Sheath and system for tip of scanning device

Abstract

In a first aspect, the present invention provides a sheath for an intra-oral scanning tip, wherein the polarization is substantially not altered during scanning.

Description

Technical Field

[0001] The present invention generally relates to a sheath for a tip of a scanning device, which allows 3D scanning of cavities inside the human body, such as the oral cavity and / or the ear cavity, without contaminating the scanning device from the external environment. Background Art

[0002] In the field of 3D scanning, in particular 3D scanning of cavities inside the human body, such as the oral cavity and / or the ear cavity, contamination of scanning devices is well known.

[0003] Typically, when, for example, 3D scanning teeth inside the oral cavity, an intraoral scanning device with a tip needs to be placed inside the oral cavity. This exposes the tip to various bacteria of the first patient. Therefore, to scan another patient, the tip must be free of the bacteria of the first patient. This problem can be solved by having a disposable tip, so that for each patient the entire tip is replaced by another disposable tip. This solution may be associated with quite high costs, since the tip itself may include high-cost elements, such as reflective elements and / or electronics. Therefore, another solution to this problem may be to sterilize the tip between patients, for example by an autoclave. This solution requires that the tip is configured for autoclaving and is therefore also a rather expensive solution.

[0004] Generally, disposable sheaths for devices such as endoscopes are known. Such disposable sheaths are known to have low-cost optical elements, such as optical windows. Such disposable sheaths allow imaging of, for example, internal tissue of the human body through the optical window, so that the endoscope is not contaminated by the external environment. A sheath for an endoscope is disclosed in US 2017 / 0290492.

[0005] However, 3D scanning is generally very different from endoscopic imaging, as scanners generally require a light source to project light into a human cavity through the same optical element that is also used for imaging. Endoscopes also generally have separate light sources that may be located outside of the optical window. However, endoscopes such as disclosed in US2017 / 0290492 have optics for illumination and imaging that are located on the distal side of the endoscope and covered by a sheath.

[0006] Because 3D scanning usually requires a light source to project light into a person's cavity through the same optical element that is also used for imaging, a 3D scanning device may be very sensitive to any object in the light path. If the path of light is blocked even by a transparent surface, the scanning device may be subject to internal reflections of light emitted by the light source inside the scanning device. Internal reflections may affect imaging during the scanning process and appear as one or more oversaturated bright spots on the acquired image, thereby reducing the quality of the 3D data. One solution to avoid internal reflections is through the use of anti-reflective coatings. Such coatings may also be associated with high costs.

[0007] In addition, since 3D intraoral scanning typically requires a light source to project light into a person's cavity through the same optical elements that are also used for imaging, and requires imaging of translucent objects (such as teeth), 3D scanning devices may rely on a specific polarization. Changing polarization may seriously affect image acquisition and model construction of 3D models. Polarization is usually not a problem when using an endoscope because only 2D images are of interest. In addition, endoscopes typically image all reflections, not just specular reflections from teeth in the mouth, for example. Therefore, 3D intraoral scanners have higher requirements for optics than those required in 2D imaging endoscopes. One solution to avoid changing the polarization of a 3D scanning device is to not insert optical elements into the path of the intraoral scanning device. However, this solution may cause the intraoral scanning device to be contaminated.

[0008] Therefore, there is a need for a low-cost solution to provide a sheath for an intra-oral scanning tip, at least such that the polarization does not change during scanning, and at the same time does not contaminate the scanning device. Summary of the invention

[0009] In a first aspect, the present invention provides a sheath for a scanning tip, wherein the polarization is substantially not altered during scanning.

[0010] In a first aspect, the present invention provides a sheath configured to be replaceably mounted to at least a portion of a tip of an intraoral scanning device, thereby being configured to be used in conjunction with the intraoral scanning device to scan the interior of the oral cavity.

[0011] The sheath includes a hollow body including a distal sheath end, a proximal sheath end, and a sheath sidewall therebetween, wherein the proximal sheath end defines a sheath opening sized relative to at least a portion of the tip.

[0012] In addition, the sheath includes an optical window mounted to or located in the sheath sidewall near the distal sheath end such that when the sheath is replaceably mounted to at least a portion of the tip through the sheath opening, the optical window covers at least a portion of the optical aperture of the tip.

[0013] The optical window is made of a material configured to not substantially alter the polarization of light exiting and entering the intraoral scanning device through the optical aperture of the tip and arriving and coming from the intraoral cavity through the optical window. Thus, the optical window ensures that the scanning device provides substantially the same scan of the intraoral cavity regardless of whether the sheath is replaceably mounted to at least a portion of the tip.

[0014] In a most preferred embodiment of the first aspect, the thickness of the optical window is greater than 400 microns. Thus, in most embodiments, the optical window is non-flexible, meaning that the optical window will not bend or similarly deform when mounted to or located in the jacket sidewall, at least not easily. However, it should be understood that the optical material can be made of a material that is defined as flexible in certain circumstances. For example, if a high pressure is applied to an optical window having a thickness greater than 400 microns, the window may bend or similarly deform in such circumstances.

[0015] As provided in the first aspect, the present invention allows 3D intraoral scanning to be performed using a 3D intraoral scanning device including an internal light source, which projects light and acquires images through the same optical element, so that internal reflections are not acquired during scanning and / or polarization is not changed during scanning, and at the same time, the scanning device is not contaminated by the external environment.

[0016] Contamination is avoided because the optical window can also be sealed and thus have no access into the hollow body.According to the invention, the optical window is located on or mounted to the jacket side wall, whereby the scanning device can scan sideways instead of in a forward direction.

