WO2025202067A1

WO2025202067A1 - An intraoral scanning system with improved scan sequence schedules

Info

Publication number: WO2025202067A1
Application number: PCT/EP2025/057818
Authority: WO
Inventors: Martin Krusborg ANDERSEN; Asger Cronberg IPSEN
Original assignee: 3Shape AS
Current assignee: 3Shape AS
Priority date: 2024-03-26
Filing date: 2025-03-21
Publication date: 2025-10-02
Anticipated expiration: 2026-09-26

Abstract

The present disclosure relates to an intraoral scanning system configured to determine 3D data of a dental object in dental object. The intraoral scanning system comprising a projector unit configured to emit a first visible light, a second visible light and infrared light during a scan sequence, wherein the emitted first visible light includes an illumination pattern, an image sensor unit configured to acquire two-dimensional visible images based on the first visible light and the second visible light and/or two-dimensional infrared images based on the infrared light from the dental object, and one or more processors configured to control the projector unit and/or the image sensor unit according to a plurality of scan sequence schedules, wherein each of the plurality of scan sequence schedules includes timing of the projector unit and/or the image sensor. The one or more processors is configured to determine a 3D model of the dental object based on the two-dimensional visible images that includes the first visible light, and wherein the one or more processors is configured to shift between each of the plurality of scan sequence schedules.

Description

AN INTRAORAL SCANNING SYSTEM WITH IMPROVED SCAN SEQUENCE SCHEDULES

FIELD

The disclosure relates to an intraoral scanning system. More specifically, the disclosure relates to one or more processors of the system that is configured to control to a plurality of scan sequence schedules, wherein each of the plurality of scan sequence schedules includes timing of a projector unit and/or an image sensor.

BACKGROUND

Many dental and orthodontic procedures can benefit from accurate three-dimensional (3D) descriptions of a patient's dentition and intraoral cavity. In particular, it would be helpful to provide a three-dimensional description of both the surface and internal structures of the teeth, including the enamel and dentin, as well as caries and the general internal composition of the tooth volume. Although pure surface representations of the 3D surfaces of teeth have proven extremely useful in the design and fabrication of dental restorations (e.g., crowns or bridges) the ability to image internal structures including the development of caries and dental cracks in the enamel and underlying dentin would be tremendously useful, particularly in conjunction with a surface topographical mapping.

State of the art, ionizing radiation (e.g., X-rays) has been used to image the teeth for diagnostic purposes. For example, X-ray bitewing radiographs are often used to provide non-quantitative images of the teeth's internal structures. However, in addition to the risk of ionizing radiation, such images are typically limited in their ability to show early tooth mineralization changes (e.g. initial caries) resulting in underestimation of the demineralization depth; they are unable to assess the presence or not of micro-cavitation; they result in frequent overlap of the approximal tooth surfaces which requires repetition of radiograph acquisition and thus may involve a lengthy and expensive procedure.

Some intraoral features such as soft tissues and dental plaque are usually not visualized via X-ray because of their low density. Other techniques, such as cone beam computed tomography (CBCT) may provide tomographic images and be used to collect more information about the tissues and internal structure, but still require ionizing radiation. Furthermore, it is known that near-infrared (NIR) light can be used for assessing internal structure of a tooth and tooth surface in the form of transillumination of teeth or light reflection and backscattering from teeth. The NIR range offers a non-ionizing and safe approach to assess dental caries, restorations, cracks, enamel and dentin defects.

The subsurface diagnostics provided by infrared/near-infrared imaging can be supplemented with fluorescence visualization of the teeth by agitating bacteria in the plaque with blue/UV light and capturing the fluorescent signal that can be converted into images combined with the 3D information of the jaw to aid in the diagnosis of early caries formation risk and aid with the communication of proper dental hygiene practices.

A fundamental requirement of the intraoral scanner should be that the additional diagnostic capabilities should not impair the 3D scan quality.

In known intraoral scanner devices a scan sequence is preprogrammed in such a way that customizing scan sequences is difficult to perform without performing significant changes to the firmware of the scanner. Therefore, a user may settle with the preprogrammed scan sequence which may not be suitable for the scan the user needs to perform on the patient.

SUMMARY

It is an aspect of the present disclosure to provide a scan sequence, meaning a sequence of capturing structural and diagnostics information during a regular scan of the jaw which provide a solution to the fundamental requirement on the intraoral scanner.

Another aspect of the present disclosure is to provide the user the ability to change the scan sequence without the involvement of or with minimal involvement of the manufacture of the intraoral scanning system.

According to the aspects, an intraoral scanning system is disclosed. The intraoral scanning system may be configured to determine a three-dimensional (3D) model of a dental object. The intraoral scanning system may comprise a projector unit configured to emit a first visible light, a second visible light and infrared light during a scan sequence, wherein the emitted first visible light includes an illumination pattern. The second visible light may include the illumination pattern. The system may include an image sensor unit configured to acquire two-dimensional visible images based on the first visible light and the second visible light and/or two-dimensional infrared images based on the infrared light from the dental object. The captured first visible light may include the illumination pattern which may be used for determining a three-dimensional model of a dental object. The second visible images that may include the second visible light may include illuminations pattern that may not be used for determining a 3D model, instead the second visible images are used for generating a compose scan information in combination with first visible light and the captured infrared images.

The projector unit may include multiple light sources configured to emit different wavelengths, such as a first visible light within a wavelength range of 450 nm and 750 nm, a second visible light within a wavelength range of 350 and 450 nm, and infrared light within a wavelength range of 800 nm an 1150 nm.

The projector unit may be configured to emit light with different wavelengths during time periods onto at least a dental object, wherein the different wavelengths include at least a near-infrared wavelength and at least a visible wavelength. The wavelength of each time periods may be different.

The projector unit may include multiple light sources that are configured to emit light that is ideal for determining surface information, fluorescence information and internal structure information of teeth of the dental arch.

The projector unit may include one or more first light sources and at least one or more second light sources, wherein the one or more first light sources is configured to emit light within a first group of time periods at the near-infrared wavelength spectrum, and the one or more second light sources are configured to emit light within a second group of time periods at the visible wavelength spectrum. The system may be configured to switch between the one or more first light sources and the at least one or more second light sources. The switching may implies turning on and off the light sources, and/or adjusting the power to the light sources.

The light sources may be a combination of one or more of following:

• light Emitting Diode (LED),

• broadband Light Emitting Diode, and

• continuous broadband Light Emitting Diode.

The projector unit may include at least one or more third light sources, wherein the one or more second light sources may be configured to emit light within a second group of time periods at a first visible wavelength, and the one or more third light sources may be configured to emit light within a third group of time periods at a second visible wavelength. The first visible wavelength may be different from the second visible wavelength, and wherein the visible light information may include information corresponding to reflection caused by the first visible wavelength and captured by the image sensor, and wherein the visible light information may include information corresponding to fluorescence information caused by the second visible wavelength and captured by the image sensor unit.

The near-infrared wavelength may be between 800 nm and 1150 nm, a first visible wavelength may be between 380 nm and 700 nm, a second visible wavelength may be between 100 nm and 500 nm, and the visible wavelength may be between 100 nm and 700 nm.

The image sensor unit may include one or more cameras, wherein each of the one or more cameras includes an array of pixels. The image sensor unit may be arranged in a tip housing.

The image sensor unit and the projector unit may be arranged in a scan unit. In some embodiments. The scan unit may comprise at least two camera units having at least partly overlapping fields of view along different camera optical axes. Preferably, each scan unit comprises at least four camera units having at least partly overlapping fields of view along different camera optical axes. An advantage of having overlapping fields of view of the camera units is an improved accuracy due to reduced amount of image stitching errors.

