JP6766000B2 - 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 (oral scanner) for acquiring a three-dimensional shape of a tooth has been developed in order to digitally design a prosthesis or the like on a computer (Patent Document 1). The three-dimensional scanner disclosed in Patent Document 1 is a hand-held scanner that acquires a three-dimensional shape of an object by using the principle of the focusing method. Specifically, the three-dimensional scanner projects light having a linear or checkered pattern (hereinafter, also referred to as a pattern) on the surface of an object, and captures the pattern multiple times while changing the focal position. The most focused distance is obtained from the image, and the three-dimensional shape of the object is acquired.

That is, the three-dimensional scanner needs a focus variable unit for changing the focus of the pattern projected on the object at high speed. Since 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 unit within a predetermined range in the focus variable portion, the position of the lens is mechanically moved.

Japanese Patent No. 5654583

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

Further, the variable focus portion 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. A 3D scanner with a built-in large motor has the problem of restricting miniaturization because it is necessary to secure space for the motor itself, and the sound and vibration emitted from the large motor become louder, as well as power consumption and power consumption. There was a problem that the calorific value increased.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a configuration capable of miniaturization in a three-dimensional scanner having a built-in variable focus portion that mechanically moves the position of a lens. And.

The three-dimensional scanner according to the present invention is a three-dimensional scanner that acquires shape information of an object, and is a light source unit, a detection unit that detects light from a light source unit reflected by the object, and an object from the light source unit. It is equipped with a variable focus unit that can change the focal position of light that reaches the detection unit via an object within a predetermined range, and a calculation unit that calculates shape information of the object from the light detected by the detection unit. The unit includes a plurality of lenses having a positive combined lens power value and a drive unit that drives at least one of the plurality of lenses along the optical axis direction, and the plurality of lenses includes at least one set. This includes a combination of a positive lens and a negative lens, and one of the plurality of lenses driven by the drive unit is used as the counter weight of the other lens .

In the three-dimensional scanner according to the present invention, the variable focus portion includes a plurality of lenses, and the plurality of lenses include a combination of at least one set of positive and negative lenses, so that the lens power of the movable lens can be determined. Since the focal variable part can be set larger than when it is configured with a single focal lens, the focal position on the object can be moved efficiently, and the movable range of the lens position is shortened. It can be miniaturized. Further, according to another aspect, the three-dimensional scanner according to the present invention can form a reduced image of the detection unit by arranging a negative lens on the optical axis, and can adjust the magnifying projection magnification of the focal lens. The focal position on the object can be moved efficiently, and the movable range of the position of the focal lens can be shortened to reduce the size.

It is a block diagram which shows the structure of the 3D scanner which concerns on Embodiment 1 of this invention. It is the schematic for demonstrating the structure of the optical system in the handpiece which concerns on Embodiment 1 of this invention. It is the schematic for demonstrating the structure of the focal variable part which concerns on Embodiment 1 of this invention. It is a figure which shows the optical simulation result at the time of moving the focal variable part which concerns on Embodiment 1 of this invention. It is the schematic for demonstrating the structure of the focal variable part which concerns on Embodiment 2 of this invention. It is a figure which shows the optical simulation result at the time of moving the focal variable part which concerns on Embodiment 2 of this invention. It is a figure which shows the optical simulation result at the time of moving the focal variable part which concerns on Embodiment 3 of this invention. It is the schematic for demonstrating the structure of the focal variable part which concerns on Embodiment 4 of this invention. It is a figure for demonstrating the combination of the lens of the focal variable part. It is a figure for demonstrating the optical path passing through a varifocal part.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
(Embodiment 1)
The three-dimensional scanner according to the first embodiment of the present invention is a three-dimensional scanner (oral scanner) for acquiring the three-dimensional shape of teeth in the oral cavity. However, the three-dimensional scanner according to the present invention is not limited to the intraoral scanner, and can be applied to other three-dimensional scanners having a similar configuration. For example, it can be applied to a three-dimensional scanner capable of capturing the inside of a human ear other than the oral cavity and acquiring the three-dimensional shape in the outer ear.

[3D scanner configuration]
FIG. 1 is a block diagram showing a configuration of a three-dimensional scanner 100 according to a first embodiment of the present invention. The three-dimensional scanner 100 shown in FIG. 1 includes a probe 10, a connection unit 20, an optical measurement unit 30, a control unit 40, a display unit 50, and a power supply unit 60. The probe 10 is inserted into the oral cavity, projects light having a pattern on the tooth which is the object 200 (hereinafter, also referred to as a pattern), and reflects the light reflected from the object 200 on which the pattern is projected to be the optical measurement unit 30. Is leading to. Further, since the probe 10 is removable 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, high temperature and high humidity). It is possible to perform processing in the environment). When the entire device of the three-dimensional scanner is sterilized, there is a drawback that the life of the device is shortened because many optical parts and electronic parts are included, but when only the probe 10 is removed and sterilized, the defect does not occur. The connection portion 20 is a part of the optical measurement unit 30, has a shape that can be fitted with the probe 10, and is a portion that protrudes from the optical measurement unit 30. Even if the connection unit 20 has a lens system for guiding the light collected by the probe 10 to the optical measurement unit 30, an optical component such as a cover glass, an optical filter, and a retardation plate (1/4 wave plate). Good.

