Three-dimensional preparation method and optical CT microscope / 3d model generation device using the same

Abstract

To provide a three-dimensional preparation method that photographs an object to be photographed while the object and liquid are placed in a cylindrical transparent container, and that uses parallel transmitted illumination without causing refraction due to the cylindrical transparent container, as well as an optical CT microscope and 3D model generation device that uses the method.SOLUTION: The device comprises a rectangular transparent container 130 in which an object to be photographed TG is placed together with liquid to be photographed TGL inside a cylindrical transparent container 110, a three-dimensional preparation 100 containing a liquid 140 with the same refractive index as the cylindrical transparent container and the rectangular transparent container, a photographing unit 200, a rotation mechanism 300 for the cylindrical transparent container, an illumination unit 400 for illuminating the three-dimensional preparation with parallel light, a control unit 500, a synthesis unit 600 for generating an all-in-focus image BI from the captured raw image AI, a generation unit 700 for generating an image CI from multiple images BI, the horizontal axis of which is the detector brightness and the vertical axis is the rotation angle, a back projection unit 800 for back projecting the image CI in the circumferential direction to obtain a tomographic image DI, and a generation unit 900 for generating a 3D model EI from the multiple tomographic images DI.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional preparation method that can solve the problem of scattering of parallel transmitted light, which causes errors in the image, when collimated parallel light is used as transmitted light in an optical CT microscope, and to an optical CT microscope / 3D model generation device that can use the method to generate tomographic images and 3D models of microscopic objects. [Background technology]

[0002] CT technology is an abbreviation for Computed Tomography technology, also known as computerized tomography technology. In particular, X-ray CT technology has made great strides in recent years. This technology involves irradiating the human body with X-rays from multiple directions, reading the X-rays that pass through the body with a detector, and then using a computer to calculate the resulting data to create cross-sectional images, which are then superimposed to create a three-dimensional image.

[0003] Optical CT technology is a method that uses safe light instead of X-rays. However, light is strongly scattered by the object, and in the case of objects larger than a few centimeters, such as living organisms, the linear component becomes very weak and cannot be depicted as a tomographic image. Conversely, if the thickness of the target object, such as a living body, is less than 1 cm, weak straight or nearly straight light components can be measured and a tomographic image can be obtained using the same algorithm as X-ray CT.

[0004] For this reason, research and practical application of the creation of cross-sectional images and three-dimensional images of living organisms less than 1 cm in size is underway. For example, US8014063B2 It is similar to the technique of "Optical projection tomography." Also, Japanese Patent Application Laid-Open No. 08-243105 It is similar to the technology of "optical CT imaging device." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US8014063B2 No. [Non-patent literature]

[0006] [Non-Patent Document 1] Japanese Patent Publication No. 08-243105

[0007] Normally, when using optical CT to take tomographic images of an object normally submerged in liquid, such as a living cell, the object is placed in a cylindrical transparent container filled with an aqueous solution, and the object is rotated axially and photographed repeatedly. It was thought that such a device would enable accurate tomographic imaging of the object being observed and the creation of a high-quality 3D model covering the entire surface. Summary of the Invention [Problem to be solved by the invention]

[0008] However, it has been found that the above-mentioned device has the following problems. In other words, unlike X-rays, light does not travel in a straight line and is refracted at the boundary surfaces of transparent containers, etc., which ultimately causes errors in the generated tomographic images and three-dimensional images.

[0009] In the case of optical CT, since scattering from the object being imaged is significant, it is desirable to use collimated light, which is a bundle of parallel rays, for transmitted illumination.

[0010] However, the transmitted illumination light, which has been carefully aligned to be parallel, is significantly refracted in front of and behind the cylindrical transparent container filled with the solution, resulting in a problem of photographic errors.

[0011] Such an error is caused by the fact that the cylindrical transparent container and the aqueous solution surrounding the object to be photographed are made of transparent materials.

[0012] Since the object to be photographed is photographed through the cylindrical transparent container or aqueous solution, refraction by the transparent material that makes up the cylindrical transparent container occurs depending on the angle of incidence of the light, and the parallel transmitted illumination light is refracted at the boundary surface when it enters the cylindrical transparent container, causing the parallelism to be lost.