The one or more processors may be configured to control the projector unit and/or the image sensor unit according to a plurality of scan sequence schedules, wherein each of the plurality of scan sequence schedules includes timing of the projector unit and/or the image sensor. Each of the plurality of scan sequence schedules may include time slots for emitting the first visible light, the second visible light and/or the infrared light by the projector unit. A scan sequence schedule of the plurality of scan sequence schedules may be programmed by a user to include a combination of time slots that includes one or more of the first visible light, the second visible light, and the infrared light, or, the scan sequence schedule may include time slots for solely emitting one of the first visible light, the second visible light and the infrared light. Each of the plurality of scan sequence schedules may include time slots for acquiring the two-dimensional visible images and/or the two-dimensional infrared images via the image sensor unit. The time slots for emitting a specific wavelength(s) may be synchronized with the time slots for acquiring the specific wavelength(s). The specific wavelength(s) may be included in the first visible light, the second visible light or the infrared light. Each of the plurality of scan sequence schedules may include time slots for processing the acquired two-dimensional visible images and/or the two-dimensional infrared images. The timing of the processing may be aligned with the timing of the emitting of light and/or the timing of acquiring two-dimensional visible images and/or the two-dimensional infrared images. A scan sequence schedule may include time slots wherein each of the time slot includes a timing of emitting of light, acquiring of images and processing of images.

The timing of the projector and/or the image sensor unit may include timing of when to emit the first visible light and the infrared light, and/or, timing of when to acquire the two- dimensional visible images and/or the two-dimensional infrared images.

The one or more processors may be configured to process the acquired two-dimensional visible images and the two-dimensional infrared images according to the plurality of scan sequence schedules. The timing of the time slots in each of the plurality of scan sequence schedules may be based on a round robin principle that includes a certain number of time slots which are repeated in a circular order.

The processing performed by the one or more processors may include down-sampling of the acquired images for the purpose of wireless transmitting the images. The

The one or more processors may be configured to process the acquired two-dimensional visible images and/or the two-dimensional infrared images by down-sample the acquired images and/or by color space conversion the acquired images, wherein the color space conversion includes converting the images from a first color space model into a second color space model, or vice versa. The first color space model may include a Red-Green- Blue (RGB) color space model, and the second color space model includes a Y(brightness) and UV(deviation from color grey) (YUV) color space model. The conversion into YUV color space is for using a H.265 compression protocol of the YUV converted two- dimensional visible images and/or the two-dimensional infrared images. The compressed two-dimensional visible images and/or the two-dimensional infrared images are then wireless transmitted to an external processor of the system.

The system may include a user interface configured to receive a user input on a mode of operation of the intraoral scanning system, wherein the mode of operation selects one or more of the plurality of scan sequence schedules. For example, the mode of operation may be one of following modes:

• a diagnostic mode wherein a combination of infrared light and ultraviolet light (visible light ) are being emitted separately in different time slots of a scan sequence schedule, and wherein the one or more processors is configured to determine fluorescence images and infrared images,

• an infrared diagnostic mode wherein infrared light is emitted in different time slots of a scan sequence schedule, and wherein the one or more processors is configured to determine infrared images, • a fluorescence diagnostic mode wherein ultraviolet light (visible light) is emitted in different time slots of a scan sequence schedule, and wherein the one or more processors is configured to determine fluorescence images,

• a composed diagnostic mode wherein a combination of infrared light, ultraviolet light (visible light) and white light (light) are being emitted separately in different time slots of a scan sequence schedule, and wherein the one or more processors is configured to determine a composed scan image which includes a difference between fluorescence images, white light images and infrared images, and

• a three-dimensional scan mode wherein white light with an illumination pattern is emitted, and wherein the one or more processors is configured to determine a three-dimensional model based on the illumination pattern.

In another example, the three-dimensional scan mode may be combined with any of the following modes a diagnostic mode, an infrared diagnostic mode, a fluorescence diagnostic mode, and a composed diagnostic mode.

The plurality of scan sequence schedules may include two or more of following schedules:

• a 3D scan sequence schedule that includes time slots for emitting the first visible light with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object,

• an ultraviolet scan sequence schedule that includes time slots for emitting the first visible light with wavelengths between 400 nm and 750 nm and the second visible light with a wavelength between 350 nm and 450 nm emitted by the projector unit,

• a hyperspectral scan sequence schedule that includes time slots for emitting the first visible light with wavelengths between 400 nm and 750 nm, the second visible light with a wavelength between 350 nm and 450 nm, and the infrared light with a wavelength between 850 nm and 1100 nm.

The plurality of scan sequence schedules may include two or more of following schedules: • a 3D scan sequence schedule that includes time slots for acquiring the two- dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object,

• an ultraviolet scan sequence schedule that includes time slots for acquiring the two-dimensional visible images with fluorescent wavelengths from the dental object provided by the second visible light, and acquiring the two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object,

• a hyperspectral scan sequence schedule that includes time slots for acquiring the two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, the two-dimensional visible images with fluorescent wavelengths from the dental object, and the two-dimensional infrared images with a wavelength between 850 nm and 1100 nm.

• a 3D scan sequence schedule includes timing for the one or more processors to process the 3D model determined based on the two-dimensional visible images including wavelengths between 400 nm and 750 nm,

• an ultraviolet scan sequence schedule includes timing for the one or more processors to process the acquired two-dimensional visible images including fluorescent wavelengths from the dental object provided by the second visible light , and to process the acquired two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object,

• a hyperspectral scan sequence schedule that includes timing for the one or more processors to process the acquired two-dimensional visible images including wavelengths between 400 nm and 750 nm, the acquired two-dimensional visible images including fluorescent wavelengths from the dental object, and the acquired two-dimensional infrared images with a wavelength between 850 nm and 1100 nm.

The plurality of scan sequence schedules may be combined such that the 3D scan sequence schedule, the ultraviolet scan sequence schedule and the hyperspectral scan sequence schedule would include the emitting of light, acquiring of light and the processing of the acquired light. For example, the hyper spectral sequence schedule may include for each time slots:

• emitting the first visible light with wavelengths between 400 nm and 750 nm, the second visible light with a wavelength between 350 nm and 450 nm, and the infrared light with a wavelength between 850 nm and 1100 nm;

• acquiring the two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, the two- dimensional visible images with fluorescent wavelengths from the dental object, and the two-dimensional infrared images with a wavelength between 850 nm and 1100 nm; and

• processing the acquired two-dimensional visible images including wavelengths between 400 nm and 750 nm, the acquired two-dimensional visible images including fluorescent wavelengths from the dental object, and the acquired two- dimensional infrared images with a wavelength between 850 nm and 1100 nm.

For example, the 3D scan sequence schedule may include for each time slots:

• emitting the first visible light with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object,

• acquiring the two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, and

• processing the 3D model determined based on the two-dimensional visible images including wavelengths between 400 nm and 750 nm.

For example, the ultraviolet scan sequence schedule may include for each time slots:

• emitting the first visible light with wavelengths between 400 nm and 750 nm and the second visible light with a wavelength between 350 nm and 450 nm emitted by the projector unit,

• acquiring the two-dimensional visible images with fluorescent wavelengths from the dental object provided by the second visible light, and acquiring the two- dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, and • processing the acquired two-dimensional visible images including fluorescent wavelengths from the dental object provided by the second visible light, and to process the acquired two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object.

In the hyperspectral scan sequence schedule the light that is acquired by the image sensor unit may be combined into a composed scan image. Furthermore, the acquired light that includes wavelengths of the first visible light is used for determining both the 3D model of the dental object and to be combined into a composed scan image. Furthermore, the acquired fluorescent light that has been excited by the wavelengths of the second visible light may be used for determining a fluorescence image of the dental object and to be combined into the composed scan image. Furthermore, the acquired infrared light is used for determining an infrared image or for being combined into the composed scan image. The composed scan image may include a difference between the acquired light that includes wavelengths of the first visible light, the acquired fluorescent light and/or the acquired infrared light.