The optical measurement unit 30 projects a pattern on the object 200 via the probe 10 and images 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 projected on the object 200, a lens component for forming a pattern on the surface of the object 200, and a focal point. It has a variable focus unit that can change its position and an optical sensor (CCD image sensor, CMOS image sensor, etc.) that captures the projected pattern. The optical measurement unit 30 will be described below as a configuration for acquiring a three-dimensional shape using the principle of the focusing method, but the optical measurement unit 30 may be configured to acquire the three-dimensional shape using a principle such as the confocal method. That is, the optical measurement unit 30 includes a configuration in which the projection pattern and the focal position of the optical sensor are changed by the focal variable unit, and any principle can be used as long as the configuration is such that the three-dimensional shape is acquired by using an optical method. It is possible to apply even the existing configuration. The probe 10, the connecting unit 20, and the optical measuring unit 30 form 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 acquire 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 operating the CPU, and a RAM (Random Access) that functions as a work area of the CPU. Memory), input / output interfaces for maintaining signal consistency with peripheral devices, etc. are provided. Further, 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 with an input device (not shown) or the like. In addition, at least a part of the calculation for processing the captured image to acquire the three-dimensional shape may be realized as software by the CPU of the control unit 40, or as hardware that performs processing separately from the CPU. It may be realized. Further, at least a part of the processing units such as the CPU and hardware may be incorporated inside the optical measurement unit 30. Further, in FIG. 1, each component (30, 40, 50, 60) of the three-dimensional scanner 100 is drawn as if it is wired by a cable (thick line in the figure), but a part of these wires is drawn. Alternatively, all may be connected by wireless communication. Further, if the control unit 40 is sufficiently small and lightweight enough to be lifted by one hand, the control unit 40 and the optical measurement unit 30 may be integrated and configured as one 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 state, instruction manual, help screen, and the like. .. As an example of the display unit 50, for example, a stationary liquid crystal display, a head-mounted display, a wearable display of glasses, or the like can be applied. Further, there may be a plurality of display units 50, and the measurement results of the three-dimensional shape and other information may be configured to be simultaneously displayed or dividedly displayed 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. As shown in FIG. 1, the power supply unit 60 may be provided outside the control unit 40 or 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 in the handpiece]
Next, the configuration of the optical system in the handpiece will be described in more detail. FIG. 2 is a schematic view for explaining the configuration of the optical system in the handpiece 80 according to the first embodiment of the present invention. First, the handpiece 80 is provided with a light source unit 81, a focus variable unit 82, a drive unit 83, and an optical sensor 85. In addition to this, the handpiece 80 is directed toward the beam splitter, the lens system, and the object 200 that separate the light from the light source unit 81 to the object 200 and the light from the object 200 to the optical sensor 85. A reflector that reflects light is provided as needed. However, with respect to these configurations, the illustration and detailed description in FIG. 2 are omitted.

The light output from the light source unit 81 is applied to the object 200 through the focus variable unit 82 and reflected by the object 200. The light reflected by the object 200 passes through the focus variable portion 82 and is detected by the optical sensor 85. When acquiring a three-dimensional shape using the focusing method, light that has passed through a pattern generating 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 focus variable unit 82 (for example, the position of the driving lens) and the detection result of the optical sensor 85 at that position. There is. Therefore, the control unit 40 functions as a calculation unit 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 drive unit 83 has a predetermined range for changing the focal position of the projection pattern by the focus variable unit 82, which is a range (for example, 10 mm) required to acquire the shape of the tooth which is the object 200. ~ 20 mm) is secured.

Next, the configuration for securing the range in the focus variable unit 82 will be described. FIG. 3 is a schematic view for explaining the configuration of the focus variable portion 82 according to the first embodiment of the present invention. FIG. 3A shows a configuration in which a single focal lens 82z is moved by the drive unit 83 to change the focal position of the projection pattern, as used in a conventional three-dimensional scanner as a comparative example. The light emitted from the light source unit 81 is bent by the beam splitter 84, passes through the focal lens 82z and the object-side lens 86, and projects a projection pattern at the position of an object (not shown). Although not shown, a pattern generating element for generating a projection pattern is provided, for example, between the light source unit 81 and the beam splitter 84, or is included in the light source unit 81 itself. On the contrary, the light reflected by the object passes through the object-side lens 86 and the focal lens 82z, and is further detected by the optical sensor 85 through the beam splitter 84. Here, when the focal length of the focal length lens 82z is f ₁ and the focal length of the object-side lens 86 is f ₂ , the magnifying 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 for changing the focal position of the projection pattern is approximately F0 = M ² × Z, where Z is the movable distance of the focal lens 82z. The drive unit 83 has a configuration in which the position of the focus lens 82z is mechanically moved by a motor or the like. In FIG. 3 (and subsequent drawings), the lens system constituting the three-dimensional scanner 100 is depicted as a substantially telecentric optical system composed of two groups of lenses, a focal variable portion 82 and an 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, it is of course possible that another lens other than the one shown in the drawing and other optical components such as a diaphragm, a polarizing optical element, and a filter are used in the optical path of the lens system. In addition, the notation "generally" is used for numerical values such as lens magnification and focal length, because various numerical values are approximate calculation results based on the thin-wall theory. That is, since the influence of the thickness and aberration of optical components such as various lenses and beam splitters is not taken into consideration, the actual values may differ slightly. Further, even when the lens system is not a strict telecentric optical system, the actual value may be slightly different from the approximate value. In the following description, the notation "generally" may be omitted.

