Compact confocal dental scanning device

Abstract

Apparatuses and methods for confocal 3D scanning are described herein. The apparatuses can include a spatial pattern disposed on a transparent substrate and a light source configured to provide illumination to the spatial pattern and an optical system including projection / imaging optics having one or more lenses and an optical axis. The projection / imaging optics can be scanned to provide a depth scan by moving along the optical axis.

Description

[0001] This application is a divisional application of PCT National Stage application with a filing date of January 11, 2018, National Application No. 201880006862.1.

[0002] Cross-Reference to Related Applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 445,663, filed January 12, 2017, and U.S. Utility Patent Application No. 15 / 895,010, filed December 29, 2017, entitled "COMPACT CONFOCAL DENTAL SCANNING APPARATUS," which are incorporated by reference herein in their entireties.

[0004] The entire contents of the following U.S. Patent Applications are incorporated herein by reference to the extent that they are in their entirety: U.S. Patent Application No. 14 / 741,172, filed June 16, 2015, entitled "APPARATUS FOR DENTAL CONFOCAL IMAGING," and U.S. Patent Application No. 14 / 825,173, filed August 13, 2015, entitled "CONFOCAL IMAGING APPARATUS WITH CURVED FOCAL SURFACE."

[0005] Incorporation by Reference

[0006] All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. TECHNICAL FIELD

[0007] The present invention relates generally to apparatuses and methods for three-dimensional (3D) scanning of objects. In particular, the present invention relates to apparatuses and methods for three-dimensional (3D) scanning of teeth in a patient's mouth. BACKGROUND

[0008] Three-dimensional scanning of objects plays a role in many clinical applications. For example, in the field of orthodontics and prosthodontics, three-dimensional (3D) scanning of teeth can provide valuable information for diagnosis and treatment such as dental restorations and orthodontic indications. Confocal 3D scanning is one of the imaging techniques that can provide such information. Confocal microscopes can be used to perform three-dimensional scanning by illuminating and observing a single near-diffraction-limited spot, for example, by using a spatial pinhole to eliminate out-of-focus light. Confocal 3D scanning can be used to obtain images without out-of-focus blur and can allow three-dimensional visualization of an object. Other surface topography scanners have been described, but are generally relatively bulky and can be less comfortable or even difficult to use. U.S. Patent No. 8,878,905 describes a 3D scanner that uses confocal pattern projection techniques to obtain 3D geometry of an object. The 3D scanner disclosed therein uses a time-varying pattern (or a segmented light source to equivalently create a time-varying pattern). When the pattern is varied in time for a fixed focal plane, the in-focus regions on the object will show oscillating patterns of light and darkness. However, out-of-focus regions will show less or no contrast in the light oscillations.

[0009] Accordingly, there is a need to develop an apparatus and related methods for confocal scanning to have a more compact size, a lighter weight, and a lower cost than conventional confocal scanning apparatuses. SUMMARY

[0010] Described herein are apparatuses and methods for confocal 3D scanning of an object, for example, at least a portion of teeth in a patient’s mouth.

[0011] For example, described herein is an apparatus for confocal 3D scanning of a subject’s teeth. The apparatus can include a confocal illuminator configured to generate confocal illumination of an object. The confocal illuminator can include a spatial pattern disposed on a transparent substrate and a light source configured to provide illumination to the spatial pattern. The apparatus can include an optical system including one or more lenses and having an optical axis. The apparatus can include a depth scanning module configured to be movable along the optical axis. The apparatus can further include a beamsplitter configured to transmit a light beam of the confocal illuminator to the object and reflect a light beam returned from the object. The apparatus can include an image sensor configured to receive the light beam returned from the object through the beamsplitter. The apparatus can be configured for 3D scanning of at least a portion of an object, for example, intraoral dental 3D scanning for all derivatives of dental restorations and orthodontic indications.

[0012] Generally, an apparatus for confocal scanning disclosed herein can include a confocal illuminator, e.g., an LED-illuminated transparent piece confocal illuminator. Generally, the apparatus can include an optical system (including projection / imaging optics) configured to illuminate an object and image the object. The optical system can include a projection and imaging system or subsystem and an illumination subsystem (illumination optics). For example, the projection / imaging optical system can include optical elements (lenses) and the same optical path. The apparatus can include a depth scanning module, which can include a compact linear actuator, e.g., a voice coil motor (VCM). The apparatus can include a front tip, which can include a 45-degree backheated mirror.

[0013] For example, a portion of the optical system between the beamsplitter and the front tip can be configured to be small enough to be disposed entirely in the depth scanning module. Thus, the confocal scanning apparatus can include a single optomechanical module for imaging and depth scanning. The single optomechanical module, which integrates the optical system and the depth scanning module, can enable relaxed production and assembly tolerances and reduced manufacturing costs. The optical design is suitable for LED-illuminated transparent pieces, which further enables low-cost manufacturing. The optical system can further include a reduced number of lenses, e.g., the optical system can include fewer than 10 lenses, fewer than 9 lenses, fewer than 5 lenses, fewer than 3 lenses, etc. In any of the apparatuses described herein, the optical system (e.g., the protection / imaging optical system) can provide an axial magnification between 5 and 20 times (e.g., 11x). Moreover, due to the simpler configuration, the optical systems disclosed herein can be less sensitive to component errors and thermal variations than conventional confocal optical systems. The apparatus can include an optical system configured for maximum deviation from telecentricity towards the diverging chief ray for minimal front tip size. The apparatus can have a non-telecentric configuration in object space, e.g., a diverging confocal beam in object space.

[0014] Generally, the apparatuses described above can further include a polarizing beamsplitter for confocal coupling. The apparatus can be configured for invariant confocal conjugate shift. The apparatus can further support monolithic confocal conjugate components. Generally, the confocal scanning apparatus can be compact, lightweight, and low cost. For example, the apparatus can be more compact (e.g., 2x, 3x, or 4x) and lighter (e.g., 2x or 3x) than a typical conventional confocal scanner with the same scanning capability. The apparatus can also include a compact high-speed image sensor. For example, the apparatus can be compact and lightweight enough to be handheld. The scanning speed can be about 5, 10, 20, 50 scans / second, or any value therebetween. For example, the scanning speed can be about 10 scans / second.

[0015] The spatial pattern on the transparent substrate can be static (e.g., does not change over time). The transparent substrate may include a transparent element. The beam splitter may include a polarization-sensitive beam splitter, wherein the spatial pattern and the transparent substrate are bonded to a first side of the beam splitter, and wherein the image sensor is bonded to a second side of the beam splitter perpendicular to the first side to maintain a stable relative position between the image sensor and the spatial pattern.