[0017] Furthermore, the proximal sheath end of the hollow body may comprise a closed surface, making it impossible to contaminate from the outside through the proximal sheath end. Furthermore, the sheath, i.e. the hollow body, may be replaceably mounted around at least a portion of the tip of the scanning device, thereby reducing contamination even further. In some embodiments, the hollow body may also be replaceably mounted around a portion of the scanning device, and in some embodiments, around the entire scanning device. This allows also to avoid contamination of the intraoral scanning device. In particular, by having the hollow body cover the tip and a portion of the intraoral scanning device, contamination of the portion between the intraoral scanning device and the tip is avoided.

[0018] In most embodiments, the sheath according to the present invention is configured to be disposable and configured for single use.Therefore, the sheath can be made of environmentally friendly materials.

[0019] In a second aspect, the present invention provides a system of an intraoral scanning device, the system comprising: a tip of the intraoral scanning device, the tip comprising an optical orifice; and a sheath configured to be replaceably mounted to at least a portion of the tip of the intraoral scanning device, thereby being configured to be used in conjunction with the scanning device to scan the oral cavity.

[0020] The sheath includes a hollow body including a distal sheath end, a proximal sheath end, and a sheath sidewall therebetween, wherein the proximal sheath end defines a sheath opening sized relative to at least a portion of the tip.

[0021] In addition, the sheath includes an optical window mounted to or located in the sheath sidewall near the distal sheath end such that when the sheath is replaceably mounted to at least a portion of the tip through the sheath opening, the optical window covers at least a portion of the optical aperture of the tip.

[0022] The optical window is made of a material configured to not substantially alter the polarization of light exiting and entering the intraoral scanning device through the optical aperture of the tip and arriving and coming from the intraoral cavity through the optical window. Thus, the optical window ensures that the scanning device provides substantially the same scan of the intraoral cavity regardless of whether the sheath is replaceably mounted to at least a portion of the tip. In a most preferred embodiment of the second aspect, the thickness of the optical window is greater than 400 microns.

[0023] The inventors of the present invention have realized that the optimal thickness of the optical window is greater than 400 microns, because when greater than this thickness, the optical window is able to cover the field of view typically used in intraoral scanning without deforming during intraoral scanning. If the optical window is less than 400 microns, the optical window may be easily bent, and this may cause the optical window to introduce internal reflections, which may impair the imaging quality of the intraoral scanning device. In some cases, when much less than 400 microns, the optical window may even produce ripples, which can seriously impair the imaging quality of the intraoral scanning device. Therefore, the inventors have found that a thickness greater than 400 microns is the optimal thickness to provide optimal imaging in the intraoral scanning device. In addition, the inventors have realized that a thickness greater than 400 microns can also ensure that the optical window will not break during scanning. For example, when using an intraoral scanning device for intraoral scanning, the scanning tip often contacts the teeth, sometimes even with sharp teeth, and if there is a window less than 400 microns, the window is easily broken and split into the patient's mouth. In some cases, when much less than 400 microns, the optical window may even be pierced or broken. This situation must be avoided, so a solution to this situation may be to provide the optical window with a thickness greater than 400 microns. However, as previously mentioned, in intraoral scanning, the introduction of an optical window with a thickness greater than 400 microns may cause many materials to change the polarization of the emitted light, which may have a serious impact on image acquisition, but most importantly, on the model construction of the 3D model. Therefore, the present invention requires that the optical window is made of a material that is configured to substantially not change the polarization. This is also true when introducing a window with a thickness greater than 400 microns. In many cases where materials with a thickness less than 400 microns may not change the polarization, many materials with a thickness greater than 400 microns may actually change the polarization. Therefore, when introducing a window with a thickness greater than 400 microns, the material must be carefully selected so that it does not substantially change the polarization and / or introduce internal reflections. Therefore, when introducing a window with a thickness greater than 400 microns, the impact of the selected material and the thickness of the optical window must be carefully considered at the same time. Various such considerations and embodiments of the present invention are given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or other objects, features and advantages of the present disclosure are further described by the following illustrative and non-limiting detailed description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0025] Figure 1 An example of a flexible sheath is shown.

[0026] Figure 2 An example of an optical window is shown.

[0027] Figure 3 An example of a tip of a scanning device is shown.

[0028] Figure 4 An example of a tip of a scanning device is shown.

[0029] Figure 5 An example of a system including a sheath for the tip of a scanning device is shown.

[0030] Figure 6 An example of a system including a sheath for the tip of a scanning device is shown.

[0031] Figure 7 An example of a semi-flexible sheath is shown.

[0032] Figure 8 An example of an optical window of a sheath is shown.

[0033] Fig. 9 An example of a tip of a scanning device is shown.

[0034] Fig.10 An example of a system including a sheath for the tip of a scanning device is shown.

[0035] Fig.11 An example of a one-piece molded boot is shown. DETAILED DESCRIPTION

[0036] Optical Window

[0037] In an embodiment, the thickness of the optical window is greater than 600 microns, or greater than 800 microns, or greater than 1000 microns. The inventors have found that when these thicknesses are introduced, the optical window becomes more stable and less prone to cracking, especially when used for intraoral scanning of the oral cavity by an intraoral scanner having the sheath of the present invention thereon.

[0038] Introducing an optical window with considerable thickness in an intraoral scanning device, in particular on the tip of the intraoral scanning device, will of course also make the tip thicker. Thus, in another embodiment, for example in order not to cause too much discomfort to the patient during scanning, the thickness may be between 400 microns and 5000 microns. In a preferred embodiment, the thickness may be between 800 microns and 2000 microns.

[0039] In the most preferred embodiment, as already described, the thickness is selected to not substantially deform the optical window during intraoral scanning.Examples of situations with deformation and examples of thicknesses that provide solutions to avoid such situations have been described above.

[0040] Also as already described, in other embodiments the material of the optical window has a hardness selected to withstand impact with teeth within the oral cavity.