The mode of operation may be one or more of following modes:

• a first diagnostic mode that includes the hyperspectral scan sequence schedule,

• a second diagnostic mode that includes the ultraviolet scan sequence schedule,

• a three-dimensional mode that includes the 3D scan sequence schedule, and

• a fourth mode that includes two or more of the first diagnostic mode, the second diagnostic mode and the three-dimensional mode.

The one or more processors may be configured to determine a 3D model of the dental object based on the two-dimensional visible images that includes the first visible light , and wherein the one or more processors is configured to shift between each of the plurality of scan sequence schedules. The shifting between each of the plurality of scan sequence schedules may be programmed by a user for a specific scanning scenario.

The intraoral scanning system may comprise a focusing lens unit configured to change a focus of the image sensor unit during a scan sequence. The focus is change by moving a focus lens of the focusing lens unit. The focus lens may be configured to move in a first direction, and wherein the image sensor unit may be configured to acquire, via the focus lens and while the focus lens is moving at least in the first direction, two-dimensional visible images and/or two-dimensional infrared images. The focus lens may be moved in the first direction from an initial position to an end position, and a full sweep of the focus lens is when the focus lens has reached the end position. A plurality of 2D visible images and a plurality of infrared images may be acquired at different positions from the initial position and to the end position, and at each of the different positions a part of pixels of the acquired 2D visible image and the acquired infrared image is in focus, and after the full sweep, the pixels of the plurality of 2D visible images that are in focus may be combined into a three-dimensional model of a dental object. Furthermore, after the full sweep, the pixels of the plurality of infrared images that are in focus may be combined into an infrared image where all pixels are in focus.

After the full sweep, the focus lens is moved back to the initial position so that another sweep may be performed. During the move of the focus lens back to the initial position no acquisitions of images will occur. In another example, the focus lens may be configured to move in a second direction, and wherein the first direction is opposite to the second direction. The image sensor unit may be configured to, according to the plurality of scan sequence schedules, acquire the two-dimensional visible images and the two-dimensional infrared images while the focus lens is moving in the first direction and then in the second direction. In this example, the acquisition rate of the two-dimensional visible images and the two-dimensional infrared images has improved significantly. This would resolve in a faster scanning experience. A frame rate of the image sensor unit is different when the focusing lens is moving in the first and second directions. For example, intraoral scanner may include an accelerometer configured to determine a movement speed of the intraoral scanner, or, the one or more processors may be configured to determine a movement speed of the intraoral scanner by tracking a position of a known element appearing in at least two or more of the captured two-dimensional-images and the frame rate of the image sensor. Based on the movement speed the frame rate in both directions may be different. For example, if the user moves the intraoral scanner too fast, then the frame rate of the image sensor unit when the focusing lens is moving in the second direction would be larger than the frame rate of the image sensor unit when the focusing lens is moving in the first direction. In another example, if the user moves the intraoral scanner ideally, then the frame rate of the image sensor when the focusing lens is moving in the second direction would be lower than the frame rate of the image sensor unit when the focusing lens is moving in the first direction.

Each of the time slots of each of the plurality of scan sequence schedules may determine whether two-dimensional images should be acquired during the movement of the focus in both directions, or, in one of the two directions.

The timing of acquiring a set of images that includes 2D visible images, 2D visible fluorescent images, and 2D infrared images may be determined by a focus position of the focus lens. For example, the plurality of scan sequence schedules includes a focus scan sequence schedule, wherein the focus scan sequence schedule includes time slots that is timed by a focus position of the focus lens in at least the first direction and/or the second direction. The time slots of the focus scan sequence schedule are for acquiring a set of images that includes the two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, the two-dimensional visible images with fluorescent wavelengths from the dental object, and the two- dimensional infrared images with a wavelength between 850 nm and 1100 nm. The set of images may be combined into a composed scan image. Each image of the set of images may include a plurality of color channels, and the combination of two or more images of the set of images may involve one or more color fusions of the plurality of color channels. Each color channels may be assigned to a weight coefficient that is adjusted by the one or more processors for the purpose of improving the contrast of the composed scan image. Furthermore, the contrast of the composed scan image may be further improved by a contrast enhancement algorithm. The contrast enhancement algorithm may be applied one or more times to one or more of the color channels of the plurality of color channels of one or more images of the set of images. The contrast enhancement algorithm may be applied to one or more color channels of the composed scan image. The contrast enhancement algorithm may be one or more of following linear contrast enhancement algorithms or a combination of two or more of the following linear contrast enhancement algorithms:

• Minimum-Maximum Linear Contrast Stretch (MMLC),

• Percentage Linear Contrast Stretch (PLC) and Piecewise

• Linear Contrast Stretch (PWLC).

The contrast enhancement algorithm may be one or more of following non-linear contrast enhancement algorithms or a combination of two or more of the following non-linear contrast enhancement algorithms:

• Histogram Equalizations (HE) that includes a histogram distribution,

• Adaptive Histogram Equalization (AHE) and

• Homomorphic Filters (HF) including a combination of low pass and high pass filtering

The contrast enhancement algorithm may be a combination of one or more of the nonlinear contrast enhancement algorithms and one or more of the linear contrast enhancement algorithms.

The focus scan sequence schedule may include a group of time slots for emitting a sequence of light, the group of time slots is timed by the focus position such that when the focus lens has reached the focus position the group of time slots is enabled. The enablement of the group of time slots involves emitting of light for each of the grouped time slots. For example, a first time slot of the group of time slots is configured for emitting the infrared light, a second time slot of the group of time slots is configured for emitting the first visible light, and a third time slot of the group of time slots is configured for emitting the second visible light. Each time slots of the grouped time slots may involve acquiring of the emitted light and processing of the acquired light.

The focus scan sequence schedule may include another group of time slots that may be configured for emitting the first visible light when the group of time slots is not enabled. The first visible light may be used for determining a three-dimensional model of the dental object.

The focus position may be determined by the one or more processors during a first sweep of the focus lens, and the grouped time slots of the focus scan sequence schedule is enabled at the focus position during a subsequently sweep to the first sweep.

The focus position may be determined by the one or more processors during a first full sweep of the focus lens, and the grouped time slots of the focus scan sequence schedule is enabled at the focus position during a subsequently full sweep to the first sweep.

The first sweep is preceding to the sweep of the focus lens wherein the grouped of time slots is enabled.

The group of time slots of the focus scan sequence schedule may be disabled when all time slots of the group of time slots have been executed by the one or more processors.

The focus position of the focus lens may be determined by the one or more processors, and at the focus position a specific group of pixels of one of the acquired two-dimensional visible images is in focus, wherein the focus is determined by an intensity of the specific group of pixels. The specific group of pixels includes pixels of the one of the acquired two-dimensional visible images that are arranged in a centre of the one of the acquired two-dimensional visible images.

The one or more processors is configured to change from a 3D scan sequence schedule of the plurality of scan sequence schedules to a hyperspectral scan sequence schedule of the plurality of scan sequence schedules based on a trigger signal. The trigger signal may be determined by the one or more processors when the focus lens of the focusing unit is positioned at a position where a specific part of an acquired two-dimensional visible image is in focus. The one or more processors may be configured to change from the hyperspectral scan sequence schedule to the 3D scan sequence schedule when finalized the hyperspectral scan sequence schedule. The plurality of scan sequence schedules is arranged in a main sequence schedule, wherein the one or more processors may be configured to change between each of the plurality of scan sequence schedules based on the main sequence schedule.

The plurality of scan sequence schedules may be arranged in the main sequence schedule based on a Round robin principle.

