JP3984857B2 - Automatic calibration method for magnifying imaging apparatus, magnifying imaging apparatus and calibration tool therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention utilizes an automatic calibration method for an enlargement imaging apparatus including an optical system and an imaging device for obtaining an enlarged image of a measurement object and a display unit that displays the obtained image on a display screen, and the method. The present invention relates to an enlargement imaging apparatus and a calibration tool for the same.
[0002]
[Prior art]
This type of magnified imaging device is called a video microscope or a digital microscope, and displays magnified images of various measuring objects such as precision machines, electronic parts, materials, materials, and biological objects on the screen for visual check and Used to make measurements. An image of the measurement object obtained through an optical system including a lens is converted into an electrical signal by an image sensor such as a CCD (Charge Coupled Device). Based on the image signal of the measurement target obtained by processing the electrical signal, a color image of the measurement target is displayed on a display screen such as a CRT (cathode ray tube) or LCD (liquid crystal). In addition, the distance between any two points on the display screen (the length of the line segment), the radius of the circle, the angle determined by any three points, the area surrounded by a straight line connecting a plurality of arbitrary points, etc. are measured. Can be displayed on the display screen.
[0003]
In order to measure the length and area as described above in actual size, it is necessary to calculate in advance the actual size corresponding to the pixel unit constituting the display screen. The actual size per pixel can be calculated from the magnification of the optical system (and the magnification of the screen display), and this calculation or processing is called calibration.
[0004]
Depending on the measurement object or the application of the enlarged image, the optical system (lens unit) of the enlargement imaging apparatus is changed to change the enlargement magnification. When using a zoom lens, the magnification of the optical system can be changed continuously. When the magnification of the optical system changes, the actual size per pixel of the display screen changes, so the above calibration needs to be re-executed.
[0005]
In large-scale and expensive magnifying imaging devices, the lens unit reads the current optical magnification (zoom ratio) and passes the information to the main unit control unit (processing unit), which automatically performs calibration. There is something to do. In this case, the actual dimensions per pixel of the display screen are appropriately corrected even if the zoom operation is performed. Therefore, the actual dimensions such as the length of the line segment, the radius of the circle, the area of the closed figure, etc. on the display screen It can be converted to and accurately measured.
[0006]
[Problems to be solved by the invention]
However, in a relatively inexpensive and small magnifying image pickup device, the above function is not provided in the interchangeable lens. Therefore, every time the lens is replaced, the user sets (inputs) its optical magnification and recalibrates. It needs to be executed. Further, when a zoom operation is performed using a zoom lens, it is impossible to accurately know the current optical magnification (zoom ratio), and thus accurate calibration cannot be performed.
[0007]
Further, as described above, even if the lens unit is a magnification imaging device having a function of automatically performing calibration by reading the current optical magnification (zoom ratio) and giving the information to the main body control unit, In order to enable such a function, it is necessary to use a dedicated interchangeable lens unit. When an inexpensive interchangeable lens unit that does not support such an automatic calibration system is used, automatic calibration is not executed, so the length of a line segment, the radius of a circle, the area of a closed figure, etc. on the display screen Cannot be converted to actual dimensions.
[0008]
The present invention has been made in view of the above problems, and calculates the actual size per pixel on the screen while using a normal interchangeable lens unit without using a special interchangeable lens unit. It is an object of the present invention to provide an automatic calibration method for an enlargement imaging apparatus that automatically performs calibration, an enlargement imaging apparatus, and a calibration tool for the enlargement imaging apparatus.
