INTRAORAL SCANNER COMPRISING A DEFOGGING SYSTEM

Abstract

An intraoral scanning system that includes a housing and a sleeve. The housing includes optical components, a head, and a defogging unit that includes a heating unit. The head includes a primary aperture and is configured to be inserted into an oral cavity of a patient. The sleeve includes a secondary optical component arranged at a secondary aperture that is configured to be positioned in alignment with the primary aperture when the sleeve is coupled with the housing. The heating unit is configured to generate heat in response to application of electrical power to the heating unit. When the sleeve is coupled with the housing, the secondary optical component is configured to be arranged such that the generated heat is transferred from the heating unit to the secondary optical component through thermal conduction between the heating unit and secondary optical component.

Claims

1. An intraoral scanning system comprising: a housing comprising optical components, a head, comprising a primary aperture, configured to be inserted into an oral cavity of a patient, and a defogging unit comprising a heating unit; a sleeve configured to cover at least a part of the head when the sleeve is coupled with the housing, the sleeve comprising a secondary optical component arranged at a secondary aperture that is configured to be positioned in alignment with the primary aperture, wherein the heating unit is configured to generate heat in response to application of electrical power to the heating unit, and the secondary optical component is configured to be arranged such that the generated heat is transferred from the heating unit to the secondary optical component through thermal conduction between the heating unit and secondary optical component.

2. The system according to claim 1, wherein the housing comprises a connection component that is configured to establish a physical connection between the heating unit and the secondary optical component to permit transfer of the generated heat by thermal conduction from the heating unit to the secondary optical component.

3. The system according to any one or more of the preceding claims, wherein the heating unit is arranged on the connection component.

4. The system according to any one or more of the preceding claims, wherein the heating unit is physically connected to the connection component using a thermal conductive material.

5. The system according to any one or more of the preceding claims, wherein the sleeve is removably attached with the housing such that coupling the sleeve with the housing arranges the secondary optical component in physical connection with the heating unit via the connection component for permitting thermal conduction of the generated heat from the heating unit to the secondary optical component.

6. The system according to any one or more of the preceding claims, wherein the secondary optical component is made up of a material having a thermal conductivity higher than the thermal conductivity of the primary optical component.

7. The system according to any one or more of the preceding claims, wherein the secondary optical component comprises a substrate comprising a deposit of high thermal conductivity disposed on at least one of a secondary first surface or secondary second surface of the secondary optical component.

8. The system according to any one or more of the preceding claims, wherein the secondary optical component comprises a multi-layered structure where at least two layers of the multi-layered structure have different thermal conductivity and/or optical properties.

9. The system according to any one or more of the preceding claims, further comprising a primary optical component arranged at the primary aperture, the primary optical component being inhibited from receiving the generated heat from the heating unit to the primary optical component.

10. The system according to any one or more of the preceding claims, further comprising an insulating material arranged between the primary optical component and the heating unit to inhibit transfer of the generated heat from the heating unit to the primary optical component.

11. The system according to any one or more of the preceding claims, wherein the primary optical component is made up of a material having a thermal conductivity lower than the thermal conductivity of secondary optical component.

12. The system according to any one or more of the preceding claims, wherein the primary optical component comprises a substrate comprising a deposit of poor thermal conductivity disposed on at least one of a primary first surface or a primary second surface of the primary optical component.

13. The system according to any one or more of the preceding claims, wherein the primary optical component comprises a multi-layered structure where at least two layers of the multi-layered structure have different thermal conductivity and/or optical properties.

14. The system according to any of the preceding claims, wherein the thermal conductivity of the primary optical component material is lower than the thermal conductivity of the i) connection component, or ii) connection component and secondary optical component.

15. The system according to any of the preceding claims, wherein the thermal conductivity of the insulating material arranged between the primary optical component and the heating unit is lower than the thermal conductivity of the i) connection component, or ii) connection component and secondary optical component.

16. The system according to any of the preceding claims, wherein the thermal conductivity of the deposit applied on the primary connection component is lower than the thermal conductivity of the i) connection component, or ii) connection component and secondary optical component.

17. The system according to any of the preceding claims, wherein thermal conductivity of materials defining a thermal path from the heating unit to the secondary optical component is higher than the thermal conductivity of materials defining a thermal path from the heating unit to the primary optical component.

18. The system according to any one or more of the preceding claims, wherein when the sleeve is coupled with the housing, a relative position of the primary optical component and secondary optical component defines a gap therebetween, and the gap comprises a gap-width that allows thermal insulation between the primary optical component and secondary optical component.

19. The system according to any one or more of the preceding claims, wherein the gap width is at least partially filled with a thermal insulating material.

20. The system according to any one or more of the preceding claims, wherein the head comprises a primary engagement element and the sleeve comprises a secondary engagement element; and the primary engagement element and secondary engagement element are configured to physically interact during coupling of the sleeve with the housing to bring the connection component and secondary optical component/a secondary frame comprising the secondary optical component in a physical connection with each other.

21. The system according to any one or more of the preceding claims, wherein the head comprises a primary engagement element and the sleeve comprises a secondary engagement element; and the primary engagement element and secondary engagement element are configured to physically interact such that the connection component and secondary optical component/the secondary frame comprising the secondary optical component stay in a physical connection with each other when the sleeve is coupled with the housing.

22. The system according to any one or more of the preceding claims, wherein the physical connection between the connection component and secondary optical component/the secondary frame comprising the secondary optical component is defined by a contact surface area at an interface between the connection component and secondary optical component/the secondary frame.

23. The system according to any one or more of the preceding claims, wherein a portion of the connection component interfacing the secondary optical component/the secondary frame comprising the secondary optical component is dimensioned such that when the sleeve is coupled with the housing, the connection component is restricted from interfering with the signal receiving section of the secondary optical component.

24. The system according to any one or more of the preceding claims, wherein when the sleeve is coupled with the housing, a portion of the connection component interfacing the secondary optical component/the secondary frame comprising the secondary optical component is arranged in relation to the secondary optical component/the secondary frame to avoid the connection component interfering with a signal receiving section of the secondary optical component.

25. The system according to any one or more of the preceding claims, wherein one of the primary engagement element or secondary engagement element comprises a protrusion and another of the primary engagement element or secondary engagement element comprises a surface that is configured to physically interact with the protrusion; and the protrusion and the surface are configured to physically interact to bias the secondary optical element/secondary frame comprising the secondary optical element and connection component towards each other.

26. The system according to any one or more preceding claims, wherein one of the primary engagement element or secondary engagement element comprises a guide and another of the primary engagement element or secondary engagement element comprises a guide channel that is configured to receive the guide; and movement of the guide along the guide channel is configured to bias the secondary optical element/secondary frame comprising the secondary optical element and connection component towards each other.

27. The system according to any one or more preceding claims, wherein the heating unit comprises an embedded heater that is configured to solely generate heat prior to and/or during scanning of the patient's teeth.

28. The system according to any one or more preceding claims, wherein heating unit includes at least one component in the housing, the at least one component being configured to generate heat in response to the at least one component performing a scanning related function during scanning of the patient.