[0041] In one embodiment, the optical window is made of a material that is configured to not substantially change the polarization of light entering and exiting through the optical window. For example, the material of the optical window can be selected to be one or more polymers. Polymers can combine the optical properties of glass with the design freedom of molded or extruded plastics. In addition, polymers can be advantageous because inorganic nanocrystals can be added to the polymer. The polymer can be defined as being flexible at least in free form and at least when the polymer forms a window that is less than 400 microns thick and greater than 10 square millimeters. Therefore, when at least the thickness is greater than 400 microns, it can be said that the polymer is non-flexible. More generally, when the optical window is located or mounted in a sheath, the optical window is typically in a state that can be defined as non-flexible.

[0042] In another example, the optical window can be made of glass and / or quartz.

[0043] Typically, an optical window can have a degree of birefringence, whereby the optical window is configured such that it does not substantially change the polarization of light. For example, the optical refractive index along two optical directions inside the optical window (referred to as n o and n e ) can differ by up to 15% so as not to substantially change the polarization of the light. By selecting such a window, the window can substantially not affect 3D scanning. In some embodiments, the optical refractive index along the two optical directions inside the window can differ by between 0.1% and 14%, such as between 0.4% and 10%, such as between 1% and 5%. In other embodiments, the optical refractive index along the two optical directions can be less than 15%, such as less than 10%, such as less than 6%, such as less than 3%, or such as less than 1%.

[0044] Birefringence can be quantified in units of nm / cm, which is the optical path length (in nm) over the material thickness (in cm). Optical quality glass ranges from 2-20 nm / cm.

[0045] In order for the birefringence to not substantially change the polarization of light, the optical window can be defined to have a birefringence of about 2500 nm / cm.

[0046] In some embodiments, the optical window can be defined as having birefringence, such as approximately 100.000nm / cm or less, such as approximately 10.000nm / cm or less, such as approximately 1.000nm / cm or less, such as approximately 100nm / cm or less, or approximately 10nm / cm or less.

[0047] In a most preferred embodiment, the optical refractive index along the two optical directions differs by less than 1%, corresponding to a birefringence of less than 100.000 nm / cm. In this embodiment, scanning can be performed without substantially affecting the polarization.

[0048] Examples of polymer(s) that exhibit low birefringence while also providing high optical clarity are:

[0049] - Polymethyl methacrylate (PMMA) (in cast quality it can be made with very low birefringence, in extruded quality the birefringence is higher but still acceptable);

[0050] - cellulose diacetate and / or cellulose triacetate;

[0051] - low molecular weight polycarbonate resins (e.g. bisphenol A polycarbonate), for example produced by special processing equipment that reduces stress in the optical window and keeps the birefringence below 20 nm;

[0052] - an acrylate polymer having a tetraphenylethane skeleton in a side chain;

[0053] - Cyclic olefin polymers (COP);

[0054] - Polyesters containing fluorene side chains;

[0055] - polyphenylene sulfide having a fluorene-based core structure;

[0056] - polymethyl methacrylate doped with trans-stilbene as anisotropic molecule;

[0057] - highly fluorinated acrylic macromonomers and / or monomers containing perfluoroalkyl, perfluorophenyl and perfluorocyclohexyl side groups;

[0058] -Pullulan ester derivatives (PLE).

[0059] These materials have been found to not substantially alter the polarization of light.

[0060] In a preferred embodiment, the optical window is made of cellulose diacetate. This polymer has several advantages in providing, for example, high clarity and transmittance, it has very low haze, near zero birefringence, is UV stable, has good tensile strength and elongation, relatively low tear strength, high stiffness, very low water permeability, is dimensionally stable, lightweight, and is easy to cut. In addition, it can be made into an anti-fog window.

[0061] In another preferred embodiment, the material is selected as a polyester resin composition and a polycarbonate resin composition. It has been found that when the material is used as an optical window on the sheath according to the present invention, the material does not substantially change the polarization. In addition, it has been found that this material is a very good candidate for manufacturing an injection-molded optical window. When the material is injection molded, the inventors have found that the material does not introduce birefringence, that is, it does not introduce stress in the material, and many other materials introduce stress in the material when injection molded. At the same time, the material has very good optical properties, such as the best Abbe number, which makes it the best solution for the optical window in the sheath according to the present invention, even for color 3D scanning. Finally, in some embodiments, the optical window can be injection molded, for example, with this material, and this also reduces the manufacturing cost compared to other manufacturing processes.

[0062] In many embodiments, the optical window is glued, sealed or welded into the hollow body.

[0063] In one embodiment, the optical window is mechanically sealed in the hollow body by means of a rubber gasket. In a preferred solution, the rubber gasket is made of the same material as the body.

[0064] In other embodiments, the optical window is an integrated part of the hollow body. For example, the hollow body and the optical window can be made in one step, the one piece being an injection molded sheath. In this sense, although there may be no visual distinction between the hollow body and the optical window, it can still be said that the window is located in the hollow body.

[0065] In one embodiment, an optical window covers the optical aperture of the tip so that the field of view within the oral cavity is maintained.

[0066] In a related embodiment, the optical window is larger than 10 mm x 10 mm. Such a window is generally preferred in intra-oral scanning because it can provide a preferred field of view in the oral cavity.

[0067] Polarization may be affected by the structure of the surface, so in most embodiments, the optical window is planar and / or includes a planar surface. This can help not to change the polarization of the light. In some embodiments of the present invention, the optical window is a non-flexible optical window mounted in the body. However, in some embodiments, the non-flexible window can be achieved by suspending the flexible window inside a non-flexible frame (e.g., a frame made of stainless steel or another rigid material).

[0068] In another embodiment, the non-flexible optical window is made of a thin semi-flexible polymer that is formed into a frame that provides high stiffness and rigidity properties to portions of the optical window.

