Measurement system, measurement method, and measurement program

Abstract

A measurement system according to the present invention includes: a light source (52) for projecting a plurality of first optical patterns onto an object; a drive mechanism (40) for changing a relative position between the object and the light source (52); and a measurement unit for measuring a distance z between the object and the light source (52) on the basis of an image captured by an imaging unit (60) configured to capture an image of the object. The light source (52) projects the plurality of first optical patterns in directions forming different angles with a first direction. The light source (52) projects at least a part of the first optical patterns onto an imaging area of ​​the imaging unit (60).

Description

Measurement system, measurement method, and measurement program

[0001] The present disclosure relates to a measurement system, a measurement method, and a measurement program.

[0002] Conventionally, there has been known a mounting apparatus that mounts a first member held by a head onto a second member placed on a stage. In such a mounting apparatus, a measuring device is provided that measures the relative position of the first member and the second member in order to accurately mount the first member onto the second member.

[0003] The measurement device of Patent Document 1 includes a projection unit that projects linear projection light that is inclined with respect to the optical axis of the imaging unit onto the measurement object while moving the measurement object relatively, and a control unit that measures the height dimension of the measurement object by changing the inclination angle of the projection light based on the state of the measurement object.

[0004] The detection device in Patent Document 2 includes a light source that irradiates an object with a light beam as a light spot, and a receiver that detects the light beam scattered and / or reflected by the object according to triangulation theory, and outputs an object detection signal containing information about the scanning distance to the object. The light beam acts through a pixel array imaging element consisting of a photodetector in the receiver. The imaging element is an arrangement of individual imaging elements arranged in front of the pixel array. The arrangement generates a received signal pattern on the pixel array corresponding to the image of a plurality of spaced light spots, and information about the scanning distance is determined from the received signal pattern.

[0005] JP 2020-153885 A JP 2008-241693 A

[0006] Incidentally, triangulation can be used to measure the relative position between the first member and the second member. For example, spot lights from two light sources are irradiated onto a stage, and the spot lights are captured by a camera. The relative positions between the first member and the second member can be measured from the distance between the two spot lights. In this method, in order to accurately measure the relative positions between the first member and the second member, it is necessary to irradiate the two spot lights so that they fit within the imaging range of the camera.

[0007] When spot lights are projected so that they fit within the camera's imaging range, the maximum distance between the two spot lights must be set within the camera's imaging range, which may result in a decrease in measurement accuracy depending on the distance between the first and second parts.

[0008] In order to prevent a decrease in measurement accuracy, it is possible to increase the illumination angle of the spot light relative to the stage. In this case, the larger illumination angle reduces the range of distances between the first and second members that can be measured. Furthermore, since it is necessary to fit the two spot lights within the camera's imaging range, the distance between the camera and the light source increases. As a result, the size of the measurement system increases. In other words, if an attempt is made to expand the measurement range, the measurement accuracy decreases, and if an attempt is made to improve the measurement accuracy, the measurement range becomes smaller or the measurement system becomes larger.

[0009] The present disclosure aims to provide a measurement device, a measurement method, and a measurement program that can reduce the size of the measurement system while suppressing a decrease in measurement accuracy.

[0010] In order to solve the above problem, a measurement system according to one embodiment of the present disclosure includes a first light source that projects a plurality of first optical patterns onto an object, a drive unit that changes the relative position between the object and the first light source, and a measurement unit that measures the distance between the first light source and the object based on an image captured by an imaging unit that captures the object, wherein the first light source projects the first optical patterns in directions that form different angles from a first direction in which the first light source and the object face each other, and the first light source projects at least a portion of the plurality of first optical patterns onto an imaging area of ​​the imaging unit.

[0011] According to the present disclosure, it is possible to reduce the size of the measurement system while suppressing a decrease in measurement accuracy.