29. The system according to any one or more preceding claims, wherein the scanning related function is different from solely to generate heat.

30. The system according to any one or more preceding claims, wherein the at least one component is configured to generate heat comprising residual or waste heat.

31. The system according to any one or more preceding claims, wherein average surface roughness of the connection component at interface(s) to conduct heat is in the range of 0.100-3.00 μm.

32. The system according to any one or more preceding claims, wherein maximum surface roughness of the connection component at interface(s) to conduct heat is below 12 μm.

33. The system according to any one or more preceding claims, wherein the head of the housing comprises a temperature sensor.

34. The system according to any one or more preceding claims, wherein the temperature sensor is arranged proximal to the primary aperture.

35. The system according to any one or more preceding claims, wherein the temperature sensor is configured to measure temperature in the head and provide sensor measurements as signal to a control unit.

36. The system according to any one or more preceding claims, wherein the control unit, based on the received sensor measurement signal, is configured to provide feedback control signal.

37. The system according to any one or more preceding claims, wherein the control unit provides the feedback control signal at least when the sensor measurement signal is beyond a threshold temperature value.

38. The system according to any one or more preceding claims, wherein the threshold temperature value may be predefined based on a permissible temperature in the oral cavity.

39. The system according to any one or more preceding claims, wherein the feedback control signal is configured to put the scanner in a throttling mode.

40. The system according to any one or more preceding claims, wherein, the feedback control signal is configured to control the temperature setting of the embedded heating unit such that the sensor measurement at the temperature sensor is at or within the threshold temperature value.

41. The system according to any one or more preceding claims, wherein the secondary optical component comprises layers of coating of Ta.sub.2O.sub.5 and SiO.sub.2 on at least one surface of the secondary optical component.

42. The system according to any one or more preceding claims, wherein the secondary optical component comprises hydrophobic coating of Perfluorodecyltrichlorosilane (FDTS) over the layers of coating.

43. The system according to any one or more preceding claims, further comprising an intermediate bonding layer of Al.sub.2O.sub.3 sandwiched between the hydrophobic coating and coated layers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0082] The embodiments of the disclosure, together with its advantages, may be best understood from the following illustrative and non-limiting detailed description taken in conjunction with the accompanying figures in which

[0083] FIG. 1 illustrates an optical scanning system such as a 3D intraoral scanner system according to an embodiment;

[0084] FIG. 2a illustrates a defogging system from a first view according to an embodiment;

[0085] FIG. 2b illustrates defogging system from a second view according to an embodiment;

[0086] FIG. 3a illustrates a cross sectional view from a first perspective such as front view of the head and sleeve fully mounted on the housing according to an embodiment;

[0087] FIG. 3b illustrates a cross sectional view from a first perspective such as front view of the head and sleeve fully mounted on the housing according to an embodiment;

[0088] FIG. 4a illustrates, from a first view such as side view, a first stage during mounting of the sleeve onto the housing according to an embodiment;

[0089] FIG. 4b illustrates, from the first view such as side view, a second stage during mounting of the sleeve onto the housing according to an embodiment;

[0090] FIG. 4c illustrates, from the first view such as side view, a third stage during mounting of the sleeve onto the housing according to an embodiment;

[0091] FIG. 5 illustrates, from the second view such as bottom view, the first stage during mounting of the sleeve onto the housing according to an embodiment;

[0092] FIG. 6 illustrates a zoomed cross-sectional view of the head and sleeve fully mounted on the housing according to an embodiment;

[0093] FIG. 7a illustrates the primary optical component according to an embodiment;

[0094] FIG. 7b illustrates the primary optical component according to an embodiment;

[0095] FIG. 7c illustrates the secondary optical component according to an embodiment;

[0096] FIG. 7d illustrates the secondary optical component according to an embodiment;

[0097] FIG. 8 illustrates the secondary component according to an embodiment; and

[0098] FIG. 9 that illustrates a multilayered secondary component according to an embodiment.

DETAILED DESCRIPTION

[0099] In the following description, reference is made to the accompanying figures that show by way of non-limiting illustration how the disclosed method or system may be implemented.

[0100] FIG. 1 illustrates an optical scanning system such as a 3D intraoral scanner system according to an embodiment. The 3D intraoral scanner system 101 includes an intraoral scanner that includes a main body 103 enclosing at least the optical components that are configured to operate during a 3D scanning of the dental object such as oral cavity. The 3D scanning refers to the process of acquiring the plurality of two-dimensional images of the dental object based on which three-dimensional digital representation of the dental object is generated. The main body may further include one or more electronic components that are also configured to operate during 3D scanning of the dental object. The exterior surface of the main body is formed in plastic shells that is easy to clean, thus offering a hygienic solution. The intraoral scanner is designed to be held like a pen, i.e. operate in a pen grip during the 3D scanning or may include a handle grip, which is held during the 3D scanning.

[0101] Irrespective of the grip, the intraoral scanner is configured to be moved over the dental object such as the oral activity during the 3D scanning. The scanner may be a focus scanner, OCT scanner, triangulation scanner, confocal scanner or any kind of imaging apparatus capable of acquiring two-dimensional images that may be processed into 3D information such as three-dimensional digital representation. The illustrated FIG. 1 shows a handheld intraoral scanner system 101 which is a focus scanner that is configured to acquire a sequence of 2D images while moving focus optics and illuminating a pattern onto the object to be scanned. Typically, the movement of the focus optical and illuminating a pattern onto the object occurs simultaneously. The sequence of 2D images is processed into the 3D information. The 3D information may be transmitted to a scanning application software. The intraoral scanner system 101 may use an optical system where the illumination probe light and imaging probe light (i.e. reflected light) are utilizing the same path through the main part of optical system inside the main body. The intraoral scanner includes a distal end that is shaped like an elongated probe head 105 that is configured to be inserted into the oral cavity and to direct the probe light to, and reflected light from the dental object to be scanned. The housing 107 includes the head 105 and the main body 103. The head is configured to be attached with the rest of the housing, e.g. at a mounting portion of the housing. The mounting portion 127 may include a locking unit that is configured to engage with a complimentary locking unit 129 of the head to allow locking the head with the mounting portion.

[0102] The head 105 may include a mirror or prism arranged at its distal end for guiding the probe light to and reflected light back from the dental object to be scanned. The probe light (i.e. illumination signal) propagates through the framework 111 of the head 105 and reflects off the mirror and across the primary aperture 109 towards the dental object. Similarly, the reflected light from the dental object enters the head by travelling across the primary aperture 109 and propagates through the framework 111 after getting reflected from the mirror. Due to hygienic reasons, the primary aperture 109 may be sealed from the external environment. This is typically achieved by arranging the primary optical component 113 at the primary aperture. The disclosed arrangement allows for the scanning signal to be transmitted through the primary aperture 109 while maintaining a microbial barrier to the exterior of the head enclosure. The framework 111 may be manufactured by injection molding of high-performance thermoplastics like Polysulfones (PSU).