[0013] Furthermore, when light leaves the object to be photographed and travels toward the photographing unit, the light is refracted by the transparent material that constitutes the cylindrical transparent container.

[0014] In this way, an image containing errors is captured by the camera, and when tomographic imaging and 3D modeling are performed based on that image, image errors occur.

[0015] This image error is a major issue not only in biological cells, but also in the scientific and technological fields that utilize optical CT.

[0016] In addition, for images taken without using the cylindrical transparent container or aqueous solution, i.e., images taken directly of the object, there is no problem of refraction due to the cylindrical transparent container or aqueous solution, and therefore no image error related to refraction occurs.

[0017] The present invention was devised in light of the above circumstances, and aims to provide a three-dimensional preparation method that can photograph the entire circumference of an object placed inside a transparent cylindrical container together with an aqueous solution, without causing refraction due to the transparent material that makes up the cylindrical transparent container and the aqueous solution, and an optical CT microscope and 3D model generation device that uses the method. [Means for solving the problem]

[0018] The three-dimensional preparation method of the present invention involves placing a cylindrical transparent container and aqueous solution inside a transparent material with the same refractive index as the cylindrical transparent container and a flat surface with a hole, and filling the gap between the cylindrical transparent container and the hole with a liquid with the same refractive index as the transparent material, thereby removing image errors and forming error-free images, allowing for error-free tomography and full-area 3D modeling.

[0019] The optical CT microscope and 3D model generation device of the present invention comprises a transparent three-dimensional preparation unit on which an object to be photographed is placed, an imaging unit that photographs the object to be photographed, an illumination unit that illuminates the three-dimensional preparation from behind with parallel light, a rotation mechanism that rotates the cylindrical unit of the three-dimensional preparation around its cylindrical axis, a depth synthesis unit that performs depth synthesis from multiple images taken by the imaging unit to generate an image in which all images are in focus, a sinogram generation unit that arranges the multiple depth-synthesized images with the detector brightness on the horizontal axis and the rotation angle on the vertical axis, a back projection unit that processes the sinogram values ​​and back-projects them in the circumferential direction to obtain a tomographic image, a 3D model generation unit that generates a 3D model from the multiple tomographic images, and a control unit that controls each of these units.

[0020] The surfaces of the three-dimensional preparation section facing the illumination section and the photographing section are formed flat, and parallel light is transmitted from the back side of the three-dimensional preparation section to the photographing section, so that the image can be captured by the photographing section without refraction at the boundary surface of the cylindrical transparent container between the illumination section and the object to be photographed within the three-dimensional preparation, and between the object to be photographed within the three-dimensional preparation and the photographing section, and the image of the object to be photographed is output to the depth synthesis section. [Effects of the Invention]

[0021] The three-dimensional preparation method of the present invention places a transparent cylindrical container or aqueous solution into a rectangular transparent container with a flat surface that has a hole in the shape of a container, and fills the gap between the rectangular transparent container and the hole with a liquid that has the same refractive index as the transparent material, thereby eliminating refraction and making it possible to output an image of the object being photographed without image error to the depth synthesis unit.

[0022] This has the advantage of being particularly useful for capturing images of subjects that require extremely high image accuracy, such as generating cross-sectional images of living cells in the human body or 3D models of the entire circumference.

