JP7333290B2 - 3D scanner - Google Patents

Description

The present invention relates to a three-dimensional scanner that acquires shape information of an object.

In the field of dentistry, a three-dimensional scanner (intraoral scanner) for obtaining three-dimensional shapes of teeth has been developed for digital design of prostheses and the like on a computer (Patent Document 1). The three-dimensional scanner disclosed in US Pat. No. 5,900,003 is a hand-held scanner that acquires the three-dimensional shape of an object using the principle of focusing. Specifically, in the three-dimensional scanner, light having a linear or checkered pattern (hereinafter also referred to as a pattern) is projected onto the surface of an object, and the pattern is captured multiple times while changing the focal position. The three-dimensional shape of the object is obtained by finding the most focused distance from the image.

In other words, the three-dimensional scanner requires a variable focus section for rapidly changing the focus of the pattern projected onto the object. The variable focus section mechanically moves the position of the lens because it is necessary to change at least one of the focal position of the light from the light source and the focal position of the detection section within a predetermined range.

Japanese Patent No. 5654583

In order to apply the three-dimensional scanner in the dental field, the scanner body needs to be small enough to be held in one hand and to be inserted into the narrow oral cavity. However, in order to change the focal position of the light from the light source or the focal position of the detector within a predetermined range, it was necessary to change the position of the lens within a similar range. In other words, the variable focus section needs to move the lens position by a distance (for example, 10 mm to 20 mm) that is about the same as the distance at which the focal position of the light from the light source or the focal position of the detection section changes on the object. Ta. Therefore, in a three-dimensional scanner incorporating the variable focus unit, it is necessary to secure a space corresponding to at least the movable range of the lens position, which poses a problem of restricting miniaturization.

Furthermore, the variable focus unit has a motor for moving the position of the lens, and there is a problem that the motor becomes larger as the moving distance becomes longer. 3D scanners with large built-in motors need to secure space for the motor itself, which poses a problem that restricts miniaturization. There was a problem that the amount of heat generated increased.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and to provide a three-dimensional scanner having a built-in variable focus unit for mechanically moving the position of a lens, which can be miniaturized. and

A three-dimensional scanner according to the present invention is a three-dimensional scanner that acquires shape information of an object in the oral cavity, and includes a light source unit, a detection unit that detects light from the light source unit that is reflected by the object, and an oral cavity. a probe that is inserted into the inside of the body and guides the light from the light source to the target and guides the reflected light from the target to the detector; A variable focus section that can change the focal position of light reaching the detection section within a predetermined range, a calculation section that calculates shape information of an object from the light detected by the detection section, and a focus position and a variable focus section. A beam splitter that separates the optical path from the light source section and the optical path to the detection section between and between the object side lens of the positive lens on the focus position side from the pupil position and between the variable focus section, the light source section, and the detection section and, the object-side lens is provided in a connection portion that is a part of the optical measurement portion that can be fitted with the probe, and the light source portion, the detection portion, the variable focus portion, and the beam splitter are provided in the optical measurement other than the connection portion. A probe, a connection part, and an optical measurement part are provided in the unit , and a handpiece is configured with a probe, a connection part, and an optical measurement part. a driving unit for driving the lenses along the optical axis, the plurality of lenses including at least one pair of positive and negative lenses.

According to another aspect, a three-dimensional scanner according to the present invention is a three-dimensional scanner that acquires shape information of an intraoral object, and comprises a light source unit and light from the light source unit reflected by the object. , a probe inserted into the oral cavity to guide the light from the light source to the target and to guide the reflected light from the target to the detection, and the probe provided on the side closer to the light source than the probe. , a focusing lens capable of changing the focal position of light from the light source to the detection unit through the object; a driving unit that drives the focusing lens along the optical axis; At least one negative lens provided, a detection unit that detects light reflected by the object through the focal lens, and shape information of the object is calculated from the light reflected by the object detected by the detection unit. an object-side lens which is a positive lens on the focal position side of the pupil position between the computing section and the focus position and the variable focus section; and between the variable focus section and the light source section and the detection section; a beam splitter that separates the optical path to the detection unit, the object-side lens is provided in the connection unit that is a part of the optical measurement unit that can be fitted with the probe, the light source unit, the detection unit, the focusing lens, the driving The unit, the negative lens, and the beam splitter are provided in the optical measurement unit other than the connection unit, and the probe, the connection unit, and the optical measurement unit constitute a handpiece, and the combined lens power of the focus lens and the negative lens is obtained. The value is positive, and the movable range of the focal position on the object is the predetermined range.

In the three-dimensional scanner according to the present invention, the variable focus section includes a plurality of lenses, and the plurality of lenses includes a combination of at least one pair of positive and negative lenses. Since the variable focus section can be set larger than when configured with a single focus lens, the focus position on the object can be moved efficiently, and the movable range of the lens position can be shortened. It can be made smaller. According to another aspect, the three-dimensional scanner according to the present invention can form a reduced image of the detection unit by arranging the negative lens on the optical axis, and can adjust the enlarged projection magnification of the focus lens. The focus position on the object can be moved efficiently, and the movable range of the position of the focus lens can be shortened to reduce the size.

1 is a block diagram showing the configuration of a three-dimensional scanner according to Embodiment 1 of the present invention; FIG. 3 is a schematic diagram for explaining the configuration of the optical system in the handpiece according to Embodiment 1 of the present invention; FIG. FIG. 2 is a schematic diagram for explaining the configuration of a variable focus section according to Embodiment 1 of the present invention; FIG. 5 is a diagram showing optical simulation results when the variable focus section according to Embodiment 1 of the present invention is moved; FIG. 7 is a schematic diagram for explaining the configuration of a variable focus section according to Embodiment 2 of the present invention; FIG. 10 is a diagram showing optical simulation results when the variable focus section according to Embodiment 2 of the present invention is moved; FIG. 10 is a diagram showing optical simulation results when a variable focus unit is moved according to Embodiment 3 of the present invention; FIG. 11 is a schematic diagram for explaining the configuration of a variable focus section according to Embodiment 4 of the present invention; FIG. 5 is a diagram for explaining a combination of lenses in a variable focus section; FIG. 4 is a diagram for explaining an optical path passing through a variable focus section; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

(Embodiment 1)
A three-dimensional scanner according to Embodiment 1 of the present invention is a three-dimensional scanner (intraoral scanner) for acquiring a three-dimensional shape of teeth in the oral cavity. However, the three-dimensional scanner according to the present invention is not limited to intraoral scanners, and can be applied to other three-dimensional scanners having similar configurations. For example, the present invention can be applied to a three-dimensional scanner capable of capturing an image of the inside of a human ear as well as the inside of the oral cavity to obtain the three-dimensional shape of the inside of the outer ear.

[Configuration of three-dimensional scanner]
FIG. 1 is a block diagram showing the configuration of a three-dimensional scanner 100 according to Embodiment 1 of the present invention. A three-dimensional scanner 100 shown in FIG. The probe 10 is inserted into the oral cavity, projects light having a pattern (hereinafter, also referred to as a pattern) onto a tooth, which is an object 200, and measures reflected light from the object 200 onto which the pattern is projected to the optical measurement unit 30. leading to In addition, since the probe 10 is detachable from the optical measurement unit 30, as a countermeasure against infection, only the probe 10 that may come into contact with the living body is removed from the optical measurement unit 30 and sterilized (for example, subjected to high-temperature and high-humidity treatment). environmental treatment) can be applied. If the entire three-dimensional scanner device is sterilized, there is a drawback that the life of the device is shortened because many optical and electronic components are included, but if only the probe 10 is removed and sterilized, this drawback does not occur. The connection part 20 is a part of the optical measurement part 30 , has a shape that can be fitted with the probe 10 , and protrudes from the optical measurement part 30 . The connection unit 20 may have a lens system for guiding the light collected by the probe 10 to the optical measurement unit 30, and optical components such as a cover glass, an optical filter, and a retardation plate (1/4 wavelength plate). good.

The optical measurement unit 30 projects a pattern onto the object 200 via the probe 10 and captures an image of the projected pattern. Although not shown, the optical measurement unit 30 includes an optical component (pattern generation element) and a light source for generating a pattern to be projected onto the object 200, a lens component for forming an image of the pattern on the surface of the object 200, and a focal point. It has a variable focus unit whose position can be changed, and an optical sensor (such as a CCD image sensor or a CMOS image sensor) that captures an image of the projected pattern. The optical measurement unit 30 will be described below as a configuration that acquires a three-dimensional shape using the principle of the focusing method, but may be configured to acquire a three-dimensional shape using the principle of a confocal method or the like. In other words, the optical measurement unit 30 includes a configuration that changes the projection pattern and the focal position of the optical sensor by the focus variable unit, and uses any principle as long as it is a configuration that acquires a three-dimensional shape using an optical method. It is possible to apply even if the configuration is The probe 10, the connection section 20, and the optical measurement section 30 constitute a handpiece 80 for imaging the inside of the oral cavity.

The control unit 40 controls the operation of the optical measurement unit 30 and processes the image captured by the optical measurement unit 30 to obtain a three-dimensional shape. The control unit 40 includes a CPU (Central Processing Unit) as a control center, a ROM (Read Only Memory) that stores programs and control data for the CPU to operate, and a RAM (Random Access Memory) that functions as a work area for the CPU. memory), and an input/output interface for maintaining signal consistency with peripheral devices. The control unit 40 can output the acquired three-dimensional shape to the display unit 50, and can input information such as settings of the optical measurement unit 30 using an input device (not shown). Note that at least part of the calculation for processing the captured image to obtain the three-dimensional shape may be implemented as software by the CPU of the control unit 40, or may be implemented as hardware that performs processing separately from the CPU. may be implemented. At least part of the processing units such as the CPU and hardware may be incorporated inside the optical measurement unit 30 . In addition, in FIG. 1, each component (30, 40, 50, 60) of the three-dimensional scanner 100 is depicted as if wired by a cable (bold line in the figure), but some of these wiring Alternatively, all may be connected by wireless communication. Also, if the control unit 40 is small and light enough to be lifted with one hand, the control unit 40 and the optical measurement unit 30 may be integrated to form a single handpiece.

The display unit 50 is a display device for displaying the measurement result of the three-dimensional shape of the object 200 obtained by the control unit 40 . The display unit 50 can also be used as a display device for displaying other information such as setting information of the optical measurement unit 30, patient information, scanner activation status, instruction manual, and help screen. . Examples of the display unit 50 include a stationary liquid crystal display, a head-mounted type wearable display, and a glasses type wearable display. A plurality of display units 50 may be provided, and the three-dimensional shape measurement results and other information may be displayed simultaneously or dividedly on the plurality of display units 50 . The power supply unit 60 is a device for supplying electric power for driving the optical measurement unit 30 and the control unit 40 . The power supply unit 60 may be provided outside the control unit 40 as shown in FIG. 1 or may be provided inside the control unit 40 . Further, a plurality of power supply units 60 may be provided so as to separately supply power to the control unit 40 , the optical measurement unit 30 , and the display unit 50 .

[Optical configuration inside the handpiece]
Next, the configuration of the optical system within the handpiece will be described in more detail. FIG. 2 is a schematic diagram for explaining the configuration of the optical system in handpiece 80 according to Embodiment 1 of the present invention. First, the handpiece 80 is provided with a light source section 81 , a variable focus section 82 , a driving section 83 and an optical sensor 85 . In addition to this, the handpiece 80 includes a beam splitter for separating light from the light source unit 81 to the object 200 and light from the object 200 to the optical sensor 85, a lens system, and a A reflector or the like for reflecting light is provided as necessary. However, illustration and detailed description of these configurations in FIG. 2 are omitted.

The light output from the light source unit 81 passes through the variable focus unit 82 and is irradiated onto the object 200 and reflected by the object 200 . Light reflected by the object 200 passes through the variable focus section 82 and is detected by the optical sensor 85 . When obtaining a three-dimensional shape using a focusing technique, light passing through a pattern generation element (not shown) provided between the light source unit 81 and the object 200 is projected onto the object 200 and driven. The optical sensor 85 detects the light from the object 200 while changing the state of the variable focus unit 82 (the focal position of the projection pattern by the variable focus unit 82 ) in the unit 83 . The control unit 40 shown in FIG. 1 calculates the shape information of the object 200 based on the state of the variable focus unit 82 (for example, the position of the lens to be driven) and the detection result of the optical sensor 85 at that position. there is Therefore, the controller 40 functions as a calculator that calculates the shape information of the object 200 from the light detected by the optical sensor 85 . In the three-dimensional scanner 100, the range (for example, 10 mm ~ 20 mm).

Next, a configuration for securing the range in the variable focus section 82 will be described. FIG. 3 is a schematic diagram for explaining the configuration of the variable focus section 82 according to Embodiment 1 of the present invention. FIG. 3A shows, as a comparative example, a configuration in which a single focus lens 82z is moved by a drive unit 83 to change the focal position of the projection pattern, which is adopted in a conventional three-dimensional scanner. The light emitted from the light source unit 81 is bent by the beam splitter 84, passes through the focusing lens 82z and the object side lens 86, and projects a projection pattern on the position of the object (not shown). Although not shown, a pattern generation element for generating a projection pattern is provided between the light source section 81 and the beam splitter 84, or included in the light source section 81 itself. The light reflected by the object reversely passes through the object-side lens 86 and the focusing lens 82z, passes through the beam splitter 84, and is detected by the optical sensor 85. FIG. Here, if the focal length of the focusing lens 82z is f ₁ and the focal length of the object-side lens 86 is f ₂ , the enlarged projection magnification M is approximately M=f ₂ /f ₁ . Therefore, when the length of one side of the optical sensor 85 is H, the length of one side (corresponding to the field of view) of the image of the optical sensor 85 formed at the focal position is M×H. Further, the range F0 in which the focal position of the projection pattern is changed is approximately F0=M ² ×Z, where Z is the movable distance of the focal lens 82z. The drive unit 83 is configured to mechanically move the position of the focus lens 82z using a motor or the like. Note that in FIG. 3 (and subsequent drawings), the lens system that constitutes the three-dimensional scanner 100 is depicted as a substantially telecentric optical system that is composed of two groups of lenses, the variable focus section 82 and the object-side lens 86. However, the form of the lens system is not limited to this. For example, it may be a wide-angle lens. Further, other optical components than those shown in the drawings, such as lenses, diaphragms, polarizing optical elements, and filters, may of course be used in the optical path of the lens system. In addition, the notation "approximately" is used for numerical values such as magnification and focal length of the lens, but this is because various numerical values are approximate calculation results based on the theory of thinness. That is, since the effects of the thickness and aberration of optical components such as various lenses and beam splitters are not taken into consideration, the actual values may differ slightly. Also, if the lens system is not a strictly telecentric optical system, the actual values may differ slightly from the approximate values. In the following description, the notation “generally” may be omitted.

On the other hand, the variable focus section 82 according to the first embodiment includes a combination of a positive lens 82b and a negative lens 82a as shown in FIG. 3(b). A positive lens is a lens whose center is thicker than its edge. As an exception, when a special lens such as a Fresnel lens, a GI (Graded Index) lens, or a diffractive lens is used, there are positive lenses and negative lenses that have the same thickness at the edge and center of the lens. Of course, the above special lens may be employed as the variable focus unit 82 or other lenses included in the three-dimensional scanner 100 . A negative lens is a lens that is thinner at the center of the lens than at the edges of the lens. Here, since the negative lens 82a and the positive lens 82b are close to each other, they can be approximately regarded as one combined lens. When the focal length of the negative lens 82a is f _1a and the focal length of the positive lens 82b is f _1b , the composite focal length f of the variable focus section 82 is 1/{1/f _1a +1/f _1b }, and the focal length is It is set to the same value as the focal length _f1 of 82z. Also, since the combined focal length f of the variable focus section 82 is the same value as the focal length _f1 of the focal lens 82z, that is, a positive value, the focal length _f1b of the positive lens 82b is equal to the focal length _f1 of the focal lens 82z. shorter and the lens power (1/f _1b ) is greater than the lens power (1/f ₁ ) of the focusing lens 82z. Here, the expression "focal length of the variable focus section 82" is an expression intended for optical components such as lenses included in the variable focus section 82, and other parts such as a driving section included in the variable focus section 82 (Members through which light does not pass) are not objects of expression.

In the variable focus section 82 shown in FIG. 3B, the lens having the largest absolute value of the lens power among the plurality of lenses constituting the variable focus section 82 is driven by the driving section 83 along the optical axis direction. . In the variable focus unit 82, the driving unit 83 drives the positive lens 82b on the assumption that the absolute value of the lens power (1/f _1b ) of the positive lens 82b is greater than the absolute value of the lens power (1/f _1a ) of the negative lens 82a. It is driven along the optical axis direction. Here, when the movable distance of the positive lens 82b is set to the same value as the movable distance Z of the focal lens 82z, the lens power (1/f _1b ) of the positive lens 82b is greater than the lens power (1/f ₁ ) of the focal lens 82z. Since it is large, the range F1 for changing the focal position of the projection pattern is longer than the range F0. Conversely, if the range F1 has the same length as the range F0, the movable distance of the positive lens 82b can be made shorter than the movable distance Z of the focusing lens 82z. That is, when comparing FIGS. 3A and 3B, the greater the absolute value of the lens power of the lens to be driven, the more efficiently the focal position can be moved with a smaller movable distance of the lens. This is an advantageous configuration for downsizing. Note that the variable focus section 82 is not provided at the pupil position as shown in FIG. 3(b). For example, if the variable focus unit 82 is provided on the probe side such as the pupil position or the position of the object-side lens 86, the motor, which is the drive unit, must also be installed near the probe, increasing the diameter of the probe itself. . If the diameter of the probe itself becomes large, it becomes difficult to put the probe into the mouth when applied in the dental field, which poses a problem of burden on the patient. On the other hand, when the variable focus section 82 is not provided on the probe side, there is an advantage that the diameter of the probe itself can be reduced and the burden on the patient can be reduced.

The relationship between the movable distance of the lens and the range in which the focal position is changed will be described in more detail. It has been explained that in the optical configuration shown in FIG. 3(a), if the enlarged projection magnification is M, the range for changing the focal position is amplified by ^M2 times. Specifically, when the focal length _f1 of the focusing lens 82z is 50 mm and the focal length _f2 of the object-side lens 86 is 100 mm, the enlarged projection magnification M is doubled. The length of one side of the image (corresponding to the field of view) is 2H, and the range F0 in which the focal position is changed is M ² =4 times as large as the movable distance Z of the lens.

On the other hand, in the optical configuration shown in FIG. 3B, when considering the relationship between the movable distance of the lens and the range in which the focal position is changed, it is divided into two stages of the negative lens 82a and the positive lens 82b. First, consider the negative lens 82a. By placing the negative lens 82a in front of the optical sensor 85, a reduced image of the optical sensor 85 is formed between the optical sensor 85 and the negative lens 82a. For example, when the focal length f _1a of the negative lens 82a is −40 mm and the negative lens 82a is placed 50 mm (=a) in front of the optical sensor 85, the distance from the negative lens 82a toward the optical sensor 85 is 22.2 mm (= A reduced image is formed at the position b). Assuming that the length of one side of the optical sensor 85 is H, the length of one side of the reduced image is H×(b/a)=0.44H.

Next, consider the positive lens 82b. Consider an optical configuration in which a positive lens 82b is placed on a reduced image formed by a negative lens 82a. That is, the reduced image of the optical sensor 85 formed by the negative lens 82a is projected onto the object by a magnification of M1 using the positive lens 82b and the object-side lens 86, so that the image of the optical sensor 85 is focused. Consider a configuration that forms in position. However, it is necessary to determine the enlarged projection magnification M1 of the reduced image so that the length of one side (corresponding to the field of view) of the image of the optical sensor 85 formed at the focal position is the same value as M×H. Basically, the enlarged projection magnification M1 of the reduced image is larger than the enlarged projection magnification M for the optical sensor 85 that is not reduced. As the enlarged projection magnification M1 of the reduced image increases, the range F1 in which the focal position is changed also becomes F1=M1 ² ×Z>F0=M ² ×Z. For example, the enlarged projection magnification M1 for enlarging the length of one side of the reduced image of 0.44H so that the length of one side (corresponding to the field of view) at the focal position is 2H is M1=2H/0.44H=approximately 4.5. When the focal length _f2 of the object-side lens 86 is 100 mm, the focal length _f1b of the positive lens 82b is 22.2 mm in order to set the enlarged projection magnification M1 to about 4.5. If the enlarged projection magnification M1 is about 4.5, the range of changing the focal position is M1 ² =20.25.

In FIG. 3B, the variable focus section 82 includes a combination of a pair of a positive lens 82b and a negative lens 82a, so that the variable focus section 82 is composed only of a focus lens 82z as in FIG. 3A. It has been explained that the range in which the focal position is changed can be lengthened (F1>F0) compared to the case where the focal position is changed. Conversely, setting the movable distance of the positive lens 82b to be shorter than the movable distance Z of the focusing lens 82z by making the range in which the variable focus unit 82 changes the focal position the same will be described in more detail. FIG. 4 is a diagram showing optical simulation results when the variable focus unit according to the first embodiment of the present invention is moved. In the optical configuration shown in FIG. 4, an optical sensor 85 is installed at a position of 0 mm on the horizontal axis in the drawing, and an aperture unit 87 is provided on the left side of the object-side lens 86 in the drawing (pupil position). A lens for adjusting the working distance and aberration of the object-side lens 86 may be installed in the aperture unit 87. The diameter of the lens may be reduced, or the surface of the lens may be masked with a shield such as paint. By doing so, the lens itself can also function as a diaphragm. In FIG. 4 and subsequent optical simulation results, there are cases where a lens is installed in the diaphragm portion 87 . Note that the optical simulation used in FIG. 4 shows approximate calculation results based on the theoretical formula of a thin lens, but other simulation methods (for example, a strict ray tracing method based on Snell's law, etc.) ) will give similar results. Moreover, in FIG. 4, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will not be repeated. Also, the beam splitter 84 and the light source unit 81, which are shown in FIG. 3, are omitted in FIG. FIG. 4(a) shows an optical simulation corresponding to the comparative example shown in FIG. 3(a) as a comparative example. Fig. 3 shows the results of optical simulation with changing; At this time, Z is the movable distance (driving distance) of the focus lens 82z. The movable distance Z is measured by the amount of displacement in the optical axis direction at the center of the focusing lens 82z.

On the other hand, FIG. 4(b) shows an optical simulation corresponding to the embodiment shown in FIG. 3(b). That is, it shows the optical simulation result of changing the focal position of the projection pattern by moving the positive lens 82b by the driving unit 83 in the variable focus unit 82, which is a combination of a pair of the positive lens 82b and the negative lens 82a. . At this time, the movable distance of the positive lens 82b is Z1. The movable distance Z1 is measured by the amount of displacement in the optical axis direction at the center of the positive lens 82b. When the range of changing the focal position in FIG. 4A and the range of changing the focal position in FIG. It is clear from the optical simulation results that it is shorter than Z. In the optical simulation shown in FIG. 4, the focal length _f1 of the focal lens 82z is 50 mm, the focal length _f2 of the object-side lens 86 is 70 mm, the focal length f1a of the negative lens 82a is -200 mm, and the focal length _f1a of the positive lens 82b is -200 mm. The focal length _f1b is set to 40 mm.

As described above, the three-dimensional scanner 100 according to the first embodiment includes the light source unit 81, the optical sensor 85 that detects the light from the light source unit 81 that is reflected by the target object 200, and the light source unit 81 from the target object. A variable focus unit 82 that can change the focal position of the light that reaches the optical sensor 85 via the optical sensor 85 within a predetermined range, and a control unit 40 that calculates the shape information of the object 200 from the light detected by the optical sensor 85. It has The optical sensor 85 constitutes a detector that detects light reflected by the object 200 . The variable focus unit 82 includes a plurality of lenses whose combined lens power value is positive, and a driving unit 83 that drives at least one of the plurality of lenses along the optical axis direction. The plurality of lenses includes at least one pair of positive lens 82b and negative lens 82a. Therefore, the three-dimensional scanner 100 according to the first embodiment can increase the lens power of the movable lens (positive lens 82b) as compared with the conventional configuration in which only the focus lens 82z is movable. As a result, the focal position can be moved efficiently, and the movable range of the lens position can be shortened to reduce the size of the lens. In the three-dimensional scanner 100, by shortening the movable range of the lens position, the size of the motor of the drive unit 83 can be reduced, and the power consumption and heat generation of the motor can be reduced. In addition, by configuring the variable focus section 82 with a plurality of lenses, the number of lens curved surfaces that can be adjusted to reduce aberrations and the number of glass materials that can be selected increase in optical design. There is

In the three-dimensional scanner 100, a single focal lens 82z as shown in FIG. 82a, it becomes possible to set the lens power of the lens to be driven larger than that of the conventional one, realizing highly efficient focus driving. However, the configuration shown in FIG. You can also look at it from another perspective. That is, the positive lens 82b can also be regarded as the focal lens 82z. A reduced image of the optical sensor 85 is formed by adding a negative lens 82a to the configuration shown in FIG. It can be said that the positive lens 82b functions as a focusing lens 82z. That is, as another aspect, the three-dimensional scanner 100 includes a light source unit 81, an optical sensor 85, and a focal point capable of changing the focal position of light from the light source unit 81 to the optical sensor 85 via the object 200. A configuration comprising a lens (positive lens 82b), a driving unit 83 that drives the focusing lens along the optical axis direction, at least one negative lens 82a provided on the same optical axis as the focusing lens, and a control unit 40. can be taken as The combined lens power value of the focus lens and the negative lens 82a is positive, and the movable range of the combined focus position is a predetermined range. A reduced image of the optical sensor 85 is formed by adding the negative lens 82a on the optical axis. This configuration is advantageous for downsizing the three-dimensional scanner 100 .

Further, the driving section 83 may drive the lens (positive lens 82b) having the largest absolute value of lens power among the plurality of lenses forming the variable focus section 82 along the optical axis direction. Specifically, since the absolute value of the lens power (1/f _1b ) of the positive lens 82b is greater than the absolute value of the lens power (1/f _1a ) of the negative lens 82a, the drive unit 83 moves the positive lens 82b. Let For example, when the lens power (1/f _1b ) of the positive lens 82b is 1/(40 mm) and the lens power (1/f _1a ) of the negative lens 82a is 1/(−200 mm), the lens power of the positive lens 82b is the absolute value of becomes larger. By driving the lens having the maximum absolute value of the lens power, the focal position on the object can be efficiently driven.

Furthermore, the plurality of lenses forming the variable focus section 82 may include at least a lens having a larger absolute value of lens power than the combined absolute value of lens power. Specifically, the absolute value of the lens power (1/f _1b ) of the positive lens 82b is the combined lens power of the variable focus unit 82 {(f _1a +f _1b )/(f _1a ·f _1b )}=focusing lens 82z is greater than the absolute value of the lens power (1/f ₁ ). For example, when the lens power (1/f _1b ) of the positive lens 82b is 1/(40 mm) and the lens power (1/f _1a ) of the negative lens 82a is 1/(−200 mm), the combined lens power {( The lens power 1/(40 mm)=5/(200 mm ₎ of the positive lens 82b is larger than f 1a +f 1b )/(f _1a ·f _1b ) _} =4/(200 mm).

3(b) and 4(b), the negative lens 82a and the positive lens 82b are arranged in this order from the optical sensor 85 side. Not limited. That is, the positions of the negative lens 82a and the positive lens 82b may be interchanged. Moreover, although the negative lens 82a has been described as a single lens, it may be a synthetic negative lens. For example, a doublet lens or a triplet lens having a negative combined focal length may be used.

(Embodiment 2)
In the three-dimensional scanner 100 according to Embodiment 1, the configuration in which only the positive lens 82b is movable as shown in FIG. 3B has been described. In the three-dimensional scanner according to the second embodiment, the configuration of the variable focus section that moves the counterweight in accordance with the movement of the lens will be described.

FIG. 5 is a schematic diagram for explaining the configuration of a variable focus unit according to Embodiment 2 of the present invention. 5, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will not be repeated. In FIG. 5A, as a comparative example, a single focus lens 82z is moved by the drive unit 83 to change the focal position of the projection pattern. The drive unit 83 uses a motor to move the focusing lens 82z fixed to the slider 83a on the rail 83b extending in the optical axis direction. The drive unit 83 fixes the counterweight 83d to the slider 83c and moves the counterweight 83d on the rail 83b in the opposite phase to the focusing lens 82z. Since the counterweight 83d is moved in opposite phase with the movement of the focus lens 82z, the vibration generated by the movement of the focus lens 82z is canceled by the vibration generated by the movement of the counterweight 83d and can be reduced. Note that the focusing lens 82z shown in FIG. 5A has a movable distance Z and a range F in which the focal position of the projection pattern is changed.

In the variable focus section 82 shown in FIG. 3B, the counterweight 83d shown in FIG. 5A can be similarly provided corresponding to the movable positive lens 82b. That is, in the configuration shown in FIG. 5A, the focusing lens 82z is replaced with a positive lens 82b, and a negative lens 82a is added. Although the number of parts is increased by adding the counterweight 83d, the vibration caused by the movable positive lens 82b can be reduced.

On the other hand, in FIG. 5B, the variable focus section 82 includes a combination of a positive lens 82b and a negative lens 82a, and the driving section 83 moves the positive lens 82b and the negative lens 82a along the optical axis direction. Drive in opposite directions. The drive unit 83 moves the positive lens 82b fixed to the slider 83a and the negative lens 82a fixed to the slider 83c by a motor on the rail 83b extending in the optical axis direction. Of course, the positive lens 82b and the negative lens 82a are moved in opposite phases. Thereby, the negative lens 82a can function as a counterweight for reducing vibration caused by the movement of the positive lens 82b, and there is no need to add a separate counterweight 83d. That is, the negative lens 82a is used as a counterweight for the positive lens 82b. The weight and amplitude of the negative lens 82a are adjusted so as to function as a counterweight for the positive lens 82b. That is, the weight and drive amplitude of the negative lens 82a are set so as to cancel (counterbalance) the momentum (=amplitude x drive direction x lens weight) of the positive lens 82b, and the momentum of the positive lens 82b and the momentum of the negative lens 82a is 0 (zero). For example, when the weight of the positive lens 82b is greater than the weight of the negative lens 82a, the amplitude on the positive lens 82b side can be adjusted to be smaller than the amplitude on the negative lens 82a side. Of course, a counterweight (not shown) whose weight compensates for the difference between the positive lens 82b and the negative lens 82a may be provided on one of the sliders 83a and 83c in order to add it to the lighter side. In addition, by adjusting not only the weight of the lens but also the weight of other driving members (for example, the weight of the holder member for holding the lens and the weight of the sliders 83a and 83b themselves), the entire movable portion can be adjusted. It may be configured to be counterbalanced.

Furthermore, in the variable focus section 82, the positive lens 82b and the negative lens 82a are driven in opposite directions along the optical axis, so that the movable distance Z2 of each of the positive lens 82b and the negative lens 82a is equal to that of the positive lens 82b. It is shorter than the movable distance Z1 in the case of moving only. As described above, if one of the weight of the positive lens 82b and the weight of the negative lens 82a is greater than the other, e.g. The amplitude on the 82a side may be different. Even in this case, the movable distance Z2b of the positive lens 82b and the movable distance Z2a of the negative lens 82a are the same as the movable distance when only the positive lens 82b is moved. It is preferable to configure it to be shorter than Z1. A specific description will be given based on optical simulation results. FIG. 6 is a diagram showing optical simulation results when the variable focus unit according to the second embodiment of the present invention is moved. 6, the same components as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will not be repeated. In FIG. 6(a), in the variable focus unit 82, which is a combination of a pair of a positive lens 82b and a negative lens 82a, only the positive lens 82b is moved by a driving unit 83 to change the focal position of the projection pattern. 4 shows simulation results. At this time, the movable distance of the positive lens 82b is Z1.