[0016] For example, a confocal illuminator can be configured such that the image of the light source is positioned at the entrance pupil of the optical system. The aforementioned spatial pattern can be set at the conjugate plane of the image sensor such that, for the image sensor, the relative lateral offset of the position of the object's image with respect to the spatial pattern remains constant. The exit pupil of the optical system can be configured to point towards the maximum deviation of the diverging principal ray from the telecenter.

[0017] An optical system may include a projection subsystem and an imaging subsystem, which may be combined into a projection / imaging system (also known as a projection / imaging subsystem), wherein the projection subsystem and the imaging subsystem share one or more lenses and the same optical path between the beam splitter and the object.

[0018] The aforementioned device may further include a leading tip. The optical system (the projection / imaging optics portion of the system) between the beam splitter and the leading tip can be fully integrated into the depth scanning module as a single optomechanical module. The leading tip may include a folding mirror configured at a 45-degree angle to the optical axis. The depth scanning module can be configured as a unit movable from 0.1 mm to 5 mm along the optical axis, and has a depth scanning range between 5 mm and 40 mm. The leading tip may have a height of less than 20 mm.

[0019] In general, this document discloses an apparatus for confocal scanning. The apparatus may include illumination optics comprising a confocal illuminator configured to generate confocal illumination of an object. The apparatus may also include projection / imaging optics configured to project light (e.g., a transparent pattern) onto the object and image it; the projection / imaging optics may have an optical axis. The projection / imaging optics (part or subsystem of an optical system) may include one or more lenses and an exit pupil configured to deviate to the maximum telecentric direction of the diverging principal ray. The apparatus may include a depth scanning module configured to be movable along the optical axis. The apparatus may include a beam splitter configured to direct a beam from the confocal illuminator onto the object and reflect a beam returning from the object. The apparatus may further include an image sensor configured to receive the beam returning from the object via the beam splitter.

[0020] This document also describes a method for confocal 3D scanning, which may include initiating a confocal illuminator configured to generate confocal illumination of an object, the confocal illuminator including a spatial pattern disposed on a transparent substrate and a light source configured to provide illumination to the spatial pattern. The method may include illuminating the spatial pattern, projecting the pattern onto the object, and imaging the object using an optical system including one or more lenses and having an optical axis (e.g., a projection / imaging optics). The method may include scanning the object using a depth scanning module configured to be movable along the optical axis. The method may include delivering light from the confocal illuminator to the object (via the projection / imaging optics) via a beam splitter and imaging the light returning from the object using an imaging optics (e.g., again via the projection / imaging optics), and directing the returning light onto an image sensor using the beam splitter.

[0021] The method may include using one or more spatial patterns on a transparent substrate that does not change over time. For example, the method may include using a spatial pattern in which the transparent substrate is bonded to a spatial pattern on a first side of the beam splitter, wherein the image sensor is bonded to a second side of the beam splitter perpendicular to the first side to maintain a stable relative position between the image sensor and the spatial pattern.

[0022] This method may include setting an image of the light source at the entrance pupil of the optical system (after passing through a transparent pattern). For example, the method may include setting a spatial pattern at the conjugate plane of the image sensor such that the relative lateral offset of the position of the image of the object with respect to the spatial pattern is constant for the image sensor. The method may include setting the exit pupil of the optical system to the maximum deviation from the telecentric direction of the diverging principal ray. The method may include scanning the object by moving the depth scan as a unit along the optical axis within a range of 0.1 mm to 5 mm, to have a depth scan range between 5 mm and 40 mm.

[0023] As described above, handheld devices for confocal (3D) scanning are described herein. These devices (equipment, systems, etc.) can be compact and lightweight and may include LED-based emitters that provide reduced speckle noise. These devices can be used without precise alignment (pre-alignment), having a maximum alignment error of about 0.5 micrometers or less, unlike other systems that use dot arrays to provide confocal imaging. By using a continuous pattern instead of a dot array, the confocal devices described herein can be operated without requiring such precise alignment. As mentioned herein, a simple transparent element can replace the dot array used in other systems. Typically, these devices may require far fewer components than prior art devices; the devices described herein eliminate the need for one or more of the following: lasers, color-capture assisted illumination, and light-transmitting heat defogging devices. Furthermore, the devices described herein can have a reduced number of lenses (e.g., fewer lenses are required compared to the prior art). Thus, small projection / imaging optics systems can allow for very compact devices and, in particular, can be used with small axial actuators such as compact voice coil motors (VCMs).

[0024] Compared to existing technologies, the resulting optical structures are simpler and less sensitive to component errors and thermal variations. Furthermore, these devices can be used for direct color realization without requiring separate illumination and dichroic filters.

[0025] For example, this document describes a handheld device for confocal scanning, which may include: a light source (e.g., one or more LEDs, including white LEDs and / or light collectors and / or homogenizers); a transparent element having a spatial pattern disposed thereon and configured to be illuminated by the light source; a beam splitter (e.g., a polarizing beam splitter) having a first surface and a second surface and an image sensor on the second surface; an imaging optical system (which in some variations may alternatively be referred to as a projection / imaging optical subsystem) including an optical gain and focusing lens and an exit pupil, the imaging optical system having an optical axis; a tip front portion (e.g., a hollow tip front portion) extending from the imaging optical system in the optical axis and including a folding mirror at a distal end of the hollow tip front portion, wherein there is no optical surface between the exit pupil and the folding mirror in the optical axis; and an axial scanner coupled to the imaging optical system and configured to move the imaging optical system in the optical axis relative to the folding mirror.

[0026] Unlike prior art devices, the projection / imaging optics system can be configured to provide a telecentric deviation of the principal ray between the projection / imaging optics system and the folding mirror relative to the scanning field of view size, with this deviation being between 3 and 10 degrees. Previously, it was considered (see, for example, U.S. Patent No. 8,878,905) that the optical system of a scanner should be substantially telecentric in the space of the object being detected (the scanned object) (e.g., having an angle of less than 3 degrees, preferably much smaller than 3 degrees). In contrast, the device described herein can be non-telecentric, for example, deviating from the telecentric by a predetermined amount (e.g., between 3 and 10 degrees, such as 8.5 degrees). The optical design of the device described herein can have a light source space containing non-telecentric aperture imaging, such that the entire projection / imaging optics is compact and lightweight enough for full axial translation (e.g., by a linear actuator / axial scanner, such as a VCM) to facilitate depth scanning.