On the other hand, the variable focus unit 82 according to the first embodiment includes a combination of a set of a positive lens 82b and a negative lens 82a as shown in FIG. 3B. A positive lens is a lens whose center is thicker than the edge of the lens. 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 in which the thickness is the same at the edge and center of the lens. Of course, the special lens may be adopted as the focal variable unit 82 or another lens included in the three-dimensional scanner 100. A negative lens is a lens in which the center of the lens is thinner than the edge 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 composite 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 combined focal length f of the variable focal length portion 82 is 1 / {1 / f _1a + 1 / f _1b }, which is the focal length lens. It is combined to the same value as the focal length _{f 1} of the 82z. Further, since the combined focal length f of the focal variable portion 82 is the same value as the focal length f ₁ of the focal lens 82z, that is, a positive value, the focal length f _{1b of the} positive lens 82b is the focal length f _{1 of the} focal lens 82z. It becomes shorter and the lens power (1 / f _1b ) becomes larger than the lens power (1 / f ₁ ) of the focal length lens 82z. Here, the expression "focal length of the variable focus unit 82" is an expression for an optical component such as a lens included in the variable focus unit 82, and other parts such as a drive unit included in the variable focus unit 82. (Members through which light does not pass) are not objects of expression.

In the focus variable unit 82 shown in FIG. 3B, the drive unit 83 drives the lens having the maximum absolute value of the lens power among the plurality of lenses constituting the focus variable unit 82 along the optical axis direction. .. The variable focus unit 82, the absolute value of the lens power of the positive lens 82b (1 _{/ f 1b)} is, as an absolute value greater than the lens power of the negative lens 82a (1 _{/ f 1a),} a positive lens 82b by the driving unit 83 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 higher than the lens power (1 / f ₁ ) of the focal lens 82z. Since it is large, the range F1 that changes the focal position of the projection pattern is longer than the range F0. On the contrary, 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 focal lens 82z. That is, comparing FIGS. 3 (a) and 3 (b), the larger the absolute value of the lens power of the driving lens, the more efficiently the focal position can be moved with a smaller moving distance of the lens, and the three-dimensional scanner 100 It is an advantageous configuration for miniaturization of. The variable focus unit 82 is not provided at the pupil position as shown in FIG. 3 (b). For example, when the focus variable portion 82 is provided on the probe side such as the position of the pupil or the position of the lens 86 on the object side, the motor as the driving unit must also be installed near the probe, and the aperture of the probe itself becomes large. .. If the diameter of the probe itself becomes large, it becomes difficult to put the probe in the mouth when applied in the dental field, and there is a problem that the burden on the patient is placed. On the other hand, when the variable focus portion 82 is not provided on the probe side, there is an advantage that the aperture 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. In the optical configuration shown in FIG. 3 (a), a range of changing the focal position when the enlargement projection magnification and M has been described to be amplified to ^twice M. Specifically, when the focal length f ₁ of the focal lens 82z is 50 mm and the focal length f ₂ of the object-side lens 86 is 100 mm, the magnifying projection magnification M is doubled, so that the optical sensor 85 formed at the focal position is formed. the length of the image of one side (corresponding to the visual field) range F0 to change the 2H next, the focal position is M ^{2 =} 4 times that of 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, the negative lens 82a and the positive lens 82b are considered in two stages. 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 negative lens 82a is 22.2 mm (=) toward the optical sensor 85 side. A reduced image is formed at the position b). When 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 this as an optical configuration in which the positive lens 82b is placed on the reduced image formed by the negative lens 82a. That is, the image of the optical sensor 85 is focused by projecting the reduced image of the optical sensor 85 formed by the negative lens 82a on the object at a magnification of M1 using the positive lens 82b and the object-side lens 86. Consider the configuration to be formed at the position. However, it is necessary to determine the magnified 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 has the same value as M × H. Basically, the magnified projection magnification M1 of the reduced image is a value larger than the magnified projection magnification M with respect to the unreduced optical sensor 85. As the magnified projection magnification M1 of the reduced image increases, the range F1 for changing the focal position also becomes F1 = M1 ² × Z> F0 = M ² × Z. For example, the magnifying projection magnification M1 for enlarging the length of one side of the reduced image to 0.44H so that the length of one side at the focal position (corresponding to the field of view) is 2H is M1 = 2H / 0.44H = about. It becomes 4.5. When the focal length f ₂ of the object-side lens 86 is 100 mm, the focal length f _1b of the positive lens 82b is 22.2 mm in order to set the magnifying projection magnification M1 to about 4.5. If the magnified projection magnification M1 is about 4.5, the range in which the focal position is changed is M1 ² = 20.25 times.

In FIG. 3B, the variable focus unit 82 includes a pair of a positive lens 82b and a negative lens 82a, so that the variable focal length portion 82 is composed of only the focal lens 82z as shown in FIG. 3A. It was explained that the range in which the focal position can be changed can be lengthened (F1> F0) as compared with the case of. On the contrary, it will be described in more detail that the movable distance of the positive lens 82b is made shorter than the movable distance Z of the focal lens 82z by making the range in which the focal variable portion 82 changes the focal position the same. FIG. 4 is a diagram showing an optical simulation result when the focus variable portion according to the first embodiment of the present invention is moved. In the optical configuration shown in FIG. 4, the optical sensor 85 is installed at a position where the coordinates on the horizontal axis in the figure are 0 mm, and the aperture portion 87 is provided on the left side (pupil position) in the figure of the object-side lens 86. A lens for adjusting the working distance and aberration of the object-side lens 86 may be installed in the aperture portion 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 function as an aperture. In FIG. 4 and the subsequent optical simulation results, a lens may be installed in the aperture portion 87. The optical simulation used in FIG. 4 shows an approximate calculation result based on the theoretical formula of the thin-walled lens, but another simulation method (for example, a strict ray tracing method based on Snell's law) is shown. It goes without saying that a similar result can be obtained by). Further, in FIG. 4, for the same configuration as that shown in FIG. 3, the same reference numerals are given and detailed description will not be repeated. Further, the beam splitter 84 and the light source unit 81 shown in FIG. 3 are omitted in FIG. FIG. 4A shows an optical simulation corresponding to the comparative example shown in FIG. 3A as a comparative example, in which a single focal lens 82z is moved by the drive unit 83 to determine the focal position of the projection pattern. The changing optical simulation results are shown. At this time, the movable distance (driven distance) of the focal lens 82z is Z. The movable distance Z is measured by the amount of displacement in the optical axis direction at the center of the focal lens 82z.

