflective element 12, here taking a reflector as an example. In this embodiment, the reflective element 12 is configured to change the direction of (the central beam of) the projection light 34 from a direction substantially parallel to the longitudinal axis 4 of the scanning device 1 to a direction substantially orthogonal to the longitudinal axis 4. In this embodiment, the scanning device also includes a wireless module 31, which is configured to wirelessly transmit scan data (e.g., images, 3D data or other data) to a computer system 26, for example, via a Wi-Fi router 29 or a Wi-Fi access point. The scan data can be transmitted continuously and / or in real time. The computer system 26 may include a display 30 for displaying a 3D representation of a dental object. In addition, the scanning device may include a battery 28 for powering the scanning device.

[0153] Fig.11 An embodiment of a scanning device 1 is shown, which comprises a scanning unit 5, which comprises a reflective element 12, here a reflector as an example. In this embodiment, the scanning device is configured to transmit scan data using a wired connection 32, such as a USB cable or an Ethernet cable. In addition, the scanning device can be powered by a wired connection 32 to a power source 33. The scanning device can transmit data to a computer system 26, which comprises a display 30 for displaying a 3D representation of a dental object.

[0154] Fig.12An embodiment of a scanning device is shown, which includes a first scanning unit 14 and a second scanning unit 15, wherein each scanning unit further includes a reflective element 12, here a reflector. Therefore, the first reflective element is associated with the first scanning unit, and the second reflective element is associated with the second scanning unit. In this figure, some elements of the scanning device are omitted to highlight other elements. Specifically, the housing and the frame have been removed so that the scanning unit, the reflective element and the flexible cable 40 are visible. In this embodiment, four flexible printed circuit boards (PCBs) 40 are shown, wherein each flexible PCB is connected to the image sensor of the camera. The fifth flexible PCB is connected to the projector unit. The figure also defines two planes, a first plane 38 and a second plane 39. In this embodiment, each flexible PCB is bent with a first radius of curvature, wherein the first radius of curvature is located in the first plane 38. In addition, each flexible PCB is manufactured to have a predetermined shape, wherein the second portion includes one or more turns. Then each flexible PCB is bent so that the second portion is located in the second plane 39. In this example, the first plane is substantially parallel to the longitudinal axis of the scanning device, and the second plane is perpendicular to the first plane. Note that the second scanning unit 15 intersects some of the flexible PCB; this is simply an artifact in the rendering and therefore does not accurately represent the physical device.

[0155] Fig.13 Shows Fig.12 The same embodiment shown in . In this visualization, a frame 35 of the scanning device is shown. The frame is configured to accommodate the scanning unit (14, 15). The frame is further configured so that the reflective element 12 can be inserted and installed in the frame. Note that the reflective element 12 can protrude from the frame when installed. The frame may include one or more openings for inserting the scanning unit.

[0156] Fig.14 Shows Fig.13The same embodiment shown in ; shown here in an exploded view. The frame 35 can be made in one piece and is preferably made rigid. Examples of suitable materials for the frame include: aluminum, steel, stainless steel, magnesium alloys, polymers or iron-carbon alloys. The frame 35 can include two or more openings for receiving scanning units (14, 15). In this embodiment, the frame includes a first opening for receiving the first scanning unit 14 and a second opening for receiving the second scanning unit 15. In this embodiment, the frame is configured so that the scanning units can be inserted into the frame from opposite directions, for example, the first scanning unit is inserted from above the frame and the second scanning unit is inserted from below the frame. Therefore, the scanning device can be assembled by inserting the first scanning unit 14 into the frame 35 through a first opening located in the first surface of the frame, and inserting the second scanning unit 15 into the frame 35 through a second opening located in the second surface of the frame. The reflective element 12 can be inserted into the frame from below. The frame 35 can be configured so that the reflective element 12 forms a certain angle relative to the longitudinal axis of the scanning device when installed.

[0157] Fig.15 Shows Figure 12-14 The same embodiment shown in FIG. 1 is different in that in this figure both the frame 35 and the housing 37 of the scanning device are visible, as well as the optical window 41. The figure shows a cross section of the distal part of the scanning device, when the scanning unit (14, 15) and the reflective element 12 are mounted in the frame 35, and when the elements and the frame are housed in the housing 37 of the scanning device. The optical window 41 can be flush with the surface of the housing 37.