[0103] The scanner head 105 may additionally be configured to receive a sleeve 115 or sheath, which can be detachably mounted to the scanner housing 105. The sleeve is configured to at least partially cover the head 105. The sleeve 115 may have a similar shape as the head 105 and may contain a second aperture 117 which is configured to be aligned with the primary aperture 109 when the sleeve 115 is securely positioned such as mounted on the housing 105. The secondary aperture 117 is configured to contain a secondary optical component 119, which is configured to allow the probe light to be transmitted without substantially alteration of characteristics of the probe light, such as the polarization.

[0104] To restrict fogging of the secondary optical component 119 when scanning inside humid environment such as the human oral cavity, the head unit includes a defogging unit 121. Fogging may cause condensation at the secondary optical component 119 and this may deteriorate the quality of transmission of the scanning signal (e.g. illumination light and/or reflected light), leading to loss in data acquisition quality. The defogging unit 121 is constructed to avoid fogging of the secondary optical component 119 by raising the temperature of the secondary optical component 119 to a temperature above the dew point of the intended scanning environment. In case of scanning the human oral cavity, the target temperature is typically approximately in the range of 30° C. to 40° C.

[0105] The defogging unit 121 may include a heating unit 123 for converting electricity into heat. In the disclosed embodiment of FIG. 1, the heating unit is embedded into a printed circuit board (PCB) which may establish electrical connection between the main body 103 and heating unit 123, thereby controlling the heating. In one example the defogging unit is located at the connection component 125. The connection component 125 may be multi-functional as it is shaped as an insert frame part which is designed to be held at the framework 111 and simultaneously is configured to interface both with the heating unit 123 and the primary optical component 113, which is arranged at the connection component.

[0106] One functionality of the connection component 125 is to transfer the generated heat, via thermal conduction, from the heating unit 123 to the secondary optical element 119 as effectively as possible. The connection component 125 may be fabricated from a material with an intrinsic high thermal conductivity, such as a metal like aluminum (Al) like Alu 6082 T6 or an alloy or any other composite material. Alternatively, the connection component 125 may include a structure facilitating effective heat transfer to the secondary optical component 119. For example, the connection component 125 may include a plastic frame comprising one or more sheets or layers of a super conducting material such like sheets of armchair graphene nanoribbons providing thermal pathways (e.g. heat guides) for conducting the generated heat from the heating unit to the secondary optical component 119. The thermal pathways may be coated with epoxy such that the pathways are sandwiched between the frame and coating. The connection component 125 usually extends towards the secondary optical component 119 such that a physical contact between the heating unit 123, through the connection component 125, and secondary optical element 119 may be established. This allows the thermally conducting the generated to the secondary optical component and raising the temperature of the secondary optical component.

[0107] FIG. 2a illustrates a defogging system from a first view according to an embodiment. FIG. 2b illustrates defogging system from a second view according to an embodiment. The defogging system 227 includes the defogging unit 221 and connection component 225. The defogging unit 221 is shaped in a symmetric forklike flexible printed circuit board (PCB), where each of two side wings of the PCB contain a heating unit 223. The heating unit 223 includes a resistive heater traces made of thin long copper wires. To ensure an optimal thermal coupling between the heating unit 223 and the connection component 225, any cover of the PCB may be removed in those interface sections that shall be heated. The heating unit 223 may be attached to the aluminum wall of the connection component 225 by means of Pressure-sensitive adhesive (PSA) which may also provide an acceptable thermal coupling between the parts.

[0108] The defogging unit 221 may include a flexible PCB that may have a minimum bend radius of 2.5 m. The PCB may be colored black and designed by keeping components out of the optical path to avoid any straylight arising inside the framework during scanning. The PCB may contain an Inter-Integrated Circuit (I.sup.2C) and/or Pulse Width Modulation (PWM) communication 229 interface and a safety cut-off circuit 231 a EEPROM memory 233 to store information such as 2 kb AT24C02C EEPROM with an 8×256 memory organization. The region close or proximal to the embedded heating unit may include a temperature sensor 235 that is configured to provide signal, representing sensor measurements, to a control unit that is configured to provide feedback control of the temperature based on the signal. The feedback control of the temperature based on the signal allows the control unit to ensure that the temperature setting on the embedded heater is controlled such that the heat at the secondary optical component is maintained to produce necessary defogging, without overheating. Additionally or separately, the heating unit may also contain an optical sensor 237 such as an RGB color sensor located proximal to a connector interface 239 that is configured to provide electrical connection of the heating unit with the housing 103. The optical sensor is configured to monitor color changes in response to positioning of the sleeve on the housing. The optical sensor may perform monitoring by detecting color (e.g. color change) through a small optically transparent window in the head 105. The optical sensor is configured to provide signal, representing color change, to a control unit. The control unit is configured to determine whether the sleeve 115 is correctly mounted onto the housing 107 based on the signal. For example, the color sensor 237 white LED may operate in a pulse mode to check if a certain color is present or if something is simply reflecting the generated light back to the sensor 237. In this case it may be concluded that a sleeve 115 is present. The intraoral scanner may be used for scanning only after the sleeve is determined to be correctly mounted. The skilled person would appreciate that there are other ways of determining correct mounting of the sleeve onto the housing. For example, the signal may be based on establishing an electrical connection between complimentary contact points of the housing and sleeve. Establishing the electrical connection provides the signal to the control unit that determines whether the mounting is proper based on the signal. Another example includes the signal may be based on establishing an physical connection between complimentary locking points (e.g. click locking mechanism) of the housing and sleeve. Establishing the physical connection may act as a trigger event that sends a signal to the control unit that determines whether the mounting is proper based on the signal. Other variations are within the scope of the disclosure.

[0109] 209 represents primary aperture and 213 represents primary optical component arranged at the primary aperture 209.

[0110] FIG. 3a illustrates a cross sectional view from a first perspective such as front view of the head and sleeve fully mounted on the housing according to an embodiment. The front view is in the direction X (see FIG. 1), through the distal section of the head 305 of the intraoral scanner system 101 when the sleeve 315 is fully mounted, i.e. in position, onto the housing 107 with the primary aperture 309 and secondary apertures 317 in alignment with each other. It is preferred to achieve a good heat transfer from the heating unit 323 to the secondary optical component 319. This is achieved by establishing a reliable physical contact between the secondary optical component 319 and connection component 325 when the sleeve 315 is fully mounted onto the housing 107. A part of the connection component 325 surrounding the primary optical component 313 may be shaped, e.g. like narrow rectangular bars, to extend downwards away from the primary optical component 313. The term downwards denotes a direction opposite to direction Z (see FIG. 1). The protruding part may be designed as a contact interface 341 for establishing contact with the secondary optical component 319 when the sleeve is positioned such as slid onto the head 305. A pocket 343 at the top part material surface of the sleeve 315 may generate a primary engagement element 345 in the form of a protrusion on the inside of the surface. The term top denotes a direction in the direction Z (see FIG. 1). The protrusion 345 at the top part of the sleeve 315 creates a contact force such as a spring force applied on the secondary engagement element 347 at the framework 311 of the head 305 when the sleeve 315 is fully mounted on the housing. The secondary engagement element 347 may respond by applying an equal spring force in the opposite direction. This reaction force pushes the secondary optical component 319 situated in the sleeve 315 in physical contact with the contact interface 341. The part of the contact interface 341 initially receiving the secondary optical component 319 is shaped like longitudinal runners or skis similar to the structure on a sled. The force applied on the connection component 325 and the secondary optical component 315 because of the interaction between the primary engagement element 345 and secondary engagement elements 347 provides enough contact force between the connection component 325 and the secondary optical component 315 to ensure a good physical connection for thermal conduction between connection component 325 and the secondary optical component 315. The contact force is usually along the Z-direction (see FIG. 1) and may be in the range of 1 to 24 N. The weight of the connection component is kept low, for example below 1.75 g, preferably below 1.5 g, more preferably below 1.25 g such as 1.2 grams. Surface roughness of the connection component 325 such as the profile roughness parameter (Ra) at interface(s) to conduct heat is usually kept as low as possible. There may be manufacturing limitation that affects how low profile roughness parameter (Ra) value may be achieved. The profile roughness parameter (Ra) may be in the range of 0.100-3.00 μm such as around 2.00 μm. Additionally of alternatively, Maximum Surface roughness (Rm) of the connection component at interface(s) to conduct heat is typically kept low and may be below 12 μm, such as below preferably below 10 μm, more preferably below 8 μm, even more preferably below 6 μm, most preferably below 4 μm. Although it may be preferred to keep both Maximum Surface roughness and the Average Surface Average low, it is generally preferred to use the Maximum Surface roughness as a more relevant criterion.