On the other hand, FIG. 4B shows an optical simulation corresponding to the embodiment shown in FIG. 3B. That is, in the focus variable unit 82 in which a set of positive lens 82b and negative lens 82a are combined, the optical simulation result in which the positive lens 82b is moved by the drive unit 83 to change the focal position of the projection pattern is shown. .. 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 for changing the focal position in FIG. 4 (a) and the range for changing the focal position in FIG. 4 (b) are the same F, the movable distance Z1 of the focal lens 82z is the movable distance of the focal lens 82z. 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 f ₁ of the focal length lens 82z is 50 mm, the focal length f ₂ of the object-side lens 86 is 70 mm, the focal length f _1a of the negative lens 82a is −200 mm, and the positive lens 82b. The focal length f _{1b is set} to 40 mm.

As described above, in the three-dimensional scanner 100 according to the first embodiment, the light source unit 81, the optical sensor 85 that detects the light from the light source unit 81 reflected by the object 200, and the object from the light source unit 81. A focus variable unit 82 capable of changing the focal position of light reaching the optical sensor 85 via 200 in a predetermined range, and a control unit 40 for calculating shape information of the object 200 from the light detected by the optical sensor 85. It has. The optical sensor 85 constitutes a detection unit that detects the light reflected by the object 200. The focus variable unit 82 includes a plurality of lenses having a positive combined lens power value, and a drive unit 83 that drives at least one of the plurality of lenses along the optical axis direction. The plurality of lenses include a combination of at least one set of positive lenses 82b and negative lenses 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 case where only the focal lens 82z is movable as in the conventional configuration. Therefore, the focal position can be moved efficiently, and the movable range of the lens position can be shortened to reduce the size. In the three-dimensional scanner 100, by shortening the movable range of the lens position, the motor of the drive unit 83 can also be miniaturized, and the power consumption and heat generation amount of the motor can be suppressed to be small. Further, by configuring the focal variable portion 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, so that the degree of freedom in design is increased. There is.

In the three-dimensional scanner 100, a single focal lens 82z as shown in FIG. 3A is combined with a pair of positive lenses 82b and negative lenses having equivalent lens powers as shown in FIG. 3B. It was explained that by replacing with 82a, the lens power of the driving lens can be set higher than before, and highly efficient focus drive is realized. However, the configuration shown in FIG. 3 (b) is It can be seen from a different perspective. That is, the positive lens 82b can be regarded as the focal lens 82z. By adding the negative lens 82a to the configuration shown in FIG. 3A, a reduced image of the optical sensor 85 is formed, and a real small optical sensor is placed at the position of the reduced image as if it were not a reduced image. Considering that, it can be said that the positive lens 82b functions as the focal lens 82z. That is, as another aspect, the three-dimensional scanner 100 has a focus capable of changing the focal position of the light from the light source unit 81, the optical sensor 85, and the light source unit 81 through the object 200 to the optical sensor 85. A configuration including a lens (positive lens 82b), a drive unit 83 for driving the focus lens along the optical axis direction, at least one negative lens 82a provided on the same optical axis as the focus lens, and a control unit 40. Can be regarded as. The value of the lens power obtained by combining the focal lens and the negative lens 82a is positive, and the movable range of the combined focal position is within a predetermined range. By adding the negative lens 82a on the optical axis, a reduced image of the optical sensor 85 is formed, and it becomes possible to adjust the magnifying projection magnification M1 which is one of the parameters that determine the driving efficiency of the focal position. This configuration is advantageous for miniaturization of the three-dimensional scanner 100.

Further, the drive unit 83 may drive the lens (positive lens 82b) having the maximum absolute value of the lens power among the plurality of lenses constituting the focus variable unit 82 along the optical axis direction. Specifically, the drive unit 83, the absolute value of the lens power of the positive lens 82b (1 _{/ f 1b)} is larger than the absolute value of the lens power of the negative lens 82a (1 _{/ f 1a),} a movable positive lens 82b Let me. 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 The absolute value of is large. By driving the lens having the maximum absolute value of the lens power, the focal position on the object can be efficiently driven, which is advantageous for miniaturization of the three-dimensional scanner 100.

Further, the plurality of lenses constituting the focal variable unit 82 may include at least a lens having an absolute value of lens power larger than the absolute value of the combined 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 focal variable portion 82 {(f _1a + f _1b ) / (f _1a · f _1b )} = focal lens 82z. It is larger than the absolute value of the lens power (1 / f ₁ ) of. 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 that of f _1a + f _1b ) / (f _1a · f _1b )} = 4 / (200 mm).