The system may include a user interface configured to arrange or re-arrange two or more of the plurality of scan sequence schedules in the main sequence schedule. Thereby, the user is able customize the main sequence schedule to a specific scan scenario.

Each of the plurality of scan sequence schedules may include at least three time slots.

According to the aspects, an intraoral scanning system is disclosed. The intraoral scanning system may be configured to determine 3D data of a dental object in an oral cavity. The intraoral scanning system may comprise a handheld intraoral scanner that includes a projector unit configured to emit visible light and infrared light during a scan sequence, The system may comprise an image sensor unit configured to acquire the visible light signals and infrared signals from at least the dental object caused by the emitted visible light and the emitted infrared light, respectively. The image sensor unit may be a highspeed camera which has a frame rate of above 60 frames per seconds. The image sensor unit may be a very high-speed camera which has a frame rate of above 500 frames per seconds. The system may include one or more processors configured to configured to control the projector unit and/or the image sensor unit according to a plurality of scan sequence schedules, wherein each of the plurality of scan sequence schedules includes timing of the projector unit and/or the image sensor. The one or more processors may be configured to determine a 3D model of the dental object based on the two-dimensional visible images that includes the first visible light, and wherein the one or more processors is configured to shift between each of the plurality of scan sequence schedules. The one or more processors may be configured to control a power level of the emitted infrared light to a first power level during a first time period of the scan sequence, and during a second time period, the power level of the emitted infrared light switches between the first power level and a second power level, and wherein the first power level is lower than the second power level. The one or more processors may be further configured to determine 3D data based on the acquired visible light signals during the first time period and to determine an inner region of the dental object based on the acquired infrared signals during the second time period.

One or more of the plurality of single-color channels may be configured to transmit infrared light and block visible light.

The power of the projector unit which is controlled by the one or more processors may be a supply power to the projector unit.

The image sensor unit may include multiple cameras, such as, high speed camera. In one example, the multiple cameras may be arranged around the projector unit or next to the projector unit.

An inner region of the dental object may be determined by the one or more processors based on the infrared signal. The inner region may include information about dental features that are arranged within the dental object. The dental feature may be one or more of an anatomy feature, a disease feature and a mechanical feature. The anatomy feature may be an enamel, a dentine, or a pulp. The disease feature may be plauq, crack or caries. The mechanical feature may be a filling and/or a composite restoration.

The projector unit may include multiple light sources that are configured to emit one or more color lights and the infrared light. The multiple light sources may be arranged within a single module that includes multiple Light Emitting Diodes (LED) that are configured to emit different wavelengths within the visible and non-visible wavelength ranges. In another situation, the light source, i.e. one or more LEDs, that is configured to emit infrared light may be arranged separated from the light source that is configured to emit the visible light.

During the first time period, the one or more processors may be configured to determine a sub-inner region information based on the infrared signals and to enhance 3D data by the combination of the visible light signals and the sub-inner region information. In this example, sub-inner region information is subtracted from the visible light signals, and the result would be enhanced 3D data where noise that may be created in the 3D data due to the emitted infrared light during the first time period will be removed.

During the second time period, the one or more processors may be configured to determine inner region information based on the infrared signals and to determine a composed scane image based on the infrared signals and the visible light signals, and wherein the composed scan image includes enhanced inner region information. IN this example, the composed scan image may include a subtraction of the visible light signals from the infrared signals.

The first power level of the emitted infrared light during the first time period may be below a noise floor level of the image sensor unit. By not turning off the infrared light but instead turning the power of the emitted infrared light down to the first power level which is just below the noise floor level will be that the quality of the 3D data will not be affected by the emitted infrared light during the first time period. Furthermore, unwanted transients on the emitted light pulses will not appear as the infrared light is not turned off.

The one or more processors may be configured to control the projector unit during the scan sequence, and during the first time period the emitted visible light includes a first visible light that is turned on at a constant power level while the infrared light is turned on constant at the first power level. During the second time period the emitted visible light includes a second visible light that is turned on and off with a second pulse repetition rate and the first visible light is turned on and off asynchronously to the on/off switching of the second visible light and with a first pulse repetition rate, and wherein the power level of the infrared light is turned up when the first and the second visible light are turned off, and the infrared light is turned down when the first or the second visible light are turned on, and wherein the power level of the infrared light is turned up and down between the first power level and the second power level.

The inner region may be determined by composed scan image that includes a difference between the infrared signals and the visible light signals.

The fluorescence information may include green fluorescence information and/or red fluorescence information, wherein the one or more processors may be configured to determine a first difference between the infrared signal and the green fluorescence information and a second difference between the infrared signal and the red fluorescence information, and wherein the composed scan image includes a summation of the first difference and the second difference. In this example, the contrast between the dental features within the inner region of the dental object is improved significantly.

The composed scan image may include a summation of the infrared signal, the green fluorescence information and the red fluorescence information. In another example the composed scan image may include a subtraction of the infrared signal with the visible light signal including white wavelengths or green wavelengths.

The one or more processors may be configured to determine the 3D data based on one or more colors of the visible light signals, such as white, red and/or green wavelengths.

BRIEF DESCRIPTION OF THE FIGURES

Aspects of the disclosure may be best understood from the following detailed description taken in conjunction with the accompanying figures. The figures are schematic and simplified for clarity, and they just show details to improve the understanding of the claims, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts. The individual features of each aspect may each be combined with any or all features of the other aspects. These and other aspects, features and/or technical effect will be apparent from and elucidated with reference to the illustrations described hereinafter in which: FIGS. 1A, IB, and 1C illustrate different examples of the intraoral scanning system;

FIGS. 2 A, 2B and 2C illustrate different examples of a plurality of scan sequence schedules;

FIGS. 3A, 3B, and 3C illustrate different examples of a plurality of scan sequence schedules;

FIGS. 4A,4B, and 4C illustrate different examples of a plurality of scan sequence schedules;

FIGS. 5A and 5B illustrate different examples of a main sequence schedule;

FIGS. 6A,6B,6C, and 6D illustrate examples of an intraoral scanning system with a focus lens; and

FIG. 7 illustrates another example of an intraoral scanning system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. Several aspects of the devices, systems, mediums, programs and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). Depending upon particular application, design constraints or other reasons, these elements may be implemented using electronic hardware, computer program, or any combination thereof.

The electronic hardware may include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. Computer program shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

A scanning for providing intra-oral scan data may be performed by a dental scanning system that may include an intraoral scanning device such as the TRIOS series scanners from 3 Shape A/S. The dental scanning system may include a wireless capability as provided by a wireless network unit. The scanning device may employ a scanning principle such as triangulation-based scanning, confocal scanning, focus scanning, ultrasound scanning, x-ray scanning, stereo vision, structure from motion, optical coherent tomography OCT, or any other scanning principle. In an embodiment, the scanning device is capable of obtaining surface information by operated by projecting a pattern and translating a focus plane along an optical axis of the scanning device and capturing a plurality of 2D images at different focus plane positions such that each series of captured 2D images corresponding to each focus plane forms a stack of 2D images. The acquired 2D images are also referred to herein as raw 2D images, wherein raw in this context means that the images have not been subject to image processing. The focus plane position is preferably shifted along the optical axis of the scanning system, such that 2D images captured at a number of focus plane positions along the optical axis form said stack of 2D images (also referred to herein as a sub-scan) for a given view of the object, i.e. for a given arrangement of the scanning system relative to the object. After moving the scanning device relative to the object or imaging the object at a different view, a new stack of 2D images for that view may be captured. The focus plane position may be varied by means of at least one focus element, e.g., a moving focus lens. The scanning device is generally moved and angled relative to the dentition during a scanning session, such that at least some sets of sub-scans overlap at least partially, in order to enable reconstruction of the digital dental 3D model by stitching overlapping subscans together in real-time and display the progress of the virtual 3D model on a display as a feedback to the user. The result of stitching is the digital 3D representation of a surface larger than that which can be captured by a single sub-scan, i.e. which is larger than the field of view of the 3D scanning device. Stitching, also known as registration and fusion, works by identifying overlapping regions of 3D surface in various sub-scans and transforming sub-scans to a common coordinate system such that the overlapping regions match, finally yielding the digital 3D model. An Iterative Closest Point (ICP) algorithm may be used for this purpose. Another example of a scanning device is a triangulation scanner, where a time varying pattern is projected onto the dental arch and a sequence of images of the different pattern configurations are acquired by one or more cameras located at an angle relative to the projector unit.

Color texture of the dental arch may be acquired by illuminating the object using different monochromatic colors such as individual red, green and blue colors or my illuminating the object using multi chromatic light such as white light. A 2D image may be acquired during a flash of white light.

Generally the process of obtaining surface information in real time of a dental arch to be scanned requires the scanning device to illuminate the surface and acquire high number of 2D images. Typically a high speed camera is used with a framerate of 300-2000 2D frames pr second dependent on the technology and 2D image resolution. The high amount of image data needed to be handled by the scanning device to eighter directly forward the raw image data stream to an external processing device or performing some image processing before transmitting the data to an external device or display. This process requires that multiple electronic components inside the scanner is operating with a high workload thus requiring a high demand of current.

The scanning device comprises one or more light projectors configured to generate an illumination pattern to be projected on a three-dimensional dental arch during a scanning session. The light projector(s) preferably comprises a light source, a mask having a spatial pattern, and one or more lenses such as collimation lenses or projection lenses. The light source may be configured to generate light of a single wavelength or a combination of wavelengths (mono- or polychromatic). The combination of wavelengths may be produced by using a light source configured to produce light (such as white light) comprising different wavelengths. Alternatively, the light projector(s) may comprise multiple light sources such as LEDs individually producing light of different wavelengths (such as red, green, and blue) that may be combined to form light comprising the different wavelengths. Thus, the light produced by the light source may be defined by a wavelength defining a specific color, or a range of different wavelengths defining a combination of colors such as white light. In an embodiment, the scanning device comprises a light source configured for exciting fluorescent material of the teeth to obtain fluorescence data from the dental arch. Such a light source may be configured to produce a narrow range of wavelengths. In another embodiment, the light from the light source is infrared (IR) light, which is capable of penetrating dental tissue. The light projector(s) may be DLP projectors using a micro mirror array for generating a time varying pattern, or a diffractive optical element (DOF), or back-lit mask projectors, wherein the light source is placed behind a mask having a spatial pattern, whereby the light projected on the surface of the dental arch is patterned. The back-lit mask projector may comprise a collimation lens for collimating the light from the light source, said collimation lens being placed between the light source and the mask. The mask may have a checkerboard pattern, such that the generated illumination pattern is a checkerboard pattern. Alternatively, the mask may feature other patterns such as lines or dots, etc.

The scanning device preferably further comprises optical components for directing the light from the light source to the surface of the dental arch. The specific arrangement of the optical components depends on whether the scanning device is a focus scanning apparatus, a scanning device using triangulation, or any other type of scanning device. A focus scanning apparatus is further described in EP 2 442 720 Bl by the same applicant, which is incorporated herein in its entirety.

The light reflected from the dental arch in response to the illumination of the dental arch is directed, using optical components of the scanning device, towards the image sensor(s). The image sensor(s) are configured to generate a plurality of images based on the incoming light received from the illuminated dental arch. The image sensor unit may be a high-speed image sensor such as an image sensor configured for acquiring images with exposures of less than 1/1000 second or frame rates in excess of 250 frames pr. second (fps). As an example, the image sensor may be a rolling shutter (CCD) or global shutter sensor (CMOS). The image sensor(s) may be a monochrome sensor including a color filter array such as a Bayer filter and/or additional filters that may be configured to substantially remove one or more color components from the reflected light and retain only the other non-removed components prior to conversion of the reflected light into an electrical signal. For example, such additional filters may be used to remove a certain part of a white light spectrum, such as a blue component, and retain only red and green components from a signal generated in response to exciting fluorescent material of the teeth.

The network unit may be configured to connect the dental scanning system to a network comprising a plurality of network elements including at least one network element configured to receive the processed data. The network unit may include a wireless network unit or a wired network unit. The wireless network unit is configured to wirelessly connect the dental scanning system to the network comprising the plurality of network elements including the at least one network element configured to receive the processed data. The wired network unit is configured to establish a wired connection between the dental scanning system and the network comprising the plurality of network elements including the at least one network element configured to receive the processed data.

The dental scanning system preferably further comprises a processor configured to generate scan data (such as extra-oral scan data and/or intra-oral scan data) by processing the two-dimensional (2D) images acquired by the scanning device. The processor may be part of the scanning device. As an example, the processor may comprise a Field- programmable gate array (FPGA) and/or an Advanced RISC Machines (ARM) processor located on the scanning device. The scan data comprises information relating to the three- dimensional dental arch. The scan data may comprise any of: 2D images, 3D point clouds, depth data, texture data, intensity data, color data, and/or combinations thereof. As an example, the scan data may comprise one or more point clouds, wherein each point cloud comprises a set of 3D points describing the three-dimensional dental arch. As another example, the scan data may comprise images, each image comprising image data e.g. described by image coordinates and a timestamp (x, y, t), wherein depth information can be inferred from the timestamp. The image sensor(s) of the scanning device may acquire a plurality of raw 2D images of the dental arch in response to illuminating said object using the one or more light projectors. The plurality of raw 2D images may also be referred to herein as a stack of 2D images. The 2D images may subsequently be provided as input to the processor, which processes the 2D images to generate scan data. The processing of the 2D images may comprise the step of determining which part of each of the 2D images are in focus in order to deduce/generate depth information from the images. The internal depth information may be used to generate 3D point clouds comprising a set of 3D points in space, e.g., described by cartesian coordinates (x, y, z). The 3D point clouds may be generated by the processor or by another processing unit. Each 2D/3D point may furthermore comprise a timestamp that indicates when the 2D/3D point was recorded, i.e., from which image in the stack of 2D images the point originates. The timestamp is correlated with the z-coordinate of the 3D points, i.e., the z-coordinate may be inferred from the timestamp. Accordingly, the output of the processor is the scan data, and the scan data may comprise image data and/or depth data, e.g. described by image coordinates and a timestamp (x, y, t) or alternatively described as (x, y, z). The scanning device may be configured to transmit other types of data in addition to the scan data. Examples of data include 3D information, texture information such as infra-red (IR) images, fluorescence images, reflectance color images, x-ray images, and/or combinations thereof.

The examples illustrated in the below figures may be performed by one or more processors.

FIGS. 1 A to 1C illustrate different examples of an intraoral scanning system 1, which includes three different handheld intraoral scanners 1. The system 1 is configured to determine a three-dimensional (3D) model of a dental object. The system 1 includes a projector unit 7, an image sensor unit 5 and one or more processors 11. The projector unit 7 is configured to emit a first visible light, a second visible light and infrared light during a scan sequence, wherein the emitted first visible light includes an illumination pattern. The image sensor unit 5 is configured to acquire two-dimensional visible images based on the first visible light and the second visible light and/or two-dimensional infrared images based on the infrared light from the dental object. The one or more processors 11 is configured to control the projector unit 7 and/or the image sensor unit 5 according to a plurality of scan sequence schedules, wherein each of the plurality of scan sequence schedules includes timing of the projector unit and/or the image sensor. The one or more processors is configured to determine a 3D model of the dental object based on the two- dimensional visible images that includes the first visible light, and wherein the one or more processors is configured to shift between each of the plurality of scan sequence schedules. The handheld intraoral scanner 1 in FIG. 1 A is based on a focus scanning principle which includes a movable focus lens 60 along an optical axis of the scanner 1. The focus lens 60 is movable in both directions along the optical axis. In FIG. IB the handheld intraoral scanner 1 is based on triangulation scanning principle wherein the image sensor unit 5 and the projector unit 7 are arranged according to the scanning principle. In both FIGS. 1 A and IB, the image sensor unit 5 and the projector unit 7 are arranged in a main housing 3. In FIG. 1C the image sensor unit 5 and the projector unit 7 are arranged in a tip housing 2. In this example, the projector unit include multiple light sources 7, and the image sensor unit 5 includes multiple cameras 5. The scanning principle in FIG. 1C is based on triangulation.