[0111] FIG. 3b illustrates a cross sectional view from a first perspective such as front view of the head and sleeve fully mounted on the housing according to an embodiment. This figure shows a heating element and positioning of illumination unit that is different from the one disclosed in FIG. 1, which illustrates a heating unit 123 and an illumination unit (not shown) comprised in the main body 103. However, for the purpose of understanding the perspective, it is to be understood that the front view is in the direction X (see FIG. 1), through the distal section of the head 305 of the intraoral scanner system 101 when the sleeve 315 is fully mounted, i.e. in position, onto the housing 107 with the primary aperture 309 and secondary apertures 317 in alignment with each other. The heating unit includes at least one component in the housing such as in the head 305, the at least one component being configured to generate heat in response to the at least one component performing a scanning related function during scanning of the patient. The at least one component may be an illumination unit 355 such as one or more LEDs that are configured to generate light, i.e. scanning related function, for illuminating an object to be scanned. The at least one component may be an image sensor 357 configured to generate the plurality of images based on the incoming (reflected) light received from the illuminated object, i.e. scanning related function. Placing the illumination unit and/or sensor in the head allows projecting the light directly from the head onto the object and/or to acquire data at the sensor directly from the reflected light. However, in response to receiving electrical power to generate the light, the light source also generates heat that is transferred, through the connection component, to the secondary optical component in the sleeve by way of thermal conduction during scanning. The heat generated by the at least one component during the scanning may be understood as a waste or residual heat that gets generated when the at least one component performs scanning related function during scanning. The at least one component may be connected to the connection component 325 using a contact component 359 that provides a direct interface (e.g. illumination unit 355) or indirect interface (e.g. image sensor 357) between the at least one component and connection component. Alternatively, the at least one component may be attached directly onto the connection component 325 with the contact component 359. A number of components in this embodiment are same and work on the same principle as those disclosed in the embodiment of FIG. 3a unless mentioned otherwise or are contradictory to utilizing waste or residual heat from the at least one component. For example, 311 represents a framework, 343 represents a pocket, 345 represents primary engagement elements, 347 represents secondary engagement elements, 325 represents the connection component but with a different geometry as illustrated, e.g. running along at least in part along an inner surficial periphery of the secondary engagement elements 347 of the head to establish conductive contact between the at least one component and the secondary optical component 319, 341 represents contact interface, 319 represents the secondary optical component and 313 represents the primary optical component. The weight of the connection component is kept low, but is generally higher 1.25 g, and usually below 5 g. Surface roughness of the connection component 325 such as the profile roughness parameter (Ra) at interface(s) to conduct heat is usually kept as low as possible. There may be manufacturing limitation that affects how low profile roughness parameter (Ra) value may be achieved. The profile roughness parameter (Ra) may be in the range of 0.100-3.00 μm such as around 2.00 μm. Additionally of alternatively, Maximum Surface roughness (Rm) of the connection component at interface(s) to conduct heat is typically kept low and may be below 12 μm, such as below preferably below 10 μm, more preferably below 8 μm, even more preferably below 6 μm, most preferably below 4 μm. Although it may be preferred to keep both Maximum Surface roughness and the Average Surface Average low, it is generally preferred to use the Maximum Surface roughness as a more relevant criterion.

[0112] FIG. 4a illustrates, from a first view such as side view, a first stage during mounting of the sleeve onto the housing according to an embodiment. FIG. 4b illustrates, from the first view such as side view, a second stage during mounting of the sleeve onto the housing according to an embodiment. FIG. 4c illustrates, from the first view such as side view, a third stage during mounting of the sleeve onto the housing according to an embodiment. The side view is a view in the direction Y (see FIG. 1). The first stage, second stage and third stage refer to different stages of the intraoral scanner system 101 during the process of mounting the sleeve 415 onto the housing 107. FIG. 4a shows a situation just before the secondary optical component 419 is brought into contact with the connection component 425 of the defogging system 227. FIG. 4b shows a stage where the sleeve 415 is partially mounted on the head 405. The connector interface 441 of the connection component 425 has received, in part, the secondary optical component 419 and is guiding the secondary optical component into position. FIG. 4c shows the fully mounted stage where the primary engagement element 445 and secondary engagement elements 447 are in alignment and the secondary optical element is correctly positioned and in physical contact with the connection component 425, thereby placing the secondary optical component such that thermal conduction via connection component is possible.

[0113] FIG. 5 illustrates, from the second view such as bottom view (in the direction of Z), the first stage (see FIG. 4a) during mounting of the sleeve onto the housing according to an embodiment. When the sleeve 515 is fully mounted, the connection component 525 is configured to create a contact area 549, outside the propagation area through which the scanning signal passes, with the secondary optical component 519, thus establishing physical contact for thermal conduction of the generated heat. The heat is then distributed through the entire area 549 along the peripheral section of the secondary optical component 519 such that heat can flow toward the center of the secondary optical component 519 to prevent fogging during scanning. The heating time of the secondary optical component 519 is dependent on the contact area, which is a function of the width of the runners 551 in the contact interface 541. It is apparent that for same length of the runners 551, a greater width would provide a greater contact area, thereby providing a more effective heating. The width of the runners 551 may be in the range of 0.2 to 2.0 mm, preferably around 1 mm such as 0.8 mm. As the efficiency of the thermal conduction may depend upon surface roughness, the choice of width may thus depend upon the Ra value. One other consideration is mechanical integrity, i.e. that choice of width and/or runner design ensure that the secondary optical component is prevented from getting chipped during engagement or disengagement. Fast and efficient heating of the surfaces of the secondary optical element may thus be achieved by having an intimate connection between the defogging unit 121, the connection component 525 and the secondary optical component 519.