[0069] In a second embodiment, at least a portion of the optical window is sized to mechanically couple to a coupling unit on the tip. This embodiment allows the surface normal to deviate from the optical axis, thereby directing internal reflections of light exiting through the tip away from the optical axis. Furthermore, this embodiment allows the window to be a means for coupling to the tip. Thus, an advantage of this embodiment is that the optical window provides for mounting the sheath to the tip.

[0070] In a preferred embodiment, the optical window comprises a hydrophilic surface. The advantage of a hydrophilic surface is that water droplets are avoided from forming on the window, such as water droplets formed due to fogging in a humid environment (e.g., from the patient's breath). The hydrophilic surface can be achieved by a hydrophilic coating or as an inherent property of the optical window. In one embodiment, the optical window is treated with an anti-fog agent, such as in the form of a coating. By having a hydrophilic surface, water forms a film on the surface, thereby avoiding the formation of water droplets. The film does not scatter light like water droplets. Therefore, an optical window comprising a hydrophilic surface is advantageous in 3D scanning because scanning can be performed without changing the light entering and leaving the scanner.

[0071] In some embodiments, the optical window is configured to absorb light in the near infrared region and / or the lower visible region. An advantage of this configuration is that the window can be heated by the optical device. This can be an alternative to having a hydrophilic window, as heating can also prevent water droplets from forming on the window.

[0072] The main body of the sheath

[0073] In one embodiment, the hollow body is in the form of a tubular member.

[0074] In another embodiment, the hollow body is flexible. An advantage of this embodiment is that the optical window can adapt to the angled surface of the tip because the flexible hollow body provides such adaptation. For example, the optical window can be mounted on a flexible body so that when the optical window is not flexible, the optical window is allowed to be angled by pulling the flexible hollow body, and the flexible hollow body can be elastic or inelastic to allow such angulation.

[0075] In an alternative embodiment, the hollow body is non-flexible, ie rigid. A rigid hollow body can be obtained by injection molding. A non-flexible hollow body has the advantage of being easier to handle, in particular when it is necessary to place the hollow body on a tip.

[0076] In yet another embodiment, the hollow body is semi-flexible, such that the body can self-support its own shape, but at the same time be flexible enough to adapt to a scanner tip and / or a part of a scanning device, for example to ensure a tight fit. For example, such a semi-flexible structure can be obtained by blow molding a polymer material.

[0077] In a second embodiment, the hollow body is made of one or more polymers. In some embodiments, the hollow body is made of the same material as the optical window.

[0078] In an alternative embodiment, as described for the optical window, the hollow body is made of a polyester resin composition and a polycarbonate resin composition.

[0079] In most embodiments, the sheath is made of one or more materials suitable for insertion into the oral cavity.

[0080] In the most preferred embodiments, the sheath is made of one or more materials suitable for being referred to as a single-use sheath.

[0081] Tip and coupling unit

[0082] As previously described with respect to the second aspect of the invention, the system comprises a sheath and a tip.

[0083] In some embodiments, the sheath is a sheath according to the first aspect as described above.

[0084] In one embodiment, the tip includes a tip body configured to allow light to exit an intraoral scanning device through an aperture to and from the intraoral cavity into the intraoral scanning device, wherein the tip body includes a proximal tip end, a distal tip end, and a tip sidewall located between the proximal tip end and the distal tip end, wherein the proximal tip end forms an opening mounted to or located in the intraoral scanning device, and wherein the aperture is located in the tip sidewall near the distal tip end. Such a tip can be configured for scanning through the tip sidewall, which makes scanning the intraoral cavity easier than scanning through the distal tip end.

[0085] In most embodiments, such as in the case of intraoral scanning through the side wall of the tip, the tip includes a reflector inside the tip body, wherein the reflector is configured to direct light from the intraoral scanning device and through the optical aperture into the oral cavity and back to the intraoral scanning device in the same manner.

[0086] In one embodiment, the optical aperture of the tip allows mechanical access to the tip body, such that when a sheath is replaceably mounted to at least a portion of the tip through the sheath opening, the sheath blocks mechanical access. This prevents contamination of the interior of the tip.

[0087] In some embodiments, the tip is configured to be replaceably mounted to the intraoral scanning device. By having a replaceable tip and a replaceable sheath, contamination of the scanning device can be minimized. First, it allows the user to sterilize the tip and sheath and / or sterilize the tip and use a new disposable sheath for the tip. Second, the scanning device itself does not need to be sterilized, for example, in an autoclave.

[0088] Therefore, the present invention provides this embodiment to effectively avoid contamination of the scanning device.

[0089] In one embodiment, the tip comprises an optical axis, wherein the reflector is located on the optical axis so that the optical axis is redirected inside the tip. This may allow the scanning device to scan sideways rather than in a forward direction.

[0090] In one embodiment, the tip comprises a coupling unit sized to mechanically couple at least a portion of the optical window to the tip. This embodiment allows the surface normal to deviate from the optical axis, thereby directing internal reflections of light exiting through the tip away from the optical axis. Furthermore, this embodiment allows the window to be a means for coupling to the tip. Thus, an advantage of this embodiment is that the optical window provides for mounting the sheath to the tip.

[0091] In a second embodiment, the coupling unit is configured such that when the optical window is mounted to the tip, the surface normal of the optical window deviates from the optical axis by more than 5 degrees, such as more than 10 degrees, such as between 10 and 30 degrees, such as between 10 and 20 degrees, such as between 10 and 15 degrees, such as about 12 degrees, such as about 11.5 degrees and / or such as about 12.5 degrees. This allows directing the reflected light spot out of the sensor area.