[0158] Fig.16 A perspective view of an intraoral scanning device according to the present disclosure is shown. The housing 37 may include a replaceable component that can be removably mounted to the rest of the housing. The replaceable component may also include an optical window 41, for example, an optical window 41 that is placed near the distal end of the scanning device when installed. The scanning device may also include a port 42 configured to receive a cable, such as a data cable or a power cable, for charging an internal power source (e.g., a battery) inside the scanning device. In some embodiments, the port is configured to receive a data cable or a combination of data and power cables.

[0159] Fig.17 Shows Fig.16; however, in this view, the replaceable component is shown as being separated from the scanning device. In this embodiment, the replaceable component includes an optical window 41. The window is located in the replaceable component so that when the component is mounted to the rest of the housing, the optical window 41 is aligned with the opening in the shell so that the projection light from the scanning device can be emitted from the opening and propagated through the optical window. The advantage of placing the optical window 41 in the replaceable component of the housing 37 is that, for example, if the window is damaged or scratched, the window can be easily replaced. The replaceable component can also be configured to cover the compartment for accommodating the battery 28. Therefore, another advantage of the replaceable component is that the user can easily enter the compartment to replace the battery 28. In some embodiments, the battery is a rechargeable battery that can be charged using a cable inserted into the port 42.

[0160] Fig.18 1 shows a perspective view of an intraoral scanning device according to the present disclosure. In this embodiment, the scanning device includes a housing 37 that includes two replaceable components that can be assembled together and / or disassembled. In this embodiment, the first replaceable component of the housing can be configured to cover the top portion of the scanning device, and the second replaceable component of the housing can be configured to cover the bottom portion of the scanning device. Fig.17 Similar to the embodiment shown in , the replaceable component (e.g., the second replaceable component) can include an optical window. In addition, the user can access the compartment for accommodating the battery, such as with respect to Fig.17 described.

[0161] Fig.19A cross-sectional view of an embodiment of an intraoral scanning device according to the present disclosure is shown. In this embodiment, the scanning device includes two scanning units (14, 15), each of which is arranged in combination with a reflector 12. In this embodiment, each scanning unit is tilted relative to the longitudinal axis 4 of the scanning device and / or relative to a vertical plane 39 orthogonal to the longitudinal axis. As an example, each reflector 12 can define an angle between 35° and 45°, such as an angle between 40° and 45°, relative to the longitudinal axis 4 of the scanning device. In this example, the angle is measured between the plane surface of the reflector and the longitudinal axis. Similarly, the projector and camera of each scanning unit can be tilted at a similar angle, thereby maintaining the relative orientation between the projector unit and the reflector. Therefore, in some embodiments, the projector optical axis 8 defines an angle between 0° and 12°, such as between 5° and 10°, such as about 8°, with the longitudinal axis 4. The advantage of this arrangement is that each scanning unit is tilted relative to the longitudinal axis, so that for the same optical system, the end height of the scanning device can be made smaller. A smaller tip height is desirable because it is more comfortable for the patient, such as when scanning the inside of a patient's mouth, but it also makes it easier to scan hard-to-reach areas (such as areas in the back of a patient's mouth).

[0162] Fig. 20 A perspective view of an intraoral scanning device according to the present disclosure is shown. For illustrative purposes, the housing 37 in the figure is transparent so that the components inside the scanning device can be seen. In this embodiment, the scanning device includes a first scanning unit 14 and a second scanning unit 15, wherein both scanning units are arranged in combination with a reflective element 12, and the reflective element 12 is exemplified here by a reflector. The scanning device defines or includes an elongated probe having a longitudinal axis. The optical axis of the projector unit of each scanning unit (14, 15) is substantially parallel to the longitudinal axis at least until it contacts the reflective element 12, and the reflective element 12 is preferably arranged to redirect the light projected by the projector unit through an optical window 41 onto the surface of the scanned object. In this embodiment, the scanning device also includes an internal power supply 28 (e.g., a battery) and a port 42 for charging the power supply and / or for providing wired data transmission via a cable (not shown).

[0163] Fig.21An embodiment of a dental scanning system is shown, which includes an intraoral scanning device 1 and a computer system 26, here taking a laptop as an example. In this embodiment, the scanning device is configured to be connected to the computer system via a wired connection. The dental scanning system can be configured to transmit data and / or power via a wired connection. In other embodiments, the scanning device 1 is configured to wirelessly transmit data (e.g., images and / or scan data) to the computer system 26. The dental scanning system may also include a display for displaying a 3D representation of the scanned object. In this example, the laptop includes the display.