[0012] FIG. 1 is a diagram showing the basic configuration of a position adjustment system according to the first embodiment. FIG. 2 is a diagram showing an example of a captured image according to the first embodiment. A flowchart explaining the flow of a measurement process according to the first embodiment. A graph showing the measurement range and resolution of the imaging unit according to the first embodiment. A flowchart explaining the flow of a measurement process according to the second embodiment. A graph showing the relationship between the positional relationship of optical patterns according to the second embodiment and the estimated distance of the distance z. A diagram showing an example of a captured image according to the third embodiment. A diagram showing an example of a captured image according to another embodiment.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0014] (First embodiment) Fig. 1 is a diagram showing the basic configuration of a position adjustment system according to a first embodiment. A measurement system according to the present disclosure is realized as a position adjustment system. Furthermore, a measurement method according to the present disclosure is implemented as one function of the position adjustment system. In the following description, the left-right direction of Fig. 1 may be referred to as the X direction, the depth direction of the drawing as the Y direction, and the up-down direction of the drawing as the Z direction.

[0015] The position adjustment system 10 adjusts the positional relationship between the first member 11 and the second member 12. In particular, the position adjustment system 10 measures the distance z in the Z direction between the first member 11 (the first holding unit 20 and the light source unit 50) and the second member 12 (the second holding unit 30). For example, the position adjustment system 10 is installed in a production line facility that produces semiconductor products using semiconductor chips.

[0016] In this embodiment, the first member 11 is, for example, a semiconductor chip, and the second member 12 is, for example, a substrate. In the position adjustment system 10, the positional relationship between the first member 11 and the second member 12 is adjusted in the Z direction so that the first member 11 and the second member 12 face each other, and then the first member 11 is mounted (bonded) to the second member 12.

[0017] For example, a solder bump is formed on an electrode formed on the bonding surface (surface to be bonded to the substrate (second member 12)) of the semiconductor chip (first member 11), and the semiconductor chip is mounted (flip-chip mounted) on a predetermined area of ​​the substrate so that the "electrode formed on the bonding surface of the semiconductor chip" and the "electrode formed in a predetermined area of ​​the chip mounting surface of the substrate (surface on which the semiconductor chip is mounted)" are joined by the "solder bump."

[0018] As shown in FIG. 1, the position adjustment system 10 includes a first holding unit 20, a second holding unit 30 (object), a drive mechanism 40 (drive unit), a light source unit 50, an imaging unit 60, and a control device 70 (measurement unit).

[0019] (First Holding Unit) The first holding unit 20 holds the first member 11. For example, the first holding unit 20 is a head that holds the first member 11 by suction using an adsorption means such as air suction. In this embodiment, the first holding unit 20 holds the semiconductor chip, which is the first member 11, so that the bonding surface of the semiconductor chip faces downward.

[0020] (Second Holding Unit) The second holding unit 30 holds the second member 12. For example, the second holding unit 30 is a stage that holds the second member 12 by suction using an adsorption means such as air suction. In this embodiment, the second holding unit 30 holds the substrate, which is the second member 12, so that the chip mounting surface of the substrate faces upward. The second holding unit 30 also has a mounting surface on which the second member 12 is placed.

[0021] (Drive Mechanism) The drive mechanism 40 moves the positions of the first holding unit 20 and the second holding unit 30 in response to a control signal output from the control device 70. In this embodiment, the drive mechanism 40 is composed of an actuator 41 that moves the position of the first holding unit 20 and an actuator 42 that moves the position of the second holding unit 30.

[0022] Specifically, the actuator 41 moves the first holding unit 20 in the X direction and the Z direction in response to a control signal output from the control device 70 .

[0023] The actuator 42 moves the second holding unit 30 in the X direction and the Y direction in response to a control signal output from the control device 70. The actuator 42 also rotates the second holding unit 30 about a rotation axis that is perpendicular to the mounting surface of the second holding unit 30.

[0024] That is, the drive mechanism 40 changes the relative position between the first holding unit 20 (light source unit 50 and first member 11) and the second holding unit 30 (second member 12).

[0025] (Light Source) The light source unit 50 is attached to the first holding unit 20 and projects an optical pattern onto the mounting surface of the second holding unit 30. Specifically, the light source unit 50 includes a light source 51 (second light source) and a light source 52 (first light source). The light sources 51 and 52 are, for example, laser light sources constituted by LEDs (Light Emitting Diodes) or the like.