[0027] For example, the apparatus described herein may include an integrated projection / imaging optics system that is moved integrally by a driver, such as an axial actuator of a VCM. This again distinguishes it from other configurations in which a separate focusing element (which may form part of the imaging optics system) moves separately from the rest of the imaging optics system. Typically, the entire imaging optics system between the beam splitter and the hollow front tip is fully integrated into a single optomechanical module that can be moved by an axial scanner.

[0028] In any of the devices described herein, the transparent element may be attached to a first surface of the beamsplitter (e.g., an outer surface) and / or may be integrally formed as a surface in / on the optical axis of the beamsplitter. The spatial pattern on the transparent element may be static or time-varying; in some variations, the spatial pattern is not time-varying. The spatial pattern may be formed on or as part of the beamsplitter, or may be bonded to the first surface of the beamsplitter. The transparent element may be bonded to the first surface of the beamsplitter, and the image sensor may be bonded to a second surface of the beamsplitter perpendicular to the first surface to maintain a stable relative position between the image sensor and the spatial pattern. For example, the beamsplitter may be a polarization-sensitive beamsplitter, and the transparent element may be bonded to the first surface of the beamsplitter, and the image sensor may be bonded to a second surface of the beamsplitter perpendicular to the first surface to maintain a stable relative position between the image sensor and the spatial pattern.

[0029] The apparatuses (devices, systems, particularly handheld scanners) and methods described herein are particularly well-suited for use with 3D scanning employing structured light and / or light field techniques. Patterns (static and / or time-varying) that can be used with any of these apparatuses and methods can be configured to provide structured light imaging by projecting a known pattern (e.g., grids, lines, bars (e.g., horizontal bars), arrays, etc.) and analyzing the deformation of the pattern upon impact with a target surface. The aforementioned apparatuses can calculate depth and surface information of one or more objects in a scene. Therefore, any of these apparatuses can be configured as structured light 3D scanners. In some variations, the wavelengths of the light used can be different, and different light patterns corresponding to different wavelengths can be applied. For example, visible light and / or infrared light can be used. Any of these apparatuses can be configured as "invisible" or "imperceptible" structured light devices, wherein structured light is used synchronously or simultaneously without interfering with imaging at different frequencies. For example, infrared and visible light alternating between two different patterns can be applied and detected at high (including extremely high) frame rates. The patterns can be complementary or opposite (e.g., where dark areas in the first pattern are illuminated in the second pattern). Alternatively, visible light of different wavelengths, or light beyond the infrared, can be used.

[0030] The methods and apparatus described herein can also be configured as light field techniques, or alternatively as light field techniques. Light field imaging (e.g., generousoptic imaging) can capture information about the light field emanating from a scene. For example, the intensity of light in the scene and the direction of light travel in space. Any of the apparatuses and methods described herein may include a microlens array (e.g., positioned in front of one or more image sensors) to sense intensity, color, and direction information. In any of these apparatuses, the microlens array may be positioned before or after the focal plane of the main lens. Alternatively or additionally, a mask (e.g., a printed film mask) may be used. A patterned mask can attenuate light rather than bend it, and this attenuation can re-encode the light on a 2D sensor. Thus, the apparatus can focus and capture a regular 2D photograph at full sensor resolution while the original pixel values ​​retain the modulated 4D light field. The light field can be recovered by resetting the tiles of the 2D Fourier transform of the sensor values ​​to a 4D plane and calculating the inverse Fourier transform. Full-resolution image information can be recovered for the focused portion of the scene. A broadband mask can be placed at the lens to allow the calculation of a refocused image at full sensor resolution for some surfaces (e.g., diffuse surfaces) that include specific wavelengths (e.g., near-IR). Generally, light field information can be used to estimate three-dimensional (e.g., depth) information from the image.

[0031] In any of the devices described herein, the device may be configured such that the image of the light source is positioned at the entrance pupil of the projection / imaging optical system. The entrance pupil may be part of the projection / imaging optical system, or may be between the projection / imaging optical system and the beam splitter, or it may be separate from the projection / imaging optical system.

[0032] The tip can be configured to be removable from the rest of the device, which includes a housing covering the light source, beam splitter, etc. The housing may include a handle portion with a grip and / or user interface (controls), such as buttons, switches, etc. The tip can be hollow, particularly along the optical axis between the exit pupil and the folding mirror of the projection / imaging optics system. The tip can be configured to snap and / or rotate, frictionally engage, magnetically couple, etc., to the rest of the device (e.g., the housing). The tip can be single-use or reusable, including sterilizable (e.g., autoclaved, formed of a material that can be exposed to temperatures exceeding 100°C, including 121°C or higher, without deformation or damage after continuous exposure for more than 15 minutes). Optionally or additionally, these devices can be configured for use with a removable / disposable sleeve that can be mounted on the tip (including, in some variations but not all, above the optical exit at the distal / lateral end of the tooth through which it can be imaged).

[0033] In any of the devices described herein, the folding mirror may include a back-heated defogger. The folding mirror may redirect the optical axis of the device out of the side window / exit for imaging the teeth. The folding mirror may be configured to be at a 45-degree angle to the optical axis at the distal end of the hollow anterior tip (or at an angle between 30 and 60 degrees, between 35 and 55 degrees, between 40 and 50 degrees, etc.).

[0034] The entire device and / or the hollow tip can be compact; typically, the dimensions are less than 140mm × 20mm × 20mm (e.g., length, width, thickness). For example, the hollow tip portion can be 80mm × 16mm × 16mm or smaller (length, width, thickness).

[0035] Typically, a projection / imaging optical system can be moved axially to scan an object. For example, a projection / imaging optical system can be configured as a unit that is movable along the optical axis in the range of 0.1 mm to 5 mm and has a depth scanning range between 5 mm and 40 mm.

[0036] As described above, the hollow front tip may have a height of 20 mm or less (e.g., 20 mm or less, 17 mm or less, 16 mm or less, 15 mm or less, 14 mm or less, 13 mm or less, etc.). The field of view may be between 20×20 mm and 12×12 mm (e.g., between 18×14 mm or 14×14 mm, etc.).

[0037] Due to the features described above, including the spatial pattern of the transparent elements incorporated on the beam splitter, the use of an integrated projection / imaging optics system, and / or having a maximum deviation (e.g., between 3 and 10 degrees) from the telecenter toward the diverging principal ray, the device can be relatively lightweight. For example, the device can have a total weight of 300 grams or less (e.g., 250g or less, 200g or less, 180g or less, etc.). Furthermore, the diameter of the projection / imaging optics can be 15 mm or less.

[0038] For example, the handheld device for confocal scanning described herein includes: a light source; a transparent element having a spatial pattern disposed thereon and configured to be illuminated by the light source; a beam splitter having a first outer surface and a second outer surface, the transparent element being attached to the first outer surface and an image sensor located on the second outer surface; an integrated projection / imaging optics system including an optical gain, a focusing lens, and an exit pupil, the projection / imaging optics system having an optical axis; a hollow tip front portion extending from the projection / imaging optics system along the optical axis and including a folding mirror at a distal end of the hollow tip front portion, wherein there is no optical surface between the exit pupil and the folding mirror along the optical axis; and an axial scanner coupled to the projection / imaging optics system and configured to move the entire projection / imaging optics system along the optical axis relative to the folding mirror; wherein the projection / imaging optics system is configured to provide a telecentric deviation of the principal ray between the projection / imaging optics system and the folding mirror relative to the scanning field of view size, the deviation being between 3 degrees and 10 degrees.

[0039] This document also describes methods for confocal 3D scanning. Any of these methods may include the use of any of the scanning apparatuses described herein. For example, this document describes a method for confocal 3D scanning comprising: irradiating a spatial pattern (stationary or moving) located on a first side of a beam splitter; projecting the spatial pattern downward along an optical axis; passing through the beam splitter and through a projection / imaging optical system (e.g., through a projection / imaging optical subsystem, such as an integrated projection / imaging optical system including optical gain, a focusing lens, and an exit pupil); exiting from the exit pupil of the projection / imaging optical system; and passing through the front of a tip extending from the projection / imaging optical system to a folding mirror at the distal end of the front of the hollow tip, without passing through the exit pupil and the folding mirror on the optical axis. The optical surface between the points; projecting a spatial pattern onto a target (e.g., a tooth or other dental target); transmitting light from the target (e.g., reflected light, fluorescence, etc.) back through the hollow tip into the projection / imaging optical system, and through a beam splitter into an image sensor on the second side of the beam splitter; and scanning the target by axially moving the entire projection / imaging optical system relative to the folding mirror along the optical axis; wherein the projection / imaging optical system is configured to provide a telecentric deviation of the principal ray between the projection / imaging optical system and the folding mirror relative to the scanning field of view size, the deviation being between 3 and 10 degrees.

[0040] Scanning can be performed by moving the entire projection / imaging optics system as a unit along the optical axis, for example, within a range of 0.1 mm to 5 mm, to scan at a depth within a scanning range of 5 mm to 40 mm. Any suitable scanning rate can be used, including scanning at 10 Hz or higher (e.g., 15 Hz, 20 Hz, etc.).

[0041] Typically, a spatial pattern can be any suitable pattern, including patterns that change over time or do not change over time.

[0042] Illuminating the spatial pattern may include illuminating a transparent element attached to a first side of the beam splitter. An image sensor may be attached to a second side of the beam splitter perpendicular to the first side to maintain a stable relative position between the image sensor and the spatial pattern. Any of these methods may further include positioning the spatial pattern at the conjugate plane of the image sensor such that, for the image sensor, the position of the image of the object relative to the spatial pattern is laterally offset.

[0043] The method described herein may also include setting an image of the light source at the entrance pupil of the optical system.

[0044] Any of these methods may also include setting the exit pupil of the optical system toward the maximum deviation of the diverging principal ray from the telecenter.

[0045] Typically, the methods described above can include determining the confocal position through maximum correlation. Attached Figure Description

[0046] The novel features of the invention are specifically set forth in the appended claims. A better understanding of the features and advantages of the invention will be obtained by referring to the following detailed description of illustrative embodiments, in which the principles of the invention are utilized, as illustrated in the accompanying drawings:

[0047] Figure 1 An example of a compact device for 3D confocal scanning of objects, as described herein, is illustrated schematically.

[0048] Figure 2 An example of a compact device for 3D confocal scanning of an object is schematically shown (in this example, the light source is configured to illuminate a pattern on a transparent object in a Köhler illumination mode).

[0049] Figure 3A The diagram schematically illustrates a device for confocal scanning in a near-focal position, such as... Figure 1 The depth scanning module of the device shown.

[0050] Figure 3BThe diagram schematically illustrates a device for confocal scanning located at the mid-focal position, such as... Figure 1 The depth scanning module of the device shown.

[0051] Figure 3C The diagram schematically illustrates a device for confocal scanning at a far-focal position, such as... Figure 1 The depth scanning module of the device shown.

[0052] Figure 4A An example of a compact device for confocal scanning is shown, which, as described herein, includes a hollow front tip with a field of view (FOV) of 18 × 14 mm. It should be noted that the dimensions provided are for illustrative purposes only.

[0053] Figure 4B An example of a compact device for confocal scanning is shown, which, as described herein, includes a hollow front tip with a field of view (FOV) of 14 × 14 mm. It should be noted that the dimensions provided are for illustrative purposes only.

[0054] Figure 5 The non-telecentricity of the optical system of a compact device for confocal 3D scanning as described herein is schematically illustrated.

[0055] Figure 6 An example of a confocal focal plane module for a confocal scanning apparatus is schematically shown, wherein the transparent element and the image sensor are directly coupled to the beam splitter or mounted on a fixed device relative to the beam splitter.

[0056] Figure 7A An example of a disordered spatial pattern is shown that can be used as part of a compact device for 3D confocal scanning as described herein.

[0057] Figure 7B An example of an ordered spatial pattern is shown that can be used as part of a compact device for 3D confocal scanning as described herein.

[0058] Figure 8 An example of a method for confocal 3D scanning as described herein is shown. Detailed Implementation

[0059] The present invention will now be described in detail with reference to the accompanying drawings. The invention may be embodied in various forms and should not be construed as limited to the exemplary embodiments described herein.

[0060] This document describes a compact apparatus for confocal 3D scanning. These apparatuses may include a confocal illuminator configured to generate confocal illumination of an object. The confocal illuminator may include a spatial pattern disposed on a transparent substrate (transparency) and a light source configured to provide illumination to the spatial pattern such that it can be projected onto the object. The apparatus may include an optical system (including projection / imaging optics) comprising one or more lenses and having an optical axis. The apparatus may also include illumination optics for illuminating the pattern / transparency forming the spatial pattern. The apparatus may include an axial scanner (e.g., a depth scanning module) configured to move the projection / imaging optics along the optical axis. The apparatus may include a beam splitter configured to direct light from the light source (after passing through the pattern) to the object and reflect light returning from the object to an imaging sensor. Therefore, the apparatus may include an image sensor configured to receive light returning from the object (via the projection / imaging optics) via the beam splitter. The apparatus may be configured for 3D scanning of at least a portion of an object, such as intraoral dental 3D scanning for all derivatives of dental restorations and orthodontic indications.

[0061] The confocal scanning apparatus disclosed herein may include a confocal illuminator, such as a transparent confocal illuminator for LED illumination. The apparatus may include an optical system configured to project light passing through a transparent element (e.g., a pattern) onto an object and image the object. The optical system may include a projection / imaging system or subsystem comprising projection optics and imaging optics. For example, the projection optics and imaging optics may be configured to share the same optical elements (lenses) and the same optical path. The apparatus may include a depth scanning module comprising a compact linear actuator, such as a voice coil motor (VCM). The apparatus may include a front tip, which may include a 45-degree back-heated defogging folding mirror. The optical system between the beam splitter and the front tip may be configured small enough to be fully integrated into the depth scanning module. Therefore, the confocal scanning apparatus may include a single optomechanical module for projection, imaging, and depth scanning. A single optomechanical module integrating the optical system and the depth scanning module allows for looser production and assembly tolerances and reduced manufacturing costs. The optical design is suitable for LED-illuminated transparent elements, further enabling low-cost manufacturing. Therefore, compared to other confocal scanning systems, the optical system can further reduce the number of lenses; for example, the optical system may include fewer than 10 lenses, fewer than 9 lenses, fewer than 5 lenses, fewer than 3 lenses, etc. Furthermore, due to its simpler configuration, the optical system disclosed herein can be less sensitive to component errors and thermal variations than conventional confocal optical systems. The device may include an optical system configured to deviate from the telecentric desired direction of the diverging principal ray for a minimum tip size. The device may have a non-telecentric configuration in the image and source spaces.

[0062] The device may also include a polarization beam splitter as part of the confocal coupling. The device can be configured for offset-invariant confocal conjugation. The device can further support monolithic confocal conjugation components.

[0063] Typically, these devices may include an integrated projection / imaging optics system in which the entire projection / imaging optics system (e.g., a projection / imaging optics subsystem) is axially movable for scanning (not just the focusing lens). While moving the entire composite projection / imaging optics system for scanning is somewhat counterintuitive, it can be beneficial in reducing the overall size of the device, especially when combined with the spatial pattern of the projection and a configuration in which the principal ray between the projection / imaging optics system and the folding mirror deviates from the telecentric by 3 to 10 degrees relative to the scanning field of view. Due to the features described herein, these devices can be more compact (e.g., 2×, 3×, or 4×) and lighter (e.g., 2× or 3×) than typical conventional confocal scanners with the same scanning capabilities. For example, the device can be compact and lightweight for handheld use. The device may also include a compact, high-speed image sensor. Scanning speeds can be approximately 5, 10, 20, 50 scans / second or any value in between. For example, a scanning speed of approximately 10 scans / second.

[0064] Figure 1 An example of a compact device 100 for confocal scanning of an object is schematically illustrated. The device may include a confocal illuminator 101 (a light source and / or illumination optics) configured to produce confocal illumination that can be projected onto an object. The device may include a spatial pattern disposed on a transparent substrate, such as a transparent element 105 or a transparent glass plate. The light source and any illumination optics may be configured to provide illumination through the spatial pattern and may include a light collector / reflector. For example, the light source may be an LED light source (e.g., having a reflector behind it to guide light through the pattern). Conventional confocal array light sources, such as laser diodes, may be replaced by LED light sources. For example, the device may include an LED-based emitter that can reduce speckle noise. The spatial pattern may include an array of segments for achieving point illumination. The device may further include a light collector or light homogenizer to produce uniform illumination on the pattern. The device may also include a condenser lens to converge the beam of light from the light source. The device may include a white LED light source readily available for color model capture and rendering, which enables simple color implementation.

[0065] The device may include a beam splitter 109 and an image sensor 111. The beam splitter may be configured to direct the beam from the confocal illuminator to an object and reflect the beam returning from the object to the image sensor. The image sensor 111 may be configured to receive the beam returning from the object. For example, the beam splitter may be a polarization beam splitter (PBS).

[0066] The device may include an optical system (including, or composed of, a projection / imaging optical system / subsystem 115), which includes one or more lenses (e.g., focusing optics 119) and an exit pupil 121. The optical system may be configured to project light passing through the transparent element 105 onto an object and image the object onto an image sensor. For example, such as... Figure 2 As shown, the LED light source can be configured to illuminate the transparent part in a Köhler illumination mode, such that the image of the LED falls on the entrance pupil of the optical system. Light exiting the imaging optical system 115 (including the exit pupil) can pass through the hollow tip 123 until it reaches the folding mirror 125 near the distal end of the tip 123, and is guided out of the tip to the object (e.g., a tooth); light returning from the object propagates along the same path. Typically, the tip is hollow, and the entire imaging optical system is movable relative to the tip (e.g., there is no additional optical surface in the tip between the axially movable imaging optical system and the folding mirror).

[0067] and Figure 1 Similarly, refer to Figure 2 An optical system is shown, comprising a light source 201 (and may also include imaging optics such as a condenser lens 203 in this example) and an optical system 207 (e.g., which may include a projection / imaging system). For example, an illumination subsystem may be configured to illuminate a pattern (e.g., a transparent element 209) and this spatial pattern 209 may be projected onto an object. The illuminated object can be reflected and imaged through the imaging subsystem 207. The imaging subsystem may be the same as the projection / imaging subsystem between the beam splitter and the folding mirror. Figure 1 As shown, the imaging path and projection path can share the same optical path and the same optical elements, such as one or more lenses. Therefore, the object can be imaged back through the same optical system, and the light reflected from the object can be guided to the image sensor by a beam splitter. In conventional confocal systems, the imaging and projection subsystems may differ; however, unlike conventional confocal optical systems, the device disclosed herein for confocal scanning can be smaller, lighter, and less expensive than conventional confocal optical systems.

[0068] like Figure 1 As shown, the imaging optical system can be mounted on the depth scanning module (axial scanner 135). For example, the optical system between the beam splitter and the leading edge can be fully integrated and coupled to the depth scanning module for axial movement relative to the leading edge. The optical system (and in some variations, the depth scanning module) can be integrated to, for example... Figure 1In the single optomechanical module shown, this allows for loose manufacturing and assembly tolerances. The axial scanner may include a linear axial actuator that can axially translate the optical system in a controlled manner, for example, more than 0.5 mm to 3 mm, to facilitate depth scanning. The device can be configured with high axial magnification to achieve a simple depth-scanning linear actuator. The axial magnification from the transparent part to the object space being scanned can be between 4× and 30×, for example, between 5× and 12×. With the above translation and magnification ranges, periodic optical translation can produce an object space depth scan coverage range of 10 mm to 36 mm. Figures 3A-3C The diagram schematically shows the positions near the focal point ( Figure 3A ), central focal position ( Figure 3B ) and the far focal part ( Figure 3C The axial scan of the device used for confocal scanning in the image shows the translation of the entire imaging optics system 307, which includes projection / imaging optics 305. The projected spatial pattern 301 is transmitted onto / into the object, and the reflected light is received by sensor 303 for analysis to determine the 3D surface of the object.

[0069] Optical systems that include combined projection / imaging subsystems can produce simpler designs for both projection optics (focusing optics) and projection / imaging optics, and reduce the number of optical elements such as optical lenses. Projection optics can refer to optics that are identical to imaging optics except in the projection direction (e.g., from the light source to the object). For example, an optical system may include fewer than 10, 9, 5, or 3 optical elements. For example, the diameter of an optical lens in an optical system can be about 5 mm, 8 mm, 10 mm, 14 mm, 15 mm, or any value between, while an optical lens in a conventional confocal optical system may have a diameter of about 25 mm. For example, the optical system disclosed herein further reduces the following elements found in typical conventional confocal scanning devices: such as dichroic filters, microlenses, etc. Devices used for the confocal scanning disclosed herein are more compact, lighter, and less expensive than conventional confocal scanning devices. For example, in some embodiments, the device may have a weight of about 100, 200, or 300 grams. For example, in some embodiments, the device may have dimensions of less than 150mm×25mm×25mm, 140mm×20mm×20mm, or 130mm×14mm×14mm.

[0070] Figure 4A The device for compact confocal scanning is schematically shown, which includes a hollow front tip with a field of view (FOV) of 18×14 mm. Figure 4B An apparatus for compact confocal scanning is shown, comprising a hollow front tip with an 18×14 mm field of view (FOV).Figure 4A and Figure 4B As shown, the apparatus for compact confocal scanning can have a smaller tip size than conventional confocal scanning apparatuses. The apparatus can have a tip height of approximately 14 mm, with a field of view (FOV) of 14 × 14 mm. The hollow tip may include a back-heated defogging folding mirror. For example, in some embodiments, the hollow tip may have dimensions of approximately 90 mm × 20 mm × 20 mm, 80 mm × 16 mm × 16 mm, or 60 mm × 14 mm × 14 mm. These dimensions are for illustrative purposes only, and other dimensions may be used.

[0071] Typically, any device described herein can be non-telecentric. Specifically, the projection / imaging optics system can be configured to provide a telecentric deviation of the principal ray between the projection / imaging optics system and the folding mirror relative to the scanning field of view size, the deviation being between 3 and 10 degrees. Figure 5 An example of a non-telecentric optical system for a confocal scanning apparatus according to one embodiment of the invention is illustrated schematically. The optical system can be configured with non-telecentric aperture imaging in the light source space, making the optical system compact and lightweight enough to facilitate depth scanning, for example, by axial translation via a linear actuator such as a voice coil motor (VCM). The exit pupil of the optical system can be positioned to maximize the telecentric deviation toward the diverging principal ray, which allows for a minimum size of the device's front tip. For a given distance from the tip, the scanned field of view size can be the same for all design options, for example, a moderate range of scan depths. The angle of deviation from the telecentric can be determined by the exit pupil distance from the object focus and the field of view size. The tip height can be derived from the trajectory of the light beam from the light source on the folding mirror. This height can be smaller as the exit pupil becomes closer to the object focus (exit pupil forward). The possible range of the angle of deviation from the telecentric can be from approximately 3 degrees to approximately 10 degrees. For example, in some embodiments, the angle of deviation from the telecentric can be approximately 8.5 degrees. The deviation angle from the telecentric point is the range of the area in the folding plane of the mirror, which affects the tip height.

[0072] Figure 6 An example of a confocal irradiator for a confocal scanning apparatus is schematically shown, wherein in one embodiment, a transparent element (including a spatial pattern) is directly coupled to the beam splitter or mounted on a fixing device relative to the beam splitter. Figure 6As shown, the transparent element can be directly bonded to one face of the beamsplitter (e.g., a polarizing beamsplitter, PBS), while the image sensor can be bonded to another face of the beamsplitter perpendicular to the transparent element (e.g., a second surface), thus maintaining a stable relative position between the image sensor and the transparent element (“confocal condition”). The device can be configured to achieve an invariant confocal conjugate offset. The transparent element and the image sensor can be positioned on the conjugate plane of the object. The device can also support monolithic confocal conjugate assemblies. Illumination-based patterning enables conjugate imaging on the image sensor, which is invariant to relative lateral offset. The device for confocal scanning can be configured to have position-invariant correlation, making it less sensitive to assembly offset.

[0073] Figure 7A and Figure 7B An example of a spatial pattern is shown that can be used as part of any compact device for 3D confocal scanning as described herein. Figure 7A An example of a disordered pattern for a device used for confocal scanning is shown. Figure 7B An example of an ordered pattern for a confocal scanning apparatus is shown. An apparatus for confocal scanning can include an illuminated pattern to replace the beam array in a conventional confocal scanning apparatus. For example, a white LED back-illuminated pattern can be used to achieve confocal imaging. A variety of patterns can be used in a confocal illuminator, enabling design flexibility and lower signal requirements. For example, the pattern can include an array of segments to achieve equivalent point illumination. The illumination point through the pattern can be near the diffraction limit. For example, the pattern can include an array of segments having a size similar to a pinhole in a conventional confocal microscope. For example, the pattern can include an array of segments with diameters of about 1 μm, 10 μm, 25 μm, 50 μm, 1 mm, or 2 mm, or any value between these values.

[0074] For example, the apparatus for confocal scanning may also include an array of detection pinholes. For example, the detection pinholes may be disposed in a fixture between the beam splitter and the image sensor. For example, the detection pinholes may be incorporated into or integrated into the image sensor. For example, the size of the pinholes may be configured to suit the numerical aperture (NA) of the optical system and the wavelength of the light source. For example, the size of the detection pinholes may be further adapted to the magnification of the optical system.