[0164] FIG. 22 illustrates three different embodiments of how to provide a chairside solution for a dental scanning system according to the present disclosure. Fig.22A A movable cart is shown, with a display mounted on a robotic arm. The cart comprises a bracket beside the display for fixing the intraoral scanning device 1 . Fig. 22B The scanning device is shown in a stand, positioned adjacent to a power outlet for charging the scanning device. Fig. 22C The scanning device is shown placed next to other typical dental instruments for complete chairside integration.

[0165] Further details of the invention

[0166] 1. An intraoral scanning device for scanning a dental object, comprising:

[0167] Slim probe;

[0168] One or more scanning units, wherein each scanning unit comprises:

[0169] at least one projector unit; and

[0170] at least one camera including an image sensor for acquiring images;

[0171] Wherein, at least one of the scanning units further comprises a reflective element.

[0172] 2. The scanning device according to item 1, wherein the scanning device comprises two or more scanning units.

[0173] 3. The scanning device according to any preceding item, wherein the at least one projector unit is configured to project a light pattern onto a surface of the dental object.

[0174] 4. A scanning device according to any preceding item, wherein the reflective element is configured to reflect light from the projector unit(s) and / or reflect light from the surface of the dental object and reflect it onto the image sensor(s) of each camera.

[0175] 5. A scanning device according to any preceding clause, wherein the elongate probe defines a longitudinal axis of the scanning device.

[0176] 6. The scanning device according to any preceding clause, wherein the at least one projector unit defines a projector optical axis.

[0177] 7. The scanning device according to any preceding item, wherein the at least one camera defines a camera optical axis.

[0178] 8. A scanning device according to any preceding clause, wherein each scanning unit defines a field of view (FOV).

[0179] 9. A scanning device according to any preceding clause, wherein each scanning unit defines an angular field of view (AFOV).

[0180] 10. A scanning device according to any preceding clause, wherein a projector optical axis of the one or more projector units is substantially parallel to a longitudinal axis of the scanning device.

[0181] 11. A scanning device according to any preceding clause, wherein a projector optical axis of each projector unit is substantially parallel to a longitudinal axis of the scanning device.

[0182] 12. A scanning device according to any preceding clause, wherein a projector optical axis of each projector unit defines an angle with a longitudinal axis of the scanning device.

[0183] 13. A scanning device according to item 12, wherein the angle is between 1° and 12°, for example between 5° and 10°.

[0184] 14. The scanning device according to any preceding clause, wherein the scanning unit is positioned along a longitudinal axis of the scanning device.

[0185] 15. A scanning device according to any preceding clause, wherein one or more reflective elements are located on the projector optical axis.

[0186] 16. A scanning device according to any preceding clause, wherein a projector optical axis of at least one projector unit is substantially parallel to a longitudinal axis of the scanning device.

[0187] 17. The scanning device according to any preceding clause, wherein a projector optical axis of at least one projector unit defines an angle with a longitudinal axis of the scanning device, wherein said angle is between 5° and 10°.

[0188] 18. The scanning device according to any preceding clause, wherein the scanning units are configured to project the light patterns onto the same side of the scanning device.

[0189] 19. A scanning device according to any preceding clause, wherein each scanning unit comprises a reflective element.

[0190] 20. A scanning device according to any preceding clause, wherein the intraoral scanning device has a field of view which is larger than the FOV of each scanning unit.

[0191] 21. A scanning device according to any preceding clause, wherein the individual scanning units are positioned in series along a longitudinal axis of the scanning device.

[0192] 22. The scanning device according to any preceding item, wherein a minimum bounding box of the first scanning unit overlaps with a minimum bounding box of the second scanning unit.

[0193] 23. A scanning device according to any preceding clause, wherein a surface normal of each reflective element defines an angle of about 40-50 degrees, preferably about 45 degrees, relative to the projector optical axis.

[0194] 24. A scanning device according to any preceding clause, wherein the surface of each reflective element defines an angle relative to a longitudinal axis of the scanning device, wherein said angle is between 40-45 degrees, preferably approximately 41 degrees.

[0195] 25. A scanning device according to any preceding clause, wherein each reflective element is substantially rectangular.

[0196] 26. A scanning device according to any preceding clause, wherein the reflective element(s) comprises a plurality of corners, wherein at least some of the corners are rounded.

