Optical axis adjustment system, optical axis adjustment method, jig used for optical axis adjustment method, and program

Abstract

Provided is an optical axis adjustment system (1) that adjusts a surface to be imaged by an imaging device (300) and an optical axis of the imaging device (300). A mirror (11) is disposed on the surface to be imaged, and a jig is disposed on a mirror surface of the mirror (11). The jig includes: a guide that can be imaged by the imaging device (300); and a support part that supports the guide at a position separated from the mirror surface by a predetermined distance. The optical axis adjustment system comprises: a surface-to-be-imaged drive unit that moves or tilts the surface to be imaged; an imaging device drive unit that moves or tilts the imaging device (300); and a control means that controls the surface-to-be-imaged drive unit or the imaging device drive unit so that a real image of the guide and a mirror image thereof overlap in the captured image.

Description

Optical axis adjustment system, optical axis adjustment method, jig and program used in the optical axis adjustment method

[0001] The present disclosure relates to an optical axis adjustment system, an optical axis adjustment method, and a jig and program used in the optical axis adjustment method.

[0002] Techniques for adjusting the optical axis of an imaging device are known. For example, Patent Document 1 discloses a method of photographing an adjustment jig made up of two fixed plates with holes with a camera and adjusting the angle of the camera so that the holes in the front and back plates are aligned in the center when photographed. Also, Patent Document 2 discloses a method of placing a mirror on an adjustment jig for product assembly and adjusting the tilt of a microscope so that the real image and the mirror image reflected in the mirror of the adjustment jig coincide.

[0003] Japanese Patent Application Laid-Open No. 2005-049590 Japanese Patent Application Laid-Open No. 2008-070218

[0004] When adjusting the optical axis using an adjustment jig, a high-precision adjustment jig is often required. However, manufacturing the adjustment jig is time-consuming and significantly affects work efficiency. For example, in the technology disclosed in Patent Document 1, the manufacturing accuracy of the adjustment jig is directly related to the accuracy of the optical axis adjustment, so the adjustment jig must be manufactured, calibrated, and maintained with high precision, resulting in low work efficiency. Furthermore, in the technology disclosed in Patent Document 2, a mounting portion for a mirror dedicated to optical axis adjustment is formed on an adjustment jig manufactured with high precision for product assembly. During optical axis adjustment, the mirror must be mounted on the mounting portion while taking into consideration parallelism, and then removed after the optical axis adjustment is complete. This makes it more difficult to manufacture and maintain an adjustment jig manufactured with high precision for product assembly, resulting in low work efficiency. Furthermore, since the accuracy of the optical axis of the mirror mounted on the adjustment jig is directly related to the accuracy of the optical axis adjustment, optical adjustment of the mirror is essentially required before the optical adjustment.

[0005] For this reason, it is required to easily adjust the optical axis using a simple jig.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an optical axis adjustment system that easily performs optical axis adjustment using a simple jig, an optical axis adjustment method, and a jig and program used in the optical axis adjustment method.

[0007] In order to achieve the above object, the optical axis adjustment system according to the present disclosure is an optical axis adjustment system that adjusts the image target surface of an imaging device and the optical axis of the imaging device, wherein a mirror is arranged on the image target surface and a jig used for adjustment is arranged on the mirror surface of the mirror, the jig including a guide that can be imaged by the imaging device and a support part that supports the guide at a position a predetermined distance from the mirror surface, and is equipped with an image target surface drive part that moves or tilts the image target surface on which the mirror is placed, an imaging device drive part that moves or tilts the imaging device, and a control means that controls the image target surface drive part or the imaging device drive part so that the real image of the guide and the mirror image reflected on the mirror surface of the guide overlap on the image captured by the imaging device.

[0008] According to the present disclosure, the optical axis can be adjusted by placing a mirror and a jig on the surface of the object to be imaged and taking an image, which makes it easy to adjust the optical axis.

[0009] FIG. 1 is a block diagram showing an example of the overall configuration of an optical axis adjustment system according to the first embodiment; FIG. 2 is a diagram for explaining an example of alignment performed after optical axis adjustment by the optical axis adjustment system according to the first embodiment; FIG. 3 is a diagram for explaining an image pickup device, a mirror, and a jig according to the first embodiment; FIG. 4 is a diagram for explaining optical axis adjustment according to the first embodiment; FIG. 5 is a plan view for explaining horizontal movement of a mounting table in the first embodiment; FIG. 6 is a side view for explaining angle adjustment of an image pickup device in the first embodiment; FIG. 7 is a block diagram showing an example of the configuration of an operation control unit according to the first embodiment; FIG. 8 is a block diagram showing an example of the configuration of an image processing unit according to the first embodiment;

[0010] An optical axis adjustment system, an optical axis adjustment method, and a jig and program used in the optical axis adjustment method according to this embodiment will be described in detail below with reference to the drawings. Note that the same or corresponding parts in the drawings are designated by the same reference numerals.

[0011] The optical axis adjustment system according to this embodiment includes a mounting table on which a workpiece is placed and an imaging device that images the workpiece, and is applicable to various systems that require optical axis adjustment to adjust the mounting surface of the mounting table and the optical axis of the imaging device at a right angle.

[0012] As an example of an application, a substrate bonding apparatus that bonds two plate-like workpieces such as semiconductor substrates with high precision in a semiconductor manufacturing process will be described with reference to FIG.

[0013] Positioning markers Mk are formed on each of the two workpieces 1001 and 1002 to be bonded together. The substrate bonding apparatus positions the two workpieces 1001 and 1002 so that the markers Mk overlap, and then bonds them together.

[0014] The workpiece 1002 to be assembled is placed on a flat mounting surface 102 of a mounting table 101 of an alignment mechanism 100, which is capable of translational and rotational movement. The workpiece 1001 to be assembled is gripped and moved by a hand (not shown) or the like. Because the distance the workpiece 1001 moves from the supply position to the attachment position is long compared to the precision required for the final joining, it is not good at fine position adjustment and moves the same way every time. On the other hand, the alignment mechanism 100 has a short maximum adjustment distance but can move with high precision, so it performs position correction based on the relative distance between two markers Mk obtained from the image captured by the imaging device 300. This enables high-precision joining of the two workpieces 1001 and 1002 at the position where the markers Mk overlap.