On the other hand, in FIG. 6B, in the variable focus unit 82, which is a combination of a pair of a positive lens 82b and a negative lens 82a, the positive lens 82b and the negative lens 82a are respectively moved by a driving unit 83 to shift the focal position of the projection pattern. , which shows optical simulation results for changing . At this time, the movable distance of each of the positive lens 82b and the negative lens 82a is Z2. When the range of changing the focal position in FIG. 6A and the range of changing the focal position in FIG. It is clear from the optical simulation results that the length is shortened. In the optical simulation shown in FIG. 6, the focal length _f2 of the object-side lens 86 is 70 mm, the focal length _f1a of the negative lens 82a is -200 mm, and the focal length _f1b of the positive lens 82b is 40 mm.

As described above, the variable focus section 82 may further include a counterweight driven in the opposite direction to the lens driven by the driving section 83 (for example, the positive lens 82b). As a result, the variable focus section 82 can reduce vibration caused by the movement of the positive lens 82b. Also, one lens (for example, the negative lens 82a) among the plurality of lenses driven by the drive unit 83 may be used as a counterweight for the other lens (for example, the positive lens 82b). As a result, there is no need to separately provide a counterweight, so the number of components to be configured can be reduced. Further, the drive unit 83 drives the positive lens 82b and the negative lens 82a included in the plurality of lenses in directions opposite to each other along the optical axis direction, thereby driving the focal position on the object more efficiently. As a result, the movable distance Z2 of each of the positive lens 82b and the negative lens 82a can be shortened, thereby producing a synergistic effect that further miniaturization is possible.

(Embodiment 3)
In the three-dimensional scanner 100 according to Embodiment 1, as shown in FIG. 3B, the configuration having the variable focus section 82 in which a pair of the positive lens 82b and the negative lens 82a are combined has been described. In the three-dimensional scanner according to the third embodiment, it will be described that the focal position is changed by the balance of lens power between the positive lens and the negative lens that constitute the variable focus unit.

7A and 7B are diagrams showing optical simulation results when the variable focus unit according to Embodiment 3 of the present invention is moved. 7(a) to 7(c), in any configuration, the combined focal length of a plurality of lenses constituting the variable focus section 82 is 50 mm. 7(a) to 7(c). 7, the same components as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will not be repeated. In FIG. 7(a), in the variable focus unit 82, which is a combination of a pair of a positive lens 82b and a negative lens 82a, only the positive lens 82b is moved by a driving unit 83 to change the focal position of the projection pattern. 4 shows simulation results. At this time, the focal length _f1a of the negative lens 82a is assumed to be -200 mm, and the focal length _f1b of the positive lens 82b is assumed to be 40 mm.

In FIG. 7(b), in the variable focus unit 82, which is a combination of a pair of positive lens 82d and negative lens 82c, only the positive lens 82d is moved by the driving unit 83 to change the focal position of the projection pattern. 4 shows simulation results. At this time, the focal length f _1c of the negative lens 82c is assumed to be −117 mm, and the focal length f _1d of the positive lens 82d is assumed to be 35 mm. In FIG. 7(c), in the variable focus unit 82, which is a combination of a pair of positive lens 82f and negative lens 82e, only the positive lens 82f is moved by the driving unit 83 to change the focal position of the projection pattern. 4 shows simulation results. At this time, the focal length f _1e of the negative lens 82e is -75 mm, and the focal length f _1f of the positive lens 82f is 30 mm.

When the movable distances of the movable positive lenses 82b, 82d, and 82f are all the same Z, the focal position changing range F1 in FIG. 7A, the focal position changing range F2 in FIG. It is clear from the results of the optical simulation that in (c), the length increases in the order of the range F3 in which the focal position is changed. The optical simulation shown in FIG. 7 is performed with the focal length _f2 of the object-side lens 86 set to 70 mm.

As described above, by changing the lens power balance between the positive lens 82b and the negative lens 82a that constitute the variable focus section 82, it is possible to change the range F in which the focal position is changed. This has the advantage of increasing the degree of freedom in design. For example, in general, a lens with a large lens power has large aberration and poor imaging performance, and is difficult to process, resulting in an increase in manufacturing cost. If it is desired to improve the imaging performance and/or to reduce the manufacturing cost and processing burden, the positive lens 82b with a small lens power is used, and the imaging performance is degraded and/or the manufacturing cost and processing cost are reduced. If it is desired to extend the range of change in the focal position or to reduce the movable distance Z by suppressing the range of change in the focal position, a positive lens 82f having a large lens power is used. You can make an appropriate selection, such as In addition, it is possible to manufacture a product using the positive lens 82b, a product using the positive lens 82d, and a product using the positive lens 82f, thereby enhancing the product lineup.

(Embodiment 4)
In the three-dimensional scanner 100 according to Embodiment 1, as shown in FIG. 3B, the configuration having the variable focus section 82 in which a pair of the positive lens 82b and the negative lens 82a are combined has been described. However, when the variable focus section 82 is configured by combining a plurality of lenses, conditions other than the focal length _f1b of the positive lens 82b and the focal length _f1a of the negative lens 82a can be added. In the three-dimensional scanner according to the fourth embodiment, conditions added when a variable focus unit is configured with a plurality of lenses will be described.

In general, the refractive index of the material (optical glass, optical plastic, etc.) that constitutes the lens differs depending on the wavelength of light, so the focal length of the lens is dependent on the wavelength, and chromatic aberration occurs. In particular, when a variable focus unit is configured with a plurality of lenses, the wavelength dependence of the combined focal lengths of the lenses may become even greater due to the wavelength dependence of the different focal lengths of the lenses. Therefore, as a condition for preventing further increase in the wavelength dependence after combination, for example, the Abbe number of the positive lens to be driven is made larger than the Abbe number of the negative lens. The wavelength dependence of the focal length can be reduced by configuring the variable focus section based on the conditions. That is, the wavelength dependence of the focal length can be canceled by the positive lens and the negative lens. The Abbe number is a constant of an optical medium that indicates the ratio of refractive power to dispersion of light, and the smaller the Abbe number, the greater the wavelength dependence of the material.

A description will be given based on a specific example. FIG. 8 is a schematic diagram for explaining the configuration of a variable focus unit according to Embodiment 4 of the present invention. In FIG. 8, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will not be repeated. As shown in FIG. 8, the variable focus section 82 according to the fourth embodiment includes a combination of a positive lens 82h and a negative lens 82g. Then, the positive lens 82h is moved by the drive section. Illustration of the drive unit 83 is omitted. Further, the positive lens 82h is made of crown glass with a large Abbe number, and the negative lens 82g is made of flint glass with a small Abbe number. Therefore, the variable focus section 82 is configured to reduce the wavelength dependency of the composite focal length by combining a positive lens 82h with a high Abbe number and a negative lens 82g with a low Abbe number.

As described above, in the variable focus unit 82 according to the fourth embodiment, the lens to be driven is the positive lens 82h, and the Abbe number is larger than the Abbe number of the negative lens 82g included in the plurality of lenses. , the wavelength dependence of the composite focal length of the variable focus section 82 can be reduced.

Further, when the variable focus section 82 is composed of a plurality of lenses, the optical characteristic value of each lens included in the plurality of lenses may be determined so that the achromaticity condition is satisfied for the plurality of lenses as a whole. Note that the achromatic condition is, for example, a condition that the total value obtained by adding the values of lens power/Abbe number for all the lenses constituting the variable focus section 82 is approximately 0 (zero).

Furthermore, when the variable focus section 82 is composed of a plurality of lenses, the material optical characteristic value (thermal Abbe number, etc.) may be determined. For example, by designing the lens power/thermal Abbe number values under the condition that the total value obtained by summing all the lenses constituting the variable focus section 82 is approximately 0 (zero), the temperature dependency of the lens material can be reduced. The temperature dependence of the focus variable part 82 due to the nature is reduced. In addition to the temperature dependence of the lens material, the optical characteristic value (thermal Abbe number, etc.) may be determined. Since the variable focus section 82 includes at least both a positive lens and a negative lens, the degree of freedom in design for adjusting various characteristics such as chromatic aberration and temperature dependence is improved.

(Modification 1)
It has been explained that the variable focus section 82 according to Embodiments 1 to 4 of the present invention is configured by a combination of a pair of positive and negative lenses. However, the variable focus section includes a combination of a pair of positive and negative lenses, and if the sum of the lens powers is positive, even if it is a combination of three or more lenses, good. Concretely, a variable focus unit in which three lenses are combined will be described. FIG. 9 is a diagram for explaining the combination of lenses in the variable focus section. The variable focus unit shown in FIG. 9 is composed of three lenses, one negative lens 82i and two positive lenses 82j and 82k. First, in FIG. 9, the case in which the negative lens 82i is stationary and the case in which the negative lens 82i is movable are separately described. Further, in FIG. 9, driving is performed by either right driving (represented by a white arrow) that starts moving the lens from the right in the figure, or left driving (represented by a black arrow) that starts moving the lens from the left in the figure. is shown. Here, the right driving and the left driving are driving of opposite phases. In FIG. 9, the description is divided into the case where the positive lens is not driven to the left and the case where the positive lens is driven to the left.

For example, the configuration in the upper left column of FIG. 9 illustrates the configuration of the variable focus unit 82 in which the negative lens 82i is stationary and the positive lenses 82j and 82k are both driven to the right. On the other hand, the configuration in the upper right column of FIG. 9 shows the configuration of the variable focus unit 82 that keeps the negative lens 82i stationary, drives the positive lens 82j leftward, and drives the positive lens 82k rightward. The configuration in the lower left column of FIG. 9 shows the configuration of the variable focus section 82 that drives the negative lens 82i to the left and stops both the positive lenses 82j and 82k. Further, the configuration in the lower right column of FIG. 9 shows the configuration of the variable focus section 82 that drives the negative lens 82i leftward, the positive lens 82j stationary, and drives the positive lens 82k leftward.

In the pattern shown in FIG. 9, in any case, the absolute value of the sum of "{(lens power)×(sign of driving direction)} for all negative lenses 82i and positive lenses 82j and 82k is the lens It is possible to configure the variable focus section 82 so as to satisfy the condition that the power is greater than the sum of all the negative lenses 82i and the positive lenses 82j and 82k. By configuring so as to satisfy the above conditions, compared to a configuration in which only a single focus lens 82z equivalent to a combination of the variable focus section 82 (negative lens 82i and positive lenses 82j and 82k) is driven, efficiency is improved. The focus position can be driven on the object, and advantages such as miniaturization can be obtained. The above condition qualitatively means that "it is better to drive the negative lens and the positive lens in opposite phases as much as possible, and it is better to drive the positive lenses in the same phase as much as possible". "Conversely, even if the negative and positive lenses are driven in phase, or the positive lenses are driven in opposite phase, if the power of one lens is sufficiently small, there is no disadvantage. ” means. Of course, the above condition can also be applied when the variable focus section 82 is composed of four or more lenses.

(Modification 2)
In the three-dimensional scanner 100 according to Embodiments 1 to 4 of the present invention, the light emitted from the light source section 81 is bent by the beam splitter 84 as shown in FIG. A projection pattern is projected onto an object (not shown) through an object-side lens 86 . Furthermore, the light reflected by the object reversely passes through the object-side lens 86 and the variable focus section 82 , passes through the beam splitter 84 , and is detected by the optical sensor 85 . That is, in the three-dimensional scanner 100 according to Embodiments 1 to 4 of the present invention, the configuration has been described in which the light from the light source unit 81 passes through the variable focus unit 82 twice through the object 200 to reach the optical sensor 85 . However, it is not limited to this configuration, and even if the light from the light source unit 81 passes through the object 200 and reaches the optical sensor 85, it may pass through the variable focus unit 82 three times or more. good too.

Specifically, FIG. 10 is a diagram for explaining the optical path passing through the variable focus section. In FIG. 10A , light emitted from the light source section 81 passes through the variable focus section 82 and projects a pattern onto the object 200 . However, the light reflected by the object 200 is directly detected by the optical sensor 85 without passing through the variable focus section 82 . In other words, the configuration shown in FIG. 10A is a configuration in which the light from the light source unit 81 passes through the object 200 and reaches the optical sensor 85 once through the variable focus unit 82 .

In FIG. 10B, light emitted from the light source unit 81 passes through the variable focus unit 82 and projects a projection pattern onto the object 200, as in the first embodiment. Furthermore, the light reflected by the object 200 passes through the variable focus section 82 and is detected by the optical sensor 85 . That is, the configuration shown in FIG. 10B is a configuration in which the light from the light source unit 81 passes through the object 200 and reaches the optical sensor 85 twice through the variable focus unit 82 .

In FIG. 10C , the light emitted from the light source section 81 directly projects the projection pattern onto the object 200 without passing through the variable focus section 82 . On the other hand, the light reflected by the object 200 passes through the variable focus section 82 and is detected by the optical sensor 85 . That is, the configuration shown in FIG. 10C is a configuration in which the light from the light source unit 81 passes through the object 200 and reaches the optical sensor 85 once through the variable focus unit 82 . As described above, the light emitted from the light source unit 81 (hereinafter referred to as the projection optical path) and the light reflected from the object 200 (hereinafter referred to as the imaging optical path) pass through the variable focus unit 82. 10(b) is the best when the focusing method is used as the principle of measurement. In the focusing method, the image of the pattern projected on the surface of the object 200 is captured and analyzed a plurality of times while changing the focus position, and the most focused image is obtained from the image group. to obtain the three-dimensional shape of At that time, the state in which the pattern is most clearly visible on the image is determined to be "in focus". In the configuration shown in FIG. 10B, the focal position can be changed in synchronization with both the projection optical path and the imaging optical path. That is, when both the projection optical path and the imaging optical path are in focus, a clear pattern image is obtained; otherwise, both the projection optical path and the imaging optical path are simultaneously defocused. In other words, since the out-of-focus effect works twice, such as "capturing an out-of-focus projected pattern with an out-of-focus lens", the clarity of the pattern sharply drops. In other words, it becomes easy to identify the image showing the maximum degree of pattern clarity (=degree of focus). On the other hand, in the configurations of FIGS. 10(a) and 10(c), the focal position is variable only in one of the projection optical path and the imaging optical path. Since it shows the clarity of a large pattern, it is somewhat difficult to identify the image that shows the maximum value of pattern clarity. That is, the accuracy of three-dimensional measurement is lowered as compared with the configuration of FIG. 10(b). In addition to the problem of detection of the pattern clarity described above, in the configurations of FIGS. In order to obtain pan-focus, it is necessary to adopt a lens that uses a diaphragm (a light amount is reduced), so there is a risk that the light amount will decrease. However, when the light source unit 81 capable of securing a sufficient amount of light, the optical sensor 85 with little noise, or the like is adopted, or when the object 200 exhibits good reflection characteristics, the Three-dimensional measurement is sufficiently possible even with this configuration.

(Modification 3)
Although light source unit 81 according to Embodiments 1 to 4 of the present invention has been described as a single light source (for example, LED, laser element, etc.), it is not limited to this configuration. The light source unit 81 may be configured by gathering a plurality of light sources. That is, the light source section 81 may be configured by arranging a plurality of LEDs or laser elements on a substrate. The three-dimensional scanner 100 may employ a configuration in which the light from the light source unit 81 and the reflected light from the object 200 are guided to the optical sensor 85 and the object 200 using a light guide such as an optical fiber. .

(Modification 4)
In addition, the objects to be imaged by the three-dimensional scanners according to the first to fourth embodiments of the present invention are not limited to teeth and gums in the oral cavity. The present invention is widely applicable to the use of measuring/observing the inside of narrow spaces where blind spots are likely to occur.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

Reference Signs List 10 probe, 20 connection unit, 30 optical measurement unit, 40 control unit, 50 display unit, 60 power supply unit, 80 handpiece, 81 light source unit, 82 variable focus unit, 82a negative lens, 82b positive lens, 83 driving unit, 83d Counterweight, 84 beam splitter, 85 optical sensor, 86 object-side lens, 87 diaphragm, 100 three-dimensional scanner, 200 object.

Claims (8)

A three-dimensional scanner that acquires shape information of an intraoral object,
a light source;
a detection unit that detects light from the light source unit reflected by the object;
a probe inserted into the oral cavity to guide light from the light source unit to the object and to guide reflected light from the object to the detection unit;
a variable focus unit provided on a side closer to the light source unit than the probe and capable of changing a focal position of light from the light source unit through the object to the detection unit within a predetermined range;
a calculation unit that calculates shape information of the object from the light detected by the detection unit;
an object-side lens that is a positive lens between the focal position and the variable focus section and on the focal position side of the pupil position;
a beam splitter that separates an optical path from the light source unit and an optical path to the detection unit between the variable focus unit and the light source unit and the detection unit;
The object-side lens is provided in a connection portion that is a part of the optical measurement unit that can be fitted with the probe, and the light source unit, the detection unit, the variable focus unit, and the beam splitter are provided in portions other than the connection unit. Provided in the optical measurement unit,
The probe, the connection section, and the optical measurement section constitute a handpiece,
The variable focus section
a plurality of lenses whose combined lens power value is positive;
a driving unit that drives at least one of the plurality of lenses along the optical axis direction;
The three-dimensional scanner, wherein the plurality of lenses includes at least one pair of positive and negative lenses. 2. The three-dimensional scanner according to claim 1, wherein said drive unit drives a lens having the largest absolute value of lens power among said plurality of lenses along the optical axis direction. 3. The three-dimensional scanner according to claim 1, wherein said driving section drives said positive lens and said negative lens included in said plurality of lenses in directions opposite to each other along an optical axis direction. The plurality of lenses are
4. The three-dimensional scanner according to any one of claims 1 to 3, comprising at least a lens having a larger absolute value of lens power than the combined absolute value of lens power. The focus variable part is
3. The three-dimensional scanner according to claim 1, further comprising a counterweight driven in a direction opposite to the lens driven by said driving unit . 1, 2 , or 3, wherein a lens among the plurality of lenses that is driven by the driving unit is the positive lens, and has an Abbe number greater than that of the negative lens included in the plurality of lenses. 6. A three-dimensional scanner according to any one of claims 5. The three-dimensional according to any one of claims 1 to 6, wherein the optical characteristic values of the lenses included in the plurality of lenses are determined so that the plurality of lenses as a whole satisfy an achromatic condition. scanner. A three-dimensional scanner that acquires shape information of an intraoral object,
a light source;
a detection unit that detects light from the light source unit reflected by the object;
a probe inserted into the oral cavity to guide light from the light source unit to the object and to guide reflected light from the object to the detection unit;
a focal lens provided closer to the light source unit than the probe and capable of changing a focal position of light from the light source unit to the detection unit through the object;
a driving unit that drives the focus lens along the optical axis;
at least one negative lens provided on the same optical axis as the focusing lens;
a calculation unit that calculates shape information of the object from the light reflected by the object detected by the detection unit;
an object-side lens that is a positive lens between the focal position and the focal lens and on the focal position side of the pupil position;
a beam splitter that separates an optical path from the light source unit and an optical path to the detection unit between the focusing lens and the light source unit and the detection unit;
The object-side lens is provided in a connection section that is a part of an optical measurement section that can be fitted with the probe, and includes the light source section, the detection section, the focus lens, the drive section, the negative lens, and the beam splitter. is provided in the optical measurement unit other than the connection unit,
The probe, the connection section, and the optical measurement section constitute a handpiece,
A three-dimensional scanner, wherein a combined lens power value of the focus lens and the negative lens is positive, and a movable range of the focus position on the object is a predetermined range.

Images