[0009]
[Means for Solving the Problems]
An automatic calibration method for a magnifying imaging apparatus according to the present invention includes an optical system and an imaging element including a lens unit including an objective lens for acquiring a magnified image of a measurement object, and a display unit that displays the acquired image on a display screen. When,The reference scale is provided between the objective lens and the measurement object in the optical axis direction of the optical system, and the reference scale corresponds to each of the reference scale and the reference scale having different actual dimensions according to the magnification range of the optical system. In order to identify the calibration tool in which the reference mark displayed together with the reference scale is displayed on the same plane, the optical system is focused on the same plane on which the reference mark and the reference scale are displayed. A calibration tool mounting part for positioning to a position;In an automatic calibration method of an enlargement imaging device comprising a processing device that executes calibration for calculating an actual dimension corresponding to a unit pixel of the display screen,A step of recognizing the reference mark and the reference scale from an image obtained by the image pickup device; a step of determining the magnification range according to the type of the recognized reference mark; The calibration is automatically executed based on the number of pixels corresponding to the length of the reference scale corresponding to the magnification range.It is characterized by that.
[0010]
According to such a configuration, accurate calibration can be automatically performed with a normal interchangeable lens unit without using a special interchangeable lens unit having a function of reading optical magnification (zoom ratio). For example, when a zoom operation is performed, if a calibration tool prepared in advance is inserted into the field of view of the optical system, calibration is automatically executed. Once the calibration is completed, the calibration tool is not necessary and can be extracted from the field of view of the optical system. Thus, even if the zoom operation is performed with a normal interchangeable lens unit, the length of the line segment on the display screen, the radius of the circle, the area of the closed figure, etc. can be converted into actual dimensions and accurately measured. become.Further, even when the magnification range changes greatly, the reference scale length can be set within an appropriate pixel number range. In other words, by preparing multiple types of reference scales with different actual dimensions according to the magnification range and displaying a reference mark for identifying them together with the reference scale, multiple types of interchangeable lens units with greatly different magnification ranges can be obtained. Even when measurement is performed while exchanging, accurate calibration is automatically performed by using a reference scale on which a reference mark corresponding to the magnification range of each interchangeable lens unit is displayed.
[0013]
Further, the magnifying image pickup apparatus of the present invention includes an optical system and an image sensor including a lens unit including an objective lens for acquiring an enlarged image of a measurement object, a display unit that displays the acquired image on a display screen,The reference scale is provided between the objective lens and the measurement object in the optical axis direction of the optical system, and the reference scale corresponds to each of the reference scale and the reference scale having different actual dimensions according to the magnification range of the optical system. In order to identify the calibration tool in which the reference mark displayed together with the reference scale is displayed on the same plane, the optical system is focused on the same plane on which the reference mark and the reference scale are displayed. A calibration tool mounting part for positioning to a position;In a magnifying imaging device comprising: a processing device that executes calibration for calculating an actual dimension corresponding to a unit pixel of the display screen, the processing device includes:Recognizing the reference mark and the reference scale from an image obtained by the image sensor;The magnification range is determined according to the recognized type of the reference mark, and the calibration is automatically performed based on the number of pixels corresponding to the length of the reference scale according to the determined magnification range. It is characterized by doing.
[0014]
According to such a configuration, an enlargement imaging apparatus that automatically performs accurate calibration with a normal interchangeable lens unit without using a special interchangeable lens unit having a function of reading an optical magnification (zoom ratio) is realized. be able to. That is, when a zoom operation is performed, if a calibration tool prepared in advance is inserted into the field of view of the optical system, calibration is automatically executed.Further, even when the magnification range changes greatly, the reference scale length can be set within an appropriate pixel number range. In other words, by preparing multiple types of reference scales with different actual dimensions according to the magnification range and displaying a reference mark for identifying them together with the reference scale, multiple types of interchangeable lens units with greatly different magnification ranges can be obtained. Even when measurement is performed while exchanging, accurate calibration is automatically performed by using a reference scale on which a reference mark corresponding to the magnification range of each interchangeable lens unit is displayed.
[0016]
preferableIn the embodiment, the magnifying imaging device includes a diffuse illumination attachment attached to the tip of the optical system to illuminate the measurement object with diffuse light, and inserts a calibration tool from a direction perpendicular to the optical axis of the optical system. An opening is formed on the side surface of the diffuse illumination attachment.