[0114] Several aspects, discussed below in relation to FIG. 1 or other relevant figure, may be considered to optimize the heat transfer. These aspects are not limited to this embodiment but may also be used in combination with other embodiments:

[0115] First, the primary function of the connection component is to thermally conduct the generated heat from the heating unit 123 to the secondary optical component 119. As disclosed earlier, the connection component comprises a material having a high thermal conductivity. Accordingly, the connection component may allow transfer of, from the heating unit 123, the generated heat, which may get distributed throughout the entire connection component 125. Accordingly, physical characteristics of the connection component 125 may also determine effectiveness of heating of the secondary optical component. The physical characteristic may include one or more of shape, thickness, volume, mass, etc. It is preferred that the connection component 125 is designed such that the connection component is prevented from extending in regions that do not contribute to transferring heat to the secondary optical component 119. In other words, the connection component is designed such that the connection component extends primarily, such as only, towards the secondary optical component. Such extension of the connection component may provide the shortest path from the heating unit 123 to the secondary optical component 119. By altering the physical characteristic, e.g. reducing the volume of the connection components at specific regions, transfer of the generated heat may be controller and heating the secondary optical element may be achieved faster. As an example, a connection component that extends primarily, such as only, towards the secondary optical component as shown as 125 in comparison to a connection component having a shape that also goes around region 131 (FIG. 1) of the head, i.e. reducing the connection component coverage in mass by approximately 70% or more, may reduce the defogging time by at least 35%.

[0116] Additionally, the connection component 125 may define the primary aperture 109, thus the connection component may further be configured to support the primary optical component 113. In view of multi-functional role of the connection component, different portions of the connection component may include different physical characteristics. The portion of the connection component providing the support may have a different physical characteristic in comparison to that of the portion of the connection component that is primarily functioning to thermally conduct heat to the secondary optical component. For example, the portion supporting the primary optical component may be thicker than the portion designed primarily to transfer heat to the secondary optical component.

[0117] Second, the transfer of the generated heat to the primary optical component 113 may also be considered. As described previously, the connection component 125 may include a mounting frame, defining the primary aperture, for arranging the primary optical component 113. Thus, the connection component may provide mechanical support to mount the primary optical component at the primary aperture, which is defined by the connection component. This is illustrated in FIG. 6, which shows a zoomed cross-sectional view of the fully mounted sleeve 115 on the head 105, as seen from front in the direction X, according to an embodiment. This illustration corresponds to FIGS. 3a and 3b. FIG. 6 illustrates a detailed interface between the connection component 625, the primary optical component 613 and the secondary optical component 619 that is arranged in the sleeve 615. In order to inhibit the generated heat from unnecessarily transferring to the primary optical component 613, the thermal connection between the connection component 625 and the primary optical component 613 may be restricted. This is done because heating the primary optical component would increase the time or power it takes to reach the preferred temperature on the secondary optical component 625 and to achieve defogging. The primary optical component 613 may be mounted at the connection component 625 using a thermal isolating bonding adhesive 653 such as silicone, epoxy or UV curing glues which will form a heat isolating barrier thereby preventing the generated heat from being transferring from the heating unit 223 to the primary optical component 613 while simultaneously fixating the primary optical component 613 securely in place in the frame of the connection component 625.

[0118] Third, it is also useful to reduce, preferably minimize, the heat radiated between the secondary optical component 619 and the primary optical component 613. When the sleeve 615 is fully mounted onto the head, the secondary optical component 619 is fully engaged (i.e. in desired physical contact) with the connection component 625 at the contact interface 641. Apart from ensuring good physical contact for thermal conduction of the generated heat to the secondary optical component, this engagement/arrangement also ensures that the that the primary second surface 659 of the primary optical component 613 is separated from the secondary first surface 661 of the secondary optical component 619 by a gap 655. 657 represents primary first surface of the primary optical component 613 and 663 represents secondary second surface of the secondary optical component 619. The distance or gap width 655 between the primary optical component 613 and secondary optical component 619 secures that direct contact between these components is avoided. It is preferred that the distance 655 between the two optical components (613, 619) is as large as possible to inhibit heat transfer between these components such as from the secondary first surface 661 of the secondary optical component 619 by convection or radiation to the primary second surface 659 of the primary optical component 613. It may be appreciated that at least a part of the sleeve 615 and at least a part of the head unit 105 (e.g. the distal end section) is intended to be inserted into the oral cavity, offering limited space, to acquire 3D information. Therefore, there is a need to have as smallest probe head size comprising the distal end section as possible. The small size offers the advantage of easy maneuverability of the head (105) within the intraoral cavity and obtaining 3D information from many different places and angles without discomfort to the patient. In view of the conflicting requirements, it is determined that a gap width 655 between the optical components (613, 619) in the range [0.1 to 1 mm, preferably less than 0.5 mm such as 0.2 mm produce an effective defogging of the secondary optical component.

[0119] Fourth, heat transfer at the secondary optical component 619 needs to be high. In other words, the generated heat received by the secondary optical component 619 at the contact interface 641 needs to be transferred as quickly as possible across the secondary optical component (619). Thus, the received generated heat needs to be transferred from the edges of the secondary optical component 619 inwards towards the center to achieve a temperature distribution above the dew point of the scanning environment. This may be achieved by designing the secondary optical component 619 by selecting an optically transparent material with an intrinsically high thermal conductivity. Additionally, heat transfer in the primary optical component 613 may be as low as possible to further support the suppression of heat flowing directly or indirectly from the heating unit to the primary optical component 613. Thus, the material for the primary optical component 613 may be selected from optically transparent materials with an intrinsically low thermal conductivity.

[0120] In an embodiment, at least one of the primary optical components or the secondary optical component may be designed in a layered configuration. The layered configuration may be designed to provide beneficial characteristics in relation to thermal conductivity and heat transfer, as described above. This is illustrated in FIGS. 7a-7d, which illustrate optical components according to different embodiments.

[0121] Referring to FIG. 7a, the primary optical component 713 may include a substrate having a deposit of poor thermal conductivity or insulating properties. At least one of the primary first surface 757 or primary second surface 759 of the primary optical component 713 may act as a substrate with the deposit disposed over the at least one of the primary first surface 757 or primary second surface 759. Thus, use of such deposit prevents the generated heat from heating up the primary optical component 713 and/or inhibit radiated heat from the secondary optical component 719 across the gap width to heat up the primary optical component 713. In an example, the primary optical component may be made of BK7 optical grade glass with a nano transparent heat insulating coating deposit as the deposit 765 on the primary second surface 769 of the primary optical component 713. The deposit 765 may by a transparent heat insulating coating composed of antimony doped tin oxides (ATO) nanoparticles or any other suitable ceramic or metallic coatings. The deposit 765 may alternatively be composed of an ultra-thin polyester-based film. Alternatively, the substrate may include a material having a low thermal conductivity, such that heat is dispersed slower in the deposit compared to the bulk of the primary optical component 713. Such a material may be bonded to the bulk material by UV glue and be an optical transparent polymer like and amorphous thermoplastic such as Polymethylmethacrylate (PMMA) or Polycarbonate (PC).