[0023] Furthermore, the optical CT microscope and 3D model generation device of the present invention comprises a transparent 3D preparation section on which the object to be photographed is placed, an imaging section that photographs the object to be photographed, an illumination section that illuminates the 3D preparation from behind with parallel light, a rotation mechanism that rotates the cylindrical section of the 3D preparation around the cylindrical axis, a depth synthesis section that performs depth synthesis from multiple images taken by the imaging section to generate an image in which all images are in focus, a sinogram generation section that arranges the multiple depth-synthesized images with the horizontal axis representing the brightness of the detector and the vertical axis representing the rotation angle, a back projection section that processes the sinogram values ​​and back-projects them in the circumferential direction to obtain a tomographic image, a 3D model generation section that generates a 3D model from the multiple tomographic images, and a control section that controls each of these sections. Therefore, it can be useful for generating tomographic images and 3D models of all the circumferences of objects that require extremely high image accuracy, such as tomographic images of biological cells in the human body. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a mechanical explanatory diagram showing a conventional method for photographing an object to be photographed using an optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a mechanical explanatory diagram showing a method for photographing an object using a three-dimensional preparation in an optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 3] This is an optical explanatory diagram showing how parallel light irradiated from the lighting unit on the right side to photograph a conventional object in an optical CT microscope / 3D model generation device according to an embodiment of the present invention is refracted at the interface of a cylindrical transparent container. [Figure 4] This is an optical explanatory diagram showing how parallel light irradiated from the lighting unit on the right side to photograph an object using a three-dimensional preparation in an optical CT microscope / 3D model generation device according to an embodiment of the present invention does not refract at the boundary surface of the cylindrical transparent container even when passing through the three-dimensional preparation. [Figure 5] 1 is a conceptual diagram of an optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 6]1A and 1B are diagrams of an optical CT microscope and 3D model generation device according to an embodiment of the present invention, in which FIG. 1A is a schematic front view, FIG. 1B is a schematic perspective view from the front and right side, and FIG. 1C is a schematic perspective view from the front and left side. [Figure 7] 1A to 1C are schematic front, side, top, and perspective views of a three-dimensional preparation unit and a rotation mechanism that constitute an optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 8] 1A to 1C are a left side view, a front view, a right side view, a schematic oblique view from the right side, a top view, an enlarged top view, and a schematic oblique view from the left side of a three-dimensional preparation part that constitutes an optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 9] FIG. 1 is an explanatory diagram showing a method for photographing an object using a three-dimensional preparation in the three-dimensional preparation section and illumination section that constitute the optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 10] FIG. 1 is an explanatory diagram showing a method for photographing a conventional object that does not have a rectangular transparent container or a liquid with the same refractive index in the three-dimensional preparation section and illumination section that constitute the optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 11] 10 is an example of an image captured by an imaging unit in the optical CT microscope / 3D model generation device according to the embodiment of the present invention, which is input to a depth stacking unit. [Figure 12] 10 is an example of an image subjected to depth synthesis by a depth synthesis unit in the optical CT microscope / 3D model generation device according to the embodiment of the present invention, which is input to a sinogram generation unit. [Figure 13] 10 is an example of a sinogram image generated by a sinogram generating unit in the optical CT microscope / 3D model generating device according to the embodiment of the present invention, and input to a back projection unit. [Figure 14] 1 is an example of a tomographic image obtained by a back projection unit in an optical CT microscope / 3D model generation device according to an embodiment of the present invention, which is input to a 3D model generation unit. [Figure 15] 1 is an example of an image of a 3D model in an optical CT microscope / 3D model generation device according to an embodiment of the present invention. [Figure 16] 10A and 10B are example images of the results of photography by the photography unit using a conventional photography method in which there is no rectangular transparent container or liquid with the same refractive index in the three-dimensional preparation unit and illumination unit that make up the optical CT microscope and 3D model generation device according to an embodiment of the present invention. [Figure 17] 10A and 10B are examples of images captured by the imaging unit using the imaging method using the three-dimensional preparation in the three-dimensional preparation unit and illumination unit that make up the optical CT microscope and 3D model generation device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The optical CT microscope and 3D model generating device 1000 according to the embodiment of the present invention includes a rectangular transparent container 130 in which an object to be photographed TG is placed together with a liquid to be photographed TGL in a cylindrical transparent container 110, a three-dimensional preparation 100 containing a liquid 140 having the same refractive index as the cylindrical transparent container 110 and the rectangular transparent container 130, an imaging unit 200 that images the object to be photographed TG, a rotation mechanism 300 that rotates the cylindrical transparent container 110, an illumination unit 400 that illuminates the three-dimensional preparation 100 with parallel light, and a control unit 500 that controls each unit. The apparatus is equipped with a depth synthesis unit 600 that performs depth synthesis from a plurality of raw images AI captured by the imaging unit 200 to generate a depth synthesis image BI that is all in focus, a sinogram generation unit 700 that generates a sinogram image CI from the plurality of depth synthesised depth synthesis images BI, with the horizontal axis representing the detector brightness and the vertical axis representing the rotation angle, a back projection unit 800 that processes the values ​​of the sinogram image CI and back projects them in the circumferential direction to obtain a tomographic image DI, and a 3D model generation unit 900 that generates a 3D model EI from the plurality of tomographic images DI.

