Patent Description:
In the field of dentistry, a three-dimensional scanner (oral scanner) for obtaining a three-dimensional shape of a tooth has been developed in order to design a prosthesis or the like digitally on a computer (<CIT>). The three-dimensional scanner disclosed in <CIT> is a handheld scanner for obtaining a three-dimensional shape of an object body using principles of a focusing method. Specifically, according to this three-dimensional scanner, light having a linear or checkerboard design pattern (hereinafter also referred to as a pattern) is projected onto a surface of an object body, a best focused distance is obtained from a plurality of images of the pattern taken while changing a focusing position, and thus a three-dimensional shape of the object body is obtained.

In other words, this three-dimensional scanner requires a varifocal unit for changing the focus of the pattern projected onto the object body at a high speed. Here, it is possible to obtain the three-dimensional shape using principles of a triangulation method or white light interferometry, other than the focusing method. Unlike the focusing method, these principles do not use the focus, and therefore it is basically possible to perform three-dimensional measurement without any varifocal unit. However, even with those principles, providing functions of zoom adjustment and focus adjustment for an optical system improves conveniences in measurement. In this case, a three-dimensional scanner using principles other than the focusing method also requires a varifocal unit for changing a focal position of light from a light source.

<CIT> discloses an intra-oral measurement device and an intra-oral measurement system capable of measuring an inside of an oral cavity, which device includes a light projecting unit for irradiating a measuring object including at least a tooth within an oral cavity with light, a lens system unit for collecting light reflected by the measuring object, a focal position varying mechanism for changing a focal position of the light collected by the lens system unit, and an imaging unit for imaging light passed through the lens system unit.

However, according to this three-dimensional scanner, it is necessary to correctly grasp a focal position of the projected pattern that has been projected to obtain an accurate three-dimensional shape. Further, even in a case in which the three-dimensional shape is obtained using principles such as the triangulation method and the white light interferometry other than the focusing method, if the optical system includes a varifocal unit, it is necessary to correctly grasp the focal position to obtain an accurate three-dimensional shape. In particular, when a liquid lens is used for a varifocal unit, it is difficult to correctly grasp the focal position as the liquid lens has hysteresis characteristics where its focal position is different between a case in which an applied voltage value is increased and a case in which an applied voltage value is decreased. Here, in order to correctly grasp the focal position of the project pattern, it is necessary to correctly grasp conditions of the varifocal unit. Examples of the condition of the varifocal unit include a position of the lens, a curvature shape of the lens, and a refractive index of the lens. The condition of the varifocal unit may change depending on ambient temperature, deformation with age of the varifocal unit, and the like, in addition to the hysteresis characteristics. A three-dimensional scanner applicable to manufacturing of dental prostheses requires extremely high measurement accuracy in a practical sense, and in particular, it is necessary to correctly grasp conditions of a varifocal unit.

The present invention has been made in order to address the above problems, and an object of the present invention is to provide a three-dimensional scanner capable of correctly grasping conditions of a varifocal unit and obtaining an accurate three-dimensional shape, and a probe.

The above problems are solved by a three-dimensional scanner according to claim <NUM>.

The above problems are further solved by a probe as defined in claim <NUM>.

The three-dimensional scanner according to the present invention determines the condition of the varifocal unit based on the light that has been reflected on the reference unit and detected by a part of the detection unit, and therefore the scanner is able to correctly grasp the condition of the varifocal unit and obtain the accurate three-dimensional shape. Further, the probe according to the present invention includes the reference unit, within its housing, for determining the condition of the varifocal unit, and therefore the probe allows the three-dimensional scanner to correctly grasp the condition of the varifocal unit and to obtain the accurate three-dimensional shape.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

A three-dimensional scanner according to Embodiment <NUM> of the present invention is a three-dimensional scanner (oral scanner) for obtaining a three-dimensional shape of a tooth in the mouth. However, the three-dimensional scanner according to the present invention is not limited to the oral scanner, and can be applied to other types of the three-dimensional scanner having a similar configuration. As one example, other than the interior of the mouth, the three-dimensional scanner according to the present invention is applicable to a three-dimensional scanner capable of taking images of an interior of a person's ear and obtaining a three-dimensional shape of an interior of an outer ear.

<FIG> is a block diagram illustrating a configuration of a three-dimensional scanner <NUM> according to Embodiment <NUM> of the present invention. Three-dimensional scanner <NUM> shown in <FIG> includes a probe <NUM>, a connecting section <NUM>, an optical measurement unit <NUM>, a control unit <NUM>, a display unit <NUM>, and a power unit <NUM>. Probe <NUM> is inserted into the mouth, projects light having a pattern (hereinafter also referred to as a pattern) onto a tooth as an object body <NUM>, and guides reflection light reflected from object body <NUM> on which the pattern is projected, to optical measurement unit <NUM>. Further, as probe <NUM> is detachable from optical measurement unit <NUM>, it is possible to perform sterilization (for example, a treatment in an environment with high temperature and high humidity), as infection control, to probe <NUM> that may be brought into contact with a living body after removing the probe from optical measurement unit <NUM>. While sterilizing an entire device of the three-dimensional scanner has a disadvantage that the duration of the device's life becomes shorter as it includes a number of optical and electronic components, this disadvantage does not occur when only probe <NUM> is removed and sterilized. Connecting section <NUM> is a part that protrudes from optical measurement unit <NUM>, and has a shape that is fittable with probe <NUM>. Connecting section <NUM> may include a lens system for guiding light collected by probe <NUM> to optical measurement unit <NUM>, and optical components such as a cover glass, an optical filter, and a retardation plate (quarter wavelength plate).

Optical measurement unit <NUM> projects a pattern onto object body <NUM> via probe <NUM>, and takes an image of the projected pattern. While not illustrated, optical measurement unit <NUM> includes an optical component (pattern generating element) for generating a pattern to be projected onto object body <NUM>, a light source, a lens component for forming an image of the pattern on a surface of object body <NUM>, a varifocal unit capable of changing a focal position, and an optical sensor for taking an image of the projected pattern (such as a CCD image sensor or a CMOS image sensor). Here, while optical measurement unit <NUM> is described to have a configuration for obtaining a three-dimensional shape using principles of a focusing method, optical measurement unit <NUM> is not limited to such a configuration, and may have a configuration for obtaining a three-dimensional shape using principles of a method such as confocal method, triangulation method, white light interferometry, stereo method, photogrammetry, SLAM method (Simultaneous Localization and Mapping), and optical coherence tomography (Optical Coherence Tomography: OCT). In other words, optical measurement unit <NUM> is applicable to any configuration using any principles, as long as the configuration is such that a varifocal unit is included and a three-dimensional shape is obtained using an optical method. Here, probe <NUM>, connecting section <NUM>, and optical measurement unit <NUM> constitute a handpiece <NUM> for taking an image of an interior of the mouth.