[0092] By having a surface normal that is offset from the optical axis, the internally reflected light is not directed back directly on the optical axis as it would be if the surface normal was parallel to the optical axis. Therefore, the internally reflected light is not directed toward the imaging sensor in the scanning device, and the use of an anti-reflective coating is avoided. Instead, by the above embodiments, the internally reflected light is directed out of the sensor area by making the surface normal of the optical window at an angle relative to the optical axis. Therefore, the above embodiments provide a low-cost solution for a sheath for a scanning device, where the purpose is to avoid internal reflections. The angling of the surface normal of the optical window can be achieved in many ways. For example, if the sheath includes a non-flexible body, the non-flexible body can have an angled surface on which the optical window is mounted. Alternatively, if the sheath includes a flexible body, the tip can have an angled surface on which the optical window is mounted. In the latter example, the optical window can adapt to the angled surface of the tip because the flexible body provides such adaptation. For example, the optical window can be mounted on a flexible body so that the optical window is allowed to be angled by pulling the flexible body. The flexible body can be elastic or inelastic to allow such angling.

[0093] In another embodiment, the coupling unit is a slit or groove, wherein the height of the slit or groove is greater than the thickness of the optical window, and / or wherein the length and / or width of the slit or groove is less than the length and / or width of the optical window, such as half of the optical window, or such as one third of the optical window, or such as one tenth of the optical window. The specified thickness allows the optical window to fit into the slit, while the specified length and / or width allows material saving, so that the sheath can be manufactured at low cost.

[0094] In a preferred embodiment, the coupling unit is located around a portion of the aperture so that the optical window can be coupled on top of the aperture. This allows light to exit through the aperture and the optical window and enter the optical axis, in particular so that the aperture is closed, thereby avoiding contamination.

[0095] Intraoral Scanner

[0096] In one embodiment of the second aspect, the system further comprises an intraoral scanner. The intraoral scanner is configured to form a 3D model of an intraoral object such as teeth and gums. Typically, the intraoral scanner comprises a light source that emits light, for example to project a pattern onto the intraoral object, whereby imaging by the intraoral scanning device uses the pattern to form the 3D model.

[0097] In an embodiment, the intraoral scanner is configured to emit light as linearly polarized light.

[0098] In another embodiment, the intraoral scanner is configured to emit light as circularly polarized light. In this embodiment, when the circularly polarized light is specularly reflected from an intraoral object, the helicity of the polarization changes, for example from right-handed circular polarization to left-handed circular polarization. Therefore, the circularly polarized light is received at the optical window of the sheath, and in order to image the specular reflection, the scanner is configured to allow only light with circular polarization to pass into the imaging device, for example by including a quarter-wave retarder. In such a scanner, it is critical that the optical window of the sheath according to the present invention does not substantially change the polarization - if the polarization is changed, the results of the 3D model will change very significantly and may not be accurate enough for operations related to dental restorations or other important operations of 3D model control.

[0099] Example 1 – Flexible sheath, as shown in top view

[0100] Figure 1 An example of a sheath (1) according to the invention is shown in a top view.

[0101] Figure 1 A sheath (1) for a tip (2) of a scanning device (3) is shown, comprising: a body (4) in the form of a tubular member (5) comprising a distal end (6) and a proximal end (7). The proximal end (7) comprises an opening (8) which is dimensioned at least relative to the tip (2) of the scanning device (3) so that the tubular member (5) can be replaceably mounted to at least a portion of the tip (2) of the scanning device (3).

[0102] The body (4) includes a non-flexible optical window (9) mounted in the body between the distal end (6) and the proximal end (7) of the body such that the optical window (9) allows light to exit and enter the scanning device (3) through an optical axis (10) inside the tip (2). The optical window (9) is mounted in the body (4) such that when the tubular member (5) is replaceably mounted around at least the tip (2) of the scanning device (3), the optical window (9) includes a surface normal (11) that deviates from the optical axis (10), thereby directing internal reflections of light exiting through the tip (2) away from the optical axis (10). As can be seen from the figure, the optical window (9) is made of a material, wherein the material is configured to not substantially change the polarization of light exiting and entering through the optical window (9).

[0103] The optical window (9) comprises a planar surface and is dimensioned to be mechanically coupled to a coupling unit (13) on the tip (2).

[0104] In this example, the body (4) is made of plastic and is flexible. In other words, the body (4) is a plastic bag. The body is shown lying flat. In other words, only the top surface of the body (4) is shown.

[0105] The optical window (9) may be fixed to the punched out cutout, for example the optical window may be a hard polymer window glued and / or welded to the inside of the plastic bag.

[0106] Alternatively, the optical window (9) may be part of a flexible plastic body and suspended in a frame to ensure the flatness of the window, for example where the frame is glued to the inside of the plastic body.

[0107] The plastic bag shown here is inexpensive to produce, since production can be fully automated. In addition, the flatness of the optical window (9) can be fully ensured.

[0108] A big advantage of the flexible body is that it is very small when packaged, especially because the body (4) is flat when not attached to the tip (2) of the scanning device (3).

[0109] Example 2 – Optical Window, shown unmounted

[0110] Figure 2 An example of an optical window according to the present invention is shown.

[0111] The optical window (9) is shown here unmounted from the body (4).

[0112] However, the optical window is formed so that when the body (4) is replaceably mounted around at least the tip (2) of the scanning device (3), the optical window (9) includes a surface normal (11) that deviates from the optical axis (10), thereby directing internal reflections of light exiting through the tip (2) away from the optical axis (10). In other words, the optical window is configured so that when the body (4) is replaceably mounted around at least the tip (2) of the scanning device (3), the optical window (9) includes a surface normal (11) that deviates from the optical axis (10), thereby directing internal reflections of light exiting through the tip (2) away from the optical axis (10).

[0113] The configuration of the surface normal relative to the optical axis is ensured by the optical window comprising guiding members (12). These guiding members (12) can be used, for example, to guide the optical window (9) to a certain position on the tip (2) so that the optical window (9) is placed on the tip (2) at a certain angle, α, relative to the optical axis (10). The optical window also has a portion (13) configured to enable the optical window to be locked in the tip (2), here in the form of a recess, which is configured to lock into a locking mechanism (17) of the optical window (9), such as Figure 3 shown.