[0017]
The calibration tool of the present invention used in the above-described enlargement imaging apparatus is inserted through an opening formed on the side surface of the diffuse illumination attachment, and has a tip at 45 degrees with respect to the optical axis of the optical system. A mirror having a reflective surface with a certain angle is attached, and a reference scale surface on which a reference scale is displayed is provided at a base end portion perpendicular to the optical axis from the mirror, and the focal point of the optical system is connected to the reference scale surface. As described above, the distance between the mirror and the reference scale surface is set.
[0018]
According to such a configuration, the calibration tool is inserted from the opening on the side surface of the diffuse illumination attachment when the calibration is necessary due to the zoom operation or the like, and when the calibration re-execution is not necessary, the calibration tool is inserted. Extraction can be easily performed.
[0019]
In yet another preferred embodiment, the magnifying imaging device includes a diffuse illumination attachment attached to the tip of the optical system for illuminating the measurement object with diffuse light, and the calibration tool is attached to the tip of the diffuse illumination attachment. The reference scale is displayed on the inner surface of the cap-shaped member to be mounted. When the focal plane of the optical system is located at the tip of the diffuse illumination attachment, the reference scale is recognized by the processor simply by placing the diffuse illumination attachment with such a simple configuration on the tip of the diffuse illumination attachment. Accurate calibration is performed. After the calibration is completed, the calibration tool can be removed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a block diagram showing a configuration of an enlargement imaging apparatus (video microscope) according to an embodiment of the present invention. This magnified imaging device includes a lamp 11 for illuminating a measurement object (hereinafter referred to as a workpiece) WK, a camera unit 12 incorporating an image sensor (CCD) 20, a CCD drive circuit 13, a processing device 14, a display device 15, The interface 16 is configured. A lens unit (interchangeable lens unit) 19 that is an optical system is attached to the tip of the camera unit 12, and a diffuse illumination attachment 17 is attached to the tip of the camera unit 12.
[0022]
The illumination light emitted from the lamp passes through the optical fiber 18 and exits from the diffuse illumination attachment 17 attached to the tip of the lens unit 19 to illuminate the work WK. The reflected light from the work WK is condensed on the image sensor 20 of the camera unit 12 through the lens unit 19. The image sensor 20 converts a light signal including image information of the workpiece WK into an electrical signal. The electric signal is input to the processing device 14 through the CCD driving circuit 13.
[0023]
The processing device 14 includes an image memory 21, an image processing means 22, and a measurement means 23. The image processing means 22 and the measurement means 23 are constituted by microprocessor software. The signal from the CCD drive circuit 13 is stored in the image memory 21 and then undergoes image processing such as edge enhancement by two-dimensional filter processing performed by the image processing means 22 to become a predetermined image signal. This image signal is given to the display device 15, and an enlarged image of the work WK is displayed on the screen of the display device 15. The display device 15 is composed of, for example, a high-definition liquid crystal monitor device capable of SXGA display (display with a pixel number of 1280 × 1024).
[0024]
The enlarged image displayed on the display device 15 can be printed out from the video printer 24 connected to the processing device 14 via the interface 16. As the video printer 24, for example, a sublimation thermal transfer type digital color printer is used, whereby a clear and high-quality color print can be obtained.
[0025]
Further, an auxiliary storage device 25 is also connected to the interface 16, and an enlarged image displayed on the display device 15 can be stored and stored in the auxiliary storage device 25. As the auxiliary storage device 25, for example, a high-density magnetic disk device (super disk) that is upwardly compatible with a flexible disk is used. This high-density magnetic disk device has a storage capacity of 120 MByte. The image file is recorded, for example, in the JPEG format (compressed image data) or the TIFF format (uncompressed image data). Image files and text files stored on a super disk or flexible disk can be read and used by another personal computer equipped with a disk reader.
[0026]
Further, a mouse 26 as a pointing device is connected to the interface 16. The mouse 26 is used to make various settings of the magnifying image pickup device and instruct various operations based on a selection menu or message displayed on the display device 15. Basically, all functions of the magnifying image pickup device can be used only by this mouse operation.
[0027]
The measuring means 23 performs a process of measuring the distance (the length of the line segment) between the two points indicated on the enlarged image displayed on the display device 15 and displaying the measured value. In addition to the length of the line segment, the radius of curvature of the curve, an angle determined by arbitrary three points, an area surrounded by a straight line connecting a plurality of arbitrary points, and the like can also be measured. The mouse 26 is also used to indicate points necessary for measurement on the screen. In addition, in order to measure the length, area, and the like as described above with actual dimensions, the measurement unit 23 executes calibration for calculating the actual dimensions per pixel.
[0028]
Normally, the actual size per pixel can be calculated from the magnification of the optical system (and the magnification of the screen display), but when the zoom operation is performed using the zoom lens unit, the current zoom ratio is read. A zoom lens unit having no function cannot accurately determine the magnification of the optical system. Even in such a case, the magnifying imaging apparatus of the present embodiment can perform accurate calibration by the processing described later.
[0029]
FIG. 2 is a diagram showing the lens unit 19 and the diffuse illumination attachment 17 attached to the tip of the lens unit 19. In FIG. 2, the left side shows the outer shape from the center line AX, which is the optical axis of the lens unit 19 (optical system), and the right side shows a cross section. An optical system composed of a plurality of lenses is built in the internal space of the cylindrical lens unit 19, but only the objective lens 19a is depicted in FIG.
[0030]
An optical fiber 18 is provided in the cylindrical member 19b of the lens unit 19 so as to penetrate in the axial direction. A plurality of optical fibers 18 are provided at regular intervals in the circumferential direction, and are configured so that annular illumination light is irradiated from the tip of the cylindrical member 19 b of the lens unit 19. The light emitted from the tip of the optical fiber 18 is incident on the light guide member 35 of the diffuse illumination attachment 17 from the upper surface and is emitted from the conical inner surface (lower surface). A light diffusion surface is formed on the inner surface of the light guide member 35, and the emitted light is diffused in all directions as indicated by an arrow line LT. An opening 34 into which a calibration tool 27 (to be described later) is inserted is formed on the side surface of the movable ring 32 constituting the diffuse illumination attachment 17.
[0031]
FIG. 3 is a view showing the diffuse illumination attachment 17 in a state where the calibration tool 27 is inserted. The diffuse illumination attachment 17 includes a mounting ring 31 and a movable ring 32 that are metal processed products, and a light guide member 35 that is a resin processed product. A calibration tool 27 is inserted into an opening 34 formed on the side surface of the movable ring 32.
[0032]
A groove 31 a is formed on the entire outer periphery of the lower portion of the attachment ring 31 over 360 degrees, and four small screws (headless screws) 33 that engage with the groove 31 a are attached to the movable ring 32. The movable ring 32 is configured to be rotatable with respect to the mounting ring 31 in a state where the plurality of small screws 33 are engaged with the groove 31 a. A slit 36 penetrating in the radial direction is formed in the upper part of the movable ring 32, and a light shielding plate (not shown) is inserted into the slit 36. The light shielding plate partially blocks the annular illumination light described above. Then, by rotating the movable ring 32 relative to the attachment ring 31, the direction in which the illumination light strikes the workpiece WK can be adjusted.
[0033]
The light guide member 35 is made of a transparent resin (acrylic resin or the like), and the upper surface 35a on which the irradiation light is incident is polished so as to suppress light reflection loss. A light reflecting surface 35b on which aluminum is deposited is formed on the outer peripheral surface. The light reflecting surface 35b functions as a light reflecting film that prevents outside light from entering the inside of the light guide member 35 and suppresses a loss of the irradiation light LT incident on the light guide member 35 to the outside. Instead of vapor deposition of the aluminum layer, the light reflecting surface 35b may be formed by attaching a reflective film or covering a metal cover. On the inner peripheral surface, a light diffusion surface 35c for diffusing the emitted light is formed as described above.
[0034]
The distal end portion of the diffuse illumination attachment 17, that is, the distal end portion 35d of the light guide member 35 is often set so as to cover the workpiece WK. By doing so, only the light from the diffuse illumination attachment 17 illuminates the work WK, excluding the influence of outside light, so that a clear image of the work WK can be obtained. In this case, the focus of the lens unit 19 (optical system) is adjusted to the vicinity of the front end portion 35 d of the light guide member 35.
[0035]
FIG. 4 is a diagram showing a structural example of the calibration tool 27. (A) is a plan view, (b) is a side view, and (c) is a reference scale surface (inner surface) 29a.
[0036]
As shown in FIG. 3, the calibration tool 27 is inserted through an opening 34 formed on the side surface of the movable ring 32 of the diffuse illumination attachment 17, and has a tip at 45 degrees with respect to the optical axis AX of the optical system. And a reference scale surface 29a on which a reference scale 41 is displayed is provided at the base end portion away from the mirror 28 in the direction perpendicular to the optical axis AX. That is, the calibration tool 27 has a frame structure in which the mirror 28 at the distal end and the base end member 29 are connected by a pair of side surface members 27a, and the inner surface of the base end member 29 is the reference scale surface 29a. .
[0037]
A reference mark 42 determined in advance according to the magnification range of the lens unit (optical system) 19 is displayed on the reference scale surface 29a together with a reference scale 41 having a predetermined length. For example, a double circle reference mark 42 as shown in FIG. 4C represents a high magnification zoom lens, a single circle reference mark represents a medium magnification zoom lens, and a black circle reference mark represents a low magnification lens. As described above, one of the predetermined reference marks is displayed on the reference scale surface 29 a together with the reference scale 41. In FIG. 4C, the sizes of the reference scale 41 and the reference mark 42 are exaggerated.
[0038]
Further, the distance between the mirror 28 and the reference scale surface 29a is such that the focal point of the lens unit (optical system) 19 is determined by the optical path bent at a right angle by the reflection surface 28a of the mirror 28 as indicated by a broken line LP in FIG. It is determined to be tied to 29a. Of course, if the position of the opening 34 formed on the side surface of the movable ring 32 in the direction of the optical axis AX is determined, the appropriate distance is determined, which is irrelevant to the insertion depth of the calibration tool 27 with respect to the optical axis AX.
[0039]
In the magnifying imaging apparatus of this embodiment, the processing device 14 (the measuring unit 23) automatically executes calibration by using the calibration tool 27 as described above. That is, the processing device 14 performs processing as shown in FIG. 5 at regular intervals by timer interruption, and the calibration tool 27 is inserted from the opening 34 formed on the side surface of the movable ring 32 as shown in FIG. If so, calibration is automatically performed.
[0040]
FIG. 5 is a flowchart of timer interrupt processing performed by the processing device 14 for automatic calibration. In step # 101, it is checked whether or not the reference mark 42 is present in the image obtained from the image sensor 20. When there is no reference mark 42, it is a case where the calibration tool 27 is not inserted, and the timer interruption process is terminated and the process returns to the main routine.
[0041]
If there is a reference mark 42, the magnification range of the optical system (lens unit 19) corresponding to the reference mark 42 is determined (step # 102). In the subsequent step # 103, the edges (both ends) of the reference scale 41 displayed next to the reference mark 42 are extracted, and the length between the edges (reference scale length) is measured (step # 104). That is, the number of pixels corresponding to this length is measured.
[0042]
In the next step # 105, it is checked whether or not there is a change in the measurement value (number of pixels) of the reference scale length. If there is no change, the timer interruption process is terminated and the process returns to the main routine. If there is a change, the length (actual dimension) per pixel is calculated based on the magnification range determined in step # 102 and the number of pixels corresponding to the reference scale length measured in step # 104. It is set (step # 106). For example, when the measurement value of the reference scale length with an actual dimension of 1 mm is 200 pixels, an actual dimension of 5 μm per pixel is calculated and set. This completes automatic calibration and returns to the main routine.
[0043]
FIG. 6 is a diagram illustrating a structure example of a calibration tool 27 according to another embodiment. (A) is sectional drawing of the diffuse illumination attachment 17 which mounted | wore the calibration tool 27, (b) has shown the reference | standard scale surface (inner surface) 29a of the calibration tool 27. FIG. In FIG. 6B, the sizes of the reference scale 41 and the reference mark 42 are exaggerated.
[0044]
The calibration tool 27 is attached to the distal end portion of the diffuse illumination attachment 17 (that is, the distal end portion of the light guide member 35) when calibration becomes necessary due to replacement of the lens unit 19 or the like. That is, the inner surface of the cap-shaped member attached to the distal end portion of the light guide member 35 is the reference scale surface 29a. Like the calibration tool 27 shown in FIG. 4, the reference scale 41 and the reference mark are placed on the reference scale surface 29a. 42 is displayed.
[0045]
As described above, the lens unit (optical system) 19 is usually focused on the vicinity of the tip of the light guide member 35. Therefore, if the calibration tool 27 is attached to the tip of the light guide member 35 as shown in FIG. 6, the reference scale surface 29a is focused, and the reference scale 41 and the reference are included in the image obtained from the image sensor 20. The mark 42 is recognized.
[0046]
Also in this embodiment, calibration is automatically performed by the processing executed by the processing device 14 described with reference to FIG. However, unlike the calibration tool 27 shown in FIG. 4, the cap-shaped calibration tool 27 of this embodiment is attached to the distal end portion of the diffuse illumination attachment 17 only when calibration is necessary, and calibration is performed. You will need to remove it when you are done.
[0047]
As mentioned above, although embodiment of this invention was described, this invention is not restricted to said embodiment, It can implement with a various form. The calibration tool 27 is not limited to the structure illustrated in FIG. 4 or FIG. 6. For example, a reference scale 41 (and a reference mark 42) may be displayed on the surface of a simple plate. In this case, if the reference scale 41 (and the reference mark 42) is imaged in the same manner as a normal work and WK, the above-described calibration is executed.
[0048]
Further, the structure of the calibration tool shown in FIG. 4 is only an example of the most simplified structure. In order to avoid the adverse effects of external light, the space between the pair of side members 27a may be covered with a top plate and a bottom plate to form a box shape. Such a structure is preferable in order to ensure mechanical strength. As a matter of course, it is necessary to provide an opening so that the upper portion of the mirror 28 is not covered with the top plate.
[0049]
In the above embodiment, the processing device 14 repeatedly performs calibration at regular intervals by timer interruption. However, as another embodiment, the calibration is performed only once when the calibration tool is set in the field of view of the optical system. May be executed. Alternatively, calibration by timer interruption may be repeatedly executed for a predetermined time. For example, when the calibration tool is set in the field of view of the optical system, the above processing is triggered by the processing device 14 processing the image obtained from the image sensor 20 and identifying the reference scale 41 or the reference mark 42. Can be executed automatically.
[0051]
【The invention's effect】
As described above, according to the automatic calibration method and the magnification imaging apparatus and the calibration tool of the magnification imaging apparatus of the present invention, even without using a special interchangeable lens unit having a function of reading the optical magnification, Accurate calibration can be automatically performed with a normal interchangeable lens unit. Thus, even when a zoom operation is performed with a normal interchangeable lens unit, the length of a line segment on a display screen, the radius of a circle, the area of a closed figure, and the like can be converted into actual dimensions and accurately measured.Further, even when the magnification range changes greatly, the reference scale length can be set within an appropriate pixel number range. In other words, by preparing multiple types of reference scales with different actual dimensions according to the magnification range and displaying a reference mark for identifying them together with the reference scale, multiple types of interchangeable lens units with greatly different magnification ranges can be obtained. Even when measurement is performed while exchanging, accurate calibration is automatically performed by using a reference scale on which a reference mark corresponding to the magnification range of each interchangeable lens unit is displayed.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a magnification imaging apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a lens unit and a diffuse illumination attachment attached to the tip of the lens unit.
FIG. 3 is a diagram showing a diffuse illumination attachment with a calibration tool inserted.
FIG. 4 is a view showing a structural example of a calibration tool.
FIG. 5 is a flowchart of timer interrupt processing performed by the processing device for automatic calibration.