[0026] The imaging unit 200, the rotation mechanism 300, the depth stacking unit 600, the sinogram generation unit 700, the back projection unit 800, and the 3D model generation unit 900 are controlled by a control unit 500.

[0027] The three-dimensional preparation 100 is composed of a cylindrical transparent container 110 made of a transparent material such as flat glass or acrylic plate and containing the object to be photographed TG, a liquid to be photographed TGL filled into the cylindrical transparent container 110, a rectangular transparent container 130 made of a transparent material such as flat glass or acrylic plate and having a container-shaped hole with a flat surface when viewed from the lighting unit and the surface when viewed from the photographing side, and a liquid 140 having the same refractive index as the rectangular transparent container 130, and is set to a size that allows the object to be photographed TG to be inserted.

[0028] This three-dimensional preparation 100 is formed as shown in Figure 8, with a liquid 140 having the same refractive index and a cylindrical transparent container 110 placed inside a rectangular transparent container 130, and a liquid TGL to be photographed and an object TG to be photographed placed inside the cylindrical transparent container 110.

[0029] On the upper surface side of the three-dimensional preparation 100 described above, the upper part of a cylindrical transparent container 110 is connected to a connection part of a rotation mechanism 300 . When this cylindrical transparent container 110 is photographed by the photographing unit 200 located on the opposite side of the lighting unit 400, the object TG to be photographed inside the cylindrical transparent container 110 in the three-dimensional preparation 100 can be photographed from any angle by the rotation mechanism 300.

[0030] The photographing unit 200 uses a CCD camera 230 that can photograph raw images AI. The photographing section 200 incorporates a focus adjustment mechanism 240, which will be described later, and is configured to photograph the photographing target TG placed on the three-dimensional preparation 100 from any focal position.

[0031] The raw image AI captured by the image capturing unit 200 is output to a depth stacking unit 600 that generates a depth stacked image BI that is entirely in focus.

[0032] The photographing unit 200 has an objective lens 210 for performing microscopic photographing, a microscope barrel 220 for performing microscopic photographing, a CCD camera 230, and a focus adjustment mechanism 240 that moves the objective lens 210, microscope barrel 220, and CCD camera 230 along the optical axis direction of the CCD camera.

[0033] The rotation mechanism 300 includes a drive motor 310 and a coupling 320 that connects the cylindrical transparent container 110 and the drive motor 310 . A coupling 320 connecting the cylindrical transparent container 110 and the drive motor 310 is set in a rotatable state. One of the couplings 320 is placed on a straight line connecting the cylindrical transparent container 110 and the center of rotation of the drive motor 310 . As will be described later, since the imaging unit 200 is moved intermittently, it is desirable to use a stepping motor as the drive motor 310.

[0034] The focus adjustment mechanism 240 moves the objective lens 210 , the microscope lens barrel 220 , and the CCD camera 230 along the optical axis of the CCD camera 230 . Since the focus adjustment mechanism 240 is moved intermittently as will be described later, it is desirable to use a stepping motor for the drive motor 241.

[0035] The imaging unit 200 configured in this manner is operated as follows. A focus adjustment mechanism 240 to which an objective lens 210, a microscope lens barrel 220, and a CCD camera 230 are attached is set to an initial position AP where the innermost part of the object to be photographed TG is brought into focus, and the object to be photographed TG is photographed. Next, the focus adjustment mechanism 240, to which the objective lens 210, microscope lens barrel 220, and CCD camera 230 are attached, is moved by a minute position DP in the direction toward the subject TG, and the subject TG is photographed. The above-mentioned movement of the DP by the minute position and photographing of the photographing object TG are repeated until the position BP where the foremost part of the photographing object TG is in focus.

[0036] Since the photographed object TG is located inside the three-dimensional preparation 100, the parallel light beams emitted from the illumination unit 400 are irradiated without being refracted at the boundary surfaces of the cylindrical transparent container 110 and the rectangular transparent container 130 along the way. This is the most distinctive feature.

[0037] By repeating the above-mentioned movement of the DP by the minute position and photographing the object to be photographed TG from the initial position AP where the focus is on the innermost part of the object to be photographed TG to the position BP where the focus is on the innermost part of the object to be photographed TG, an image will be taken with the focus somewhere.