[0114] Example 3 – The tip of the scanning device, as seen from the outside

[0115] Figure 3An example of a tip (2) of a scanning device (3) according to the second aspect of the invention is shown, shown from the outside.

[0116] Figure 3 A tip (2) for a scanning device (3) is shown, wherein the tip is replaceably mounted on the scanning device (3), the tip comprising an aperture (14) on the optical axis so as to allow light to exit and enter the scanning device through the optical axis (10).

[0117] The tip (2) comprises a reflector (15) located on the optical axis (10) so that the optical axis (10) is redirected inside the tip (2). The reflector (15) and the optical axis (10) are not visible in this figure because only the exterior is shown. However, this can be seen in the next figure. Figure 4 Seen in.

[0118] The tip (2) comprises a coupling unit (16) sized to mechanically couple at least a portion of the optical window (9) to the tip. The coupling unit (16) is configured such that when the optical window (9) is mounted to the tip (2), a surface normal (11) of the optical window (9) deviates from the optical axis (10) by approximately 11.5 degrees. The surface normal (11) of the optical window (9) deviates from the optical axis by an angle, referred to as α. Figure 4 This is clearly shown.

[0119] like Figure 3 As shown, the coupling unit (16) is a groove, wherein the height of the groove is greater than the thickness of the optical window (9). The length and / or width of the groove is less than the length and / or width of the optical window, and is approximately one tenth of the optical window. Figure 3 It can also be seen that the coupling unit (16) is located around a portion of the aperture (14), so that the optical window (9) can be coupled at the top of the aperture (14), that is, on the outside of the aperture (14).

[0120] The tip (2) comprises a locking mechanism (17) for the optical window (9), in this example a snap lock, onto which the portion (13) of the optical window (9) fits.

[0121] The tip (2) may be an injection molded tip.

[0122] Example 4 – The tip of the scanning device, as seen from the inside

[0123] Figure 4 An example of a tip (2) of a scanning device (3) according to the second aspect of the invention is shown, shown from the inside. Various parts of the sheath relative to various parts of the tip (2) are also shown to view these parts in relation to each other. Figure 4A tip (2) for a scanning device (3) is shown, wherein the tip is replaceably mountable on the scanning device (3), the tip comprising an aperture (14) on an optical axis (10) to allow light to exit and enter the scanning device through the optical axis (10). An optical element (18) is shown residing inside the scanning device (3).

[0124] The tip (2) comprises a reflector (15) located on the optical axis (10) so that the optical axis (10) is redirected inside the tip (2). Figure 4 1 and 2. The reflector (15) and the optical axis (10) are clearly seen in the figure. As can be seen from this figure, the reflector is inclined by 45 degrees relative to the optical axis (10). The optical axis is thus oriented so that the optical axis comprises two optical axes that are perpendicular to each other, however, these two optical axes define the optical system of the scanning device. However, in some embodiments, the reflector is inclined by less than or more than 45 degrees relative to the optical axis (10), for example so that the light exits the aperture at an angle different from perpendicular to the optical axis along the body, i.e. the optical axis goes from the proximal end (7) to the distal end (6).

[0125] The tip (2) comprises a coupling unit (16) sized to mechanically couple at least a portion of the optical window (9) to the tip. The coupling unit (16) is configured such that when the optical window (9) is mounted to the tip (2), a surface normal (11) of the optical window (9) deviates from the optical axis (10) by approximately 11.5 degrees. The surface normal (11) of the optical window (9) deviates from the optical axis by an angle, referred to as α. Figure 4 This is clearly shown.

[0126] If the reflector has been placed at an orientation less than or greater than 45 degrees relative to the optical axis (10), the optical window can be placed flush with the tip (2), i.e. parallel to the optical axis (10) along the body (4), i.e. the optical axis (10) runs from the proximal end to the distal end. In this way, the surface normal (11) of the optical window (9) will also deviate from the optical axis (10).

[0127] Example 5 - System including a sheath for an intraoral scanning device tip, shown unmounted

[0128] Figure 5 A system of an intraoral scanning device (3) is shown, the system comprising: Figure 1 The sheath (1) shown is for a tip (2) of an intraoral scanning device (3), wherein the tip (2) is replaceably mountable on the intraoral scanning device (3). The tip (2) includes an aperture (14) on the optical axis so that light is allowed to exit and enter the intraoral scanning device (3) through the optical axis (10). Figure 5 In FIG. 1 , the sheath ( 1 ), the tip ( 2 ) and the scanning device ( 3 ) are shown unmounted from one another.

[0129] Example 6 - System including a sheath for the tip of a scanning device, shown installed

[0130] Figure 6 A system of an intraoral scanning device (3) is shown, the system comprising: Figure 1 The sheath (1) shown is for a tip (2) of an intraoral scanning device (3), wherein the tip (2) is replaceably mountable on the scanning device (3). The tip (2) includes an aperture (14) on the optical axis so that light is allowed to exit and enter the scanning device (3) through the optical axis (10). Figure 6 In FIG. 1 , the sheath ( 1 ), the tip ( 2 ) and the scanning device ( 3 ) are shown mounted to each other.

[0131] Example 7 – Semi-flexible sheath, as shown in perspective

[0132] Figure 7 Another example of a sheath (1) according to the invention is shown.

[0133] Figure 7 A semi-flexible sheath (1) for a tip (2) of a scanning device (3) is shown, comprising: a semi-flexible body (4) comprising a distal end (6) and a proximal end (7). The proximal end (7) comprises an opening (8) sized relative to at least the tip (2) of the scanning device (3) so that the body (4) can be replaceably mounted around at least a portion of the tip (2) of the scanning device (3).