[0197] 27. The scanning device according to any preceding item, wherein the reflective element is selected from the group consisting of: a mirror, a prism, and / or a combination thereof.

[0198] 28. The scanning device according to any preceding clause, wherein at least one scanning unit comprises a mirror as a reflective element.

[0199] 29. The scanning device according to any preceding clause, wherein at least one scanning unit comprises a prism as a reflective element.

[0200] 30. A scanning device according to item 29, wherein the prism is configured to change the direction of the central light beam of the projected light pattern from being substantially parallel to the longitudinal axis of the scanning device to a direction having an angle of at least 45 degrees relative to said longitudinal axis.

[0201] 31. A scanning device according to item 29, wherein the prism is configured to change the direction of the central light beam of the projected light pattern from being substantially parallel to the longitudinal axis of the scanning device to a direction having an angle of approximately 90 degrees relative to said longitudinal axis.

[0202] 32. A scanning device according to any preceding clause, wherein each projector unit comprises an optical mask configured to define a light pattern.

[0203] 33. The scanning device according to item 32, wherein the optical mask defines a polygonal pattern comprising a plurality of polygons.

[0204] 34. The scanning device according to any of items 32-33, wherein the polygon is selected from the following group: triangle, rectangle, square, pentagon, hexagon and / or their combination.

[0205] 35. A scanning device according to any of items 32-34, wherein the pattern comprises a plurality of repeating units, wherein each repeating unit comprises a predefined number of polygons, wherein the repeating unit is repeated throughout the pattern.

[0206] 36. A scanning device according to any of items 32-35, wherein the pattern is non-encoded such that no part of the pattern is unique.

[0207] 37. A scanning device according to any of items 32-36, wherein the light pattern is a checkerboard pattern comprising alternating dark and light squares.

[0208] 38. A scanning device according to any of items 32-37, wherein the checkerboard pattern comprises at least 140 x 140 alternating light and dark squares.

[0209] 39. A scanning device according to any preceding clause, wherein each scanning unit comprises at least two cameras having at least partially overlapping fields of view along different camera optical axes.

[0210] 40. The scanning device according to any preceding item, wherein each scanning unit comprises at least four cameras, all said cameras having at least partially overlapping fields of view along different camera optical axes.

[0211] 41. A scanning device according to any preceding clause, wherein, for each scanning unit, the cameras are located substantially in the same plane.

[0212] 42. A scanning device according to item 41, wherein each scanning unit comprises a projector unit and a plurality of cameras, wherein the plurality of cameras are arranged on two axes to form a cross in a plane, wherein the projector unit is located at the center of the cross when viewed along the projector optical axis.

[0213] 43. A scanning device according to item 42, wherein each scanning unit comprises four cameras.

[0214] 44. A scanning device according to any of items 41-43, wherein the first camera is located above the projector in the plane, the second camera is located below the projector in the plane, the third camera is located to the left of the projector in the plane, and the fourth camera is located to the right of the projector in the plane.

[0215] 45. A scanning device according to any of items 42-44, wherein two axes of the cross are substantially parallel to at least two edges of the reflective element.

[0216] 46. ​​A scanning device according to any preceding clause, wherein each projector unit comprises an optical mask configured to define a light pattern, and wherein the image sensor, the optical mask and the reflective element each comprise four edges, said edges forming a rectangle.

[0217] 47. A scanning device according to any preceding clause, wherein, for each scanning unit, one or more edges of the image sensor, the optical mask and the reflective element are substantially aligned such that corresponding edges are substantially parallel.

[0218] 48. A scanning device according to any preceding clause, wherein the projector optical axis and the camera optical axis define a camera-projector angle of approximately 5 to 25 degrees.

[0219] 49. A scanning device according to any preceding clause, wherein the projector optical axis and the camera optical axis define a camera-projector angle of approximately 5 to 15 degrees.

[0220] 50. A scanning device according to any preceding clause, wherein the projector optical axis and the camera optical axis define a camera-projector angle of approximately 5 to 10 degrees.

[0221] 51. A scanning device according to any preceding clause, wherein the projector optical axis and the camera optical axis define a camera-projector angle of approximately 8 to 10 degrees.

[0222] 52. A scanning device according to any preceding clause, wherein each scanning unit defines an angular field of view (AFOV) between 50° and 80°.

[0223] 53. A scanning device according to any preceding clause, wherein each scanning unit defines an angular field of view (AFOV) between 60° and 75°.

[0224] 54. A scanning device according to any preceding clause, wherein at least one camera(s) in at least one scanning unit is a light field camera.

[0225] 55. The scanning device according to any preceding item, wherein each scanning unit comprises at least one light field camera.

[0226] 56. The scanning device according to any preceding item, wherein the scanning device comprises at least three scanning units.

[0227] 57. A scanning device according to any preceding item, wherein the projector unit is configured to project the light pattern such that the light pattern is focused at a predefined focal distance measured along the projector optical axis.

[0228] 58. A scanning device according to item 57, wherein the predefined focal length differs between the projector units.

[0229] 59. The scanning device according to any of items 57-58, wherein the scanning device comprises:

[0230] a first scanning unit comprising a first projector unit configured to project a light pattern at a predefined first focal length, and

[0231] The second scanning unit comprises a second projector unit configured to project a light pattern at a predefined second focal length.

[0232] 60. The scanning device according to item 59, wherein the scanning unit is located at the distal end of the elongated probe.

[0233] 61. A scanning device according to any of items 59-60, wherein the first scanning unit is positioned further towards the distal end of the probe than the second scanning unit.

[0234] 62. A scanning device according to any of items 59-61, wherein the second focal length is greater than the first focal length.

[0235] 63. A scanning device according to any of items 59-62, wherein the second scanning unit is focused further from the end than the first scanning unit.

[0236] 64. The scanning device according to any preceding item, wherein the elongated probe comprises an opening and / or an optical window for each scanning unit of the scanning device.

[0237] 65. A scanning device according to item 64, wherein the second scanning unit is focused farther from the opening / optical window than the first scanning unit.

[0238] 66. A scanning device according to any of items 59-65, wherein the first scanning unit includes a reflective element, such as a mirror or a prism, which is configured to reflect light from a projector unit of the first scanning unit and / or reflect light from the surface of the dental object and reflect it onto an image sensor (one or more) of the first scanning unit.

[0239] 67. A scanning device according to any of items 59-66, wherein the projector optical axis of the first projector unit is substantially parallel to the longitudinal axis of the scanning device, and wherein the projector optical axis of the second projector unit is substantially orthogonal to the longitudinal axis of the scanning device.

[0240] 68. A scanning device according to any of items 59-67, wherein the first and second focal lengths are substantially the same when measured along each respective projector optical axis.

[0241] 69. A scanning device according to any of items 59-68, wherein the first scanning unit is positioned as close as possible to the second scanning unit without cutting off light that has been reflected by a reflective element of the first scanning unit.

[0242] 70. The scanning device according to any of items 59-69, wherein the minimum bounding box of the first scanning unit overlaps with the minimum bounding box of the second scanning unit.

[0243] 71. The scanning device according to any of items 59-70, wherein the scanning device further comprises a third scanning unit comprising a third projector unit configured to project a light pattern with a predefined third focal length.

[0244] 72. A scanning device according to any of items 59-71, wherein the first scanning unit is configured to project a first scanning volume at a first distance below the slender probe, and wherein the second scanning unit is configured to project a second scanning volume at a second distance below the slender probe.

[0245] 73. The scanning device according to any preceding item, wherein the elongated probe comprises one or more openings and / or one or more optical windows at a distal end of the elongated probe.

[0246] 74. The scanning device according to any preceding item, wherein the elongated probe comprises an opening and / or an optical window for each scanning unit of the scanning device.

[0247] 75. The scanning device according to any preceding item, wherein the projector unit is configured to project the light pattern such that the light pattern is defocused at the opening of the probe and / or at the surface of the optical window.

[0248] 76. The scanning device according to any preceding clause, wherein the camera is defocused at the opening of the probe and / or at the surface of the optical window.

[0249] 77. A scanning device according to any preceding clause, wherein the FOV of each scanning unit is at least 300 mm 2 , preferably at least 400 mm 2 , preferably at least 500 mm 2, preferably at least 550 mm 2 , wherein the area is measured for a given predefined distance below a lower surface of the distal end of the elongated probe.

[0250] 78. A scanning device according to item 77, wherein the predefined distance is approximately 1 to 10 mm.

[0251] 79. A scanning device according to item 77, wherein the predefined distance is approximately 5 to 7 mm.

[0252] 80. A scanning device according to any of items 77-79, wherein the area is measured about 6 mm below the surface of the optical window or opening.