[0015] If the imaging device 300 used for positioning is tilted relative to the surface to be imaged, i.e., the surface of the workpieces 1001 and 1002, a bias in the distance per pixel will occur throughout the entire imaging area of ​​the image element, resulting in a deterioration in the accuracy of image recognition. Image correction may be considered as a solution, but since image correction involves processing such as stretching, the bias within the image can be corrected, but the bias in the amount of information per pixel will remain in principle. Therefore, the accuracy of image recognition will be deteriorated compared to when the imaging device is positioned directly in front of the workpiece.

[0016] Furthermore, as explained in the section on the prior art, it is costly to manufacture, calibrate, and use a highly accurate jig, and then maintain that high accuracy.

[0017] Therefore, in this embodiment, an optical axis adjustment function is provided that does not require high machining precision of the jig by performing relative translation between the imaging device and the object to be photographed and adjusting the optical axis of the imaging device.Furthermore, by providing a function to assist the adjustment work, an inexpensive and highly convenient optical axis adjustment device is provided.

[0018] Next, the overall configuration of the optical axis adjustment system 1 according to the first embodiment will be described with reference to Fig. 1. Note that the following configuration corresponds to the configuration of an apparatus that requires optical axis adjustment, for example, the aforementioned substrate bonding apparatus, extracted from the configuration of the portion used for optical axis adjustment.

[0019] As shown in FIG. 1, the optical axis adjustment system 1 includes an alignment mechanism 100, an imaging device 300, an operation control unit 200 that controls the alignment mechanism 100 and the imaging device 300, an image processing unit 400 that processes images captured by the imaging device 300, and a setting terminal 500 that performs various settings used for processing in the image processing unit 400.

[0020] The alignment mechanism 100 includes a mounting table 101 and an X-axis driver 111, a Y-axis driver 112, and a θ driver 113 that move the mounting table 101 in the horizontal direction. The X-axis driver 111, the Y-axis driver 112, and the θ driver 113 each include an actuator, and together they form an X-Y-θ stage. As shown in FIG. 6, this X-Y-θ stage moves the mounting table 101 in the horizontal X-axis direction, the Y-axis perpendicular to the X-axis, and around the vertical θ-axis. The X-axis driver 111, the Y-axis driver 112, and the θ driver 113 each include a position sensor such as an encoder that detects their position and outputs a position signal.

[0021] 6 moves as the X-Y-θ stage moves the mounting table 101 horizontally. The amount of horizontal movement of the mounting table 101, i.e., the distance on the mounting table 101, and the corresponding number of pixels in the captured image are previously determined in association with each other and stored in the operation control unit 200. Therefore, the amount of movement of the image can be determined in pixel units from the amount of movement of the mounting table 101, and it is also possible to determine the amount of movement of the mounting table 101 from the number of pixels in the image.

[0022] 1, drive control devices 121, 122, and 123 are connected to X-axis drive device 111, Y-axis drive device 112, and θ drive device 113, respectively. Drive control devices 121, 122, and 123 control the positions of X-axis drive device 111, Y-axis drive device 112, and θ drive device 113, respectively, based on control signals from motion control unit 200 and position signals from X-axis drive device 111, Y-axis drive device 112, and θ drive device 113. Drive control devices 121, 122, and 123 are each composed of, for example, a servo amplifier. X-axis drive device 111, Y-axis drive device 112, θ drive device 113, and drive control devices 121 to 123 collectively are an example of an imaging target surface drive device that drives an imaging target surface.

[0023] The imaging device 300 is an imaging device that images the mounting table 101 from above the alignment mechanism 100, and is a camera with sufficient resolution to achieve precision in optical axis adjustment of the optical axis adjustment system 1. Imaging can be performed under various conditions. For example, imaging can be performed in accordance with an imaging command sent to the imaging device 300 from another device, or it can be performed continuously at regular intervals during adjustment work when captured images are continuously visually checked. The imaging device 300 is installed above approximately the center of the mounting table 101 of the alignment mechanism 100. The target imaged by the imaging device 300 is the mounting surface 102 of the mounting table 101, and its optical axis is adjusted to be perpendicular to the mounting surface 102, i.e., the surface to be imaged.

[0024] 3A, the imaging device 300 includes an imaging element 302 and a lens 304. The imaging element 302 includes a semiconductor imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) imaging element. The lens 304 forms an image of a subject on the imaging surface of the imaging element 302.

[0025] The imaging device 300 is equipped with a gimbal mechanism 301 that adjusts the tilt angle of the imaging device 300. As shown in FIG. 1, a gimbal driver 311 is connected to the gimbal mechanism 301. The gimbal driver 311 includes an actuator and drives the gimbal mechanism 301 to individually adjust the tilt angle φx around the X axis and the tilt angle φy around the Y axis of the imaging device 300, as shown in FIG. 7. The gimbal driver 311 also includes an angle sensor such as a rotary encoder, detects the tilt angles φx and φy, and outputs tilt angle signals. Note that in FIG. 7, the tilt angle φy is indicated by the angle difference with respect to the vertical direction Ag.

[0026] The imaging position of imaging device 300 changes as the tilt angles φx and φy of imaging device 300 change. For example, as shown in Fig. 7 , a change in tilt angle φy around the y-axis causes the imaging range Ar to move in the X-axis direction. The amount of change in tilt angles φx and φy and the number of pixels on the captured image corresponding to the amount of change in tilt angles φx and φy are previously determined in association with each other and stored in operation control unit 200.

[0027] 1 , a drive control device 321 is connected to the gimbal driver 311. The drive control device 321 controls the gimbal driver 311 and adjusts the tilt angles φx and φy based on a control signal from the motion control unit 200 and a tilt angle signal from the gimbal driver 311. The drive control device 321 is, for example, a servo amplifier. The gimbal driver 311 and the drive control device 321 as a whole are an example of an imaging device driver that tilts or moves the imaging device 300.

[0028] The motion control unit 200 is a motion controller that issues commands to the drive control devices 121, 122, 123, and 321 regarding the operations of the X-axis drive unit 111, the Y-axis drive unit 112, the θ drive unit 113, and the gimbal drive unit 311, and includes, for example, a PLC (Programmable Logic Controller). The motion control unit 200 generates control signals based on information acquired from the drive control devices 121, 122, 123, and 321 and the image processing unit 400, and outputs the control signals to the drive control devices 121, 122, 123, and 321.

[0029] 8, the operation control unit 200 includes a processor 210, a volatile memory 220, a non-volatile memory 230, a clock 240, and a communication interface 250. The processor 210, the volatile memory 220, the non-volatile memory 230, the clock 240, and the communication interface 250 are communicatively connected to one another via a bus B1.

[0030] The processor 210 includes, for example, a CPU (Central Processing Unit), and functions as a movement amount calculation unit 212 and a command unit 213 by reading and executing a control program stored in a control program storage unit 231 of the non-volatile memory 230.

[0031] The movement amount calculation section 212 of the processor 210 calculates the movement amounts by which the mounting table 101 is moved in the X direction, Y direction, and θ direction, based on the captured image processed by the image processing unit 400. The movement amount calculation section 212 also calculates the adjustment amount of the tilt angle of the imaging device 300, based on the captured image processed by the image processing unit 400. The command section 213 outputs a control signal based on the movement amount calculated by the movement amount calculation section 212 to the drive control devices 121, 122, and 123. The command section 213 also outputs a control signal based on the adjustment amount calculated by the movement amount calculation section 212 to the drive control device 321. Details of the processing performed by the movement amount calculation section 212 will be described later.

[0032] The volatile memory 220 is a work memory that can read and write data at high speed during arithmetic processing executed by the processor 210, and includes, for example, a RAM (Random Access Memory). The non-volatile memory 230 includes a control program storage unit 231 that stores control programs for implementing various functions of the operation control unit 200, and a control data storage unit 232 that stores control data including parameters used when executing the control programs, past detection data, and command data. The non-volatile memory 230 includes, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory), a non-volatile semiconductor memory such as a flash memory, a magnetic disk, or an optical disk.

[0033] The clock 240 includes a real-time clock (RTC) and synchronizes the operation of the drive control devices 121 , 122 , 123 , and 321 .

[0034] The communication interface 250 is an interface for the operation control unit 200 to communicate with the drive control devices 121, 122, 123, 321, the imaging device 300, and the image processing unit 400, and includes an interface that complies with communication standards such as CC-Link IE / field and CC-Link IE / TSN.

[0035] 1 processes the captured image acquired from the imaging device 300 to obtain adjustment information representing information related to the position of the alignment mechanism 100 and the adjustment of the tilt angle of the imaging device 300. Details of the processing executed by the image processing unit 400 will be described later.

[0036] 9, the image processing unit 400 includes a processor 410, a volatile memory 420, a non-volatile memory 430, and a communication interface 440. The processor 410, the volatile memory 420, the non-volatile memory 430, and the communication interface 440 are communicatively connected to one another via a bus B2.

[0037] The processor 410 includes, for example, a CPU, and functions as an image acquisition unit 411 and an adjustment information calculation unit 414 by reading and executing a control program stored in a control program storage unit 431 of the nonvolatile memory 430 .

[0038] An image acquisition unit 411 of the processor 410 acquires an image captured by the imaging device 300. An adjustment information calculation unit 414 processes the captured image to obtain adjustment information. Details of this processing will be described later.

[0039] The volatile memory 420 is a work memory, such as a RAM, that can read and write data at high speed during arithmetic processing executed by the processor 410. The nonvolatile memory 430 includes a control program storage unit 431 that stores control programs for implementing various functions of the image processing unit 400, and a control data storage unit 432 that stores control data including parameters used when executing the control programs and past detection data. The nonvolatile memory 430 includes, for example, a nonvolatile semiconductor memory such as an EEPROM or a flash memory, a magnetic disk, or an optical disk.

[0040] The communication interface 440 is an interface for the image processing unit 400 to communicate with the drive control devices 121, 122, 123, 321, the operation control unit 200, and the imaging device 300, and includes an interface that complies with communication standards such as CC-Link IE / field and CC-Link IE / TSN.

[0041] 1 is a terminal installed with an application program capable of managing the image processing unit 400, and includes, for example, a personal computer. The setting terminal 500 has a function for managing the image processing unit 400, including inputting or changing parameters stored in the non-volatile memory 430 of the image processing unit 400. The setting terminal 500 also displays information including calculated values ​​output by the image processing unit 400 or the operation control unit 200. The communication interface used by the setting terminal 500 to communicate with the image processing unit 400 is any interface corresponding to the interface of the image processing unit 400, and includes, for example, a USB interface or an RS232C interface. The operation control unit 200 and the image processing unit 400 are examples of control means.

[0042] In the optical axis adjustment according to this embodiment, a mirror 11 and a jig 12 are used, as shown in FIGS.

[0043] During optical axis adjustment, mirror 11 is placed approximately in the center of mounting surface 102 of mounting table 101. As shown in FIG. 3B , mirror 11 has a flat plate shape and includes a back surface 11b that is placed on mounting table 101 and a mirror surface 11a that is parallel to back surface 11b. Because back surface 11b and mirror surface 11a are parallel, when mirror 11 is placed on mounting table 101, mirror surface 11a becomes parallel to mounting surface 102 of mounting table 101. Therefore, by controlling the optical axis of imaging device 300 to be perpendicular to mirror surface 11a, the optical axis of imaging device 300 can be adjusted to be perpendicular to mounting surface 102.

[0044] 3A, during optical axis adjustment, the jig 12 is placed on the mirror surface 11a of the mirror 11 arranged on the mounting surface 102 of the mounting table 101. The jig 12 has a guide 12a, a support 12b that supports the guide 12a, a leg 12c that contacts the mirror surface 11a, and a column 12d that vertically connects the leg 12c and the support 12b.

[0045] The guide 12a is formed in a circular ring shape and is supported substantially parallel to the mirror surface 11a. The position of the center point Hp of the guide 12a can be obtained by image processing of the real image of the guide 12a and image processing of the mirror image.

[0046] The support portion 12b extends horizontally to support the guide 12a. The tip of the support portion 12b extends to the center point Hp of the perfect circle of the guide 12a. The center point Hp of the guide 12a and the tip Hp of the support portion 12b are positions where the center point Hp of the real image and the center point Hp of the mirror image overlap when the jig 12 is viewed from a direction perpendicular to the mirror surface 11a, and are examples of characteristic points. In this disclosure, the overlap of the real image and the mirror image means that "the image of the guide 12a and the mirror image of the guide 12a reflected on the mirror surface 11a overlap on the captured image." Furthermore, the mirror image means the image of the mirror image on the captured image. Here, the image of the mirror image is abbreviated to "mirror image."

[0047] The leg portion 12c has a ring shape with a substantially circular shape that is larger than the circular shape of the guide 12a. The pillar portion 12d has a rod shape that extends vertically upward from the leg portion 12c. The support portion 12b has a rod shape that extends horizontally from the tip of the pillar portion 12d that is vertically upward.

[0048] Due to this structure, the imaging device 300 can capture both the real image of the guide 12a and its mirror image reflected on the mirror surface 11a. The size of the mirror surface 11a is the size at which the mirror image of the guide 12a is reflected when the imaging device 300 captures an image of the guide 12a. The distance at which the guide 12a is separated from the mirror surface 11a, which is the installation surface, is a height at which the real image and mirror image of the guide 12a are easily recognized based on the depth of field of the imaging device 300, and a longer distance is preferable. The guide 12a is also arranged symmetrically with respect to a plane parallel to the mirror surface 11a.

[0049] Next, from the viewpoint of optical axis adjustment, we will explain how light rays pass through the guide 12a and form a real image and a mirror image on the image element 302 when the mirror 11 and the jig 12 are placed on the mounting table 101 as shown in Figure 4.

[0050] FIG. 4 shows the mirror surface 11a and the imaging element 302 as viewed from the side, and shows the positions of the real image and mirror image of the guide 12a formed on the imaging surface of the imaging element 302. Light ray Ax1, shown by a solid line, is reflected by the mirror surface 11a, passes through the guide 12a and the center LC of the lens 304, and forms a real image on the imaging element 302. Light ray Ax2, shown by a dashed line, passes through the guide 12a, reflects off the mirror surface 11a, passes through the center LC of the lens, and forms a mirror image on the imaging element 302. The dashed-dotted line indicates the perpendicular line VL of the mirror surface 11a. In this example, the imaging element 302 and the mirror surface 11a are not directly facing each other. The real image and mirror image are formed at separate positions on the imaging surface of the imaging element 302. Here, when the center LC of the lens 304 and the guide 12a are adjusted so that they are positioned on the same perpendicular line VL of the mirror surface 11a, the light rays Ax1 and Ax2 overlap, and the real image and mirror image of the guide 12a are formed overlapping on the imaging surface of the image element 302.

[0051] In Figure 5, as in Figure 4, the imaging element 302 and the mirror surface 11a do not face each other directly. However, in Figure 5, the guide 12a is located on the perpendicular line VL of the mirror surface 11a that passes through the center LC of the lens 304. As a result, the real image and the mirror image overlap. However, the imaging positions of the real image and the mirror image are away from the center of the imaging element 302. In this way, if the optical system is adjusted so that the center LC of the lens 304 is located in the perpendicular direction from the center of the imaging element 302, the imaging element 302 and the mirror surface 11a face each other directly when the real image and the mirror image coincide at the center of the imaging element 302.

[0052] Therefore, if the optical system is adjusted so that the center LC of the lens 304 is positioned in the direction perpendicular to the center of the imaging element 302, the alignment mechanism 100 and the imaging device 300 can be adjusted so that the real image and mirror image of the guide 12a captured by the imaging device 300 overlap at the center of the imaging element 302, thereby adjusting the optical axis of the imaging device 300 perpendicular to the mounting table 101. To determine whether the real image and mirror image accurately overlap, for example, it is sufficient to determine whether the real image and mirror image overlap at the center point Hp of the guide 12a. Note that, from the perspective of the influence of aberrations of the lens 304 of the imaging device 300 and ensuring a sufficient range of movement during optical axis adjustment, it is desirable that the real image and mirror image of the guide 12a be located near the center of the imaging surface of the imaging element 302. For this reason, in this embodiment, adjustment is also performed so that the imaging positions of the real image and mirror image are at the center of the imaging element 302.

[0053] A specific optical axis adjustment process performed by the optical axis adjustment system 1 having the above-described configuration will now be described. The optical axis adjustment process is appropriately performed, for example, at the start of the substrate bonding operation described with reference to FIG. 2 , when a preset number of lots have been processed, etc. The worker first returns the alignment mechanism 100 to the reference position and returns the gimbal mechanism 301 to the reference tilt angle. Next, the worker places the mirror 11 with the mirror surface 11a facing up at approximately the center of the mounting table 101. Next, the worker places the jig 12 at approximately the center of the mirror 11. In this example, the jig 12 is placed on the mirror 11 with the support portion 12b oriented to extend in the X-axis direction. This positions the mirror 11 and the jig 12 within the imaging range Ar of the imaging device 300.

[0054] Next, the operator transmits a command to start the optical axis adjustment control process from the setting terminal 500 to the image processing unit 400. In response to the command, the image processing unit 400 transmits a command to the imaging device 300 to instruct it to start imaging. In response to the command, the imaging device 300 starts imaging, and as shown in Fig. 10, the image acquisition unit 411 acquires the captured image from the imaging device 300 (step S101). Note that the imaging device 300 captures images at predetermined time intervals. The imaging device 300 captures images at intervals of, for example, 10 ms (milliseconds).

[0055] The adjustment information calculation unit 414 uses image processing technology to determine the coordinates of the center point Hp of the real image of the guide 12a in the captured image. The adjustment information calculation unit 414 outputs the determined coordinates of the center point Hp of the real image of the guide 12a to the operation control unit 200.

[0056] The movement amount calculation unit 212 in the motion control unit 200 calculates the amount by which the mirror 11 should be moved to move the center point Hp of the real image to the center of the captured image. The amount by which the mirror 11 should be moved is calculated by the difference between the coordinates (Xr, Yr) of the center point Hp of the real image on the image and the coordinates (0, 0) of the center point of the captured image. The command unit 213 in the motion control unit 200 issues a command to move the center point Hp of the real image to the center of the captured image (step S102). Specifically, the motion control unit 200 outputs control signals to the drive control devices 121, 122, and 123 to realize movement in each direction. Then, the X-axis drive unit 111, the Y-axis drive unit 112, and the θ drive unit 113 move the mounting table 101 on which the mirror 11 is placed under the control of the drive control devices 121, 122, and 123 based on the control signals.

[0057] After moving the mounting table 101, the image acquisition unit 411 acquires a captured image from the imaging device 300 (step S103). The adjustment information calculation unit 414 uses image processing technology to determine the coordinates of the center point Hp of the real image of the guide 12a in the captured image and the coordinates of the center point Hp of the mirror image of the guide 12a. Note that, by the processing of step S102, the center point Hp of the real image of the guide 12a has moved to the center (0, 0) of the captured image.

[0058] The adjustment information calculation unit 414 calculates the distance L between the coordinates (Xr, Yr) on the image of the center point Hp of the real image of the guide 12a and the coordinates (Xi, Yi) on the image of the center point Hp of the mirror image of the guide 12a, as follows: L=√{(Xr-Xi) ２ +(Yr-Yi) ２} is equal to or less than a predetermined reference distance Lr (step S104).

[0059] If it is determined that the distance L>Lr (step S104: No), the command section 213 in the motion control unit 200 sends a command to the drive control device 321 to move the coordinates (Xi, Yi) of the center point Hp of the mirror image to the center coordinates (0, 0) of the captured image (step S105).

[0060] In accordance with the command, the drive control device 321 drives the gimbal drive unit 311 to control the gimbal mechanism 301 and adjust the tilt angles φx and φy of the image capture device 300. For example, in the case of a right-handed coordinate system, to adjust the tilt of the image capture device 300 and move it to the origin, if the X coordinate is positive, the command is to rotate in the positive direction around the Y axis. Also, if the Y coordinate is positive, the command is to rotate in the negative direction around the X axis.

[0061] When the tilt angle of the imaging device 300 is adjusted by the process of step S105, the center point of the real image of the guide 12a moves from the image center. Therefore, the process returns to step S101, the process of acquiring the captured image (step S101) is performed, and a command process of moving the center point of the real image to the image center is again performed (step S102). Then, after the process of step S103, the processes of steps S101 to S105 are repeated until it is determined in step S104 that the distance between the center of the real image and the center of the mirror image is within a predetermined distance range (step S104: Yes).

[0062] On the other hand, if it is determined that the distance L≦Lr (step S104: Yes), it can be said that the real image and the mirror image of the guide 12b are substantially overlapping and formed, although there is a difference in the distance between the center of the real image and the center of the mirror image. As described with reference to FIG. 4, in this state, the optical axis of the imaging device 300 passes almost through the center point Hp of the guide 12a, and the optical axis and the mirror surface 11a of the mirror 11 are perpendicular. Furthermore, since the mirror surface 11a and the mounting surface 102 are parallel, the optical axis of the imaging device 300 and the mounting surface 102 are perpendicular. Therefore, the optical axis adjustment control process ends.

[0063] The image processing unit 400 notifies the operator that the optical axis adjustment has been completed via the setting terminal 500. In response to the notification, the operator removes the mirror 11 and the jig 12 from the mounting table 101 and proceeds to the normal substrate bonding process.

[0064] As described above, in the optical axis adjustment system 1 according to this embodiment, the mirror 11 and the jig 12 are placed on the mounting table 101, the guide 12a of the jig 12 is photographed with the imaging device 300, and the alignment mechanism 100 and the imaging device 300 are adjusted so that the center point of the real image of the guide 12a and the center point of the mirror image coincide with each other at the center of the image, thereby performing optical axis adjustment of the imaging device 300. This makes it easy to perform optical axis adjustment so that the optical axis of the imaging device 300 is perpendicular to the mounting surface 102 of the mounting table 101.

[0065] (Variations of First Embodiment) In the first embodiment, the guide 12a is circular, but is not limited to a circular shape. Other shapes, such as a rectangle or triangle, may be used, as long as they have identifiable feature points, such as a center point or center of gravity. For example, the guide 12a may not be provided, and the tip of the support 12b may be used as the feature point. Alternatively, any point may be used as the feature point, as long as the position on the real image and the position on the mirror image coincide with each other when the optical axis of the imaging device 300 is perpendicular to the mounting surface 102. The shape, structure, and number of the support 12b, legs 12c, and columns 12d may be arbitrary, as long as the guide 12a is spaced a certain distance from the mirror surface 11a and the imaging device 300 can observe the real image and mirror image of the guide 12a. In the first embodiment, the positions of the real image and mirror image of the guide 12a were adjusted to be the center of the imaging element 302. Here, the "central portion" does not mean the strict center or centre, but means a central portion that includes the center and a preset peripheral portion thereof to the extent that adverse effects on optical axis adjustment are sufficiently small.

[0066] In the first embodiment, whether the real image and the mirror image of the guide 12a overlap is determined based on whether the distance L between the center points Hp of the real image and the mirror image of the guide 12a is equal to or less than the reference value Lr. This disclosure is not limited to this. For example, the guide 12a may have a shape that allows the real image and the mirror image to match, and whether the real image and the mirror image overlap may be determined based on whether the imaging pattern of the real image and the imaging pattern of the mirror image match. Alternatively, any other method may be used to determine whether the real image and the mirror image of the guide 12a overlap and whether the optical axis of the imaging device 300 is perpendicular to the imaging target surface, the mirror surface 11a, and the placement surface 102.

[0067] In the first embodiment, the angle adjustment amount of the imaging device 300 is the amount by which the center point of the mirror image of the guide 12a moves toward the image center, but the present disclosure is not limited to this. For example, the initial angle adjustment amount of the imaging device 300 may be a value greater than the amount by which the center point of the mirror image of the guide 12a moves toward the image center, such as 2 times, 1.5 times, or the like. By setting such a movement amount, the mirror 11 is translated and the angle adjustment of the imaging device 300 is repeated, gradually approaching the image center, and the initial large swing amplitude reduces the number of trials.

[0068] Furthermore, during the angle adjustment process of the imaging device 300, the imaging magnification of the imaging device 300 may be reduced to a magnification lower than that used during normal processing to enable more precise adjustment. For example, if the position of the mirror image center is initially (X, Y) = (30, 20), and the angle is adjusted to the image center position (X, Y) = (0, 0), the adjustment is performed at a high magnification of approximately (a, b) = (-20 × 5, 30 × 5). Then, when the position of the mirror image center approaches (X, Y) = (6, 4), the adjustment may be performed by lowering the magnification to (a, b) = (-4 × 2, 6 × 2) to prevent overshooting. The calculation of (a, b) may use a unit vector that expresses only a direction without distance information, rather than (the conversion value of the position of the mirror image center × the magnification), in which case the angle may be adjusted by multiplying it by a magnification proportional to the distance to the center of the mirror image (unit vector × magnification).

[0069] Furthermore, instead of directly supplying information regarding the parallel movement of the mirror 11 or the angle adjustment of the imaging device 300 to the drive control devices 121 to 123 and 321, the information may be displayed on the screen of the setting terminal 500 and communicated to the adjustment worker, who may then instruct the amount of movement, etc., from the setting terminal 500.

[0070] For example, as illustrated in Fig. 11 , the direction in which the center point of the guide 12a moves when the X-axis driver 111 and the Y-axis driver 112 are operated may be displayed at the edge of the screen, etc. Furthermore, the amount of movement to the center point of the image, which is the intersection of the X-axis and the Y-axis, may be displayed near the actual image of the guide 12a, etc. In the example shown in Fig. 11 , it is displayed that the X-axis driver 111 should be moved 26 in the positive direction and the Y-axis driver 112 should be moved 29 in the negative direction. Furthermore, dotted line guidelines are also displayed to make it easier to understand the center of the image and the movement directions of the X-axis driver 111 and the Y-axis driver 112.

[0071] 12, for example, the direction and amount of movement of the real image and mirror image of the guide 12a by operating the gimbal driver 311 may be displayed on the edge of the screen. In the example of FIG. 12, the instruction is to adjust the angle of the imaging device 300 to the right and toward the user. When an operation based on this instruction is performed, the position of the mirror image of the guide 12a moves toward the center of the image. The numerical value is the adjustment amount calculated from the number of pixels from the center of the image to the center point of the mirror image of the guide 12a, and if calibration of the angle and number of pixels of the imaging device 300 has been completed, the numerical value will be in accordance with that calibration.

[0072] 11 and 12, the adjustment operator can instruct the parallel movement of mirror 11 and the angle adjustment of imaging device 300 from setting terminal 500. In this case, image processing unit 400 transmits control signals according to the instructions to drive control devices 121 to 123 and 321 via operation control unit 200.

[0073] In addition, the angle of the imaging device 300 is adjusted manually by an operator, and parallel movement to move the center point of the real image of the guide 12a to the center of the image may be realized by a movement command sent from the command unit 213 to the drive control devices 121 to 123, and by the X-axis drive unit 111, the Y-axis drive unit 112, and the θ drive unit 113.

[0074] The translation stage for the mirror 11 in the optical axis adjustment system 1, in other words the X-Y-θ stage, may be implemented in any manner as long as it has the function of moving the center point of the guide 12a to the center of the image. For example, the translation command for the mirror 11 may be a command value for the combined movement of the drive units, rather than the amount of movement of each drive unit in the X-axis direction, Y-axis direction, or around the θ-axis.

[0075] In the optical axis adjustment system 1 according to the first embodiment, the optical axis adjustment is performed based on the real image of the guide 12 a, but the optical axis adjustment may also be performed based on the mirror image of the guide 12 a. The real image and the mirror image are interchangeable in the optical axis adjustment of the present disclosure, and either may be used as the reference for the optical axis adjustment.

[0076] Furthermore, any configuration is possible as long as it is possible to control the relative position between the imaging device 300 and the mirror surface 11a of the mirror 11, in other words, to adjust the relative movement and tilt. For example, a configuration opposite to that of embodiment 1 may be used. Specifically, a translational movement drive unit may be provided on the imaging device 300 side, and a goniostage capable of tilt adjustment may be arranged on the mirror 11 side.

[0077] Furthermore, the installation direction of the imaging device 300 may be changed from that of the first embodiment by using mirrors, prisms, lenses, etc. in the optical system of the imaging device 300. Furthermore, multiple imaging elements may be used, and optical axis adjustment may be performed between the imaging device 300, which is an integrated imaging element, and the imaging surface. When different imaging elements are used, for example, light is split by a beam splitter and images are formed on two imaging elements. In this case, the optical system is shared, and only one angle adjustment is required. Calibration of the multiple imaging elements within the device is performed separately.

[0078] In the optical axis adjustment control process according to the first embodiment, the optical axis adjustment control process is terminated when the coordinate distance on the image between the real image center Hp and the mirror image center Hp is within a predetermined distance range. However, the present disclosure is not limited to this. For example, the process may be terminated when the movement process in steps S102 and S105 is executed a predetermined number of times. Alternatively, the process may be terminated when the movement amount per one time falls within a reference range.

[0079] In addition, in the optical axis adjustment control process according to the first embodiment, in step S104, it is determined whether or not a termination condition is met, and if it is determined that the termination condition is met, the optical axis adjustment control process is automatically terminated. However, the present disclosure is not limited to this. The adjustment operator may determine whether or not to terminate the optical axis adjustment control process. For example, in step S104 of the optical axis adjustment control process in FIG. 10 , as illustrated in FIGS. 11 and 12 , the coordinate positions of the real image center Hp and the mirror image center Hp may be displayed on the setting terminal 500, and if the adjustment operator determines that the distance therebetween is within a predetermined range, the adjustment operator may issue an instruction to terminate the optical axis adjustment control process from the setting terminal 500, thereby terminating the process.

[0080] Upon completion of the optical axis adjustment control process, the movement amount calculation unit 212 may record or display the magnitude of the error contained in the adjusted optical axis. Here, unless estimation is performed using image processing such as averaging, image recognition leaves behind quantization errors that prevent changes smaller than one pixel from being recognized. While the minimum recognition accuracy varies depending on the image recognition algorithm, the amount of change per pixel serves as a guide. For example, in step S104 of FIG. 10 , the optical axis adjustment control process is terminated when the distance L between the real image center Hp and the mirror image center Hp is within a predetermined range. Therefore, if the maximum number of pixels within the predetermined range, i.e., the reference value, is Tn, the distance L includes an error of up to Tn pixels. Therefore, for example, the movement amount calculation unit 212 may calculate Tn × (the movement distance of the mounting table 101 per pixel) as the maximum error ΔL in the optical axis adjustment process, and record the calculated maximum error ΔL in the control data storage unit 432 of the image processing unit 400, or record or display the calculated maximum error ΔL on the setting terminal 500.

[0081] Similarly, the movement amount calculation unit 212 may calculate the change amount Δφ in the angle φ of the imaging device 300 per pixel, and record or display the product of the calculated change amount Δφ and a predetermined reference value Tn as the maximum possible remaining tilt of the optical axis. For example, with respect to the tilt angle φ of the imaging device 300, the angle change amount per pixel can be calculated based on the angle adjustment amount and the movement amount of the center point of the mirror image of the guide 12a in the image. This is an example that focuses only on the angle adjustment of the imaging device 300, separate from the translation of the mirror 11. For example, if an angle adjustment of 0.01 degrees around the X axis moves the center point of the mirror image by 5 pixels in the Y axis direction, the angle change amount per pixel is calculated as 0.01 / 5. For example, the maximum value of the error contained in the optical axis obtained in this way may be associated with the product lot of the processing performed using that optical axis, and the associated data may be recorded in the control data storage section 432 of the image processing unit 400, or may be displayed on the setting terminal 500 and used for subsequent defect analysis, thereby enabling the relationship between defects and the accuracy of the optical axis to be analyzed.

[0082] Second Embodiment A second embodiment for carrying out the present disclosure will now be described with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0083] The overall configuration and the hardware configuration of each part of the optical axis adjustment system 1 according to the second embodiment are the same as those of the first embodiment. The optical axis adjustment system 1 according to the second embodiment differs from the first embodiment in that the optical axis adjustment control process shown in Fig. 13 is performed instead of the optical axis adjustment control process shown in Fig. 10. The following description of the second embodiment will focus on the differences from the first embodiment.

[0084] The optical axis adjustment control process according to the second embodiment will be described below with reference to FIGS. 13 and 14. FIG.

[0085] 13 are the same as those in embodiment 1. After step S102, movement amount calculation unit 212 stores the translation amount of mirror 11 obtained in step S102 in control data storage unit 232 (step S211). The translation amount of mirror 11 is periodically stored in control data storage unit 232.

[0086] After step S211, the process goes through step S103, which is the same as in the first embodiment, and the adjustment information calculation unit 414 stores the position of the center point Hp of the mirror image of the guide 12a, for example, point a1 shown in FIG. 14, in the control data storage unit 432 (step S212). Note that the position of the center point Hp of the mirror image is accumulated rather than updated even when the process of step S212 is repeated thereafter. The position of the center point Hp of the mirror image is periodically stored in the control data storage unit 432.

[0087] After step S212, the process of step S104 is performed in the same manner as in embodiment 1. In step S104, if it is determined that the distance L between the position of the center point Hp of the real image and the position of the center point Hp of the mirror image is equal to or less than the reference value Lr (step S104: Yes), the optical axis adjustment control process ends, as in embodiment 1.

[0088] If it is determined in step S104 that the distance L between the position of the center point Hp of the real image and the position of the center point Hp of the mirror image is greater than the reference value Lr (step S104: No), the adjustment information calculation unit 414 determines whether the number of center points of the mirror image saved in step S212 is two or more (step S213). At this point, the saved center point of the mirror image is one, point a1 shown in FIG. 14. Therefore, it is determined that the number of center points of the saved mirror image is not two or more (step S213: No), and the process proceeds to step S105. The process of step S105 is the same as in the first embodiment.

[0089] After the process of step S105, the movement amount calculation unit 212 stores the angle adjustment amount of the imaging device 300 obtained in step S105 in the control data storage unit 232 (step S215). The angle adjustment amount of the imaging device 300 is periodically stored in the control data storage unit 232. After step S215, the process returns to step S101, and the processes of steps S101, S102, S211, and S103 are performed.

[0090] After step S103, in step S212, the adjustment information calculation unit 414 stores the position of the center point of the mirror image, for example, point a2 shown in Fig. 14, in the control data storage unit 432 (step S212). After step S212, if it is determined in step S104 that the distance L between the position of the center point Hp of the real image and the position of the center point Hp of the mirror image is greater than the reference value Lr (step S104: No), the process proceeds to step S213.

[0091] Here, since the center points Hp of the mirror image guide 12a are two points a1 and a2 shown in FIG. 14, it is determined that the number of stored center points Hp of the mirror image guide 12a is two or more (step S213: Yes).

[0092] The adjustment information calculation unit 414 calculates the adjustment rate α (step S214). Here, the adjustment rate α refers to the ratio for adjusting the amount of translation of the mirror 11 and the amount of angle adjustment of the imaging device 300. Specifically, the adjustment rate α is calculated by a formula that determines how many times the distance from the center point Hp of the current mirror image to the center position of the image is multiplied by the difference between the center point Hp of the current mirror image and the center point Hp of the previous mirror image. For example, in the case of FIG. 14, if the distances from the image center to points a1 and a2 are distances d1 and d2, respectively, the adjustment rate α is calculated by α=d2 / (d1-d2). The adjustment rate α is output to the motion control unit 200.

[0093] After step S214, the process proceeds to step S105. When the process of step S105 is performed after step S214, the movement amount calculation unit 212 calculates a new angle adjustment amount by multiplying the angle adjustment amount stored in the control data storage unit 232 by the adjustment rate α calculated in step S214. Based on the new angle adjustment amount, the command unit 213 sends a command to the drive control device 321 to move the mirror image (step S105). The drive control device 321 controls the gimbal drive unit 311 based on the control signal from the command unit 213.

[0094] The movement amount calculation unit 212 stores the angle adjustment amount of the imaging device 300 obtained in step S105 in the control data storage unit 232 (step S215). After step S215, the process returns to step S101, and the process of step S101 is performed.

[0095] After step S101, the movement amount calculation unit 212 calculates a new translation amount by multiplying the translation amount stored in the control data storage unit 232 by the adjustment rate α calculated in step S214. Based on the new translation amount, the command unit 213 sends a command to move the real image to the drive control devices 121, 122, and 123 (step S102). The drive control devices 121, 122, and 123 control the X-axis drive unit 111, the Y-axis drive unit 112, and the θ drive unit 113 based on the control signal from the command unit 213.

[0096] The movement amount calculation unit 212 stores the translation amount of the mirror 11 obtained in step S102 in the control data storage unit 232 (step S211). After step S211, the process proceeds to step S212 via step S103.

[0097] In step S212, the adjustment information calculation unit 414 stores the position of the center point Hp of the mirror image, for example, point a3 shown in FIG. 14, in the control data storage unit 432 (step S212). If it is determined that the distance L between the center point Hp of the real image and the center point Hp of the mirror image is equal to or less than the reference value Lr (step S104: Yes), the optical axis adjustment control process ends. If it is determined that the distance L is greater than the reference value Lr (step S104: No), the processes of steps S213 to S214, S105, S215, S101, S102, S211, S103, S212, and S104 are repeated.

[0098] As described above, in the optical axis adjustment control process of the second embodiment, the adjustment information calculation unit 414 calculated the adjustment rate α based on the position of the center point Hp of the mirror image of the guide 12a when the center point Hp of the real image of the guide 12a was moved to the image center. The movement amount calculation unit 212 calculated a new translation amount by multiplying the previous translation amount of the mirror 11 by the adjustment rate α. The movement amount calculation unit 212 also calculated a new angle adjustment amount by multiplying the previous angle adjustment amount of the imaging device 300 by the adjustment rate α. The translation of the mirror 11 based on the new translation amount and the angle adjustment of the imaging device 300 based on the new angle adjustment amount can reduce the number of attempts to adjust the optical axis.

[0099] (Variation of Embodiment 2) The optical axis adjustment control process may be performed in both positive and negative directions, with the midpoint between the positions where each adjustment is completed being the final adjustment position. Specifically, as shown in FIG. 15 , for example, when angle adjustment is performed around the X and Y axes of the image, the first optical axis adjustment control moves the point a1, ..., point a4, approaching the image center from the positive direction in both X and Y directions on the image sensor. The second optical axis adjustment control moves the point b1, ..., point b4, approaching the image center from the negative direction in both directions. The final position may be the midpoint between point a4, the final position of the first optical axis adjustment control, and point b4, the final position of the second optical axis adjustment control. For example, due to quantization error of the image sensor 302, errors may remain even if the adjustment work is performed only from one direction. By performing adjustment control in both the positive and negative directions and setting the midpoint between them as the final adjustment position, the accuracy of the optical axis adjustment work can be improved.

[0100] Various embodiments and modifications are possible without departing from the broad spirit and scope of the present disclosure. Furthermore, the above-described embodiments are intended to illustrate the present disclosure and do not limit the scope of the present disclosure. That is, the scope of the present disclosure is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and within the meaning of the disclosure equivalent thereto are considered to be within the scope of the present disclosure.

[0101] 1 Optical axis adjustment system, 11 Mirror, 11a Mirror surface, 11b Back surface, 12 Jig, 12a Guide, 12b Support portion, 12c Leg portion, 12d Pillar portion, 100 Alignment mechanism, 101 Mounting table, 102 Mounting surface, 111 X-axis drive portion, 112 Y-axis drive portion, 113 θ drive portion, 121, 122, 123, 321 Drive control device, 200 Motion control unit, 210 Processor, 212 Movement amount calculation portion, 213 Command portion, 220 Volatile memory, 230 Non-volatile memory, 231 Control program storage portion, 232 Control data storage portion, 240 Clock, 250 Communication interface, 300 Imaging device, 301 Gimbal mechanism, 302 Image element, 304 Lens, 311 Gimbal drive portion, 400 Image processing unit, 410 processor, 411 image acquisition unit, 414 adjustment information calculation unit, 420 volatile memory, 430 non-volatile memory, 431 control program storage unit, 432 control data storage unit, 440 communication interface, 500 setting terminal, 1001, 1002 work, a1, a2, a3, a4, b1, b2, b3, b4 point, LC center, VL perpendicular line, Ax1, Ax2 light ray, Ag vertical direction, Ar shooting range, B1, B2 bus, d1, d2 distance, HP center point, tip, φx, φy tilt angle, Mk marker.

Claims

1. An optical axis adjustment system for adjusting an imaging target surface of an imaging device and an optical axis of the imaging device, comprising: a mirror arranged on the imaging target surface, and a jig used for adjustment arranged on the mirror surface of the mirror, the jig including a guide that can be imaged by the imaging device and a support part that supports the guide at a position a predetermined distance from the mirror surface; an imaging target surface drive part that moves or tilts the imaging target surface on which the mirror is placed; an imaging device drive part that moves or tilts the imaging device; and control means that controls the imaging target surface drive part or the imaging device drive part so that a real image of the guide and a mirror image of the guide reflected on the mirror surface of the guide overlap on the image captured by the imaging device.

2. The optical axis adjustment system according to claim 1, wherein said control means controls said imaging target surface drive section or said imaging device drive section so that the positions of specific feature points derived from the real image and mirror image of said guide respectively coincide with each other.

3. The optical axis adjustment system according to claim 1 or 2, wherein the control means controls either the imaging subject surface drive unit or the imaging device drive unit so as to move one of the real image and mirror image of the guide to the center of the captured image.

4. The optical axis adjustment system according to claim 3, wherein the control means controls the other of the imaging subject surface drive unit and the imaging device drive unit so as to move the other of the real image and mirror image of the guide to the center of the captured image.

5. An optical axis adjustment system as described in claim 3 or 4, wherein, when it is determined that the real image of the guide and the mirror image of the guide do not overlap, the control means controls the other of the imaging subject surface drive unit and the imaging device drive unit so as to move the other of the real image and the mirror image to the center of the captured image.

6. The optical axis adjustment system described in claim 5, wherein the control means determines a position of one of the real image and the mirror image, and determines an adjustment rate representing a ratio of adjusting the amount of movement required to move the position of one of the real image and the mirror image to the center of the captured image based on the determined position of the one and a position of the one determined a predetermined period before the determination time, and the control means controls one of the imaging subject surface driving unit and the imaging device driving unit so as to move the position of one of the real image and the mirror image to the center of the captured image based on the adjustment rate and the distance between the position of one of the real image and the mirror image and the center of the captured image.

7. The optical axis adjustment system according to claim 6, wherein the control means controls the other of the imaging subject surface drive unit and the imaging device drive unit so as to move the position of the other of the real image and the mirror image so that the real image and the mirror image overlap, based on the adjustment ratio and the distance on the captured image between the real image and the mirror image.

8. The optical axis adjustment system according to any one of claims 1 to 7, wherein the control means determines the distance between the real image of the guide and the mirror image of the guide, terminates the process of adjusting the optical axis when the distance is equal to or less than a reference value, and records the product of either the reference value and the moving distance and tilt angle of the imaged object surface or the moving distance and tilt angle of the imaging device per pixel of the captured image as a maximum error.

9. An optical axis adjustment method comprising: placing a mirror on a surface to be imaged; placing a guide on the mirror at a distance from the mirror; determining the position of a real image and a mirror image of the guide on an image captured by an imaging device; and controlling the relative position of the surface to be imaged and the imaging device so that the real image and the mirror image overlap on the image.

10. A jig for use in the optical axis adjustment method according to claim 9, the jig being placed on the mirror surface of the mirror installed on the surface to be imaged, the jig including the guide and a support part that supports the guide above and at a predetermined distance from the mirror surface.

11. A program that causes a computer to execute a process of determining the position of a real image and the position of a mirror image of the guide on an image of an object surface on which a mirror and a guide are arranged, captured by an imaging device, and controlling the relative position of the object surface and the imaging device so that the real image and the mirror image overlap on the captured image.

Images