[0134] The body (4) includes a non-flexible optical window (9) mounted in the body between the distal end (6) and the proximal end (7) of the body such that the optical window (9) allows light to exit through an optical axis (10) inside the tip (2) and enter the scanning device (3). The optical window (9) is mounted in the tip (3) such that the optical window (9) includes a surface normal (11) that deviates from the optical axis (10) so as to direct internal reflections of light exiting through the tip (2) away from the optical axis (10).

[0135] The optical window (9) is located within the body. The sheath (1) is sized to fit around at least a portion of the tip (2) of the scanning device (3). Figure 7 In the example shown, the optical window (9) is made of a suitable injection moulded polymer, while the body (4) is made of a thin blow moulded polymer to which the optical window (9) is mounted.

[0136] Example 8 - Optical Window, Shown Unmounted

[0137] Figure 8 Another example of an optical window according to the present invention is shown.

[0138] The optical window (9) is shown here unmounted from the body (4).

[0139] However, the optical window is formed so that when mounted to the scanning device (3) Fig. 9 When the tip (2) is mounted in the scanning device (3), the optical window (9) includes a surface normal (11) that deviates from the optical axis (10), thereby directing internal reflections of light exiting through the tip (2) away from the optical axis (10). In other words, the optical window is configured such that when assembled in the tip (2) of the scanning device (3), the optical window (9) includes a surface normal (11) that deviates from the optical axis (10), thereby directing internal reflections of light exiting through the tip (2) away from the optical axis (10).

[0140] The configuration of the surface normal relative to the optical axis is ensured by a rigid frame (18) being part of the optical window (9) comprising a guiding member (12). In other words, the optical window comprises a rigid frame (18). The guiding member (12) can, for example, be used to guide the optical window (9) to a certain position on the tip (2) so that the optical window (9) is placed at the tip (2).

[0141] The optical window also has a portion (13) configured to enable the optical window to be locked in the tip (2), here in the form of a protrusion, which is configured to lock into a locking mechanism (17) of the optical window (9), such as Fig. 9 shown.

[0142] Example 9 - Tip of scanning device shown from outside

[0143] Fig. 9 Another example of a tip (2) of a scanning device (3) according to the second aspect of the invention is shown, shown from the outside.

[0144] Figure 8 A tip (2) for a scanning device (3) is shown, wherein the tip is replaceably mountable on the scanning device (3), the tip comprising an aperture (14) on the optical axis so as to allow light to exit and enter the scanning device through the optical axis (10).

[0145] The tip (2) comprises a reflector (15) located on the optical axis (10) so that the optical axis (10) is redirected inside the tip (2). The reflector (15) and the optical axis (10) are not visible in this figure as only the exterior is shown.

[0146] like Fig. 9 As shown, the coupling unit (16) is a groove. Fig. 9 It can also be seen that the coupling unit (16) is located around a portion of the aperture (14), so that the optical window (9) can be coupled at the top of the hole (14), that is, on the outside of the aperture (14).

[0147] The tip (2) includes a coupling unit (16) having dimensions configured to mechanically couple to the optical window (9) (e.g. Figure 8 shown).

[0148] The coupling unit (16) is configured so that when the optical window (9) is installed in the tip (2), the surface normal (11) of the optical window (9) deviates from the optical axis (10) by about 11.5 degrees. The surface normal (11) of the optical window (9) deviates from the optical axis by an angle, referred to as α.

[0149] Tip (2) includes Figure 8 The locking mechanism (17) of the optical window (9) is shown. In this example, it is a snap in the form of an intrusion that matches the protrusion (13) of the optical window.

[0150] The tip (2) may be an injection molded tip.

[0151] Example 10 - System including a sheath for a tip of an intraoral scanning device, shown unmounted

[0152] Fig.10 Another example system of an intraoral scanning device (3) is shown, which includes: Figure 7 The sheath (1) shown, as Fig. 9 A tip (2) for a scanning device (3) is shown, wherein the tip (2) is replaceably mountable on an intra-oral scanning device (3). The tip (2) includes an aperture (14) on the optical axis so that light is allowed to exit and enter the scanning device (3) through the optical axis (10). Fig.10 In FIG. 1 , the sheath ( 1 ), the tip ( 2 ) and the scanning device ( 3 ) are shown unmounted from one another.

[0153] Example 11 - One-piece semi-flexible molded jacket shown in perspective

[0154] Fig.11 Another example of a sheath (1) according to the invention is shown.

[0155] Fig.11 A semi-flexible injection molded sheath (1) for a tip (2) of a scanning device (3) is shown, comprising: a semi-flexible body (4) comprising a distal end (6) and a proximal end (7). The proximal end (7) comprises an opening (8) sized relative to at least the tip (2) of the scanning device (3) so that the body (4) can be replaceably fitted around at least a portion of the tip (2) of the scanning device (3).

[0156] The body (4) is molded with a resin composition characterized by a high refractive index, low birefringence, high heat resistance and transparency. When mounted on the tip (2), the portion of the body (4) located below the tip orifice (14) will therefore constitute an optical window (9), so that the optical window (9) allows light to exit and enter the scanning device (3) through the optical axis (10) inside the tip (2) without substantially changing the polarization of the light. The optical window (9) constituted by the body (4) is positioned so that the optical window (9) includes a surface normal (11) that deviates from the optical axis (10), thereby guiding the internal reflection of the light exiting through the tip (2) away from the optical axis (10). The optical window may include a hydrophilic coating so that the window will not fog when exposed to a humid environment such as the oral cavity.