[0253] 81. The scanning device according to any preceding clause, wherein the scanning unit is located at a distal end of the elongated probe.

[0254] 82. A scanning device according to any preceding item, wherein, for a given scanning unit, the center-to-center distance between the projector unit and a given camera of the scanning unit is between 2 and 5 mm, preferably between 3 and 4 mm.

[0255] 83. An intraoral scanning device for scanning a dental object, comprising:

[0256] - an elongated probe defining a longitudinal axis of the scanning device;

[0257] - A first scanning unit, comprising:

[0258] - a first projector unit configured to project a light pattern onto a surface of the dental object, wherein the first projector unit defines a first projector optical axis;

[0259] - at least one camera, comprising an image sensor for acquiring an image, wherein the at least

[0260] At least one camera defines the camera optical axis; and

[0261] - a reflective element configured to reflect light from the first projector unit and / or light from the surface of the dental object and reflect it onto the image sensor(s) of each camera;

[0262] - A second scanning unit, comprising:

[0263] - a second projector unit configured to project a light pattern onto a surface of the dental object, wherein the second projector unit defines a second projector optical axis; and

[0264] - at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis;

[0265] Therein, each scanning unit defines a field of view (FOV).

[0266] 84. A scanning device according to item 83, wherein the second scanning unit further comprises a reflective element configured to reflect light from the second projector unit and / or reflect light from the surface of the dental object onto an image sensor of each camera of the second scanning unit.

[0267] 85. A scanning device according to any of items 72-84, wherein the first and second projector optical axes define an angle of at least 45°.

[0268] 86. A scanning device according to any of items 72-85, wherein the first and second projector optical axes define an angle of at least 75°.

[0269] 87. A scanning device according to any of items 72-86, wherein the first and second projector optical axes define an angle of at least 85°.

[0270] 88. A scanning device according to any of items 85-87, wherein the angle is measured in a plane substantially parallel to the longitudinal axis of the scanning device.

[0271] 89. A scanning device according to any of items 85-87, wherein the angle is measured in a plane substantially orthogonal to the longitudinal axis of the scanning device.

[0272] 90. A scanning device according to any of items 72-86, wherein the first and second projector optical axes are substantially orthogonal.

[0273] 91. A scanning device according to any of items 72-88, wherein the first projector optical axis is substantially parallel to the longitudinal axis of the scanning device, and wherein the second projector optical axis is substantially orthogonal to the longitudinal axis of the scanning device.

[0274] 92. A scanning device according to any of items 59-91, wherein the first scanning unit is configured to project a first scanning volume at a first distance below the slender probe, and wherein the second scanning unit is configured to project a second scanning volume at a second distance below the slender probe.

[0275] 93. A scanning device according to item 92, wherein the second distance is greater than the first distance.

[0276] 94. A scanning device according to any of items 92-93, wherein the first and second scanning volumes overlap in time and / or space.

[0277] 95. A scanning device according to any of items 72-84, wherein the optical axes of the first and second projectors are substantially parallel.

[0278] 96. A scanning device according to any of items 72-95, wherein each scanning unit comprises at least two cameras.

[0279] 97. A scanning device according to any of items 72-96, wherein each scanning unit comprises four cameras.

[0280] 98. A scanning device according to any preceding item, wherein the scanning device is configured to wirelessly transmit scan data (eg, images or 3D data) to an external device (eg, a computer).

[0281] 99. A scanning device according to any preceding item, wherein the scanning device further comprises a wireless module configured to wirelessly transmit the scan data.

[0282] 100. A scanning device according to any preceding clause, wherein the scanning device comprises a frame for housing the scanning unit(s).

[0283] 101. A scanning device according to item 100, wherein the frame is further configured to accommodate one or more reflective elements, such as mirrors.

[0284] 102. The scanning device according to any of items 100-101, wherein the frame is a rigid frame, and wherein the frame comprises two or more openings for receiving the scanning unit.

[0285] 103. A scanning device according to any of items 100-102, wherein the frame is made in one piece.

[0286] 104. A scanning device according to any of items 100-103, wherein the frame is made of a material selected from the following group: aluminum, steel, stainless steel, magnesium alloy, polymer or iron-carbon alloy.

[0287] 105. A scanning device according to any of items 100-104, wherein the scanning device further comprises a housing for accommodating the frame.