In the focus variable portion 82 described with reference to FIGS. 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, but the order of arranging the lenses is this. Not limited. That is, the positions of the negative lens 82a and the positive lens 82b may be exchanged. Further, although the negative lens 82a has been described as a single lens, a synthetic negative lens may also be used. For example, it may be a doublet lens or a triplet lens having a negative composite focal length.

(Embodiment 2)
In the three-dimensional scanner 100 according to the first embodiment, a 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 focus variable portion in which the counterweight is moved according to the movement of the lens will be described.

FIG. 5 is a schematic view for explaining the configuration of the focus variable portion according to the second embodiment of the present invention. Note that, in FIG. 5, for the same configuration as that shown in FIG. 3, the same reference numerals are given and detailed description 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 moves the focus lens 82z fixed to the slider 83a on the rail 83b extending in the optical axis direction by a motor. The drive unit 83 fixes the counterweight 83d to the slider 83c, and moves the counterweight 83d on the rail 83b in a phase opposite to that of the focus lens 82z. Since the counterweight 83d moves in the opposite phase in accordance with the movement of the focus lens 82z, the vibration generated by the movement of the focus lens 82z can be canceled and reduced by the vibration generated by the movement of the counterweight 83d. In the focal lens 82z shown in FIG. 5A, the movable distance is Z, and the range in which the focal position of the projection pattern is changed is F.

In the focal variable portion 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 focal lens 82z is replaced with the positive lens 82b, and the negative lens 82a is further added. Although the number of parts increases by the addition of 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 unit 82 includes a combination of a set of a positive lens 82b and a negative lens 82a, and a drive unit 83 connects 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. As a result, the negative lens 82a can function as a counterweight for reducing vibration due to 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, amplitude, and the like of the negative lens 82a are adjusted so as to function as a counterweight of 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. The sum with and is 0 (zero). For example, when the weight of the positive lens 82b is larger 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 counter weight (not shown) that compensates for the difference between the positive lens 82b and the negative lens 82a may be provided on one of the slider 83a and the slider 83c in order to add a counter weight (not shown) to the light side. Further, 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 part can be adjusted. It may be configured to be counterbalanced.

Further, in the variable focus unit 82, the positive lens 82b and the negative lens 82a are driven in opposite directions along the optical axis direction, so that the movable distances Z2 of the positive lens 82b and the negative lens 82a are the positive lens 82b. It is shorter than the movable distance Z1 when only the lens is moved. As described above, when one of the weight of the positive lens 82b and the weight of the negative lens 82a is heavier than the other, for example, when the weight of the positive lens 82b is larger than the weight of the negative lens 82a, the amplitude on the positive lens 82b side and the negative lens The amplitude on the 82a side may be different, and even in this case, both the movable distance Z2b of the positive lens 82b and the movable distance Z2a of the negative lens 82a are the movable distances when only the positive lens 82b is moved. It is preferable that the lens is shorter than Z1. Specifically, the description will be given based on the optical simulation results. FIG. 6 is a diagram showing an optical simulation result when the focus variable portion according to the second embodiment of the present invention is moved. Note that, in FIG. 6, for the same configuration as that shown in FIG. 4, the same reference numerals are given and detailed description will not be repeated. In FIG. 6A, in the focus variable unit 82 in which a set of positive lens 82b and negative lens 82a are combined, only the positive lens 82b is moved by the drive unit 83 to change the focal position of the projection pattern. The simulation results are shown. At this time, the movable distance of the positive lens 82b is Z1.

On the other hand, in FIG. 6B, in the focal variable unit 82 in which a pair of positive lens 82b and negative lens 82a are combined, the positive lens 82b and the negative lens 82a are moved by the drive unit 83 to move the focal position of the projection pattern. The optical simulation result of changing the lens is shown. At this time, the movable distances of the positive lens 82b and the negative lens 82a are Z2. When the range in which the focal position is changed in FIG. 6A and the range in which the focal position is changed in FIG. 6B are the same F, the movable distance Z2 of the positive lens 82b is larger than the movable distance Z1 of the positive lens 82b. It is clear from the optical simulation results that it is shortened. In the optical simulation shown in FIG. 6, the focal length f ₂ of the object-side lens 86 is 70 mm, the focal length f _1a of the negative lens 82a is −200 mm, and the focal length f _1b of the positive lens 82b is 40 mm.

As described above, the variable focus unit 82 may further include a counterweight driven in the direction opposite to the lens driven by the drive unit 83 (for example, the positive lens 82b). As a result, the variable focus unit 82 can reduce the vibration generated by the movement of the positive lens 82b. Further, one lens (for example, the negative lens 82a) of 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, it is not necessary to separately provide a counterweight, so that the number of constituent parts 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 opposite directions along the optical axis direction to more efficiently drive the focal position on the object. Therefore, the movable distance Z2 of each of the positive lens 82b and the negative lens 82a can be shortened, and a synergistic effect is produced in which further miniaturization becomes possible.

(Embodiment 3)
In the three-dimensional scanner 100 according to the first embodiment, as shown in FIG. 3B, a configuration having a focal variable portion 82 in which a set of a positive lens 82b and a negative lens 82a are combined has been described. In the three-dimensional scanner according to the third embodiment, it will be described that the range in which the focal position is changed changes depending on the balance of the lens powers of the positive lens and the negative lens constituting the focal variable portion.

FIG. 7 is a diagram showing an optical simulation result when the focus variable portion according to the third embodiment of the present invention is moved. In FIGS. 7 (a) to 7 (c), the combined focal lengths of the plurality of lenses constituting the variable focus unit 82 are set to 50 mm in any of the configurations, but the variable focal length unit 82 is configured. The power balances of the plurality of lenses are different in FIGS. 7 (a) to 7 (c). Note that, in FIG. 7, the same components as those shown in FIG. 4 are designated by the same reference numerals, and detailed description thereof will not be repeated. In FIG. 7A, in the focus variable unit 82 in which a set of positive lens 82b and negative lens 82a are combined, only the positive lens 82b is moved by the drive unit 83 to change the focal position of the projection pattern. The simulation results are shown. At this time, the focal length f _1a of the negative lens 82a is set to −200 mm, and the focal length f _1b of the positive lens 82b is set to 40 mm.

In FIG. 7B, in the focal variable unit 82 in which a set of positive lens 82d and negative lens 82c are combined, only the positive lens 82d is moved by the drive unit 83 to change the focal position of the projection pattern. The simulation results are shown. At this time, the focal length f _1c of the negative lens 82c is set to -117 mm, and the focal length f _1d of the positive lens 82d is set to 35 mm. In FIG. 7C, in the focal variable unit 82 in which a set of positive lens 82f and negative lens 82e are combined, only the positive lens 82f is moved by the drive unit 83 to change the focal position of the projection pattern. The simulation results are shown. At this time, the focal length f _1e of the negative lens 82e is set to −75 mm, and the focal length f _1f of the positive lens 82f is set to 30 mm.

When the movable distances of the movable positive lenses 82b, 82d, and 82f are all set to the same Z, the range F1 for changing the focal position in FIG. 7A and the range F2 for changing the focal position in FIG. 7B, FIG. It is clear from the optical simulation results that the range F3 in which the focal position is changed becomes longer in the order of (c). In the optical simulation shown in FIG. 7, the focal length f ₂ of the object-side lens 86 is set to 70 mm.

As described above, by changing the balance of the lens power between the positive lens 82b and the negative lens 82a constituting the focal variable portion 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 having a large lens power has a large aberration and poor imaging performance, and is difficult to process, so that the manufacturing cost increases. If you want to improve the imaging performance and / or reduce the manufacturing cost and processing burden, use a positive lens 82b with a small lens power to deteriorate the imaging performance and / or manufacture the manufacturing cost and processing. If you want to extend the range of change in the focal position or if you want to keep the range of change in the focal position small and reduce the movable distance Z even if you allow the load to increase, use a positive lens 82f with a large lens power. You can make an appropriate selection. It is also possible to manufacture all products using the positive lens 82b, products using the normal lens 82d, and products using the normal lens 82f to enhance the product lineup.

(Embodiment 4)
In the three-dimensional scanner 100 according to the first embodiment, as shown in FIG. 3B, a configuration having a focal variable portion 82 in which a set of a positive lens 82b and a negative lens 82a are combined has been described. However, when configuring the varifocal portion 82 by combining a plurality of lenses, it can be added to the focal length f _1b and focal length conditions other than f _1a of the negative lens 82a of the positive lens 82b. In the three-dimensional scanner according to the fourth embodiment, the conditions to be added when the focal variable portion is formed by a plurality of lenses will be described.

In general, the refractive index of a material (optical glass, optical plastic, etc.) constituting a lens differs depending on the wavelength of light, so that the focal length of the lens becomes wavelength-dependent and chromatic aberration occurs. In particular, when the focal variable portion is composed of a plurality of lenses, the wavelength dependence after the combination may be further increased due to the wavelength dependence of different focal lengths in each lens. Therefore, as a condition for configuring the combination so that the wavelength dependence does not become larger, for example, the Abbe number of the driven positive lens is made larger than the Abbe number of the negative lens. By configuring the focal variable portion based on the conditions, the wavelength dependence of the focal length can be reduced. That is, the wavelength dependence of the focal length can be canceled between the positive lens and the negative lens. The Abbe number is a constant of the optical medium showing the ratio of the refractive index to the dispersion of light, and the smaller the Abbe number, the larger the wavelength dependence of the material.

This will be described based on a specific example. FIG. 8 is a schematic view for explaining the configuration of the focus variable portion according to the fourth embodiment of the present invention. Note that, in FIG. 8, the same configuration as that shown in FIG. 3 is given the same reference numerals and detailed description will not be repeated. The variable focus unit 82 according to the fourth embodiment includes a combination of a set of a positive lens 82h and a negative lens 82g as shown in FIG. Then, the positive lens 82h is moved by the drive unit. The drive unit 83 is not shown. Further, a crown glass having a large Abbe number is used for the positive lens 82h, and a flint glass having a small Abbe number is used for the negative lens 82g. Therefore, the focal variable unit 82 is configured to reduce the wavelength dependence of the combined focal length by combining a positive lens 82h having a high Abbe number and a negative lens 82g having a low Abbe number.

As described above, in the focal length variable unit 82 according to the fourth embodiment, the driven lens 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 combined focal length of the focal variable unit 82 can be reduced.

Further, when the focal variable unit 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 in the entire plurality of lenses. The achromatic condition is a condition in which, for example, the total value obtained by adding the values of the lens power / Abbe number for all the lenses constituting the focal variable unit 82 is approximately 0 (zero).