Claims

1. A sheath configured to be replaceably mounted to at least a portion of a tip of a 3D intra-oral scanning device, so as to be used in combination with the 3D intra-oral scanning device to scan the intraoral cavity, the sheath comprising: - a hollow body comprising a distal sheath end, a proximal sheath end and a sheath sidewall located between the distal sheath end and the proximal sheath end, wherein said proximal sheath end defines a sheath opening sized relative to at least said portion of said tip; and an optical window mounted to or located in the sheath sidewall proximate the distal sheath end such that when the sheath is replaceably mounted to at least the portion of the tip through the sheath opening, the optical window covers at least a portion of the optical aperture of the tip, wherein the optical window is made of a material configured to not alter the polarization of light exiting and entering the 3D intraoral scanning device through the optical aperture of the tip and arriving at and coming from the oral cavity through the optical window, thereby ensuring that the scanning device provides the same scan of the oral cavity regardless of whether a sheath is replaceably mounted to at least the portion of the tip, wherein the optical window is birefringent, whereby the optical window has two refractive indices n o and n e , and among them, n o and n e differ from each other by less than 1%; and, Wherein, the thickness of the optical window is greater than 400 microns.

2. The sheath according to claim 1, wherein: The thickness is greater than 600 microns or greater than 800 microns.

3. The sheath according to claim 1, wherein: The thickness is between 400 microns and 5000 microns.

4. The sheath according to any one of claims 1 to 3, wherein: The thickness is selected so as not to deform during scanning of the oral cavity.

5. The sheath according to any one of claims 1 to 3, wherein: The optical window covers the optical orifice of the tip so that the field of view within the oral cavity is maintained.

6. The sheath according to any one of claims 1 to 3, wherein: The optical window is larger than 10 mm×10 mm.

7. The sheath according to any one of claims 1 to 3, wherein: The optical window is planar.

8. The sheath according to any one of claims 1 to 3, wherein: The optical window includes a hydrophilic surface.

9. The sheath according to any one of claims 1 to 3, wherein: The optical window is configured to absorb light in the near infrared region and / or in the lower visible region.

10. The sheath according to any one of claims 1 to 3, wherein: The optical window is injection molded.

11. The sheath according to any one of claims 1 to 3, wherein: The optical window is glued, sealed or welded into the hollow body.

12. The sheath according to any one of claims 1 to 3, wherein: The material has a hardness selected to withstand impact with teeth within the oral cavity.

13. The sheath according to any one of claims 1 to 3, wherein: The material is selected to be one or more polymers.

14. The sheath according to any one of claims 1 to 3, wherein: The materials are selected from a polyester resin composition and a polycarbonate resin composition.

15. The sheath according to any one of claims 1 to 3, wherein: The hollow body is flexible.

16. The sheath according to any one of claims 1 to 3, wherein: The hollow body is rigid.

17. The sheath according to any one of claims 1 to 3, wherein: The hollow body is made of one or more polymers.

18. The sheath according to any one of claims 1 to 3, wherein: The hollow body is made of the same material as the optical window.

19. The sheath according to any one of claims 1 to 3, wherein: The sheath is made of one or more materials suitable for insertion into the oral cavity.

20. The sheath according to any one of claims 1 to 3, wherein: The sheath is made of one or more materials suitable for use as a single-use sheath.

21. The sheath of claim 13, wherein: The polymer is PMMA.

22. The sheath of claim 13, wherein: The polymer is cellulose diacetate.

23. The sheath of claim 13, wherein: The polymer is cellulose triacetate.

24. The sheath according to any one of claims 1 to 3, wherein: The hollow body is made of a polyester resin composition and a polycarbonate resin composition.

25. A system of a 3D intra-oral scanning device, comprising: - a tip of the 3D intra-oral scanning device, said tip comprising an optical aperture; and - a sheath, the sheath being configured to be replaceably mounted to at least a portion of the tip of the 3D intra-oral scanning device, so as to be configured to be used in combination with the scanning device to scan the oral cavity, the sheath comprising: a hollow body comprising a distal sheath end, a proximal sheath end, and a sheath sidewall therebetween, wherein the proximal sheath end defines a sheath opening sized relative to at least a portion of the tip; and an optical window mounted to or located in the sheath sidewall proximate the distal sheath end such that when the sheath is replaceably mounted to at least the portion of the tip through the sheath opening, the optical window covers at least a portion of the optical aperture of the tip, wherein the optical window is made of a material configured to not alter the polarization of light exiting and entering the 3D intraoral scanning device through the optical aperture of the tip and arriving at and coming from the oral cavity through the optical window, thereby ensuring that the scanning device provides the same scan of the oral cavity regardless of whether a sheath is replaceably mounted to at least the portion of the tip, wherein the optical window is birefringent, whereby the optical window has two refractive indices n o and n e , and among them, n o and n e differ from each other by less than 1%; and Wherein, the thickness of the optical window is greater than 400 microns.

26. The system of claim 25, wherein: The tip includes a tip body configured to allow light to exit the 3D intra-oral scanning device through the aperture to the oral cavity and light from the oral cavity to enter the 3D intra-oral scanning device, The tip body includes a proximal tip end, a distal tip end, and a tip sidewall located between the proximal tip end and the distal tip end. wherein the proximal tip end forms an opening mounted to or located in the 3D intra-oral scanning device, or wherein the orifice is located in the tip sidewall near the distal tip end.

27. The system of claim 26, wherein: The tip includes a reflector inside the tip body, wherein the reflector is configured to direct light from the 3D intra-oral scanning device and into the oral cavity through the optical aperture and back to the 3D intra-oral scanning device in the same manner.

28. The system of claim 25 or 26, wherein: The tip is configured for replaceable mounting to the 3D intra-oral scanning device.

29. The system of claim 26, wherein: The optical aperture of the tip allows mechanical access to the tip body such that when the sheath is replaceably mounted to at least the portion of the tip through the sheath opening, the sheath blocks mechanical access.

30. The system of claim 25 or 26, wherein: The system also includes an intraoral scanner.

31. The system of claim 30, wherein: The intraoral scanner is configured to emit light as linearly polarized light.

32. The system of claim 30, wherein: The intraoral scanner is configured to emit light as circularly polarized light.

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