FIG. 6 is a view showing a structural example of a calibration tool according to another embodiment.
[Explanation of symbols]
14 Processing equipment
15 Display device (display unit)
17 Diffuse lighting attachment
19 Lens unit (optical system)
20 Image sensor (image sensor)
27 Calibration tools
28 Mirror
29a Reference scale surface
41 Reference scale
42 fiducial mark
AX Optical axis of optical system
34 Opening

Claims (7)

An optical system and an imaging device including a lens unit including an objective lens for acquiring an enlarged image of the measurement object;
A display unit for displaying the acquired image on the display screen;
The reference scale is provided between the objective lens and the measurement object in the optical axis direction of the optical system, and the reference scale corresponds to each of the reference scale and the reference scale having different actual dimensions according to the magnification range of the optical system. In order to identify the calibration tool in which the reference mark displayed together with the reference scale is displayed on the same plane, the optical system is focused on the same plane on which the reference mark and the reference scale are displayed. A calibration tool mounting part for positioning to a position;
In an automatic calibration method of an enlargement imaging device comprising a processing device that executes calibration for calculating an actual dimension corresponding to a unit pixel of the display screen,
Recognizing the reference mark and the reference scale from an image obtained by the image pickup device by the processing device;
Determining the magnification range according to the type of the recognized reference mark;
Automatically executing the calibration based on the number of pixels corresponding to the length of the reference scale according to the determined magnification range;
An automatic calibration method for an enlargement imaging apparatus comprising: By exchanging multiple types of the lens units with different magnification ranges, the magnification range is changed,
2. The automatic calibration method according to claim 1, wherein the calibration is performed by using the reference scale on which the reference mark corresponding to the magnification range is displayed. 3. The automatic calibration method according to claim 1, wherein the lens unit is a zoom lens, and the optical magnification of the lens unit is continuously changed by a zoom operation of the zoom lens. An optical system and an imaging device including a lens unit including an objective lens for acquiring an enlarged image of the measurement object;
A display unit for displaying the acquired image on the display screen;
The reference scale is provided between the objective lens and the measurement object in the optical axis direction of the optical system, and the reference scale corresponds to each of the reference scale and the reference scale having different actual dimensions according to the magnification range of the optical system. In order to identify the calibration tool in which the reference mark displayed together with the reference scale is displayed on the same plane, the optical system is focused on the same plane on which the reference mark and the reference scale are displayed. A calibration tool mounting part for positioning to a position;
A processing device for performing calibration to calculate actual dimensions corresponding to unit pixels of the display screen;
In a magnifying imaging device comprising:
The processing device recognizes the reference mark and the reference scale from an image obtained by the image sensor , determines the magnification range according to the recognized type of the reference mark, and determines the determined magnification range. An enlargement imaging apparatus, wherein the calibration is automatically executed based on the number of pixels corresponding to the length of the reference scale. An opening for inserting the calibration tool from a direction perpendicular to the optical axis of the optical system, comprising a diffuse illumination attachment attached to the tip of the optical system for illuminating the measurement object with diffused light The magnifying imaging device according to claim 4, wherein the magnifying imaging device is formed on a side surface of the diffuse illumination attachment. 6. A calibration tool used in the magnifying imaging device according to claim 5, wherein the tip is inserted from an opening formed in a side surface of the diffuse illumination attachment with respect to the optical axis of the optical system. A mirror having a reflection surface with an angle of 45 degrees is attached, and a reference scale surface on which the reference scale is displayed is provided at a base end portion away from the mirror in a direction perpendicular to the optical axis. A calibration tool, wherein a distance between the mirror and the reference scale surface is set so as to be connected to the reference scale surface. 5. A calibration tool used in the magnifying imaging apparatus according to claim 4, wherein a diffusion is attached to the tip of the optical system in order to illuminate the measurement object with diffused light at the tip of the optical system. A calibration tool, wherein the reference scale and the reference mark are displayed on the inner surface of an upper cap member attached to the tip of the illumination attachment.

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