FIGS. 2 A to 2C illustrate different examples of a plurality of scan sequence schedules (25A,25B,25C). FIG. 2A illustrates an example of a 3D scan sequence schedule 25A wherein all time slots 20 is configured to emit and acquire first visible light with an illumination pattern for determining three-dimensional model. In each of the time slots the projector unit 7 emits the first visible light with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object. Additionally, in each of the time slots the image sensor unit 5 acquire two-dimensional visible images. In each of the time slots, the one or more processors 11 is configured to process the 3D model determined based one the two-dimensional visible images. FIG. 2B illustrates an example of an ultraviolet scan sequence schedule 25B. In this example, the time slots 20 are configured to emit first visible light 21 A for determining a 3D model of a dental object and then to emit second visible light 2 IB for acquiring two-dimensional fluorescent images. In this example, the projector unit 7 is configured to switch between emitting the first visible light 21 A in a first time slot and emitting the second visible light 2 IB in a second time slot. In the respective time slots 20, two-dimensional visible images with fluorescent wavelengths are acquired 21B, and two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object are acquired 21 A. In the respective time slots 20 the one or more processors is configured to process the acquired two-dimensional visible images including fluorescent wavelengths 21B, and to process the acquired two-dimensional visible images with wavelengths between 400 nm and 750 nm 21A for determining the 3D model of the dental object. The FIG. 2C illustrates an example of a hyperspectral scan sequence schedule 25C. In this example, the time slots 20 are configured to emit first visible light 21 A, emit second visible light 2 IB, and infrared light 21C, in another example the arrangement of the time slots may include following sequence, 3D, UV, 3D, IR and 3D, and then this sequence will be repeated. For example, the sequence will be repeated in a Round robin manner. In this example, the projector unit 7 is configured to switch between emitting the first visible light 21 A in a first time slot, emitting the second visible light 21B in a second time slot, and emitting the infrared light 21C in a third slot. In the respective time slots 20, two- dimensional visible images with fluorescent wavelengths are acquired 21B, two- dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object are acquired 21A, and infrared images is acquired 21C. Furthermore, the visible images with fluorescent wavelengths and the two-dimensional visible images with wavelengths between 400 nm and 750 are combined with the acquired infrared images for determining a composed scan image. The order of the time slots may be changed such that the first time slot 21 A may include emitting and acquiring infrared light, the second time slot 2 IB may include emitting and acquiring the first visible light, and the third time slot 21C may include emitting the second visible light and acquiring fluorescent light excited by the second visible light. In the respective time slots 20 in FIG. 2C the one or more processors is configured to process the acquired two-dimensional visible images including fluorescent wavelengths 21B, the acquired two-dimensional visible images with wavelengths between 400 nm and 750 nm 21B for determining the 3D model of the dental object, and the infrared images.

FIGS. 3A to 3C illustrate different examples of a plurality of scan sequence schedules (25A,25B,25C) wherein the processing 22 in each time slots 20 includes down-sampling (Down) of the acquired images 21. In FIG. 3C, the processing 22 in each time slots 20 includes color space conversions (YUV) of the images 21 of the corresponding time slots 20, and especially, for the time slots 20 that includes emitting UV light, the processing 22 includes a combination of down-sampling and color conversions (YUV+Down). The one or more processors is configured to process the acquired 21 two-dimensional visible images and/or the two-dimensional infrared images by down-sample 22 the acquired images and/or by color space conversion 22 the acquired images, wherein the color space conversion includes converting the images from a first color space model into a second color space model, or vice versa. The first color space model includes a Red-Green-Blue (RGB) color space model, and the second color space model includes a Y(brightness) and UV(deviation from color grey) (YUV) color space model. The conversion into YUV color space is for using a H.265 compression protocol of the 3D, IR and UV time slots in the hyperspectral scan sequence schedule 25C.

In an example wherein the intraoral scanning system 1 includes a focus lens 60 wherein the focus lens is configured to move in a first and a second direction, and wherein the first direction is opposite to the second direction. Each of the time slots is configured to emit and acquire light 21, and processing 22 the light/image when the focus lens is moving in the first direction 40A. Each of the time slots is further configured to emit and acquire light 23, and processing 24 the light/image when the focus lens 60 is moving in an opposition direction 40B, see FIGS. 4A to 4C. In the examples illustrated in FIGS. 4A to 4C, the image sensor unit 5 is configured to, according to the plurality of scan sequence schedules, acquire (21,23) the two-dimensional visible images while the focus lens is moving in the first direction and then in the second direction. Especially, for FIG. 4C, the image sensor unit 5 is configured to, according to the plurality of scan sequence schedules, acquire (21,23) the two-dimensional visible images and the two-dimensional infrared images while the focus lens is moving in the first direction and then in the second direction. The sequence of the time slots 23 in the second direction for FIG. 4B is UV, 3D,UV,3D, UV, and the sequence of the time slots 23 in the second direction for FIG. 4C is UV, 3D, IR,3D, and UV.

FIGS. 5A and 5B illustrate different examples of a main sequence schedule 50 that includes a plurality of scan sequence schedules (25,25A,25B,25C). In both examples, the plurality of scan sequence schedules (25,25A,25B,25C) is arranged in the main sequence schedule 50, wherein the one or more processors 11 is configured to change between each of the plurality of scan sequence schedules (25,25A,25B,25C) based on the main sequence schedule 50. The plurality of scan sequence schedules is arranged in the main sequence schedule based on a Round robin principle. In the specific example of FIG. 5A, a first time slot 20A includes a 3D scan sequence schedule (25A,3D-SS), and a second time slot 20B includes yet another 3D scan sequence schedule (25A, 3D-SS). A third time slot 20C includes an ultraviolet scan sequence schedule 25B and a sixth time slot 20D includes a hyperspectral scan sequence schedule 25C. The system may include a user interface that is configured to arrange or re-arrange two or more of the plurality of scan sequence schedules (25,25A,25B,25C) in the main sequence schedule 50. FIG. 5B includes a main sequence schedule 50 wherein the arrangement of the plurality of scan sequence schedule (25,25A,25B) includes the 3D scan sequence schedule 25A and the ultraviolet scan sequence schedule 25B. Another example of the main sequence schedule 50 would include four times 3D-SS scan sequence schedules followed by a IR-SS scan sequence schedule and three times 3D-SS scan sequence schedules. The main sequence schedule may be repeated numerous of times in for example a Roub robin manner.

FIGS. 6 A and 6B illustrate an intraoral scanning system 1 which includes a focus lens 60. In FIG. 6B, the plurality of scan sequence schedules focus 25 includes a focus scan sequence schedule 25D, wherein the focus scan sequence schedule 25C includes time slots 21 that is timed by a focus position (Pl, P2) of the focus lens 60 in at least the first direction 40A and/or the second direction 40B. In this specific example, the one or more processors 11 is configured to control the projector unit 7, the image sensor unit 5 and the one or more processors 11 based on the focus scan sequence schedule 25D, wherein the projector unit emits first visible light 21 A for determining a 3D model a dental object until the focus lens reach a focus position P2. According to the focus scan sequence schedule 25D, the one or more processors 11 is triggered 20’ by the focus position P2 to emit and acquire infrared light /images 21B preceding to emitting the first visible light 21B’ and the second visible light 21B” in respective time slots 20.