[0026] The light source 51 projects an optical pattern 53 (second optical pattern) onto the mounting surface of the second holding unit 30. The light source 51 projects the optical pattern 53 along the Z direction. The optical pattern 53 is a single optical pattern.

[0027] The light source 52 projects optical patterns 54 to 57 (first optical patterns) onto the mounting surface of the second holding unit 30. The optical patterns 54 to 57 are projected so as to form different angles with respect to the Z direction when viewed from the Y direction. In the example of FIG. 1 , the optical patterns 54 to 57 are projected in directions that form angles θ1 to θ4 with respect to the Z direction when viewed from the Y direction. Each of the optical patterns 54 to 57 is a single optical pattern. In other words, the light source 52 projects multiple (four in this case) optical patterns onto the mounting surface of the second holding unit 30.

[0028] The optical patterns 53 to 57 are set so as to be distinguishable from one another in the image captured by the imaging unit 60. For example, the optical patterns 53 to 57 are set so as to have different shapes, different hues, or different illuminances. Alternatively, some or all of the optical patterns 53 to 57 may have the same shape. In this case, the optical patterns 53 to 57 can be distinguished from one another based on their positional relationships or relative positions. In other words, the optical patterns 53 to 57 may have any shape, etc., as long as they are distinguishable from one another.

[0029] Furthermore, the optical patterns 53 to 57 may be set to have different wavelengths, regardless of whether there is a difference in shape. For example, by providing each of the light sources 51 and 52 with a spectroscopic element and irradiating light in the projection direction through the spectroscopic element, even if the light from the light source is one color, such as white, it is possible to irradiate light of different wavelengths at different projection angles. The spectroscopic element is, for example, a prism.

[0030] FIG. 2 is a diagram showing an example of a captured image according to the first embodiment. In the example of FIG. 2, the shapes of the optical patterns 53 to 57 are set to be circular. Note that the shapes of the optical patterns 53 to 57 are not limited to circular and can be set to any shape, such as a cross or a square. For example, each of the light sources 51 and 52 may be provided with a diffractive optical element (DOE), and by irradiating light in the projection direction through the diffractive optical element, an optical pattern of a desired shape can be projected. This allows the light source 52 to project multiple optical patterns, even when the light source 52 is configured with a single light source.

[0031] In this embodiment, the light source 52 is configured with one light source, but may be configured with multiple light sources. In this case, the multiple light sources that make up the light source 52 may be configured to project one optical pattern.

[0032] Furthermore, in the present embodiment, the light source 52 projects four optical patterns (54 to 57) and all four optical patterns are projected onto the imaging area of ​​the imaging unit 60 (the mounting surface of the second holding unit 30), but this is not limiting. The light source 52 may project multiple (two or more) optical patterns. In this case, the light source 52 may project one or more of the multiple optical patterns onto the imaging area of ​​the imaging unit 60 (the mounting surface of the second holding unit 30), or may project all of the optical patterns onto the imaging area of ​​the imaging unit 60 (the mounting surface of the second holding unit 30). Furthermore, the driving mechanism 40 may move the relative position between the first holding unit 20 (light source 52) and the second holding unit 30 so that one or more of the multiple optical patterns projected by the light source 52 are projected onto the imaging area of ​​the imaging unit 60 (the mounting surface of the second holding unit 30), or may move the relative position between the first holding unit 20 (light source 52) and the second holding unit 30 so that all of the optical patterns are projected onto the imaging area of ​​the imaging unit 60 (the mounting surface of the second holding unit 30).

[0033] (Imaging Unit) The imaging unit 60 captures an image of the placement surface of the second holding unit 30 and outputs the captured image to the control device 70. The imaging unit 60 is, for example, a camera having an image sensor such as a CCD image sensor or a CMOS image sensor. The imaging direction of the imaging unit 60 is the Z direction. The imaging unit 60 is supported by a support member (a member configured to prevent vibrations of the first holding unit 20 and the second holding unit 30 from propagating; not shown) that is independent of the first holding unit 20 and the second holding unit 30.