Control unit <NUM> controls an operation of optical measurement unit <NUM>, and processes an image taken by optical measurement unit <NUM> to obtain a three-dimensional shape. Control unit <NUM> includes a CPU (Central Processing Unit) as a control center, a ROM (Read Only Memory) that records programs and control data for causing the CPU to be operated, a RAM (Random Access Memory) that serves as a work area of the CPU, an input-output interface for maintaining consistency with signals from peripheral devices, and the like. Further, control unit <NUM> is able to output the obtained three-dimensional shape to display unit <NUM>, and receives information such as setting of optical measurement unit <NUM> via an unillustrated input device or the like. Here, at least of a part of calculation for processing taken images and obtaining a three-dimensional shape may be realized as software by the CPU of control unit <NUM>, or as hardware performing the processes separately from the CPU. Further, at least a part of processing units such as the CPU and the hardware may be incorporated within optical measurement unit <NUM>. Moreover, while <FIG> shows the components (<NUM>, <NUM>, <NUM>, and <NUM>) of three-dimensional scanner <NUM> as being connected by cables (thick lines in the figure), a part or all of the connection may be realized by wireless communication. In addition, if control unit <NUM> is enough small and light to be held by one hand, control unit <NUM> and optical measurement unit <NUM> may be combined and configured as a single handpiece.

Display unit <NUM> is a display device for displaying results of measurement of the three-dimensional shape of object body <NUM> obtained by control unit <NUM>. Further, display unit <NUM> is also usable as a display device for displaying other information such as configuration information of optical measurement unit <NUM>, patient information, and a startup status, an operation manual, and a help screen of the scanner. As display unit <NUM>, a standing liquid crystal display and a wearable display of head-mounted type or a glass type can be used, for example. Further, more than one display unit <NUM> may be provided, and it is possible to display results of the measurement of the three-dimensional shape and other information at the same time or separately on the plurality of display units <NUM>. Power unit <NUM> is a device for supplying electric power for driving optical measurement unit <NUM> and control unit <NUM>. Power unit <NUM> may be provided outside control unit <NUM> as illustrated in <FIG>, or may be provided inside control unit <NUM>. Moreover, more than one power unit <NUM> may be provided so that electric power may be separately fed to control unit <NUM>, optical measurement unit <NUM>, and display unit <NUM>.

Next, a configuration of an optical system within the handpiece will be described more in detail. <FIG> is a schematic diagram illustrating a configuration of an optical system within handpiece <NUM> according to Embodiment <NUM> of the present invention. First, handpiece <NUM> includes a light source unit <NUM>, a varifocal unit <NUM>, a reference unit <NUM>, a light path length adjustment unit <NUM>, and an optical sensor <NUM>. In addition to these components, handpiece <NUM> also includes other components as needed, such as a beam splitter for splitting light from light source unit <NUM> to object body <NUM> and light from object body <NUM> to optical sensor <NUM>, a lens system, and a light reflector for reflecting light to object body <NUM> and reference unit <NUM>. However, configurations of these components are neither illustrated in <FIG>, nor described in detail.

Light output form light source unit <NUM> irradiates object body <NUM> through varifocal unit <NUM>, and is reflected on object body <NUM>. The light reflected on object body <NUM> travels through varifocal unit <NUM>, and is detected by optical sensor <NUM>. When a three-dimensional shape is obtained using techniques of the focusing method, light that has passed through the pattern generating element (not illustrated) provided between light source unit <NUM> and object body <NUM> is projected upon object body <NUM>, and the light from object body <NUM> is detected by optical sensor <NUM> while changing conditions of varifocal unit <NUM> (a focal position of the projected pattern of varifocal unit <NUM>). Control unit <NUM> illustrated in <FIG> calculates shape information of object body <NUM> based on the condition of varifocal unit <NUM> and results of the detection by optical sensor <NUM> at this position. Therefore, it is not possible to obtain an accurate three-dimensional shape without correctly grasping the condition of varifocal unit <NUM>.

Here, examples of the configuration of varifocal unit <NUM> include a configuration in which the focal position of the project pattern is changed by mechanically moving the position of the lens, and a configuration in which a varifocal lens (for example, liquid lens) that does not mechanically move the position of the lens is used. The above configurations are described respectively with reference to the drawings. <FIG> is a schematic diagram illustrating a configuration of the varifocal unit according to Embodiment <NUM> of the present invention. Here, a reference sign V in the figure indicates a controller for supplying electric power and control signals to varifocal unit <NUM>. With the varifocal unit illustrated in <FIG>, a focus lens 82a is fixed to a slider 82b, and the project pattern and the focal position of optical sensor <NUM> are changed by moving slider 82b along a rail 82c that extends along a light axis. While the varifocal unit illustrated in <FIG> mechanically moves focus lens 82a by supplying electric power to slider 82b, it is necessary to provide a configuration in which a gauge is separately provided for focus lens 82a and the gauge is optically detected, in order to know the position of focus lens 82a on the light axis. Providing this configuration within handpiece <NUM> requires a space for accommodating the configuration, resulting in a problem in which a size of handpiece <NUM> itself is increased.

On the other hand, the varifocal unit illustrated in <FIG> employs a liquid lens 82d as a varifocal lens that does not mechanically move the position of the lens. One example of liquid lens 82d has such a configuration in which an electrode is provided on a side of a container enclosing aqueous solution and oil, and the boundary between the aqueous solution and the oil is changed by applying a voltage on the electrode to change the focal position (<FIG> schematically shows liquid lens 82d as a single biconvex lens, and details such as the aqueous solution and the oil are not shown). Therefore, the varifocal unit illustrated in <FIG> does not require the configuration of providing a gauge for the lens to perform optical detection. However, liquid lens 82d has a problem that it is difficult to correctly grasp the focal position as the liquid lens has hysteresis characteristics where its focal position is different between a case in which an applied voltage value is increased and a case in which an applied voltage value is decreased. Therefore, this embodiment provides a configuration with which the focal position can be correctly grasped and a reduced size can be provided even when varifocal unit <NUM> takes either of the configuration in which the position of the lens is moved mechanically, and the configuration in which the position of the lens is not moved mechanically.

Here, examples of the condition of varifocal unit <NUM> of the configuration in which the position of the lens is moved mechanically include a position of the lens, a refractive index of the lens, and a curvature shape of the lens. Further, examples of the condition of varifocal unit <NUM> of the configuration in which the position of the lens is not moved mechanically include a refractive index of the lens, and a curvature shape of the lens. In the following description, reference unit <NUM> having a known design pattern is prepared, and the condition of varifocal unit <NUM> is correctly grasped using results of taken images of the design pattern provided for reference unit <NUM>. Further, in the following description, a liquid lens is used as varifocal unit <NUM>. However, varifocal unit <NUM> is not limited to a liquid lens, and may take the configuration in which the position of the lens is moved mechanically. Moreover, while in the following description, the condition of varifocal unit <NUM> is indirectly grasped using reference unit <NUM>, it should be understood that the condition of varifocal unit <NUM> can be directly grasped by providing another configuration in which values of a refractive index of the lens and a curvature shape of the lens are directly measured based on light traveling through varifocal unit <NUM> and the like.