The time slots 20’ of the focus scan sequence schedule 25D are configured to acquire a set of images (21B,21B’,21B”) that includes the two-dimensional visible images 21B’ with wavelengths between 400 nm and 750 nm, the two-dimensional visible images 21B” with fluorescent wavelengths from the dental object, and the two-dimensional infrared images 21 with a wavelength between 850 nm and 1100 nm. The focus scan sequence schedule 25D includes a group of time slots 20’ that is enabled by the focus position P2, wherein the group of time slots 20’ include a first time slot configured for emitting the infrared light 2 IB, a second time slot configured for emitting the first visible light 21B’, and a third time slot configured for emitting the second visible light 21B”. The time slots for emitting the first visible light 21 A are assigned to another group of time slots 20 of the focus scan sequence schedule 25D. FIG 6C illustrates an example of the main sequence schedule wherein the hyperspectral scan sequence schedule 25C is enabled (20’) as the focus lens 60 has reached the focus position P2.

The focus lens 60 may be moved in the first direction 40A from an initial position (Pinit) to an end position (Pend), and a full sweep of the focus lens 60 is when the focus lens has moved from the initial position (Pinit) to the end position (Pend), or vice versa when moving in a second direction. The focus position P2 is determined by the one or more processors 1 during a first sweep of the focus lens, wherein the first sweep and the grouped time slots 20’ of the focus scan sequence schedule 25D is enabled at the focus position P2 during a subsequently sweep to the first sweep.

The focus position P2 is determined by the one or more processors 11 during a first full sweep of the focus lens 60, and the grouped time slots 20’ of the focus scan sequence schedule 25D is enabled at the focus position during a subsequently full sweep to the first sweep.

In FIG. 6D, the trigger signal 20’ is determined by the one or more processors 11 when the focus lens 60 of the focusing unit is positioned at a position P2 where a specific part of an acquired two-dimensional visible image (71 A,71B) is in focus. The information of the images are divided into an array of pixels, and in this specific example, the focus position P2 is determined when a central part of the array of pixels are in focus. At a focus position Pl the central part of the array of pixels are not in focus.

FIG. 7 illustrates an example of the intraoral scanning system 1, wherein the one or more processors 11 are arranged in a handheld intraoral scanner 100, and external computer 202, and a server 204. In this specific example, the handheld intraoral scanner 100 is configured to communicate with the server 204 and the external computer 202 via a wireless link 95. In another example, the communication 95 may be via a wired link.

Although some embodiments have been described and shown in detail, the disclosure is not restricted to such details, but may also be embodied in other ways within the scope of the subject matter defined in the following claims. In particular, 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 invention.

Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s)/ unit(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or components/ elements of any or all the claims or the invention. The scope of the invention is accordingly to be limited by nothing other than the appended claims, in which reference to an component/ unit/ element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” A claim may refer to any of the preceding claims, and “any” is understood to mean “any one or more” of the preceding claims.

It is intended that the structural features of the devices described above, either in the detailed description and/or in the claims, may be combined with steps of the method, when appropriately substituted by a corresponding process.

As used, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (i.e. to have the meaning “at least one”), unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element but an intervening elements may also be present, unless expressly stated otherwise. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or" includes any and all combinations of one or more of the associated listed items. The steps of any disclosed method is not limited to the exact order stated herein, unless expressly stated otherwise.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" or “an aspect” or features included as “may” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the disclosure. The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects.

The claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more.

ITEMS

1. An intraoral scanning system configured to determine a three-dimensional (3D) model of a dental object, the intraoral scanning system comprising:

• a projector unit configured to emit a first visible light, a second visible light and infrared light during a scan sequence, wherein the emitted first visible light includes an illumination pattern, • an image sensor unit configured to acquire two-dimensional visible images based on the first visible light and the second visible light and/or two-dimensional infrared images based on the infrared light from the dental object, and

• one or more processors configured to control the projector unit and/or the image sensor unit according to a plurality of scan sequence schedules, wherein each of the plurality of scan sequence schedules includes timing of the projector unit and/or the image sensor, and wherein the one or more processors is configured to determine a 3D model of the dental object based on the two-dimensional visible images that includes the first visible light, and wherein the one or more processors is configured to shift between each of the plurality of scan sequence schedules.

2. The intraoral scanning system according to item 1, comprising a focusing lens unit configured to change focus during the scan sequence by moving a focus lens of the focusing lens unit, wherein the focus lens is configured to move in a first direction, and wherein the image sensor unit is configured to acquire, via the focus lens and while the focus lens is moving at least in the first direction, two-dimensional visible images and/or two-dimensional infrared images.

2B. The intraoral scanning system according to item 1, wherein the timing of the projector and/or the image sensor unit includes timing of when to emit the first visible light and the infrared light, and/or, timing of when to acquire the two-dimensional visible images and/or the two-dimensional infrared images.

2C. The intraoral scanning system according to any of the previous items, wherein the one or more processors is configured to process the acquired two-dimensional visible images and the two-dimensional infrared images according to the plurality of scan sequence schedules. 3. The intraoral scanning system according to any of the previous items, wherein the focus lens is configured to move in a second direction, and wherein the first direction is opposite to the second direction.

4. The intraoral scanning system according to any of the previous items, wherein the image sensor unit is configured to, according to the plurality of scan sequence schedules, acquire the two-dimensional visible images and the two-dimensional infrared images while the focus lens is moving in the first direction and then in the second direction.

5. The intraoral scanning system according to any of the previous items, wherein each of the plurality of scan sequence schedules include time slots for emitting the first visible light, the second visible light and/or the infrared light by the projector unit.

6. The intraoral scanning system according to any of the previous items, wherein each of the plurality of scan sequence schedules include time slots for acquiring the two- dimensional visible images and/or the two-dimensional infrared images via the image sensor unit.

7. The intraoral scanning system according to any of the previous items, wherein each of the plurality of scan sequence schedules include time slots for processing the acquired two-dimensional visible images and/or the two-dimensional infrared images.

8. The intraoral scanning system according to any of the previous items, wherein the timing of the time slots is based on a round robin principle.

9. The intraoral scanning system according to any of the previous items, wherein the plurality of scan sequence schedules includes two or more of following schedules:

• a 3D scan sequence schedule that includes time slots for emitting the first visible light with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental obj ect,

10. The intraoral scanning system according to any of the previous items, wherein the plurality of scan sequence schedules includes two or more of following schedules:

• a 3D scan sequence schedule that includes time slots for acquiring the two- dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object,

• a hyperspectral scan sequence schedule that includes time slots for acquiring the two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, the two-dimensional visible images with fluorescent wavelengths from the dental object, and the two- dimensional infrared images with a wavelength between 850 nm and 1100 nm.

11. The intraoral scanning system according to any of the previous items, wherein the plurality of scan sequence schedules includes two or more of following schedules:

• an ultraviolet scan sequence schedule includes timing for the one or more processors to process the acquired two-dimensional visible images including fluorescent wavelengths from the dental object provided by the second visible light, and to process the acquired two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object,

12. The intraoral scanning system according to any of the previous items, wherein the one or more processors is configured to process the acquired two-dimensional visible images and/or the two-dimensional infrared images by down-sample the acquired images and/or by color space conversion the acquired images, wherein the color space conversion includes converting the images from a first color space model into a second color space model, or vice versa.