[0034] The imaging unit 60 captures an image of a predetermined imaging area on the placement surface of the second holding unit 30 when the first member 11 is mounted (bonded) to the second member 12. For example, the imaging area includes the optical patterns 53 to 57 and a position mark 58 provided on the second holding unit 30. The position mark 58 is provided near the second member 12 (near the area where the first member 11 is to be mounted). The shape of the position mark 58 is not limited to a circle, and can be set to any shape such as a cross or a square.

[0035] (Control Device) The control device 70 controls each part of the position adjustment system 10. The control device 70 is configured with a microcomputer including a CPU (Central Processing Unit), a semiconductor memory, and the like.

[0036] In this embodiment, the control device 70 executes the mounting process based on the captured image output from the imaging unit 60. Specifically, when the first member 11 is mounted (joined) to the second member 12, the control device 70 determines the relative position between the first member 11 and the second member 12 based on the captured image output from the imaging unit 60.

[0037] More specifically, the control device 70 corrects the positional misalignment of the first member 11 and the second member 12 in the XY plane based on the captured image. For example, the control device 70 calculates the position of the center of gravity of the image of the position mark 58 included in the captured image and the position of the center of gravity of the optical pattern 53. The control device 70 outputs control signals to the actuators 41, 42 so that the position of the center of gravity of the position mark 58 and the position of the center of gravity of the optical pattern 53 are located at predetermined positions (for example, coincident positions). This moves the first holding unit 20 and the second holding unit 30 in the X direction and the Y direction, thereby correcting the positional misalignment of the first member 11 and the second member 12 in the XY plane.

[0038] The control device 70 also executes a measurement process to measure the distance z between the first member 11 and the second member 12 in the Z direction based on the captured image.

[0039] (Regarding Measurement Processing) FIG. 3 is a flowchart illustrating the flow of measurement processing according to the first embodiment.

[0040] The imaging unit 60 captures an image of an imaging area on the placement surface of the second holding unit 30 (step S1). The imaging unit 60 outputs the captured image to the control device .

[0041] The control device 70 detects optical patterns from the captured image output from the imaging unit 60 (step S2). For example, the control device 70 detects each optical pattern from the captured image while referring to images of each preset optical pattern. In the example of Fig. 3, the control device 70 detects optical patterns 53 to 57 from the captured image.

[0042] The control device 70 selects the optical pattern projected in the direction that forms the largest angle with respect to the Z direction when viewed from the Y direction, from among the optical patterns projected from the light source 52 (step S3).

[0043] Here, the control device 70 selects, from among the optical patterns projected from the light source 52, the optical pattern (optical pattern 57 in FIG. 3 ) that is located farthest in the X direction from the optical pattern 53 projected from the light source 51. As described above, the optical pattern 53 projected from the light source 51 is projected along the Z direction. Furthermore, the optical patterns 54 to 57 projected from the light source 52 are projected in directions that form different angles with respect to the Z direction when viewed from the Y direction. Therefore, from among the optical patterns projected from the light source 52, the optical pattern that is located farthest in the X direction from the optical pattern 53 projected from the light source 51 is the optical pattern that is located farthest in the X direction from the optical pattern 53 projected from the light source 51.

[0044] In step S3, the optical pattern to be selected may be determined based on the positional relationship of the optical patterns projected from the light source 52. In the example of Fig. 3, of the optical patterns projected from the light source 52, the optical pattern projected in a direction that forms the largest angle with respect to the Z direction is displayed on the rightmost side in the X direction of the captured image. Therefore, the control device 70 selects the optical pattern that is on the rightmost side in the X direction of the captured image. In other words, if the positional relationship between the optical pattern projected from the light source 52 and the captured image is determined in advance, the optical pattern may be selected based on this relationship.

[0045] The control device 70 calculates the position of the center of gravity of the selected optical pattern (step S4), and then calculates (measures) the distances of the first member 11 and the second member 12 in the Z direction from the position of the center of gravity (step S5).