Further, when the focal variable portion 82 is composed of a plurality of lenses, the material optical characteristic value (heat) constituting each lens included in the plurality of lenses is adjusted so as to adjust the temperature dependence of the combined focal lengths of the plurality of lenses. The Abbe number, etc.) may be determined. For example, by designing the value of the lens power / thermal Abbe number under the condition that the total value obtained by adding all the lenses constituting the varifocal lens 82 is approximately 0 (zero), the temperature depends on the material of the lens. The temperature dependence of the focus variable portion 82 due to the property is reduced. Further, not only the temperature dependence of the lens material, but also the optical characteristic value (heat Abbe number, etc.) so as to reduce the temperature dependence of the combined focal length of the focal variable portion 82 due to the thermal expansion of the lens housing. May be determined. Since the focus variable portion 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 example 1)
It has been explained that the focal variable unit 82 according to the first to fourth embodiments of the present invention is composed of a pair of a positive lens and a negative lens. However, the variable focus unit includes a combination of a pair of positive lenses and a negative lens, and if the sum of the lens powers is positive, even if the configuration is a combination of three or more lenses. Good. Specifically, a variable focus unit that combines three lenses will be described. FIG. 9 is a diagram for explaining a combination of lenses of the variable focus portion. The variable focus portion 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 where the negative lens 82i is stationary and the case where the negative lens 82i is moved are described separately. Further, in FIG. 9, the lens is driven by either right drive (indicated by a white arrow) in which the lens is started to move from the right direction in the figure or left drive (indicated by a black arrow) in which the lens is started to move from the left direction in the figure. It is illustrated that it is done. Here, the right drive and the left drive are driven in opposite phases. In FIG. 9, the left drive of the positive lens is further divided into the left drive of the positive lens and the left drive of the positive lens.

For example, in the configuration in the upper left column of FIG. 9, the configuration of the focus variable unit 82 in which the negative lens 82i is stationary and the positive lenses 82j and 82k are both driven to the right is illustrated. On the other hand, in the configuration in the upper right column of FIG. 9, the configuration of the focus variable portion 82 in which the negative lens 82i is stationary, the positive lens 82j is driven to the left, and the positive lens 82k is driven to the right is illustrated. Further, in the configuration in the lower left column of FIG. 9, the configuration of the focus variable portion 82 in which the negative lens 82i is driven to the left and the positive lenses 82j and 82k are both stationary is illustrated. Further, in the configuration in the lower right column of FIG. 9, the configuration of the focus variable portion 82 in which the negative lens 82i is driven to the left, the positive lens 82j is stationary, and the positive lens 82k is driven to the left is illustrated.

In the pattern shown in FIG. 9, in any case, the absolute value of the sum of "{(lens power) x (sign of driving direction)} for all negative lenses 82i and positive lenses 82j and 82k is the lens. It is possible to configure the varifocal unit 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, it is more efficient than a configuration in which only a single focal lens 82z equivalent to a composite of the focal variable portions 82 (negative lens 82i and positive lens 82j, 82k) is driven. The focal position can be driven on the object, and advantages such as miniaturization can be obtained. The above condition qualitatively means that "the negative lens and the positive lens should be driven in opposite phases as much as possible, and the positive lenses should be driven in the same phase as much as possible". Also, "On the contrary, even if the negative lens and the positive lens are driven in the same phase or the positive lenses are driven in the opposite phase, there is no disadvantage if the power of one lens is sufficiently small. It means that. Of course, the above conditions can also be applied when the variable focus unit 82 is composed of four or more lenses.

(Modification 2)
In the three-dimensional scanner 100 according to the first to fourth embodiments of the present invention, as shown in FIG. 3B, the light emitted from the light source unit 81 is bent by the beam splitter 84, and the focus variable unit 82 and the focus variable unit 82 and The projection pattern is projected to the position of the object (not shown) through the lens 86 on the object side. Further, the light reflected by the object passes through the object-side lens 86 and the varifocal lens 82, and is further detected by the optical sensor 85 through the beam splitter 84. That is, in the three-dimensional scanner 100 according to the first to fourth embodiments of the present invention, the configuration in which the light from the light source unit 81 through the object 200 to the optical sensor 85 passes through the focus variable unit 82 twice has been described. However, the configuration is not limited to this, and even if the light from the light source unit 81 through the object 200 to the optical sensor 85 passes through the focus variable unit 82 once, it passes three times or more. May be good.

Specifically, FIG. 10 is a diagram for explaining an optical path passing through the focal variable portion. In FIG. 10A, the light emitted from the light source unit 81 passes through the focus variable unit 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 focus variable portion 82. That is, the configuration shown in FIG. 10A is such that the light from the light source unit 81 through the object 200 to the optical sensor 85 passes once through the focus variable unit 82.

In FIG. 10B, similarly to the first embodiment, the light emitted from the light source unit 81 passes through the focus variable unit 82 and projects a projection pattern on the object 200. Further, the light reflected by the object 200 passes through the focus variable portion 82 and is detected by the optical sensor 85. That is, the configuration shown in FIG. 10B is such that the light from the light source unit 81 through the object 200 to the optical sensor 85 passes through the focus variable unit 82 twice.