13. The intraoral scanning system according to any of the previous items, wherein the first color space model includes a Red-Green-Blue (RGB) color space model, and the second color space model includes a Y(brightness) and UV(deviation from color grey) (YUV) color space model.

14. The intraoral scanning system according to any of the previous items, comprising a user interface configured to receive a user input on a mode of operation of the intraoral scanning system, wherein the mode of operation selects one or more of the plurality of scan sequence schedules.

15. The intraoral scanning system according to item 14, wherein the mode of operation is one or more of following modes:

• a three-dimensional mode that includes the 3D scan sequence schedule, and a fourth mode that includes two or more of the first diagnostic mode, the second diagnostic mode and the three-dimensional mode.

Hyper focus schedule:

16. The intraoral scanning system according to any of the previous items, wherein the plurality of scan sequence schedules includes a focus scan sequence schedule, wherein the focus scan sequence schedule includes time slots that is timed by a focus position of the focus lens in at least the first direction and/or the second direction.

17. The intraoral scanning system according to any of the previous items, wherein the time slots are for acquiring the two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, the two- dimensional visible images with fluorescent wavelengths from the dental object, and the two-dimensional infrared images with a wavelength between 850 nm and 1100 nm.

18. The intraoral scanning system according to any of the previous items, wherein the one or more processors is configured to control the projector unit to emit a sequence of light that includes a group of time slots of the focus scan sequence schedule at the focus position of the focus lens, wherein the group of time slots include a first time slot for emitting the infrared light, a second time slot for emitting the first visible light, and a third time slot for emitting the second visible light.

19. The intraoral scanning system according to any of the previous items, wherein the focus scan sequence schedule is configured to emit the first visible light when the sequence of light that includes the group of time slots has not been initiated by the position of the focus lens.

20. The intraoral scanning system according to any of the previous items, wherein the focus position of the focus lens is determined by the one or more processors, and at the focus position a specific group of pixels of one of the acquired two-dimensional visible images is in focus, wherein the focus is determined by an intensity of the specific group of pixels. 21. The intraoral scanning system according to any of the previous items, wherein the specific group of pixels includes pixels of the one of the acquired two-dimensional visible images that are arranged in a center of the one of the acquired two-dimensional visible images.

22. The intraoral scanning system according to any of the previous items, wherein the one or more processors is configured to change from a 3D scan sequence schedule of the plurality of scan sequence schedules to a hyperspectral scan sequence schedule of the plurality of scan sequence schedules based on a trigger signal.

23. The intraoral scanning system according to any of the previous items, wherein the trigger signal is determined by the one or more processors when the focus lens of the focusing unit is positioned at a position where a specific part of an acquired two- dimensional visible image is in focus.

24. The intraoral scanning system according to any of the previous items, wherein the one or more processors is configured to change from the hyperspectral scan sequence schedule to the 3D scan sequence schedule when finalized the hyperspectral scan sequence schedule.

25. The intraoral scanning system according to any of the previous items, wherein the plurality of scan sequence schedules is arranged in a main sequence schedule, wherein the one or more processors is configured to change between each of the plurality of scan sequence schedules based on the main sequence schedule.

26. The intraoral scanning system according to any of the previous items, wherein the plurality of scan sequence schedules is arranged in the main sequence schedule based on a Round robin principle. 27. The intraoral scanning system according to any of the previous items, comprising a user interface configured to arrange or re-arrange two or more of the plurality of scan sequence schedules in the main sequence schedule. 28. The intraoral scanning system according to any of the previous items, wherein each of the plurality of scan sequence schedules includes at least 3 time slots.

Claims

• a projector unit configured to emit a first visible light, a second visible light and infrared light during a scan sequence, wherein the emitted first visible light includes an illumination pattern,

• an image sensor unit configured to acquire two-dimensional visible images based on the first visible light and the second visible light and/or two-dimensional infrared images based on the infrared light from the dental object,

• a focusing lens unit configured to change focus during the scan sequence by moving a focus lens of the focusing lens unit, wherein the focus lens is configured to move in a first direction and a second direction, and wherein the image sensor unit is configured to acquire, via the focus lens and while the focus lens is moving in the first direction and in the second direction, two-dimensional visible images and/or two-dimensional infrared images, and

2. The intraoral scanning system according to claim 1, wherein a frame rate of the image sensor unit is different when the focusing lens is moving in the first and second directions.

3. The intraoral scanning system according to claim 2, wherein the first direction is opposite to the second direction.

4. The intraoral scanning system according to any of the previous claims, wherein the image sensor unit is configured to, according to the plurality of scan sequence schedules, acquire the two-dimensional visible images and the two-dimensional infrared images while the focus lens is moving in the first direction and then in the second direction.

5. The intraoral scanning system according to any of the previous claims, wherein each of the plurality of scan sequence schedules include time slots for emitting the first visible light, the second visible light and/or the infrared light by the projector unit.

6. The intraoral scanning system according to any of the previous claims, wherein each of the plurality of scan sequence schedules include time slots for acquiring the two- dimensional visible images and/or the two-dimensional infrared images via the image sensor unit.

7. The intraoral scanning system according to any of the previous claims, wherein each of the plurality of scan sequence schedules include time slots for processing the acquired two-dimensional visible images and/or the two-dimensional infrared images.

8. The intraoral scanning system according to any of claims 5 to 7, wherein the timing of the time slots is based on a round robin principle.

9. The intraoral scanning system according to any of the previous claims, wherein the plurality of scan sequence schedules includes two or more of following schedules:

• an ultraviolet scan sequence schedule that includes time slots for emitting the first visible light with wavelengths between 400 nm and 750 nm and the second visible light with a wavelength between 350 nm and 450 nm emitted by the projector unit, • a hyperspectral scan sequence schedule that includes time slots for emitting the first visible light with wavelengths between 400 nm and 750 nm, the second visible light with a wavelength between 350 nm and 450 nm, and the infrared light with a wavelength between 850 nm and 1100 nm.

10. The intraoral scanning system according to any of the previous claims, wherein the plurality of scan sequence schedules includes two or more of following schedules:

11. The intraoral scanning system according to any of the previous claims, wherein the plurality of scan sequence schedules includes two or more of following schedules:

• an ultraviolet scan sequence schedule includes timing for the one or more processors to process the acquired two-dimensional visible images including fluorescent wavelengths from the dental object provided by the second visible light, and to process the acquired two-dimensional visible images with wavelengths between 400 nm and 750 nm for determining the 3D model of the dental object, • a hyperspectral scan sequence schedule that includes timing for the one or more processors to process the acquired two-dimensional visible images including wavelengths between 400 nm and 750 nm, the acquired two-dimensional visible images including fluorescent wavelengths from the dental object, and the acquired two-dimensional infrared images with a wavelength between 850 nm and 1100 nm.

12. The intraoral scanning system according to any of the previous claims, wherein the plurality of scan sequence schedules includes a focus scan sequence schedule, wherein the focus scan sequence schedule includes time slots that is timed by a focus position of the focus lens in at least the first direction and/or the second direction.

13. The intraoral scanning system according to claim 12, wherein the time slots of the focus scan sequence schedule are configured to acquire a set of images that includes the two-dimensional visible images with wavelengths between 400 nm and 750 nm, the two- dimensional visible images with fluorescent wavelengths from the dental object, and the two-dimensional infrared images with a wavelength between 850 nm and 1100 nm.

14. The intraoral scanning system according to any of claims 12 and 13, wherein the focus scan sequence schedule includes a group of time slots that is enabled by the focus position, wherein the group of time slots include a first time slot configured for emitting the infrared light, a second time slot configured for emitting the first visible light, and a third time slot configured for emitting the second visible light.

15. The intraoral scanning system according to claim 14, wherein the focus scan sequence schedule includes another group of time slots that is configured for emitting the first visible light when the group of time slots is not enabled.