[0046] 3, the optical pattern 57 is selected in step S3. In steps S4 and S5, the distance z in the Z direction between the first member 11 and the second member 12 is calculated (measured) from the position of the center of gravity of the optical pattern 57. For example, the distance X in the X direction between the optical patterns 53 and 57 is calculated (measured) from the position of the center of gravity of the optical pattern 53 and the position of the center of gravity of the optical pattern 57. ４ The angle θ4 of the optical pattern 57 with respect to the Z direction when viewed from the Y direction is known, so the distance X ４ and the angle θ4, the distance z can be calculated.

[0047] The distance z can be calculated from the center of gravity of the optical pattern 57 and the center of gravity of any one of the optical patterns 54 to 56. For example, when calculating the distance z from the center of gravity of the optical pattern 57 and the center of gravity of the optical pattern 54, the distance in the X direction between the optical patterns 53 and 57 (X ４ -X １ ) is calculated. Since the angle θ1 of the optical pattern 53 with respect to the Z direction when viewed from the Y direction is known, the distance (X ４ -X １ ) and the angles θ1 and θ4, the distance z can be calculated.

[0048] Furthermore, the distance z can be calculated from the arrangement position of the imaging unit 60 and the position of the center of gravity of any one of the optical patterns 54 to 57. Because the arrangement position of the imaging unit 60 does not change, if the positional relationship between the center of gravity of any one of the optical patterns 54 to 57 and the distance z is known, the distance z can be calculated based on the position of the center of gravity of any one of the optical patterns 54 to 57.

[0049] Here, assuming that the detection of the optical patterns 54 to 57 is performed in units of one pixel of the imaging unit 60 (assuming that the imaging direction of the imaging unit 60 coincides with the Z direction), the resolution Δx of the imaging unit 60 in the X direction is given by

[0050]

[0051] Here, H is the number of pixels in the X direction of the imaging unit 60, d is the distance from the imaging unit 60 to the placement surface of the second holding unit 30, and θ ｆｏｖis the angle of view of the imaging unit 60. On the other hand, the estimation formula for the distance z from the light source 52 (first holding unit 20) to the placement surface of the second holding unit 30 is

[0052]

[0053] In addition, θ Ｌ is one of the angles θ1 to θ4. Therefore, the resolution Δz in the Z direction of the imaging unit 60 is

[0054]

[0055] The maximum value z of the measurement range z in the Z direction of the imaging unit 60 is ｍａｘ and the minimum value z ｍｉｎ teeth,

[0056]

[0057]

[0058] Therefore, the measurement range z of the imaging unit 60 in the Z direction is

[0059]

[0060] Therefore, the resolution Δz in the Z direction of the imaging unit 60 is

[0061]

[0062] This becomes:

[0063] 4 is a graph showing the measurement range and resolution of the imaging unit according to the first embodiment. In FIG. 4, the measurement range z of the imaging unit 60 is shown by a solid line, and the resolution (1 / Δz) of the imaging unit 60 in the Z direction is shown by a dashed line. The horizontal axis also shows the angle (tilt) between the projection direction of the optical pattern projected from the light source 52 and the Z direction.

[0064] 4 , it can be seen that the resolution improves as the angle between the projection direction of the optical pattern projected from the light source 52 and the Z direction increases. In the measurement process of this embodiment, in step S3, of the optical patterns projected from the light source 52, the optical pattern projected in the direction that forms the largest angle with respect to the Z direction when viewed from the Y direction is selected. This allows the distance in the Z direction between the first member 11 and the second member 12 to be calculated using an optical pattern in a region with high resolution, thereby improving the measurement accuracy of the distance in the Z direction between the first member 11 and the second member 12.

[0065] 3, the optical patterns 54 to 57 are projected onto different positions in the X direction relative to the second holding unit 30. That is, the light source 52 projects light onto the mounting surface of the second holding unit 30 so that the optical patterns 54 to 57 do not overlap one another. This allows the control device 70 to distinguish and recognize the optical patterns 54 to 57 in the captured image.

[0066] As described above, the position adjustment system according to the first embodiment includes the light source 52 (first light source) that projects optical patterns 54 to 57 (first optical pattern) onto the second holding unit 30 (object), the imaging unit 60 that images the second holding unit 30, the drive mechanism 40 (drive unit) that changes the relative position of the second holding unit 30 and the light source 52, and the control device 70 (measurement unit) that calculates (measures) the distance z between the first member 11 (light source 52) and the second member 12 (second holding unit 30) based on the image captured by the imaging unit 60. The light source 52 projects the optical patterns 54 to 57 in directions that form different angles with respect to the Z direction (first direction). The light source 52 projects at least some of the optical patterns 54 to 57 onto the imaging area of ​​the imaging unit 60.

[0067] According to this configuration, the light source 52 projects multiple optical patterns (optical patterns 54 to 57) onto the second holding unit 30 in directions that form different angles with the Z direction. At least a portion of the multiple optical patterns is projected onto the imaging area of ​​the imaging unit 60. If an image of a portion of the multiple optical patterns is included in the image captured by the imaging unit 60, the angle between the projection direction of the optical pattern and the Z direction is known, and therefore the distance z between the first member 11 (light source 52) and the second member 12 (second holding unit 30) can be calculated. Therefore, it is not necessary to project all of the optical patterns projected from the light source 52 onto the imaging area of ​​the imaging unit 60, and it is also not necessary to expand the imaging area of ​​the imaging unit 60. This makes it possible to reduce the size of the measurement system (position adjustment system) while suppressing a decrease in measurement accuracy.

[0068] Second Embodiment Fig. 5 is a flowchart illustrating the flow of measurement processing according to the second embodiment. In Fig. 5, steps S11 to S15 are executed instead of steps S3 to S5 in Fig. 1.

[0069] After step S2, the control device 70 calculates the center of gravity position of each optical pattern included in the captured image (step S11). In the example of FIG. 3, the control device 70 calculates the center of gravity position u of each of the optical patterns 54 to 57. １ ~u ４ Calculate.

[0070] The control device 70 calculates an estimated distance z between the first member 11 and the second member 12 from the respective center-of-gravity positions (step S12).

[0071] 6 is a graph showing the relationship between the positional relationship of the optical patterns according to the second embodiment and the estimated distance z. In FIG. 6, the horizontal axis represents the center of gravity position u of the optical patterns 54 to 57. １ ~u ４ and the center of gravity position of the optical pattern 53, and the vertical axis is the estimated distance z. Note that the straight lines L1 to L4 correspond to the optical patterns 54 to 57, respectively.

[0072] 6, broken lines are arranged in the vertical direction at the same pitch Δx. These broken lines indicate the range of error due to the resolution of the image capturing unit 60. Since the image captured by the image capturing unit 60 contains errors, the center of gravity position u １ ~u ４ The distance z cannot be determined to a specific value depending on the position of the optical patterns 54 to 57. Therefore, it is necessary to estimate the distance z by taking into consideration the error in the image captured by the imaging unit 60. In FIG. 6, the value of the true distance z is indicated by a broken line. At this time, each area surrounded by a broken line corresponds to the center of gravity position u of the optical patterns 54 to 57. １ ~u ４ Here, the estimated distance is the distance z corresponding to the center of gravity position u １ ~u ４ Each of the estimated distances of distance z corresponding to １ ~Z ４ In step S13, the control device 70 calculates the estimated distance Z １ ~Z ４ Calculate.

[0073] 6, the slope of the lines L1 to L4 becomes gentler, which indicates that the greater the angle of the optical pattern projected by the light source 52 with respect to the Z direction, the higher the accuracy of estimating the distance z.

[0074] The control device 70 calculates the estimated distance Z １ ~Z ４ The upper limit A of the overlapping area １ (Step S13). The control device 70 calculates the estimated distance Z １ ~Z ４ The lower limit A of the overlapping area ２ is calculated (step S14).

[0075] In the example of FIG. １ is the center of gravity position u of the optical pattern 55 ２ The estimated distance Z corresponding to ２ is the upper limit value of ２ is the center of gravity position u of the optical pattern 55 ２ The estimated distance Z corresponding to ３ is the lower limit of

[0076] The control device 70 determines the upper limit A １ and lower limit A ２ The midpoint between these points is calculated as the distance z between the first member 11 and the second member 12 in the Z direction (step S15).

[0077] As described above, in the second embodiment, the control device 70 calculates (measures) the distance z between the first member 11 (light source 52) and the second member 12 (second holding unit 30) based on the multiple optical patterns (optical patterns 54 to 57) projected from the light source 52. This makes it possible to improve the measurement accuracy (resolution).

[0078] Third Embodiment In a third embodiment, the control device 70 corrects an error in the light projection direction of each optical pattern projected by the light source 52. Because the light source 52 is provided in the first holding unit 20, the light projection direction of the light source 52 may be shifted due to, for example, movement of the first holding unit 20. In the third embodiment, the control device 70 corrects the error due to the shift in the light projection direction of the light source 52.

[0079] 7 is a diagram showing an example of a captured image according to the third embodiment. In FIG. 7, the positions of the optical patterns 54 and 55 in the case where no error occurs are indicated by dashed lines, and the positions of the actual optical patterns 54 and 55 (54' and 55' in FIG. 7) (positions in the case where an error occurs) are indicated by solid lines. Note that FIG. 7 only illustrates the optical patterns 54 and 55 (54' and 55'), and the distance z between the first holding unit 20 and the second holding unit 30 is the same in the actual case and the case where no error occurs.

[0080] As shown in FIG. 7 , the distance T1 between the optical patterns 54 and 55 when no error occurs is different from the distance T2 between the actual optical patterns 54′ and 55′. Because the optical patterns 54 and 55 are projected from the same light source 52 provided in the first holding unit 20, the amount of deviation in the light projection direction is the same. Therefore, the distance between the optical patterns 54 and 55 changes depending on the amount of deviation in the light projection direction of the optical patterns 54 and 55. Therefore, by calculating in advance the correlation between the distance T1 and the amount of deviation in the light projection direction, it is possible to correct the error in the light projection direction of the optical patterns 54 and 55. The control device 70 corrects the error in the light projection direction of each optical pattern projected by the light source 52 in accordance with this correlation.

[0081] Furthermore, an error in the light projection direction of the optical patterns 54, 55 may be corrected based on the positional relationship (distances T1, T2) between the optical patterns 54, 55. That is, by correcting the distance T2 to be equal to the distance T1, the error in the light projection direction of the optical patterns 54, 55 can be corrected.

[0082] Furthermore, the error of the optical patterns 54, 55 may be corrected based on the positional relationship (distances T1, T2) between the optical patterns 54, 55 and the positional relationship between the optical patterns 54, 54' (or the optical patterns 55, 55'). In this case, the error of the optical pattern is caused by a deviation in the light projection direction of the light source 52 or a fluctuation in the position of the light source 52 in the z direction. Theoretically, the distance T2 between the actual optical patterns 54', 55' is the same due to a deviation in the light projection direction of the light source 52 and a fluctuation in the position of the light source 52 in the z direction. In this case, the positional relationship of the optical patterns 54, 54' (or the optical patterns 55, 55') will differ between a case in which the error of the optical pattern is caused by a deviation in the light projection direction of the light source 52 and a case in which the error of the optical pattern is caused by a fluctuation in the position of the light source 52 in the z direction. For this reason, it is assumed that the angles θ1, θ2 formed by the optical patterns 54, 55 with the Y direction are known, but it is possible to determine from the positional relationship of the optical patterns 54, 54' (or the optical patterns 55, 55') whether the error in the optical patterns is caused by a deviation in the light projection direction of the light source 52 or by a change in the position of the light source 52 in the z direction. Therefore, it is possible to correct the error in the optical patterns 54, 55 based on the positional relationship (distances T1, T2) between the optical patterns 54, 55 and the positional relationship between the optical patterns 54, 54' (or the optical patterns 55, 55').

[0083] Furthermore, even when three or more optical patterns are included in a captured image, it is possible to correct the deviation in the light projection direction of the light source 52 and the fluctuation in the position of the light source 52 in the z-direction (hereinafter referred to as the error of the optical system 52). For example, assume that the captured image includes optical patterns 54, 55, and 56. As described above, a correction value (hereinafter referred to as the first correction value) for the error of the light source 52 is calculated based on the distances T1 and T2. A correction value (hereinafter referred to as the second correction value) for the error of the light source 52 is calculated based on the distance T3 between the optical patterns 54 and 56 when no error occurs and the distance T4 between the actual optical patterns 54 and 56. The first and second correction values ​​actually have a range of values ​​depending on the resolution of the captured image. By taking the intermediate value between the lower of the upper limit of the first correction value and the upper limit of the second correction value and the higher of the lower limit of the first correction value and the lower limit of the second correction value, it is possible to correct the error of the light source 52 with high accuracy. Even if there are three or more optical patterns, the error of the light source 52 can be corrected with high precision by calculating each correction value based on the distance between each optical pattern, comparing the upper and lower limit values, and taking the intermediate value.

[0084] In this embodiment, the above processing is possible if there are two optical patterns.

[0085] (Other Embodiments) In the above embodiment, a portion of the optical pattern projected from the light source 52 may be connected by another optical pattern. As shown in Fig. 8, the optical patterns 54 and 55 are connected by a linear optical pattern 59 (third optical pattern). In other words, the optical pattern projected from the light source 52 may be a plurality of connected optical patterns, or a portion of a specific optical pattern may be used as a single optical pattern. In this case, the optical pattern may be any shape, such as a line or a circle, as long as it occupies a certain area.

[0086] REFERENCE SIGNS LIST 10 Position adjustment system (measurement system) 11 First member 12 Second member 20 First holding unit 30 Second holding unit (object) 40 Drive mechanism (drive unit) 50 Light source unit 51 Light source (second light source) 52 Light source (first light source) 53 Optical pattern (second optical pattern) 54 to 57 Optical patterns (first optical pattern) 59 Optical pattern (third optical pattern) 60 Imaging unit 70 Control device (measurement unit)

Claims

1. A measurement system comprising: a first light source that projects a plurality of first optical patterns onto an object; a drive unit that changes the relative position between the object and the first light source; and a measurement unit that measures a distance between the first light source and the object based on an image acquired from an imaging unit that images the object, wherein the first light source projects the first optical patterns in directions that form different angles with respect to a first direction in which the first light source and the object face each other, and the first light source projects at least a portion of the plurality of first optical patterns onto an imaging area of ​​the imaging unit.

2. The measurement system according to claim 1, wherein the first light source projects light so that the multiple first optical patterns do not overlap each other on the surface of the object.

3. The measurement system of claim 1, wherein the angle that the first optical pattern makes with the first direction increases as the distance to the object increases.

4. The measurement system of claim 1, further comprising a second light source that projects a second optical pattern onto the object, the second light source projecting the second optical pattern along the first direction.

5. The measurement system of claim 1, wherein said first light source comprises a diffractive optical element for generating said plurality of first optical patterns.

6. The measurement system of claim 1, wherein the driving unit changes the relative position between the object and the first light source so that at least a portion of the plurality of first optical patterns are projected onto an imaging area of ​​the imaging unit.

7. The measurement system described in claim 6, wherein the measurement unit measures the distance between the object and the light source based on the first optical pattern projected in the captured image in a direction that forms the largest angle with the first direction among the multiple first optical patterns.

8. The measurement system according to claim 6, wherein the measurement unit measures the distance between the object and the light source based on the plurality of first optical patterns in the captured image.

9. The measurement system according to claim 1, wherein the first light source projects a third optical pattern that connects at least a portion of the plurality of first optical patterns onto an imaging area of ​​the imaging section.

10. The measurement system according to claim 1, wherein the measurement unit generates and outputs information relating to the angle of the first light source.

11. The measurement system of claim 1, wherein the plurality of first optical patterns have different projection angles and light wavelengths.

12. A measurement method using the measurement system described in any one of claims 1 to 11, comprising a step in which the measurement unit measures the distance between the object and the light source based on the first optical pattern that, among the plurality of first optical patterns, forms the largest angle with the first direction in the captured image.

13. A measurement method using the measurement system described in any one of claims 1 to 11, wherein the measurement unit has a step of measuring the distance between the object and the light source based on the multiple first optical patterns in the captured image.

14. A measurement program for causing a computer to execute the measurement method according to claim 12.

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