[0038] Once a series of photographs focused on a certain point on the object TG has been completed, the cylindrical transparent container 110 containing the object TG is rotated by a certain amount AT using the rotation mechanism 300, and the series of photographs focused on a certain point on the object TG is completed in the same manner as before. This operation of rotating the object AT by a certain amount and completing a series of photographs with the focus on somewhere on the object TG is repeated until the object GT has rotated half a turn (or one turn). The rotation angle of this fixed amount AT is determined by the number of times the object TG is rotated halfway (or one full rotation). In other words, the rotation angle of this fixed amount AT should be set small when a more detailed image is desired.

[0039] A series of captured raw images AI of the object TG to be photographed within the three-dimensional preparation 100 including the rectangular transparent container 130 are output directly to the depth stacking unit 600.

[0040] A series of raw images AI taken from a certain rotation angle are input to the depth synthesis unit 600 and synthesized within the depth synthesis unit to generate a single depth synthesis image BI that is in focus over a wide range from the foreground to the background. The rotation mechanism 300 processes a plurality of the depth-stitched images BI for half a rotation (or one rotation), and outputs a series of depth-stitched images BI to the sinogram generation unit 700.

[0041] The depth stacked image BI input to the sinogram generation unit 700 generates a sinogram image CI in which the horizontal axis is the brightness of the detector and the vertical axis is the rotation angle. The generated sinogram images CI are processed for a half rotation (or one rotation), and a series of sinogram images CI are output to the back projection unit.

[0042] The series of sinogram images CI input to the back projection unit 800 undergoes processing such as filtering, and then undergoes back projection processing in which the images are added in accordance with the imaging angle to generate a tomographic image DI. A plurality of the generated tomographic images DI are processed and output to the 3D model generating unit 900.

[0043] The series of tomographic images DI input to the 3D model generation unit 900 undergoes 3D image display processing to generate a 3D model EI.

[0044] In particular, in the conventional method, as shown in FIG. 1, the parallel light emitted from the illumination unit 400 is refracted at the boundary surface of the cylindrical transparent container 110 along the way, and is not irradiated as parallel light onto the photographing target TG. Furthermore, transmitted light emitted from the photographing object TG is also refracted at the interface of the cylindrical transparent container 110 along the way, and light of different conditions reaches the photographing unit 200 depending on the location of the photographing object TG. This is a major issue, especially in the case of optical CT, where scattering is significant, and is a factor that causes errors in the captured images. FIG. 3 is a diagram showing how parallel light irradiated from the illumination unit 400 on the right side is refracted in this conventional cylindrical transparent container 110. This shows how the parallel light emitted from the right lighting unit 400, which should travel straight and remain parallel, is refracted.

[0045] In contrast to the conventional method, in the present invention, as shown in Figure 2, the parallel light emitted from the illumination unit 400 enters the three-dimensional preparation 100 and the cylindrical transparent container 110 without being refracted along the way, and is then irradiated as parallel light onto the object to be photographed TG. Furthermore, the transmitted light emitted from the object to be photographed TG does not refract at the boundary surface between the three-dimensional preparation 100 and the cylindrical transparent container 110 along the way, and light under the same conditions reaches the photographing unit 200 regardless of the location of the object to be photographed TG. This is a major advantage, especially in the case of optical CT, where scattering is significant, and is characterized by the fact that it does not cause errors in the captured images compared to conventional methods. FIG. 4 is a diagram showing how parallel light irradiated from the right illumination unit 400 is refracted on the three-dimensional preparation 100 of the present invention. The figure shows how parallel light emitted from the right lighting unit 400, which is intended to travel straight and remain parallel, travels straight without being refracted.