Referring back to <FIG>, a specific method for correctly grasping the condition of varifocal unit <NUM> will be described. First, light output from a part of light source unit <NUM> irradiates reference unit <NUM> through varifocal unit <NUM>, and is reflected on reference unit <NUM>. The light reflected on reference unit <NUM> travels through varifocal unit <NUM>, and is detected by a part of optical sensor <NUM>. Here, as reference unit <NUM> is provided within a housing of handpiece <NUM>, a light path from the part of light source unit <NUM> to the part of optical sensor <NUM> via reference unit <NUM> is shorter than a light path from light source unit <NUM> to optical sensor <NUM> via object body <NUM>. Therefore, light path length adjustment unit <NUM> for adjusting a length of the light path from light source unit <NUM> to optical sensor <NUM> via object body <NUM> and a length of the light path from the part of light source unit <NUM> to the part of optical sensor <NUM> via reference unit <NUM> is provided along the light path from the part of light source unit <NUM> to the part of optical sensor <NUM> via reference unit <NUM>.

Light path length adjustment unit <NUM> may be any optical element that is able to adjust the length of the light path along the light path from the part of light source unit <NUM> to the part of optical sensor <NUM> via reference unit <NUM>, and examples of light path length adjustment unit <NUM> include a glass block, a light guide, a lens or a lens array, an offset mirror/prism, a dichroic mirror, a delay line, and a pentaprism. By making the lengths of the light paths substantially match using light path length adjustment unit <NUM>, it is possible to take images that are generally focused by the optical sensor for both of object body <NUM> and reference unit <NUM>. Specifically, it is possible to make correspondence between a focusing position for object body <NUM> and a focusing position for reference unit <NUM>. Therefore, it is possible to correctly grasp the condition of varifocal unit <NUM> by analyzing images of reference unit <NUM> taken using the part of optical sensor <NUM> to obtain the focusing position for reference unit <NUM>.

A configuration of reference unit <NUM> will be described with reference to the drawings. <FIG> is a schematic diagram illustrating a configuration of a reference unit according to Embodiment <NUM> of the present invention. Reference unit <NUM> illustrated in <FIG> is a flat plate having a striped design pattern, and disposed so as to be inclined with respect to a light axis of optical sensor <NUM>. Therefore, when the condition of varifocal unit <NUM> that are not illustrated is changed to bring a focus to a position 83a on an upper section of reference unit <NUM> (<FIG>), an image taken by the part of optical sensor <NUM> shows the striped pattern only at a position on the left side of the image. As the remaining portion of the image is out of focus, the striped design pattern is not shown as the contrast of the pattern is vague due to image blur. By analyzing this image, it is possible to obtain a signal showing a waveform only at the position on the left side of the image. As examples of a method for analyzing an image to obtain a signal, the striped pattern that appears at different portions of images depending on the condition of varifocal unit <NUM> can be analyzed using a known algorithm such as a differentiation method, a pattern matching method, and an envelope detection method. Here, a position of the waveform in the signal obtained from the striped pattern and the condition of varifocal unit <NUM> correspond on a one-on-one basis. Control unit <NUM> illustrated in <FIG> is able to correctly grasp the condition of varifocal unit <NUM> based on this signal. In other words, control unit <NUM> serves as a determination unit for determining the condition of varifocal unit <NUM> based on light reflected on reference unit <NUM> that has been detected by the part of optical sensor <NUM>. Further, control unit <NUM> calculates shape information of object body <NUM> from an image taking light reflected on object body <NUM> that has been detected by optical sensor <NUM>, using information of the condition of varifocal unit <NUM> that has been determined.

Similarly, when the condition of varifocal unit <NUM> that are not illustrated is changed to bring a focus to a position 83b on a middle section of reference unit <NUM> (<FIG>), an image taken by optical sensor <NUM> shows the striped pattern only at a position at the center of the image. By analyzing this image, it is possible to obtain a signal showing a waveform only at the position at the center of the figure. Further, when the condition of varifocal unit <NUM> that is not illustrated is changed to bring a focus to a position 83c on a lower section of reference unit <NUM> (<FIG>), an image taken by the part of optical sensor <NUM> shows the striped pattern only at a position on the right side of the image. By analyzing this image, it is possible to obtain a signal showing a waveform only at the position on the right side of the figure. As described above, each position of the waveform in the signal obtained from the taken image of reference unit <NUM> and the condition of varifocal unit <NUM> correspond on a one-on-one basis.

According to three-dimensional scanner <NUM>, light source unit <NUM> is a single light source (for example, an LED), and light from the part of light source unit <NUM> irradiates reference unit <NUM>, and light reflected on reference unit <NUM> is detected by the part of optical sensor <NUM>. Therefore, an image taken by optical sensor <NUM> contains a part of the image of the reference unit <NUM> in the image of object body <NUM>. <FIG> is a diagram illustrating one example of images taken by optical sensor <NUM>. The image shown in <FIG> shows an image of reference unit <NUM> in a region 81a on the left side of the figure, and an image of object body <NUM> in a region 81b in the remaining part of the figure. Further, a striped pattern 81c is shown on an upper section of the image of reference unit <NUM> in region 81a. Therefore, it is possible to specify that the image of object body <NUM> in <FIG> is an image that has been taken on the condition of varifocal unit <NUM> on which the focus is brought to the position of the upper section of reference unit <NUM> as illustrated in <FIG>. According to three-dimensional scanner <NUM>, it is possible to obtain the three-dimensional shape of object body <NUM> by combining a plurality of images of object body <NUM>, based on the condition of varifocal unit <NUM> specified from the image of reference unit <NUM> in region 81a.

According to three-dimensional scanner <NUM>, characteristics of varifocal unit <NUM> is first grasped, and therefore pre-calibration for obtaining correspondence between the focusing position for object body <NUM> and the focusing position for reference unit <NUM> is performed. Pre-calibration of varifocal unit <NUM> is performed, for example, at the shipment of three-dimensional scanner <NUM> by the manufacturer, or before the usage of three-dimensional scanner <NUM> by the user. Hereinafter, the pre-calibration will be described with reference to a flowchart. <FIG> is a flowchart for describing pre-calibration of varifocal unit <NUM>. First, in order to perform the pre-calibration of varifocal unit <NUM>, three-dimensional scanner <NUM> is fixed, and an object body having a known shape is placed on a stage that can be accurately moved with respect to three-dimensional scanner <NUM>. Examples of the object body having a known shape include a ceramic flat plate on which a squared pattern is printed, and a ceramic plate with step processing. Further, while in the following example, a stage that is movable accurately is used as a device for pre-calibration, a jig that can correctly grasp a positional relation between three-dimensional scanner <NUM> and the object body (a jig having a tubular housing that can be accurately fitted to connecting section <NUM>) may be used in place of the stage that is movable accurately.

Control unit <NUM> illustrated in <FIG> accepts a command for starting calibration (for example, such as pressing an activation button) (Step S101). Control unit <NUM> transmits a control signal to varifocal unit <NUM>, and set a focus (Step S102). Varifocal unit <NUM> changes a focal position based on the control signal. Control unit <NUM> takes an image of an object body by optical sensor <NUM> on conditions of varifocal unit <NUM> that has been set (Step S103). Here, the image that has been taken includes the image of reference unit <NUM> and the image of the object body as described with reference to <FIG>.

Next, control unit <NUM> performs image processing to the image taken in Step S103 (Step S104). Specifically, control unit <NUM> calculates a focusing degree (quantification on how match the image is in focus) for each pixel from the image of the object body, and calculates the condition of varifocal unit <NUM> (e.g., a position of waveform shown in a signal illustrated in <FIG>) from the image of reference unit <NUM>. Control unit <NUM> determines whether or not a number of times the focus is set in Step S102 is greater than or equal to a specified number (Step S105). If the number of times the focus is set is less than the specified number (Step S105: NO), control unit <NUM> returns the processing to Step S102 and sets a next focus. In other words, from a minimum position to a maximum position at which setting can be performed, control unit <NUM> changes the condition of varifocal unit <NUM> at least once, and repeats image processing of images taken at corresponding focal positions (Steps S103 and S104).

If the number of times the focus is set is greater than or equal to the specified number (Step S105: YES), control unit <NUM> detects the condition of varifocal unit <NUM> with a focusing degree calculated at each image (i, j) is maximized (Step S <NUM>). In other words, control unit <NUM> obtains images that are in focus (all of focused images), and information of the condition of varifocal unit <NUM> at each time. Further, control unit <NUM> obtains X and Y coordinates at each image (i, j) from analysis of all of the focus images of the object body having a known shape (e.g., squared-pattern design), and a Z coordinate from a position of the stage at each image (i, j), and obtains relations between the coordinates and the condition of varifocal unit <NUM> respectively (Step S107).

Next, control unit <NUM> determines whether or not a number of times the stage is moved is greater than or equal to a predetermined number (Step S108). If the number of times the stage is moved is less than the predetermined number (Step S <NUM>: NO), control unit <NUM> returns the processing to Step S <NUM> and moves the stage to a next position. In other words, from a minimum position to a maximum position at which three-dimensional scanner <NUM> can take image, control unit <NUM> moves the stage at least once, and repeats image processing of images taken at corresponding positions of the stage (Steps S103 and S104). If the number of times the stage is moved is greater than or equal to the predetermined number (Step S108: YES), control unit <NUM> obtains relations between the coordinates and the condition of varifocal unit <NUM> respectively at the positions to which the stage is moved (Step S109).

Next, control unit <NUM> stores all of the relations obtained in Step S <NUM> (calibration information) in a recording unit (e.g., flash memory, or the like) as a table (Step S1 <NUM>). Control unit <NUM> stores the table, and terminates the pre-calibration processing of varifocal unit <NUM>.

Here, while control unit <NUM> is described to store all of the relations obtained in Step S109 (calibration information) in the recording unit as a table, all of the relations (calibration information) may not be stored as a table and may be approximated by a function, and only an expression and a coefficient of the function may be stored. Further, the pre-calibration processing may be separately performed for each of the coordinates (X, Y, and Z). For example, after the pre-calibration processing (pre-calibration for the Z coordinate) is performed using a white plate is first used as the object body, a squared-pattern plate is placed as the object body and the pre-calibration processing (pre-calibration for the X and Y coordinates) is performed.

In the above description, an example of the pre-calibration of the three-dimensional scanner using the principles of the focusing method has been described. The pre-calibration is configured roughly by three processing parts described below:.

As the processing part (<NUM>) can be realized using principles of any method such as trigonometry other than the focusing method, similar pre-calibration can be applied regardless of the principles. It should be understood that this applies to the following description of measurement of the object body, regardless of the employed principles.

Three-dimensional scanner <NUM> measures the object body using the relations obtained by the pre-calibration processing of varifocal unit <NUM>. Hereinafter, the measurement of the object body will be described with reference to a flowchart. <FIG> is a flowchart describing measurement of an object body by the three-dimensional scanner according to Embodiment <NUM> of the present invention.

Control unit <NUM> illustrated in <FIG> accepts a command for starting measurement of object body <NUM> (for example, such as pressing a measurement button) (Step S201). Control unit <NUM> transmits a control signal to varifocal unit <NUM>, and set a focus (Step S202). Varifocal unit <NUM> changes a focal position based on the control signal. Control unit <NUM> takes an image of an object body by optical sensor <NUM> on conditions of varifocal unit <NUM> that has been set (Step S203).

Next, control unit <NUM> performs image processing to the image taken in Step S203 (Step S204). Specifically, control unit <NUM> determines a focusing degree for each pixel from the image of the object body, and calculates the conditions of varifocal unit <NUM> from the image of reference unit <NUM>. Control unit <NUM> determines whether or not the number of times the focus is set in Step S202 is greater than or equal to a specified number (Step S205). If the number of times the focus is set is less than the specified number (Step S205: NO), control unit <NUM> returns the processing to Step S202 and sets a next focus. In other words, from a minimum position to a maximum position at which setting can be performed, control unit <NUM> changes the condition of varifocal unit <NUM> at least once, and repeats image processing of images taken at corresponding focal positions (Steps S203 and S204).

If the number of times the focus is set is greater than or equal to the specified number (Step S205: YES), control unit <NUM> detects the condition of varifocal unit <NUM> with a focusing degree calculated at each image (i, j) is maximized (Step S206). In other words, control unit <NUM> obtains images that are in focus, and information of the condition of varifocal unit <NUM> at each time. Further, control unit <NUM> refers to the table stored in Step S110, and reads a three-dimensional coordinate (X, Y, and Z coordinates) corresponding to a result detected for each pixel in Step S206 (the condition of varifocal unit <NUM>) (Step S207). At this time, if the condition of varifocal unit <NUM> stored in the table does not match the condition of varifocal unit <NUM> detected in Step S206, it is possible to perform interpolation processing using values close to the stored conditions of varifocal unit <NUM> in the table. Further, if a value close to the condition of varifocal unit <NUM> detected in Step S206 is not present in the table, it is determined that a measurement error occurs and it is possible to perform outlier processing in which a coordinate is not generated. Based on Steps S202 to S208, control unit <NUM> obtains three-dimensional coordinates for all of the coordinates, and obtains three-dimensional data of object body <NUM> (Step S208).

Next, control unit <NUM> accepts a command for terminating the measurement of object body <NUM> (for example, such as pressing a termination button) (Step S209). If a command for terminating the measurement is not accepted (Step S209: NO), control unit <NUM> returns the processing to Step S202 in order to continue the measurement processing, and repeats the processing for obtaining the three-dimensional data (Steps S202 to S208). By repeating the above steps, it is possible to perform successive three-dimensional measurement like a video. On the other hand, if a command for terminating the measurement is accepted (Step S209: YES), control unit <NUM> terminates the measurement processing.

As described above, three-dimensional scanner <NUM> according to Embodiment <NUM> of the present invention includes: light source unit <NUM>, optical sensor <NUM> for detecting the light from light source unit <NUM> that has been reflected on object body <NUM>; and reference unit <NUM> for being irradiated with a part of the light from light source unit <NUM>. Three-dimensional scanner <NUM> further includes: varifocal unit <NUM> capable of changing the focal position, varifocal unit being a unit through which both of the light from light source unit <NUM> to optical sensor <NUM> via object body <NUM> and the light from light source unit <NUM> to optical sensor <NUM> via reference unit <NUM> travel at least once; and the light path length adjustment unit for adjusting the length of the light path from object body <NUM> to optical sensor <NUM> and the length of the light path from reference unit <NUM> to optical sensor <NUM>. Further, three-dimensional scanner <NUM> causes control unit <NUM> to determine the condition of varifocal unit <NUM> based on the light detected by the part of optical sensor <NUM> (the light reflected on reference unit <NUM>), and to calculate the shape information of object body <NUM> from the light detected by optical sensor <NUM> using the information of the determined condition of varifocal unit <NUM>. Therefore, three-dimensional scanner <NUM> is able to correctly grasp the condition of varifocal unit <NUM>, and to obtain an accurate three-dimensional shape. In addition, as three-dimensional scanner <NUM> does not require a configuration in which the lens of varifocal unit <NUM> is provided with a gauge and optical detection is performed, a size of handpiece <NUM> itself can be reduced.

Further, reference unit <NUM> is provided within the housing of handpiece <NUM>, it is possible to perform pre-calibration processing without probe <NUM>. Moreover, optical sensor <NUM> is configured by a single optical sensor, and the part of optical sensor <NUM> detects the light reflected on reference unit <NUM>, and the remaining part of optical sensor <NUM> detects the light reflected on object body <NUM>. Therefore, it is possible to reduce a number of components of three-dimensional scanner <NUM>. It should be appreciated that optical sensor <NUM> may be configured by a plurality of optical sensors, and one of the optical sensors is used to detect the light reflected on reference unit <NUM>, and the other of the optical sensors is used to detect the light reflected on object body <NUM>.

According to three-dimensional scanner <NUM> illustrated in <FIG>, the light from light source unit <NUM> to optical sensor <NUM> via object body <NUM> travels through varifocal unit <NUM> two times, and the light from light source unit <NUM> to optical sensor <NUM> via reference unit <NUM> also travels through varifocal unit <NUM> two times. However, it is sufficient if the light from light source unit <NUM> to optical sensor <NUM> via object body <NUM> and the light from light source unit <NUM> to optical sensor <NUM> via reference unit <NUM> travel through varifocal unit <NUM> at least once. In order to provide a configuration in which both of the light from light source unit <NUM> to optical sensor <NUM> via object body <NUM> and the light from light source unit <NUM> to optical sensor <NUM> via reference unit <NUM> travel through varifocal unit <NUM> once, varifocal unit <NUM> may be provided closer to light source unit <NUM> or optical sensor <NUM> than a beam splitter that is not illustrated in <FIG>.

Further, it is possible to provide a configuration in which only the light from light source unit <NUM> to optical sensor <NUM> via reference unit <NUM> travels through varifocal unit <NUM> once, or only the light from light source unit <NUM> to optical sensor <NUM> via object body <NUM> travels through varifocal unit <NUM> once. <FIG> is a schematic diagram illustrating a configuration of an optical system within a handpiece according to a modified example of Embodiment <NUM> of the present invention. Here, in the configuration illustrated in <FIG>, components that are the same as those in the configuration illustrated in <FIG> are indicated by the same reference numbers and not described in detail. The configuration illustrated in <FIG> is such that only the light from light source unit <NUM> to optical sensor <NUM> via reference unit <NUM> travels through varifocal unit <NUM> once, and the light from light source unit <NUM> is split using a light guide <NUM> (for example, such as an optical fiber) to directly irradiate reference unit <NUM>. In other words, light output from a light guide <NUM> after being split irradiates reference unit <NUM> without traveling through varifocal unit <NUM>. The light irradiating reference unit <NUM> is reflected on reference unit <NUM>, travels through a collimate lens <NUM>, varifocal unit <NUM>, and a beam splitter <NUM>, and is detected by the part of optical sensor <NUM>. On the other hand, light output from the other light guide after being split by light guide <NUM> travels through a collimate lens <NUM>, a pattern generating element <NUM>, beam splitter <NUM>, and varifocal unit <NUM>, and irradiates the object body. Here, the configuration illustrated in <FIG> is mere example, and a part of the components in this configuration may be replaced by an equivalent optical element.

The configuration illustrated in <FIG> is such that only the light from light source unit <NUM> to optical sensor <NUM> via object body <NUM> travels through varifocal unit <NUM> once, and the light reflected on reference unit <NUM> is directly guided to optical sensor <NUM> using a light guide <NUM> (for example, such as an optical fiber). In other words, a part of the light from light source unit <NUM> that has traveled through varifocal unit <NUM> once irradiates reference unit <NUM>, and the light reflected on reference unit <NUM> is collected by an imaging lens <NUM> and guided to optical sensor <NUM> by light guide <NUM>. On the other hand, the light reflected on object body <NUM> travels through beam splitter <NUM>, varifocal unit <NUM>, and beam splitter <NUM>, and is detected by optical sensor <NUM>. Here, the configuration illustrated in <FIG> is mere example, and a part of the components in this configuration may be replaced by an equivalent optical element. Further, while not described in the above configuration, it is possible to provide a configuration having a light path along which light travels through varifocal unit <NUM> by a number of times greater than or equal to three.

While light source unit <NUM> is described to be a single light source (for example, an LED, and a laser element), light source unit is not limited to such a configuration. Light source unit <NUM> may be configured by combining a plurality of light sources. In other words, light source unit <NUM> may be configured by a plurality of LEDs or laser elements arranged on a substrate. Further, light source unit <NUM> irradiates reference unit <NUM> with a part of the light, and irradiates object body <NUM> with the other part of the light. Therefore, light source unit <NUM> may be configured by a light source unit A that emits light irradiating object body <NUM>, and a light source unit B that emits light irradiating reference unit <NUM>. Moreover, light source unit A and light source unit B are not required to be disposed close to each other, and light source unit A and light source unit B may be disposed at distant positions. Here, according to three-dimensional scanner <NUM>, it is possible to employ a configuration in which the light from light source unit <NUM> is guided to reference unit <NUM> and object body <NUM> using a light guide such as an optical fiber.

Embodiment <NUM> describes three-dimensional scanner <NUM> having a configuration, as illustrated in <FIG>, in which reference unit <NUM> is provided within the housing of handpiece <NUM>. However, a three-dimensional scanner according to Embodiment <NUM> is provided with a reference unit within a probe detachable from an optical measurement unit, in place of the reference unit within the housing of the handpiece. Hereinafter, a three-dimensional scanner having a reference unit within a probe will be described.

First, a configuration of the probe will be described in detail. <FIG> is a schematic diagram illustrating a configuration of a probe 10a according to Embodiment <NUM> of the present invention. Here, in <FIG>, components that are the same as those in the configuration illustrated in <FIG> and <FIG> are indicated by the same reference numbers and not described in detail. Probe 10a includes a housing <NUM> having an opening for connection with connecting section <NUM>, a measurement window <NUM> (lighting window unit) provided for housing <NUM> on the other side of the opening, and a mirror <NUM> (reflection unit) for reflecting light received through measurement window <NUM> to optical measurement unit <NUM>. The opening of probe 10a is an insertion portion through which connecting section <NUM> is inserted. With this, even if an external force is applied to housing <NUM>, probe 10a does not be easily separated from connecting section <NUM>. Further, as illustrated in <FIG>, an end portion of probe 10a is in contact with optical measurement unit <NUM>. With this, even if probe 10a is pressed toward a direction of optical measurement unit <NUM>, probe 10a does not move toward optical measurement unit <NUM> anymore.

Mirror <NUM> is an optical element for changing directions of the light from light source unit <NUM> and the light reflected on object body <NUM>, and includes a reference unit at a part thereof. Here, in order to realize the configuration in which "mirror <NUM> includes the reference unit at a part thereof, the reference unit may be provided by forming a design pattern or the like on a part of a surface of mirror <NUM>, or the reference unit may be provided by applying a separate member having a design pattern on a part of a surface of mirror <NUM>. Further, mirror <NUM> may be configured by combining an optical element for reflecting light and a reference unit as a separate member.

Next, a configuration of an optical system of the three-dimensional scanner according to Embodiment <NUM> will be described more in detail. <FIG> is a schematic diagram illustrating a configuration of an optical system of a three-dimensional scanner according to Embodiment <NUM> of the present invention. Here, in <FIG>, components that are the same as those in the configuration illustrated in <FIG> and <FIG> are indicated by the same reference numbers and not described in detail. First, the three-dimensional scanner according to Embodiment <NUM> includes light source unit <NUM>, varifocal unit <NUM>, reference unit <NUM>, light path length adjustment unit <NUM>, optical sensor <NUM>, and beam splitter <NUM>. Here, <FIG> only shows a light path from the part of light source unit <NUM> to the part of optical sensor <NUM> through reference unit <NUM>. A light path from light source unit <NUM> to optical sensor <NUM> through object body <NUM> is the same as the light path described in Embodiment <NUM>, and not described in detail.

Light from light source unit <NUM> travels through beam splitter <NUM>, varifocal unit <NUM>, and light path length adjustment unit <NUM>, and irradiates mirror <NUM>. With mirror <NUM>, striped patterns 14b formed on both sides serve as reference unit <NUM>, and the remaining part serves as a light reflector 14a. A part of the light irradiating mirror <NUM> is reflected on reference unit <NUM> on which striped patterns 14b are formed. The light reflected on reference unit <NUM> travels through light path length adjustment unit <NUM>, varifocal unit <NUM>, and beam splitter <NUM>, and is detected by optical sensor <NUM>. Optical sensor <NUM> detects the light from object body <NUM> at a central portion 85a, and detects the light from reference unit <NUM> at portions 85b on the both sides. Similarly to the example shown in <FIG>, as a surface having the striped pattern is disposed so as to be inclined with respect to a light axis of light sensor, a striped design pattern appears in an image at a position corresponding to the condition of varifocal unit <NUM> on a one-on-one basis.

As described above, as reference unit <NUM> is provided for probe 10a detachable from the opening of three-dimensional scanner, and no reference unit is required within the housing of the handpiece, a size of the housing can be reduced. Further, as reference unit <NUM> is provided for a part of mirror <NUM> as an optical element, a number of the components can be reduced as compared to a case in which a reference unit is prepared as a separate member. Here, reference unit <NUM> is not limited to the example illustrated in <FIG> in which reference unit <NUM> is provided on the both sides of mirror <NUM>, and may be provided only on one side of mirror <NUM>.

Probe 10a illustrated in <FIG> and <FIG> has the configuration in which reference unit <NUM> is provided for the part of mirror <NUM>. However, the reference unit may be provided for a different position within the probe, instead of the part of mirror <NUM>. <FIG> is a schematic diagram illustrating a configuration of a probe according to a modified example of Embodiment <NUM> of the present invention. A probe 10b illustrated in <FIG> includes reference unit <NUM> near measurement window <NUM>, and an offset mirror <NUM> for reflecting the light from reference unit <NUM> next to mirror <NUM>. Offset mirror <NUM> also serves as a light path length adjustment unit for adjusting a length of the light path from the part of light source unit <NUM> to the part of optical sensor <NUM> through reference unit <NUM>. Further, in order to cause offset mirror <NUM> to serve as the light path length adjustment unit, and in order to provide the light axis of the light sensor inclined with respect to reference unit <NUM>, an angle of mirror <NUM> with respect to the surface in which measurement window <NUM> is formed and an angle of offset mirror <NUM> with respect to this surface are different.

In three-dimensional scanner <NUM> according to Embodiment <NUM>, as illustrated in <FIG>, the light from the light source unit <NUM> irradiates reference unit <NUM>. While the light irradiating reference unit <NUM> is reflected on reference unit <NUM>, there is a case in which a part of the light irregularly reflects and reaches the optical sensor as stray light. The stray light is a cause of a decreased accuracy of the three-dimensional measurement. A three-dimensional scanner according to Embodiment <NUM> has a configuration for suppressing such stray light.

<FIG> is a schematic diagram illustrating a configuration of an optical system within a handpiece according to Embodiment <NUM> of the present invention. Here, in <FIG>, components that are the same as those in the configuration illustrated in <FIG> and <FIG> are indicated by the same reference numbers and not described in detail. First, a handpiece 80b according to Embodiment <NUM> includes light source unit <NUM>, varifocal unit <NUM>, reference unit <NUM>, light path length adjustment unit <NUM>, and optical sensor <NUM>. Further, handpiece 80b includes a diaphragm unit <NUM> for adjusting light to optical sensor <NUM> at any position along the light path from reference unit <NUM> to optical sensor <NUM>. Diaphragm unit <NUM> cuts the light that irregularly reflects on reference unit <NUM> as stray light so that the light does not be detected by optical sensor <NUM>. Diaphragm unit <NUM> may have any diaphragm mechanism as long as it is possible to cut light.

As described above, by further providing diaphragm unit <NUM> for adjusting light to optical sensor <NUM>, it is possible to cut the light that irregularly reflects on reference unit <NUM> as stray light, and to improve accuracy of the three-dimensional measurement. Here, <FIG> shows the configuration in which diaphragm unit <NUM> is provided for an optical system within the handpiece having reference unit <NUM> within the housing. However, a diaphragm unit may also be provided for an optical system within a handpiece having a reference unit within a probe.

According to the probe according to Embodiment <NUM>, reference unit <NUM> is provided for the part of mirror <NUM>. A probe according to Embodiment <NUM> has a configuration in which a retardation plate is provided for a surface of a reference unit provided for a part of a mirror.

<FIG> is a schematic diagram illustrating a configuration of a probe 10c according to Embodiment <NUM> of the present invention. Here, in <FIG>, components that are the same as those in the configuration illustrated in <FIG> and <FIG> are indicated by the same reference numbers and not described in detail. Probe 10c includes a housing <NUM> having an opening for connection with a connecting section of the optical measurement unit, a measurement window <NUM> (lighting window unit) provided for housing <NUM> on the other side of the opening, and a mirror <NUM> (reflection unit) for reflecting light received through measurement window <NUM> to optical measurement unit <NUM>.

Mirror <NUM> includes reference unit <NUM> at a part thereof. Here, while reference unit <NUM> is provided only on one side of mirror <NUM> as illustrated in <FIG>, reference unit <NUM> may be provided on both sides of mirror <NUM>. Further, a quarter wavelength plate <NUM> as a retardation plate is provided for the surface of reference unit <NUM>. By providing quarter wavelength plate <NUM> for the surface of reference unit <NUM>, it is possible to efficiently detect the light reflected on reference unit <NUM> by optical sensor <NUM>. Here, a quarter wavelength plate is a retardation plate having a function for producing a <NUM>/<NUM> wavelength phase difference in a specific polarization component contained in an incident light beam. With this, polarization states of incident light and reflection light may be operated. This is effective, for example, to a case in which beam splitter <NUM> is configured by a polarization beam splitter, and reference unit <NUM> is configured by a translucent resin material or the like, and it is possible to emphasize contrast of a pattern projected onto the surface of reference unit <NUM> by employing quarter wavelength plate <NUM>. Specifically, utilizing a difference between the polarization states of a component reflected near the surface (a component having favorable contrast of the pattern) and a component diffusely reflected within a translucent body (a component reducing contrast of the pattern) out of the reflection light from reference unit <NUM>, only the former component is selectively guided to optical sensor <NUM> with low loss. With this, it is possible to improve accuracy of grasping of the condition of the varifocal unit by analyzing a taken image of reference unit <NUM>. The retardation plate provided for the surface of reference unit <NUM> is not limited to quarter wavelength plate <NUM>, and a retardation plate of an appropriate type may be selected depending on the optical design.

As described above, as reference unit <NUM> has a retardation plate on the surface to be irradiated with light, use efficiency of the light reflected on reference unit <NUM> is improved. Here, <FIG> shows the configuration in which the retardation plate is provided for the surface of reference unit <NUM> provided for the part of mirror <NUM>. However, a retardation plate may be provided for a surface of a reference unit provided within the probe, or for a surface of a reference unit provided within the housing.

Embodiment <NUM> describes three-dimensional scanner <NUM> having a configuration in which a wavelength of light irradiating object body <NUM> and a wavelength of light irradiating reference unit <NUM> are the same. However, Embodiment <NUM> describes a three-dimensional scanner having a configuration in which a wavelength of light irradiating an object body and a wavelength of light irradiating a reference unit are different.

<FIG> is a schematic diagram illustrating a configuration of a probe 10d according to Embodiment <NUM> of the present invention. Here, in <FIG>, components that are the same as those in the configuration illustrated in <FIG> and <FIG> are indicated by the same reference numbers and not described in detail. Probe 10d includes housing <NUM> having an opening for connection with a connecting section of optical measurement unit <NUM>, measurement window <NUM> (lighting window unit) provided for housing <NUM> on the other side of the opening, mirror <NUM> (reflection unit) for reflecting light received through measurement window <NUM> to optical measurement unit <NUM>, a dichroic mirror <NUM> disposed on a side closer to optical measurement unit <NUM> than measurement window <NUM>, and reference unit <NUM> disposed on a side closer to optical measurement unit <NUM> than dichroic mirror <NUM>.

As one example of dichroic mirror <NUM>, an optical element that transmits visible light and reflects infrared light (IR) is used here. In other words, the three-dimensional scanner according to Embodiment <NUM> uses visible light as the light irradiating object body <NUM>, and infrared light as the light irradiating reference unit <NUM>. <FIG> is a schematic diagram illustrating a configuration of an optical system within a handpiece according to Embodiment <NUM> of the present invention. In the configuration illustrated in <FIG>, components that are the same as those in the configuration illustrated in <FIG> are indicated by the same reference numbers and not described in detail. A light path shown in <FIG> is a light path from a light source unit 81d to optical sensor 85d via object body <NUM>. A light path shown in <FIG> is a light path from light source unit 81d to an optical sensor 85d via reference unit <NUM>.

First, light source unit 81d is a light source configured to emit visible light and infrared light. Here, light source unit 81d may be, for example, configured by an LED or a laser element for emitting visible light and an LED or a laser element for emitting infrared light, the LEDs being arranged on a substrate, or by a single LED for emitting broadband light including a spectrum from visible light to infrared light. Here, light source unit 81d may be configured separately by a light source unit C for emitting visible light and a light source unit D for emitting infrared light.

With the light path shown in <FIG>, visible light emitted from light source unit 81d travels through beam splitter <NUM>, varifocal unit <NUM>, and mirror <NUM>, and irradiates object body <NUM>. Light reflected on object body <NUM> travels inversely through mirror <NUM>, varifocal unit <NUM>, and beam splitter <NUM>, and is detected by optical sensor <NUM>. On the other hand, with the light path shown in <FIG>, infrared light emitted from light source unit 81d travels through beam splitter <NUM>, varifocal unit <NUM>, and dichroic mirror <NUM>, and irradiates reference unit <NUM>. Light reflected on reference unit <NUM> travels inversely through dichroic mirror <NUM>, varifocal unit <NUM>, and beam splitter <NUM>, and is detected by optical sensor 85d.

Optical sensor 85d is able to detect visible light as well as infrared light. A specific configuration of optical sensor 85d will be described with reference to the drawings. <FIG> is a schematic diagram illustrating a configuration of an optical sensor according to Embodiment <NUM> of the present invention. An optical sensor 85d1 illustrated in <FIG> has a single-layer structure, and a region in which elements for detecting infrared light are arranged and a region in which elements for detecting visible light are arranged are disposed on a plane surface. In particular, in optical sensor 85d1, the elements for detecting infrared light are arranged in a region A, and the elements for detecting visible light are arranged in a region B. It should be noted that reference signs IR, R, G, and B in the figure indicate regions with high sensitivity/transmissivity to infrared light, red light, green light, and blue light, respectively.

An optical sensor 85d2 illustrated in <FIG> has a multi-layer structure, and a layer a is provided with a filter selectively transmitting visible light and infrared light, a layer b is provided with a color filter, and a layer c is provided with a monochrome light sensor. Optical sensor 85d2 also detects infrared light in region A, and visible light in region B. Therefore, for layer a, a filter only transmitting infrared light (IR-pass filter) is provided for region A, and a filter only transmitting visible light (IR-cut filter) is provided for region B. Here, if an image to be obtained by three-dimensional scanner is a monochrome image, the color filter for layer b is not necessary, or may be a monochrome filter.

While optical sensors 85d1 and 85d2 are configured such that the region for detecting infrared light and the region for detecting visible light are separate, an optical sensor 85d3 illustrated in <FIG> has a configuration in which infrared light and visible light are detected without separating regions. Optical sensor 85d3 has a single layer structure, and elements for detecting infrared light and elements for detecting visible light are arranged in sequence. In particular, in optical sensor 85d3, RGB elements for detecting visible light of respective colors and the elements for detecting infrared light are arranged in sequence. It should be understood that optical sensor 85d may be configured such that more than one area in which the elements for detecting visible light are disposed, and more than one area in which the elements for detecting infrared light are disposed are arranged. Further, similarly to optical sensor 85d2, optical sensor 85d3 may have a multi-layer structure in place of the single layer structure. As compared to optical sensor 85d1, 85d2 with the configuration in which an image of the reference unit is detected using a region on the side of the optical sensor, optical sensor 85d3 is able to detect infrared light at the center portion of the sensor, and therefore has an advantage that optical sensor 85d3 is less susceptible to aberration of the lens and the like.

As described above, according to the three-dimensional scanner of Embodiment <NUM>, as the wavelength of the light which is emitted from light source unit 81d and which irradiates reference unit <NUM> (infrared light) and the wavelength of the light which is emitted from light source unit 81d and which irradiates object body <NUM> (visible light) are different, even if irregularly-reflected light on reference unit <NUM> interferes an image of object body <NUM> as stray light, for example, the stray light does not be present in a taken image of object body <NUM> by the color filter. Therefore, it is possible to grasp the condition of varifocal unit <NUM> without giving any influence to the measurement of object body <NUM>.

While the three-dimensional scanner according to Embodiment <NUM> uses infrared light and visible light so that the wavelength of the light which is emitted from light source unit 81d and which irradiates reference unit <NUM> and the wavelength of the light which is emitted from light source unit 81d and which irradiates object body <NUM> are different, a combinations of other wavelengths may be employed, and for example, ultraviolet light (UV) and visible light may be used.

The three-dimensional scanner according to Embodiments <NUM> to <NUM> of the present invention is descried to have a striped pattern formed on the surface of reference unit <NUM>. However, the pattern formed on the surface of reference unit <NUM> is not limited to the striped (striped) pattern, and may be a grid pattern or a dotted pattern. Further, the surface may not be inclined with respect to the light axis of the optical sensor. For example, in a case in which a dotted pattern is formed on the surface of reference unit <NUM>, it is possible to grasp the condition of varifocal unit <NUM> based on a diameter of a dot out of focus (a diameter of a circle of confusion). Here, the pattern formed on the surface of reference unit <NUM> may be any pattern as long as visibility of the pattern changes depending on the change of the condition of varifocal unit <NUM>, and a degree of the change may be quantified. Further, reference unit <NUM> may be provided with the pattern by directly printing a pattern to the surface, or by applying a pattern printed on a separate member to the surface. Examples of reference unit <NUM> include a striped design pattern formed on a base material such as paper, plastic, metal, ceramic, and glass by screen printing, laser marking, vapor deposition, sputtering, and alternate stacking of materials of different colors by a 3D printer. Further, a design pattern may be formed by such as shape processing for concavity and convexity in place of changing surface colors, or a combination of both.

Moreover, as illustrated in <FIG>, by providing pattern generating element <NUM> along the light path, it is possible to provide a predetermined pattern for the light irradiating reference unit <NUM>. It is possible to project a predetermined pattern onto the surface of reference unit <NUM> by providing the predetermined pattern for the light irradiating reference unit <NUM>, without forming a pattern on the surface of reference unit <NUM>. It should be appreciated that a combination of reference unit <NUM> having a pattern on its surface and the light having a predetermined pattern may also be employed.

The three-dimensional scanner according to Embodiment <NUM> of the present invention is described to have the configuration in which reference unit <NUM> is provided on the side of the housing of the handpiece, and the three-dimensional scanner according to Embodiment <NUM> of the present invention is described to have the configuration in which reference unit <NUM> is provided on the side of the probe. Further, the probe according to Embodiment <NUM> of the present invention is provided with mirror <NUM> in addition to reference unit <NUM>. However, the present invention is not limited to such configurations, and a configuration in which the probe is only provided with reference unit <NUM>, and a configuration in which mirror <NUM> is provided on the side of the housing of the handpiece in addition to reference unit <NUM> may also be employed. Here, in a case in which reference unit <NUM> and mirror <NUM> are provided on the side of the housing of the handpiece, the probe is used only as a cover. Further, while the three-dimensional scanner having the probe detachable from the housing of the handpiece is described, as long as a structure with which aseptic of the handpiece as a whole can be performed is provided, the configuration described with reference to Embodiments <NUM> to <NUM> may be applied to a three-dimensional scanner having no probe.

According to the three-dimensional scanner of Embodiment <NUM> of the present invention, it is described that light path length adjustment unit <NUM> is provided along the light path on the side of reference unit <NUM> in order to adjust the length of the light path from light source unit <NUM> to optical sensor <NUM> through object body <NUM> and the length of the light path from the part of light source unit <NUM> to the part of optical sensor <NUM> through reference unit <NUM>. However, as long as it is possible to relatively adjust the length of the light path from light source unit <NUM> to optical sensor <NUM> through object body <NUM> and the length of the light path from the part of light source unit <NUM> to the part of optical sensor <NUM> through reference unit <NUM>, the light path length adjustment unit may be provided either of the light paths. It should be appreciated that the light path length adjustment unit may be provided along both of the light path for reference unit <NUM> and the light path for object body <NUM>. Further, forming an image of reference unit <NUM> or object body <NUM> at a predetermined position along the light path using a relay lens and an image guide may provide a situation that can be considered equivalent to a situation in which reference unit <NUM> or object body <NUM> is actually placed at the position at which the image is formed. Therefore, light path length adjustment unit <NUM> may be configured to specify a length of the light path for a position at which an image is formed, and to adjust the length of the light path, instead of a position at which reference unit <NUM> or object body <NUM> is actually placed.

Further, an object of the three-dimensional scanner according to Embodiments <NUM> to <NUM> of the present invention is not limited to a tooth and gum in the mouth, and may be applied to a body tissue such as an external ear canal, a gap between walls in building, a place within piping, and an industrial product having a hollow space. The present invention is versatile in various applications for measurement/observation within a small space which tends to contain blind corners.

The embodiments disclosed herein are only exemplarily and are not construed to limit the present invention. The present invention is defined by claimed subject-matter, rather than the description herein, and intended to include all modifications made within the claimed subject-matter.

Claim 1:
A three-dimensional scanner (<NUM>) for obtaining shape information of an object body (<NUM>), the three-dimensional scanner (<NUM>) comprising:
a light source unit (<NUM>);
a detection unit (<NUM>) for detecting light from the light source unit (<NUM>), the light being reflected on the object body (<NUM>);
a reference unit (<NUM>) for being irradiated with a part of the light from the light source unit (<NUM>);
a varifocal unit (<NUM>) capable of changing a focal position, the varifocal unit (<NUM>) being a unit through which both of light from the light source unit (<NUM>) to the detection unit (<NUM>) via the object body (<NUM>) and light from the light source unit (<NUM>) to the detection unit (<NUM>) via the reference unit (<NUM>) travel at least once;
a light path length adjustment unit (<NUM>) for adjusting a length of a light path from the object body (<NUM>) to the detection unit (<NUM>) and a length of a light path from the reference unit (<NUM>) to the detection unit (<NUM>);
a determination unit for determining a condition of the varifocal unit (<NUM>) based on light that has been reflected on the reference unit (<NUM>) and detected by a part of the detection unit (<NUM>); and
a calculation unit for calculating shape information of the object body (<NUM>) from light detected by the detection unit (<NUM>), using information of the condition of the varifocal unit (<NUM>) determined by the determination unit.