[0075] Confocal positions can be determined through maximum correlation. For example, the reference pattern position can remain constant. Alternatively, the depth position of each pixel or group of pixels on the image sensor can be specified, corresponding to the maximum signal obtained on the pixel or group of pixels after a depth scan. Lateral resolution does not need to be compromised because all pixels within the region of interest (ROI) can be used. For example, resolution can be improved through subpixel processing.

[0076] This document also describes a method for confocal 3D scanning of confocal three-dimensional dimensions. Typically, this method may include initiating a confocal illuminator configured to generate confocal illumination of an object. The method may include using a confocal illuminator comprising a spatial pattern disposed on a transparent substrate, a light source configured to provide illumination to the spatial pattern, and / or any additional illumination optics (e.g., a lens).

[0077] The method may include illuminating a pattern, projecting the pattern onto an object, and imaging the object through an optical system including projection / imaging optics comprising one or more lenses and having an optical axis. The method may include scanning the object using a depth scanning module configured to be movable along the optical axis. The method may include projecting a beam from a confocal illuminator onto the object using a beam splitter, and using the beam splitter to guide light returning from the object onto an imaging sensor.

[0078] For example, the method may include using a spatial pattern on a transparent substrate that does not change over time. For instance, the method may include using a spatial pattern and a transparent substrate, wherein the pattern (e.g., a transparent element) is attached to a first side of the beam splitter, and further wherein an image sensor is attached to a second side of the beam splitter perpendicular to the first side, to maintain a stable relative position between the image sensor and the spatial pattern.

[0079] A method may include positioning an image of a light source at the entrance pupil of an optical system. For example, the method may include positioning a spatial pattern at the conjugate plane of an image sensor such that the relative lateral offset of the image position of an object with respect to the spatial pattern is constant for the image sensor. For instance, the method may include arranging the exit pupil of the optical system toward the maximum deviation of the diverging principal ray from the telecenter.

[0080] One method may include arranging the object to be scanned, which includes moving a depth scanning module as a unit along the optical axis within a range of 0.1 mm to 5 mm to obtain a depth scanning range between 5 mm and 40 mm. For example, the method may include determining the confocal position by maximal correlation.

[0081] As briefly discussed above, the apparatus and methods described herein can also be configured as structured light scanning systems and / or light field 3D reconstruction systems. For example, in some variations, light field data can be captured, for instance, by configuring the imaging system as a plenotoptic apparatus, such as by including multiple microlenses before or after the focal plane of the main lens subsystem (e.g., a compact focusing optics). Thus, in some variations, light can pass through an optical surface (microlens) between the exit pupil and a folding mirror in the optical axis, or the microlens can originate from a portion of the compact focusing optics. A depth map can be created from the light field data, and this depth map can be used to create surfaces. Conventional stereo imaging methods can be used for depth map extraction, or depth data can be extracted from the light field camera by combining two or more depth estimation methods.

[0082] Figure 8 This illustrates another instance of the method described in this article. Figure 8 The method for confocal 3D scanning includes: first illuminating a spatial pattern on a first side of a beamsplitter and projecting the spatial pattern downward along the optical axis, allowing it to pass through the beamsplitter, through an integrated projection / imaging optics system including an optical gain and focusing lens and an exit pupil, exit the exit pupil, and pass through the front of a hollow tip extending from the projection / imaging optics system to a folding mirror at the distal end of the front of the hollow tip, without passing through the optical surface between the exit pupil and the folding mirror in the optical axis 801. The method then includes projecting the spatial pattern onto a target 803 and transmitting reflected light from the target back through the hollow tip to the projection / imaging optics system, through the beamsplitter, and into an image sensor on a second side of the beamsplitter 805. The method may also include scanning the target by axially moving the entire projection / imaging optics system relative to the folding mirror 807 along the optical axis, wherein the projection / imaging optics system is configured to provide a telecentric deviation of the principal ray between the projection / imaging optics system and the folding mirror relative to the scanning field of view size, the deviation being between 3 and 10 degrees.

[0083] Preferred embodiments and variations of the systems, apparatus, and methods may be at least partially embodied and / or implemented as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions are preferably executed by a computer-executable component preferably integrated with a system including a computing device configured with software. The computer-readable medium may be stored on any suitable computer-readable medium, such as RAM, ROM, flash memory, EEPROM, optical devices (e.g., CDs or DVDs), hard disk drives, floppy disk drives, or any suitable device. The computer-executable component is preferably a general-purpose or special-purpose processor, but any suitable special-purpose hardware or hardware / firmware combination may alternatively or additionally execute the instructions.

[0084] When a feature or element is referred to herein as being "on" another feature or element, it may be directly on the other feature or element, or there may be intermediate features and / or elements present. Conversely, when a feature or element is referred to as being "directly on" another feature or element, there are no intermediate features or elements present. It will also be understood that when a feature or element is referred to as being "connected," "attached," or "coupled" to another feature or element, it may be directly connected, attached, or coupled to the other feature or element, or there may be intermediate features or elements present. Conversely, when a feature or element is referred to as being "directly connected," "directly attached," or "directly coupled" to another feature or element, there are no intermediate features or elements present. Although one embodiment has been described or illustrated, the features and elements thus described or illustrated can be applied to other embodiments. Those skilled in the art will also understand that references to structures or features disposed "adjacent" to another feature may have portions overlapping with or below the adjacent feature.

[0085] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein also include the plural forms. It should also be understood that the terms “comprising” and / or “including” as used in this specification specify the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items and may be abbreviated to “ / ”.

[0086] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “up,” etc., may be used herein to describe the relationship of one element or feature to another, as illustrated in the accompanying drawings. It should be understood that, in addition to the orientations shown in the figures, spatial relative terms are intended to include different orientations of the device in use or operation. For example, if the device in the figures were inverted, an element described as “below” or “under” other elements or features would be oriented as “above” other elements or features. Thus, the exemplary term “up and down” can include both “above” and “below” orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein are interpreted accordingly. Similarly, the terms “up,” “down,” “vertical,” “horizontal,” etc., are used herein for illustrative purposes only, unless otherwise specifically indicated.

[0087] Although the terms “first” and “second” may be used herein to describe various features / elements (including steps), these features / elements should not be limited by these terms unless the context otherwise indicates. These terms are used to distinguish one feature / element from another. Thus, the first feature / element discussed below may be referred to as the second feature / element, and similarly, the second feature / element discussed below may be referred to as the first feature / element, without departing from the teachings of the invention.

[0088] Throughout the specification and the appended claims, unless the context otherwise requires, the word “comprising” and variations such as “including” and “possessing” mean that various components (e.g., compositions and apparatuses including means and methods) may be used together in methods and articles. For example, the term “comprising” will be understood to imply the inclusion of any of the stated elements or steps without excluding any other elements or steps.

[0089] Generally, any of the devices and methods described herein should be understood as inclusive, but all or a subset of the components and / or steps may alternatively be exclusive and may be expressed as “consisting of” various components, steps, subcomponents or sub-steps or alternatively “substantially consisting of” various components, steps, subcomponents or sub-steps.

[0090] As used herein in the specification and claims, including as in the examples, and unless otherwise expressly specified, all figures may be interpreted as being prefixed with the words “about” or “approximately”, even if the term is not explicitly stated. The phrase “about” or “approximately” may be used when describing size and / or location to indicate that the described value and / or location is within a reasonably expected range of value and / or location. For example, a numerical value may have + / - 0.1% of the value (or range of values), + / - 1% of the value (or range of values), + / - 2% of the value (or range of values), + / - 5% of the value (or range of values), + / - 10% of the value (or range of values), etc., and any numerical value given herein should also be understood to include approximately or about that value unless the context otherwise requires. For example, if the value “10” is disclosed, “about 10” is also disclosed. Any numerical ranges referenced herein are intended to include all subranges contained therein. It should also be understood that when a value is disclosed, the possible range of values ​​"less than or equal to" that value, "greater than or equal to" that value, and values ​​in between are also disclosed, as should be understood by those skilled in the art. For example, if the value "X" is disclosed, then "less than or equal to X" and "greater than or equal to X" (e.g., where X is a numerical value) are also disclosed. It should also be understood that throughout the application, data is provided in a variety of different formats, and the data represents endpoints and starting points, as well as a range of arbitrary combinations of data points. For example, if a specific data point "about 10" and a specific data point "about 15" are disclosed, it should be understood that they are greater than, greater than or equal to, less than, less than or equal to 10 and 15, and between 10 and 15. It should also be understood that each unit between two specific units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0091] While various illustrative embodiments have been described above, any of a variety of changes may be made to the various embodiments without departing from the scope of the invention as described in the claims. For example, in alternative embodiments, the order in which the various described method steps are performed may typically be changed, and in other alternative embodiments, one or more method steps may be skipped entirely. Optional features of the various device and system embodiments may be included in some embodiments but not in others. Therefore, the foregoing description is provided primarily for illustrative purposes and should not be construed as limiting the scope of the invention as set forth in the claims. By way of illustration and not limitation, the examples and descriptions contained herein demonstrate specific embodiments of the subject matter that may be practiced. As mentioned, other embodiments and other embodiments derived therefrom may be utilized, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such embodiments of the subject matter of the invention may be referred to herein individually or collectively by the term "invention" for convenience only, and if more than one is actually disclosed, it is not intended to actively limit the scope of this application to any single invention or inventive concept. Therefore, while specific embodiments have been shown and described herein, any arrangement calculated to achieve the same purpose may replace the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of the various embodiments. After reading the above description, combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art.

Claims

1. A handheld device for intraoral scanning, the handheld device comprising: light source; A transparent element having a spatial pattern disposed thereon; A beam splitter having a first outer surface and a second outer surface, a transparent element attached to the first outer surface, and an image sensor located on the second outer surface; A single movable optomechanical module, the single movable optomechanical module including an integrated projection / imaging optical system, the integrated projection / imaging optical system including three to nine focusing optics and an exit pupil, the projection / imaging optical system having an optical axis, wherein the three to nine focusing optics of the projection / imaging optical system of the handheld device are completely integrated into the single movable optomechanical module; A hollow front tip, the hollow front tip extending from the projection / imaging optical system on the optical axis, and including a folding mirror located at the distal end of the hollow front tip, wherein there is no optical surface between the exit pupil and the folding mirror on the optical axis; as well as An axial scanner coupled to the projection / imaging optical system and configured to move a single movable optomechanical module comprising the entire projection / imaging optical system relative to the folding mirror on the optical axis to achieve multiple focusing settings; As the multiple focusing settings change, the three to nine focusing optics maintain a fixed position relative to each other; The projection / imaging optical system is configured to provide a telecentric deviation of the principal ray between the projection / imaging optical system and the folding mirror relative to the scanning field of view, the deviation being between 3 and 10 degrees. The transparent element is configured to be illuminated by the light source and output patterned light including a spatial pattern, allowing the patterned light to pass through the beam splitter and reach an object outside the device; and The image sensor is configured to receive reflected pattern light, which has been reflected by the object and guided back by the beam splitter.

2. The handheld device according to claim 1, wherein the spatial pattern on the transparent element does not change over time.

3. The handheld device of claim 1, wherein the beam splitter includes a polarization-sensitive beam splitter, and wherein the transparent element is coupled to a first outer surface of the beam splitter, and the image sensor is coupled to a second outer surface of the beam splitter perpendicular to the first outer surface to maintain a stable relative position between the image sensor and the spatial pattern.

4. The handheld device of claim 1, wherein the device is configured such that the image of the light source is positioned at the entrance pupil of the projection / imaging optical system.

5. The handheld device of claim 1, wherein the hollow front tip is configured to be removable and autoclaved.

6. The handheld device according to claim 1, wherein the hollow front tip has dimensions of less than 140mm × 20mm × 20mm.

7. The handheld device according to claim 1, wherein the hollow front tip has a size of 80mm × 16mm × 16mm or smaller.

8. The handheld device according to claim 1, wherein the folding mirror is configured at a 45-degree angle to the optical axis at the distal end of the hollow front tip.

9. The handheld device of claim 1, wherein the projection / imaging optical system is configured as a unit movable along the optical axis in a range of 0.1 mm to 5 mm and has a depth scanning range between 5 mm and 40 mm.

10. The handheld device according to claim 1, wherein the hollow front tip has a height of 20 mm or less.

11. The handheld device of claim 1, wherein the device has a weight of 300 grams or less.

12. The handheld device according to claim 1, wherein the folding mirror includes a back-heated defogging mirror.

13. The handheld device according to claim 1, wherein the diameter of the projection / imaging optical system on the optical axis is 15 mm or less.

Images