[0122] Referring to FIG. 7b, the substrate includes edges of the primary optical component 713 and the deposit 765 is located along the edges of the primary optical component 713. In this case, the deposit may be composed of a material having a low thermal conductivity, such that heat generated by the heating unit is inhibited from flowing, across the mechanical interface defined the deposit, to the primary optical component 713.

[0123] FIG. 7c illustrates a multi-layered secondary optical component according to the embodiment. The secondary optical component 719 includes several layers contributing to its heat transfer ability across its surface. The secondary optical component 719 may include a substrate having a deposit 765 of high thermal conductivity. At least one of the secondary first surface 761 or secondary second surface 763 of the secondary optical component 719 may act as a substrate with the deposit 765 disposed over the at least one of the secondary first surface 761 or secondary second surface 763. Thus, use of such deposit 765 facilitates the generated heat of being transferred throughout the secondary optical component 719 such that at least the secondary second surface 763 may reach the desired temperature as fast and efficiently as possible to achieve defogging. In an example, the secondary optical component 719 includes a layered structure of optical grade crown glass 766, like borosilicate glass (BK7) sandwiched in between deposit 765 composed of thin layers of corundum like sapphire glass. The thin layers of sapphire glass may have in intrinsically higher thermal conductivity then the crown glass core 766, thus facilitating the transfer of heat along the surface of the secondary optical component 719.

[0124] Referring to FIG. 7d, the secondary optical component 719 may include, such as embedded or over the surfaces, wires as deposit 765 for the purpose of defogging. The wires may be provided at least one of the secondary first surface 761 or secondary second surface 763 of the secondary optical component 719. The wires may be adhered to at least one surface of the secondary optical component. Additionally or alternatively, the wires may be embedded within the secondary optical component, i.e. sandwiched between the secondary first surface and secondary second surface. The wires may be separated by a distance along the length and/or width of the secondary optical component 719, such as equidistant from one another. Such wires 765 may be composed of a material having high thermal conductivity, such as copper, gold, Nickel chromium or alike. One or more wires may be configured to be in physical contact with the connection component when the sleeve is in mounted over the head, i.e. in fully received position with the secondary optical component being in alignment with the primary aperture. When the wires comes in contact with connection component 125, the generated heat from the heating unit 123 is configured to be conducted through the wires to efficiently heat up the secondary optical component in a fast manner. The transport of thermal energy in a material is usually governed by one or more of material properties, heat flux and temperature difference. In an example using a secondary optical component of size 25×18 mm and 30 copper wire strips along the 25 mm length and width of 20 μm and positioned at a distance of 600 μm between adjacent wires, a fill factor (f) of approximately 3% is achieved. In another example using a secondary optical component of size 25×18 mm and 30 gold wire strips along the 18 mm length and width of 20 μm and positioned at a distance of 800 μm between adjacent wires, a fill factor (f) of approximately 2.5% is achieved. Fill factor may be defined as the percentage of the secondary optical component area (e.g. surface area), covered by the wires, that is otherwise exposed to the scanning signal. Inclusion of the wires produce opaqueness, which may start interfering with the scanning signal if the fill factor exceeds a certain level. The skilled person would realize that a higher fill factor may make the heating of the secondary optical component more efficient (i.e. reduced defogging time) but at the expense of increasing area covered with wire. However, it is determined that a fill factor of below 12% such as between 2 to 12% produces negligible impact on the scanning signal. Thus, a fill factor in the disclosed range ensure that the scanning signal does not get altered substantially to negatively affect the data acquired during scanning. Furthermore, the sharpness of the acquired two-dimensional image may essentially be unaffected by presence of the wires as well. Such a deposit configuration using wires at the secondary optical component introduces the capability of transferring heat across the secondary optical component without the requirement of the secondary optical component necessarily having a high thermal conductivity. This allows a wider range of material or configuration choices for the secondary optical component. For example, the secondary optical component 719 may be made out of non-birefringent Polymethylmethacrylat (PMMA) or polycarbonate (PC) with a wire deposit 765 on surface of the secondary optical component.

[0125] A sleeve, detachable from the housing, may be used as a multi-use sleeve or a single use sleeve. The secondary optical component 719 may be detachably mounted in a multi-use sleeve or in a single use sleeve. For multi-use sleeve, at least the sleeve 115 need to withstand reprocessing (typically autoclaving, wiping with alcohol, washing with soft brush and soap etc.) in between usage on different patients. The secondary optical component 119 may be replaceable between usages or be configured to withstand the reprocessing as well.

[0126] The secondary optical component 119 may additionally be able to withstand disinfection if the sleeve 115 comprising a permanently attached secondary optical element 119 is intended to be used multiple times. Disinfection or sterilization is a step in the reprocessing of reusable dental instruments that have become contaminated, and is typically performed in a steam autoclave, which is typically performed at 134-137° C., 2.1-2.25 bar gauge pressure for at least a 3 minutes. Typically, a sleeve 115 may be used for up to 170 repeated cycles. The autoclave process may cause the light transmission properties to decay as the surfaces of the secondary optical component (119) may deteriorate over time. Multiple autoclave cycles of the sleeve 115 may also leave residues on the secondary first surface 661 and/or secondary second surfaces 663 which may cause irreversible changes as it may be very hard to clean (e.g., metal oxides, calcium carbonate or organic material). Therefore, the secondary first surface and/or secondary second surface may be coated with hydrophobic coating such as highly hydrophobic coating like Perfluorodecyltrichlorosilane (FDTS). The coating causes droplets of condensed steam to be repelled from the surfaces (661,663), rather than sticking and drying, causing deposits on the surfaces (661,663). It may be beneficial to place the sleeve 115 in the autoclave, such that the secondary optical component 119 is resting in a vertical position relative to gravity in order to allow droplets to roll off before evaporating and leaning deposits. Should deposits form on the surfaces (661,663), the FDTS coating makes the deposits much easier to be removed, thereby avoiding irreversible deterioration of secondary optical element 119.

[0127] At least one of the primary optical component 113 or secondary optical component 119 may be equipped with anti-reflective (AR) coating. In an example, two-layer coating such as layers of Ta.sub.2O.sub.5 and SiO.sub.2 on one or more surfaces of at least one of the primary optical component or secondary component may be used such as on the surfaces (659, 661, 663), which are required to withstand the cleaning process, and in some cases even autoclaving. The AR coating may have a reflectance, averaging below 1% in the visible spectrum. As the outer layer may be SiO.sub.2, additional coatings such as Perfluorodecyltrichlorosilane (FDTS) readily forms strong covalent bonds to the surface. An intermediate bonding layer such as aluminum oxide, may also be used between the outer layer and additional coating. The intermediate bonding layer may be configured to promote adhesion and may be deposited using layer deposition techniques such as atomic layer deposition. The interior surface of the framework 115 may additionally be equipped with a 3-layer AR coating, such as layers of Ta.sub.2O.sub.5, SiO.sub.2 and MgF.sub.2, with broad band low reflection and average reflection for visible light may be below 0.5% to avoid stray light inside the scanner. This is shown by way of FIG. 9 that illustrates a multilayered secondary component according to an embodiment. The secondary optical component 919 includes two layers of coating of Ta.sub.2O.sub.5 (973, 981) and SiO.sub.2 (977, 983) on both surfaces of the secondary optical component. Additional hydrophobic coating of Perfluorodecyltrichlorosilane (FDTS) (979, 987) are also provided over the coated layers on either surfaces of the secondary optical component with an intermediate bonding layer of Al.sub.2O.sub.3 (975, 985) being sandwiched between the hydrophobic coating (979, 987) and coated layers (973-975, 981-985).