[0288] 106. A scanning device according to any of items 100-105, wherein the housing is made of a thermoplastic selected from the following group: acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polycarbonate (PC), polyoxymethylene (POM), polyethylene (PE), polypropylene (PP).

[0289] 107. A scanning device according to any of items 100-106, wherein the housing is made in one piece.

[0290] 108. A scanning device according to any preceding item, wherein the projector unit and the camera of each scanning unit are arranged in a housing.

[0291] 109. A scanning device according to any preceding clause, wherein at least one flexible cable is connected to each camera, wherein each cable comprises a plurality of wires or circuits connected to the image sensor of a given camera.

[0292] 110. The scanning device according to item 109, wherein the cable is a flexible printed circuit or a flexible printed circuit board (PCB).

[0293] 111. The scanning device according to any of items 109-110, wherein each flexible cable is bent with a first radius of curvature, wherein the first radius of curvature lies in the first plane.

[0294] 112. A scanning device according to any of items 109-111, wherein each flexible cable is manufactured into a predetermined shape, wherein a first portion of each cable is straight and a second portion includes one or more turns.

[0295] 113. A scanning device according to item 111, wherein the first plane is substantially parallel to a longitudinal axis of the scanning device.

[0296] 114. A scanning device according to any of items 111-113, wherein the second plane is perpendicular to the first plane.

[0297] 115. A scanning device according to any of items 111-114, wherein the first radius of curvature is selected from about 0.5 mm to about 5 mm.

[0298] 116. A scanning device according to any of items 111-115, wherein a first portion of each cable is substantially parallel to a longitudinal axis of the scanning device and a second portion of each cable lies in a second plane.

[0299] 117. The scanning device according to any of items 111-116, wherein the cables overlap each other along a portion in which the cables are bent with a first radius of curvature.

[0300] 118. A scanning device according to any preceding clause, wherein the scanning device comprises a housing, for example for housing a scanning unit and / or electronic components.

[0301] 119. A scanning device according to item 118, wherein the housing includes a replaceable part which can be removably mounted to the rest of the housing.

[0302] 120. A scanning device according to item 120, wherein the replaceable component includes an optical window.

[0303] 121. A scanning device according to any of items 119-120, wherein the scanning device comprises a compartment for accommodating a battery, and wherein when mounted to the scanning device, the replaceable component is configured to cover the compartment.

[0304] 122. A method of assembling an intraoral scanning device according to any of the preceding claims, the method comprising the steps of:

[0305] - providing a rigid frame for housing the scanning unit, wherein the rigid frame comprises two or more openings for receiving the scanning unit;

[0306] - inserting the first scanning unit into the rigid frame through a first opening in a first surface of the frame; and

[0307] - Inserting the second scanning unit into the rigid frame through a second opening in the second surface of the frame.

[0308] 123. The method according to item 122, wherein the first surface and the second surface are opposite to each other.

[0309] Although some embodiments have been described and shown in detail, the present disclosure is not limited to these details, but may also be embodied in other ways within the scope of the subject matter defined in the appended claims. Specifically, it is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present disclosure. In addition, those skilled in the art will find that unless an embodiment is specifically presented only as an alternative, different disclosed embodiments may be combined to achieve a specific implementation, and such a specific implementation is within the scope of the present disclosure.

[0310] A claim may refer to any of the preceding claims, and “any” should be understood as “any one or more” of the preceding claims.

[0311] It should be emphasized that when used in this specification, the terms "comprise / include / including" are used to specify the existence of the features, integers, operations, steps or components, but do not exclude the existence or addition of one or more other features, integers, steps, components or groups thereof.

[0312] Reference Number

[0313] 1. Intraoral scanning device

[0314] 2. Dental objects

[0315] 3. Slim probe

[0316] 4. Longitudinal axis

[0317] 5. Scanning unit

[0318] 6. Projector unit

[0319] 7. Light Pattern

[0320] 8. Projector optical axis

[0321] 9. Camera

[0322] 10. Image Sensor

[0323] 11. Camera optical axis

[0324] 12. Reflective elements

[0325] 13. Light Pattern

[0326] 14. First scanning unit

[0327] 15. Second scanning unit

[0328] 16. First scan volume

[0329] 17. Second scanning volume

[0330] 18. Mask

[0331] 19. Focusing lens

[0332] 20. Camera lens

[0333] 21. Collimating lens

[0334] 22. Light Source

[0335] 23. Printed Circuit Board (PCB)

[0336] 24. Radiator

[0337] 25. The end of the scanning device

[0338] 26. Computer Systems

[0339] 27.3D Representation

[0340] 28.Battery

[0341] 29. Wi-Fi router

[0342] 30. Display

[0343] 31. Wireless module

[0344] 32. Wired Connection

[0345] 33. Power supply

[0346] 34. Projection Light / Scan Volume

[0347] 35. Framework

[0348] 36. Shell

[0349] 37. Shell

[0350] 38. First plane

[0351] 39. Second Plane

[0352] 40.Flexible cable / flexible PCB

[0353] 41. Optical window

[0354] 42. Port for charging and / or data transfer

Claims

1. An intraoral scanning device for scanning a dental object, comprising: - an elongated probe defining a longitudinal axis of said scanning device; - A first scanning unit, comprising: - a first projector unit configured to project a light pattern onto a surface of the dental object, wherein the first projector unit defines a first projector optical axis; - at least one camera comprising an image sensor for acquiring images, wherein the at least one camera defines a camera optical axis; and - a reflective element configured to reflect light from the first projector unit and / or light from the surface of the dental object and reflect it onto an image sensor of each camera; - A second scanning unit, comprising: - a second projector unit configured to project a light pattern onto the surface of the dental object, wherein the second projector unit defines a second projector optical axis; and - at least one camera comprising an image sensor for acquiring an image, wherein the at least one camera defines a camera optical axis; Wherein each scanning unit defines a field of view (FOV), wherein the projector optical axis and the camera optical axis of each scanning unit define a camera-projector angle between 5° and 10°. 2 . The scanning device according to claim 1 , wherein the projector unit is configured to project unpolarized white light.

3. A scanning device according to any one of the preceding claims, wherein the light pattern is static in time.

4. A scanning device according to any one of the preceding claims, wherein the scanning device comprises an optical window made of polymer or glass, wherein the optical window is located in the distal end of the elongate probe.

5. A scanning device according to any of the preceding claims, wherein the first and second scanning units are arranged to project the light pattern through the optical window.

6. A scanning device according to any one of the preceding claims, wherein the second scanning unit further comprises a reflective element configured to reflect light from the second projector unit and / or reflect light from the surface of the dental object and reflect it onto an image sensor of each camera of the second scanning unit.

7. A scanning device according to any of the preceding claims, wherein the scanning unit is positioned along a longitudinal axis of the scanning device.

8. A scanning device according to any preceding claim, wherein the first and second projector optical axes are substantially parallel.

9. The scanning device according to any one of the preceding claims, wherein a minimum bounding box of the first scanning unit overlaps with a minimum bounding box of the second scanning unit.

10. The scanning device according to any of the preceding claims, wherein the first and second scanning units are configured to project the light pattern onto the same side of the scanning device.

11. The scanning device according to any of the preceding claims, wherein each scanning unit comprises two or more cameras, wherein the cameras are configured to acquire a set of images.

12. The scanning device of claim 11, wherein the number of images in the set of images corresponds to the number of cameras in a given scanning unit.

13. A scanning device according to any one of claims 11-12, wherein the cameras are synchronised with each other such that images within the set of images are acquired simultaneously.

14. A scanning device according to any one of the preceding claims, wherein each scanning unit comprises four cameras.

15. A scanning device according to any one of the preceding claims, wherein: Each scanning unit comprises a projector unit and a plurality of cameras, wherein the plurality of cameras are arranged on two axes to form a cross in the plane, wherein the projector unit is located at the center of the cross when viewed along the projector optical axis, and wherein the two axes are substantially parallel to at least two edges of the reflective element.

16. A scanning device according to any one of the preceding claims, wherein: Each scanning unit defines an angular field of view (AFOV) between 60° and 75°.

17. A scanning device according to any one of the preceding claims, wherein: For a given scanning unit, the center-to-center distance between the projector unit and a given camera of the scanning unit is between 2 and 5 mm, preferably between 3 and 4 mm.

18. A scanning device according to any one of the preceding claims, wherein: The field of view of each scanning unit is at least 400 mm at a working distance between 15 mm and 50 mm 2 .

19. A scanning device according to any one of the preceding claims, wherein: The scanning device adopts a scanning principle based on triangulation.

20. The scanning device according to any of the preceding claims, wherein the scanning device comprises one or more processors configured to generate a three-dimensional (3D) representation of the dental object.

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