In FIG. 10C, the light emitted from the light source unit 81 directly projects the projection pattern onto the object 200 without passing through the focus variable unit 82. On the other hand, the light reflected by the object 200 passes through the focus variable portion 82 and is detected by the optical sensor 85. That is, the configuration shown in FIG. 10C is such that the light from the light source unit 81 through the object 200 to the optical sensor 85 passes once through the focus variable unit 82. As described above, depending on the number of times the light emitted from the light source unit 81 (hereinafter referred to as the projected optical path) and the light reflected from the object 200 (hereinafter referred to as the imaging optical path) pass through the focal variable unit 82. Although three types of modifications have been illustrated, the configuration shown in FIG. 10B is the best when the focusing method is used as the measurement principle. In the focusing method, an image of a pattern projected on the surface of the object 200 is imaged and analyzed multiple times while changing the focal position, and the most focused image is obtained from the image group, and the object 200 is obtained. 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 projected optical path and the imaging optical path are in focus, an image with a clear pattern is obtained, and in other states, both the projected optical path and the imaging optical path are simultaneously defocused. That is, since the out-of-focus effect works twice, such as "the out-of-focus projection pattern is imaged with the out-of-focus lens", the intelligibility of the pattern drops sharply. That is, it becomes easy to easily identify the image showing the maximum pattern clarity (= degree of focus). On the other hand, in the configurations of FIGS. 10A and 10C, the focal position is variable only for one of the projection optical path and the imaging optical path, so that the pattern clarity is not maximized to some extent. Since it shows the clarity of a large pattern, it is somewhat difficult to identify the image showing the maximum value of the clarity of the pattern. That is, the accuracy of the three-dimensional measurement is lower than that of the configuration of FIG. 10B. In addition to the problem of detecting the clarity of the pattern described above, in the configurations of FIGS. 10A and 10C, the optical path on the side where the focus variable portion 82 is not placed is generally in the projected optical path and the imaging optical path. In order to obtain pan focus, it is necessary to use a lens that uses a diaphragm (the amount of light is reduced), so that the amount of light may decrease. However, when a light source unit 81 that can secure a sufficient amount of light, an optical sensor 85 with less noise, or the like is adopted, or when the object 200 exhibits good reflection characteristics, FIGS. 10A and 10C are shown. Three-dimensional measurement is sufficiently possible even with this configuration.

(Modification 3)
Although the light source unit 81 according to the first to fourth embodiments of the present invention has been described as a single light source (for example, an LED or a laser element), the present invention is not limited to this configuration. The light source unit 81 may be configured by assembling a plurality of light sources. That is, a plurality of LEDs and laser elements may be arranged on the substrate to form the light source unit 81. The three-dimensional scanner 100 may adopt a configuration in which the light from the light source unit 81 or the reflected light from the object 200 is guided to the optical sensor 85 or the object 200 by using a light guide such as an optical fiber. ..

(Modification example 4)
Further, the object of imaging by the three-dimensional scanner according to the first to fourth embodiments of the present invention is not limited to the teeth and gingiva in the oral cavity, but is not limited to living tissues such as the ear canal, gaps in the walls of buildings, and piping. The inside of the space or an industrial product having a cavity may be used, and the present invention can be widely applied to the application of measuring / observing a space in a narrow space where blind spots are likely to occur.

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

10 Probe, 20 Connection, 30 Optical Measurement, 40 Control, 50 Display, 60 Power Supply, 80 Handpiece, 81 Light Source, 82 Varifocal Lens, 82a Negative Lens, 82b Positive Lens, 83 Drive, 83d Counterweight, 84 beam splitter, 85 optical sensor, 86 object-side lens, 87 aperture, 100 three-dimensional scanner, 200 object.

Claims (9)

A 3D scanner that acquires shape information of an object,
Light source and
A detection unit that detects light from the light source unit reflected by the object, and a detection unit.
A focus variable unit capable of changing the focal position of light from the light source unit to the detection unit via the object and a predetermined range.
It is provided with a calculation unit that calculates shape information of the object from the light detected by the detection unit.
The variable focus unit is
Multiple lenses with positive combined lens power values,
A drive unit that drives at least one of the plurality of lenses along the optical axis direction is included.
The plurality of lenses include a combination of at least one set of positive and negative lenses .
A three-dimensional scanner in which one of the plurality of lenses driven by the drive unit is used as a counterweight driven in a direction opposite to that of the other lens . The three-dimensional scanner according to claim 1, wherein the driving unit drives the lens having the maximum absolute value of the lens power among the plurality of lenses along the optical axis direction. The three-dimensional scanner according to claim 1 or 2, wherein the driving unit drives the positive lens and the negative lens included in the plurality of lenses in opposite directions along the optical axis direction. The plurality of lenses
The three-dimensional scanner according to any one of claims 1 to 3, further comprising a lens having an absolute value of lens power larger than the absolute value of the combined lens power. The lens according to claim 1 to 4 , wherein the lens driven by the driving unit among the plurality of lenses is the positive lens, and the Abbe number is larger than the Abbe number of the negative lens included in the plurality of lenses. The three-dimensional scanner according to any one item. The three-dimensional aspect according to any one of claims 1 to 5 , wherein the optical characteristic values of the lenses included in the plurality of lenses are determined so that the achromaticity condition is satisfied in the entire plurality of lenses. Scanner. The three-dimensional aspect according to any one of claims 1 to 6, wherein when one of the plurality of lenses driven by the drive unit is a positive lens, the lens used as the counterweight is a negative lens. Scanner. Any one of claims 1 to 7, wherein the amplitude of the lens used as the counter weight is adjusted so that the momentum of the lens used as the counter weight can cancel the momentum of the lens whose vibration is reduced by the counter weight. The three-dimensional scanner described in the section. The tertiary according to any one of claims 1 to 8, wherein a weight is added so that the difference between the weight of the lens used as the counter weight and the weight of the lens whose vibration is reduced by the counter weight can be canceled. Former scanner.

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