[0128] In an embodiment, the optical system of the scanner is configured to operate using polarized light signals. Thus, the primary optical component 113 and secondary optical component 119 may be configured to substantially maintain the polarization state of the light transmitted through these components (113, 119). Additionally, the secondary optical component 119 is configured to be heated quickly to allow effective defogging of the secondary optical component. To achieve the intended effective defogging, the secondary optical component may include a crystalline structure that typically offers significantly faster heating when compared to an amorphous glass material. For example, Corundom like Sapphire may be chosen as a suitable crystalline structure material for the secondary optical component because of its high thermal conductivity. Although crystalline structure like Sapphire may offer the advantage for heating, but it may intrinsically be birefringent, and may thus deteriorates the polarization state of transmitted polarized light. To mitigate this, now referring to FIG. 8, the secondary optical element 819 like sapphire is configured such that the light passing through the secondary optical component is perpendicular to crystal plane (867, c-plane (0 degree)—0001 orientation) of the crystalline structure. The light passing through the crystalline structure is defined by an optical axis 869, i.e. light path within the crystalline structure. The mirror 877 is configured to allow directing the scanning signal out of the scanner and/or towards the sensor. Alternatively, a glass prism may replace the mirror to allow directing the scanning signal.

[0129] In one embodiment, for a predefined physical arrangement of scanner components with sleeve in the mounted state onto the head and positioning of the secondary optical component with respect to optical axis (873, 875) known, configuring the crystalline structure includes designing the crystal lattice of the crystalline structure such that the light passing through the secondary optical component is perpendicular to the crystal plane. For example, if the secondary optical component 819 is positioned at an angle θ.sub.1 relative to the optical axis 873 of the scanner at the secondary first surface 861 (863 represents the secondary second surface), then the crystalline structure is cut at an angle to the c-plane such that the c-plane will be perpendicular to the optical axis 869.

[0130] In another embodiment, for a given crystalline structure having a predefined crystal plane, configuring the crystalline structure includes designing physical arrangement of scanner components for sleeve in the mounted state onto the head and positioning of the secondary optical component with respect to optical axis (873, 875) such that the light passing through the secondary optical component is perpendicular to the predefined crystal plane when sleeve is mounted onto the head. For example, the secondary first surface and secondary second surface of the secondary optical component 819 is configured to be at an angle θ.sub.2 with respect to the c-plane, such that the angle θ.sub.2 corresponds to the internal light propagation angle inside the crystal being perpendicular to the C-plane 867 of the crystal. The angle θ.sub.2 is a function of the angle of incident light and the ratio between the refractive index (n1, n2) of the materials on each side of the interface (e.g. the secondary first surface 861). The angle θ.sub.2 may be applicable in both disclosed embodiments, i.e. to design the crystalline structure and/or arranging a given secondary optical component in the scanner. In one scenario, the secondary optical component 819 is interfaced at secondary first surface 861 by air and angled at θ.sub.1 which may be in the range of 12° to 16° such as 14° and angle θ.sub.2 may be in the range of 6° to 10° such as around 7.5°. In another scenario, the secondary optical component may be interfaced at the secondary first surface 861 with another material such as a glass prism or alike. The value of at θ.sub.1 and angle θ.sub.2 may be adjusted to achieve the light passing through the secondary optical component to be perpendicular to the predefined crystal plane.

[0131] Although the disclosure is made in relation to probe light exiting the scanner and illuminating the dental object; the disclosed principle in relation to configuring the crystalline structure may equally be applicable for the reflected light received in response to illumination of the dental object. With the disclosed configuration, the birefringence may be minimized such that using the crystalline structure for the secondary optical component does not substantially alter the transmitted light.

[0132] Additionally, the negative impact of using crystalline structure like sapphire as the secondary optical component 819 on the polarization state of the probe light may additionally be correlated to thickness 871 of the crystalline structure 819. Preferably the crystalline structure needs to be as thin as possible while still being sturdy during use such as scratch resistance and not break easily upon accidental contact with teeth, and for handling during fabrication and assembly. As the percentage light transmitting across the secondary optical component with desired polarization is a function of the thickness of the secondary optical component, it is preferred that the secondary optical component is as thin as possible. It is determined that the secondary optical component 819 may have a thickness of in the range of 0.1 mm to 1 mm, such as 0.5 mm. Having a thickness in this range does not change the polarization substantially to impact the scan data quality, while still being sturdy for the purpose of intraoral scanning. It is also preferred to having the secondary optical component made of crystalline glass structure such as a sapphire. In the scenario where the secondary optical component breaks, another advantage is that sapphire will typically form a clean break, as it is crystalline, resulting in fewer, larger pieces of debris. An amorphous glass will shatter an many small sharp pieces as it breaks.