[0046] 16 and 17 show an example of a depth stacked image BI generated by the depth stacking unit 600 according to the embodiment of the present invention using a broccoli flower bud as the photographic object TG. The depth stacked image BI shown in FIG. 16 was captured by a conventional device (the imaging unit 200 without the rectangular transparent container 130 of the three-dimensional preparation 100 and the liquid 140 having the same refractive index). In the example of FIG. 16, a cylindrical transparent container 110 is made of a transparent acrylic material, and sunflower oil is used as the liquid 140 having the same refractive index. In order to make the effect easier to understand, in FIG. 16, the area of ​​the parallel light irradiated from the illumination unit 400 is made small so that only the central portion is irradiated with the parallel light. The depth stacked image BI shown in FIG. 17 was captured by the current device (the imaging unit 200 containing the rectangular transparent container 130 of the three-dimensional preparation 100 and the liquid 140 having the same refractive index). In the example of FIG. 17, the rectangular transparent container 130 and the cylindrical transparent container 110 are made of transparent acrylic material, and sunflower oil is used as the liquid 140 having the same refractive index. In order to make the effect easier to understand, the area of ​​the parallel light irradiated from the illumination unit 400 is also reduced in FIG. 17 so that only the central portion is irradiated with the parallel light. In Figure 16, it can be seen that refracted non-parallel light is irradiated onto the peripheral areas of the broccoli flower bud, particularly those near the left and right edges, causing it to shine with non-parallel light. In contrast, in Figure 17, refracted non-parallel light is not irradiated onto the peripheral areas of the broccoli flower, particularly those near the left and right edges, and the flower does not shine with non-parallel light, and it can be seen that the image was captured using only the expected transmitted parallel light.

[0047] In other words, if a conventional optical CT microscope / 3D model generation device were used that did not have the rectangular transparent container 130 of the three-dimensional preparation 100 described above and the liquid 140 with the same refractive index, the parallel illumination light would be refracted by the surface of the cylindrical transparent container 110 on the illumination unit 400 side, and the light would travel from the left and right sides of the cylindrical transparent container 110 toward the center, causing the peripheral areas of the broccoli flower buds, particularly those near the left and right edges, to shine in an unexpected way, resulting in the generation of a depth synthesis image BI that differs from the original shape. As a result, the sinogram image CI, the tomographic image DI, and the 3D model EI are also generated in a form different from the original form.

[0048] In contrast, in the optical CT microscope and 3D model generation device of this embodiment, which has the rectangular transparent container 130 of the three-dimensional preparation 100 described above and the liquid 140 having the same refractive index, the illumination light enters parallel to the rectangular transparent container 130, the liquid 140 having the same refractive index as the rectangular transparent container 130, and the cylindrical transparent container 110, and therefore the light travels without refracting, and a depth synthesis image BI is generated in its original form without the broccoli flower bud, particularly the peripheral areas near the left and right edges, shining in unexpected ways. As a result, the sinogram image CI, the tomographic image DI, and the 3D model EI are also generated in their original form. [Explanation of symbols]

[0049] 1000 Optical CT microscope and 3D model generation device 100 Three-dimensional preparations TG Shooting subject 110 Cylindrical transparent container TGL Liquid to be photographed 130 Rectangular transparent container 140 Liquids with the same refractive index 200 Photography Department 210 objective lens 220 Microscope tube 230 CCD camera 240 Focus adjustment mechanism 241 Drive motor 300 Rotation Mechanism 310 Drive motor 320 Coupling 400 Lighting Department 500 control section 600 Depth synthesis section 700 Sinogram Generation Unit 800 Back projection section 900 3D model generation unit AI-captured raw images BI depth composite image CI sinogram image DI tomographic image EI 3D models AP Initial position with focus on the back BP: The position where the foreground is in focus DP minute position AT Fixed rotation angle

Claims

1. This is a three-dimensional preparation method characterized by the fact that, whereas parallel transmitted illumination is refracted by the surface of a cylindrical transparent container, generating an image that differs from its original shape, parallel transmitted illumination is transmitted without refraction by a rectangular transparent container, a liquid having the same refractive index, and a cylindrical transparent container, generating an image in its original shape.

2. an illumination unit that illuminates the three-dimensional preparation from behind with parallel light; a rotation mechanism that rotates the three-dimensional preparation around the cylindrical axis of the cylindrical part; a depth synthesis unit that performs depth synthesis from multiple images taken by the imaging unit to generate an image in which all images are in focus; a sinogram generation unit that generates a sinogram from the multiple depth-synthesized images, with the horizontal axis representing the brightness of the detector and the vertical axis representing the rotation angle; a back projection unit that processes the values ​​of the sinogram and back-projects it in the circumferential direction to obtain a tomographic image; a 3D model generation unit that generates a 3D model from the multiple tomographic images; and a control unit that controls each of these units.

Images