List of Items

[0133] 1. An intraoral scanning system comprising: [0134] a housing comprising [0135] optical components, [0136] a head, comprising a primary aperture, configured to be inserted into an oral cavity of a patient, and [0137] a defogging unit comprising a heating unit; [0138] a sleeve configured to cover at least a part of the head when the sleeve is coupled with the housing, the sleeve comprising a secondary optical component arranged at a secondary aperture that is configured to be positioned in alignment with the primary aperture, wherein [0139] the heating unit is configured to generate heat in response to application of electrical power to the heating unit, and [0140] the secondary optical component is configured to be arranged such that the generated heat is transferred from the heating unit to the secondary optical component through thermal conduction between the heating unit and secondary optical component.
2. The system according to item 1, wherein the housing comprises a connection component that is configured to establish a physical connection between the heating unit and the secondary optical component to permit transfer of the generated heat by thermal conduction from the heating unit to the secondary optical component.
3. The system according to any one or more of the preceding items, wherein the heating unit is arranged on the connection component.
4. The system according to any one or more of the preceding items, wherein the heating unit is physically connected to the connection component using a thermal conductive material.
5. The system according to any one or more of the preceding items, wherein the sleeve is removably attached with the housing such that coupling the sleeve with the housing arranges the secondary optical component in physical connection with the heating unit via the connection component for permitting thermal conduction of the generated heat from the heating unit to the secondary optical component.
6. The system according to any one or more of the preceding items, wherein the secondary optical component is made up of a material having a thermal conductivity higher than the thermal conductivity of the primary optical component.
7. The system according to any one or more of the preceding items, wherein the secondary optical component comprises a substrate comprising a deposit of high thermal conductivity disposed on at least one of a secondary first surface or secondary second surface of the secondary optical component.
8. The system according to any one or more of the preceding items, wherein the secondary optical component comprises a multi-layered structure where at least two layers of the multi-layered structure have different thermal conductivity and/or optical properties.
9. The system according to any one or more of the preceding items, further comprising a primary optical component arranged at the primary aperture, the primary optical component being inhibited from receiving the generated heat from the heating unit to the primary optical component.
10. The system according to any one or more of the preceding items, further comprising an insulating material arranged between the primary optical component and the heating unit to inhibit transfer of the generated heat from the heating unit to the primary optical component.
11. The system according to any one or more of the preceding items, wherein the primary optical component is made up of a material having a thermal conductivity lower than the thermal conductivity of secondary optical component.
12. The system according to any one or more of the preceding items, wherein the primary optical component comprises a substrate comprising a deposit of poor thermal conductivity disposed on at least one of a primary first surface or a primary second surface of the primary optical component.
13. The system according to any one or more of the preceding items, wherein the primary optical component comprises a multi-layered structure where at least two layers of the multi-layered structure have different thermal conductivity and/or optical properties.
14. The system according to any of the preceding items, wherein the thermal conductivity of the primary optical component material is lower than the thermal conductivity of the i) connection component, or ii) connection component and secondary optical component.
15. The system according to any of the preceding items, wherein the thermal conductivity of the insulating material arranged between the primary optical component and the heating unit is lower than the thermal conductivity of the i) connection component, or ii) connection component and secondary optical component.
16. The system according to any of the preceding items, wherein the thermal conductivity of the deposit applied on the primary connection component is lower than the thermal conductivity of the i) connection component, or ii) connection component and secondary optical component.
17. The system according to any of the preceding items, wherein thermal conductivity of materials defining a thermal path from the heating unit to the secondary optical component is higher than the thermal conductivity of materials defining a thermal path from the heating unit to the primary optical component.
18. The system according to any one or more of the preceding items, wherein [0141] when the sleeve is coupled with the housing, a relative position of the primary optical component and secondary optical component defines a gap therebetween, and [0142] the gap comprises a gap-width that allows thermal insulation between the primary optical component and secondary optical component.
19. The system according to any one or more of the preceding items, wherein the gap width is at least partially filled with a thermal insulating material.
20. The system according to any one or more of the preceding items, wherein [0143] the head comprises a primary engagement element and the sleeve comprises a secondary engagement element; and [0144] the primary engagement element and secondary engagement element are configured to physically interact during coupling of the sleeve with the housing to bring the connection component and secondary optical component/a secondary frame comprising the secondary optical component in a physical connection with each other.
21. The system according to any one or more of the preceding items, wherein [0145] the head comprises a primary engagement element and the sleeve comprises a secondary engagement element; and [0146] the primary engagement element and secondary engagement element are configured to physically interact such that the connection component and secondary optical component/the secondary frame comprising the secondary optical component stay in a physical connection with each other when the sleeve is coupled with the housing.
22. The system according to any one or more of the preceding items, wherein the physical connection between the connection component and secondary optical component/the secondary frame comprising the secondary optical component is defined by a contact surface area at an interface between the connection component and secondary optical component/the secondary frame.
23. The system according to any one or more of the preceding items, wherein a portion of the connection component interfacing the secondary optical component/the secondary frame comprising the secondary optical component is dimensioned such that when the sleeve is coupled with the housing, the connection component is restricted from interfering with the signal receiving section of the secondary optical component.
24. The system according to any one or more of the preceding items, wherein when the sleeve is coupled with the housing, a portion of the connection component interfacing the secondary optical component/the secondary frame comprising the secondary optical component is arranged in relation to the secondary optical component/the secondary frame to avoid the connection component interfering with a signal receiving section of the secondary optical component.
25. The system according to any one or more of the preceding items, wherein [0147] one of the primary engagement element or secondary engagement element comprises a protrusion and another of the primary engagement element or secondary engagement element comprises a surface that is configured to physically interact with the protrusion; and [0148] the protrusion and the surface are configured to physically interact to bias the secondary optical element/secondary frame comprising the secondary optical element and connection component towards each other.
26. The system according to any one or more preceding items, wherein [0149] one of the primary engagement element or secondary engagement element comprises a guide and another of the primary engagement element or secondary engagement element comprises a guide channel that is configured to receive the guide; and [0150] movement of the guide along the guide channel is configured to bias the secondary optical element/secondary frame comprising the secondary optical element and connection component towards each other.
27. The system according to any one or more preceding items, wherein the heating unit comprises an embedded heater that is configured to solely generate heat prior to and/or during scanning of the patient's teeth.
28. The system according to any one or more preceding items, wherein heating unit includes at least one component in the housing, the at least one component being configured to generate heat in response to the at least one component performing a scanning related function during scanning of the patient.
29. The system according to any one or more preceding items, wherein the scanning related function is different from solely to generate heat.
30. The system according to any one or more preceding items, wherein the at least one component is configured to generate heat comprising residual or waste heat.
31. The system according to any one or more preceding items, wherein average surface roughness of the connection component at interface(s) to conduct heat is in the range of 0.100-3.00 μm.
32. The system according to any one or more preceding items, wherein maximum surface roughness of the connection component at interface(s) to conduct heat is below 12 μm.
33. The system according to any one or more preceding items, wherein the head of the housing comprises a temperature sensor.
34. The system according to any one or more preceding items, wherein the temperature sensor is arranged proximal to the primary aperture.
35. The system according to any one or more preceding items, wherein the temperature sensor is configured to measure temperature in the head and provide sensor measurements as signal to a control unit.
36. The system according to any one or more preceding items, wherein the control unit, based on the received sensor measurement signal, is configured to provide feedback control signal.
37. The system according to any one or more preceding items, wherein the control unit provides the feedback control signal at least when the sensor measurement signal is beyond a threshold temperature value.
38. The system according to any one or more preceding items, wherein the threshold temperature value may be predefined based on a permissible temperature in the oral cavity.
39. The system according to any one or more preceding items, wherein the feedback control signal is configured to put the scanner in a throttling mode.
40. The system according to any one or more preceding items, wherein, the feedback control signal is configured to control the temperature setting of the embedded heating unit such that the sensor measurement at the temperature sensor is at or within the threshold temperature value.
41. The system according to any one or more preceding items, wherein the secondary optical component comprises layers of coating of Ta.sub.2O.sub.5 and SiO.sub.2 on at least one surface of the secondary optical component.
42. The system according to any one or more preceding items, wherein the secondary optical component comprises hydrophobic coating of Perfluorodecyltrichlorosilane (FDTS) over the layers of coating.
43. The system according to any one or more preceding items, further comprising an intermediate bonding layer of Al.sub.2O.sub.3 sandwiched between the hydrophobic coating and coated layers.

[0151] 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. It may be understood that the comparative statements mentioning higher/lower including variations thereof, or disclosed range/values for comparative parameters or properties such as thermal conductivity and/or heat capacity are made in relation to substantially same environment conditions, for example room temperature or intraoral environment.

[0152] 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.

[0153] 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 to be limited to “only” one/single. It should be emphasized that the term “comprises/comprising/including/having” when used in this specification is taken to specify the presence of stated features, integers, operations, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. 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 are not limited to the exact order stated herein, unless expressly stated otherwise.

[0154] In claims enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage.