Method and device for calibrating a camera

Abstract

The present disclosure provides a calibration method and a calibration device for an imaging instrument, the imaging instrument comprising a stage moving in a target plane and a lens moving in a target direction perpendicular to the target plane, the calibration method comprising a preparation step and a calibration step, the preparation step comprising: controlling the lens to be at a target position, installing a calibration instrument on the imaging instrument, placing a calibration piece on the stage, the calibration piece comprising a plurality of gauge blocks arranged in the target direction, moving a probe part between adjacent gauge blocks, and forming a control scheme of the imaging instrument based on a positional relationship of the plurality of gauge blocks, the calibration step comprising: controlling the stage and the lens to move based on the control scheme so that the probe part contacts the gauge blocks, recording a moving distance of the lens in the target direction when the probe part contacts the gauge blocks, calculating a calibration error based on the moving distance and the positional relationship, and calibrating the imaging instrument based on the calibration error. According to the present disclosure, a portable calibration method and a calibration device for calibrating the imaging instrument can be provided.

Description

Technical Field

[0001] This invention relates to the intelligent manufacturing equipment industry, and more specifically to a calibration method and calibration device for an imager. Background Technology

[0002] Generally, image measuring instruments obtain the height of workpieces through grating measurement. Therefore, the accuracy of the Z-axis grating in common image measuring instruments determines the accuracy of height measurement. However, for image measuring instruments, factors such as changes in ambient temperature and the aging of mechanical equipment can easily affect their measurement accuracy. Therefore, whenever an image measuring instrument is used for height measurement, it needs to be calibrated before measurement, usually using precision instruments. Furthermore, when changing the application environment of the image measuring instrument, it is also necessary to calibrate the grating using appropriate instruments to compensate for measurement errors that may be introduced due to the change in environment.

[0003] Currently, laser interferometers are commonly used to calibrate the Z-axis grating of an image sensor to ensure its accuracy. However, laser interferometers are bulky, making them inconvenient to carry or transport. Furthermore, their operation involves complex procedures and numerous precautions, which can easily consume excessive time and effort, reducing calibration efficiency. Summary of the Invention

[0004] This disclosure was made in view of the above-mentioned state of the prior art, and its purpose is to provide a calibration method and calibration device that enables portable calibration of an image measuring instrument, thereby reducing the measurement error of the image measuring instrument.

[0005] To this end, this disclosure provides a calibration method for an imager in a first aspect. The imager includes a stage movable within a target plane and a lens movable relative to the stage along a target direction, the target direction being perpendicular to the target plane. The calibration method includes a preparation step and a calibration step. The preparation step includes: controlling the lens to move closer to the stage so that the lens is positioned at a target location; mounting a calibrator on the imager, the calibrator including a probe fixed to the lens; placing a calibrator on the stage, the calibrator including a plurality of gauge blocks arranged along the target direction; moving the probe between adjacent gauge blocks; and forming a control scheme for the imager based on the positional relationship of the plurality of gauge blocks. The calibration step includes: controlling the stage and the lens to move based on the control scheme so that the probe contacts each of the plurality of gauge blocks; recording the movement distance of the lens in the target direction when the probe contacts each of the gauge blocks; calculating a calibration error based on the movement distance and the positional relationship; and calibrating the imager based on the calibration error.

[0006] In this scenario, by having the calibrator contact the gauge blocks to convert the grating movement distance of the image sensor into the distance between the gauge blocks of the calibration component, the error of the image sensor when measuring height can be obtained relatively easily. This allows for easy compensation of the image sensor based on the error, thereby improving the accuracy of height measurement. Furthermore, since the error can be obtained using only the calibrator and calibration components during calibration, the use of bulky, inconvenient, and complex precision instruments such as laser interferometers can be reduced. Simultaneously, with the calibrator mounted on the lens and the calibration components placed on the stage, the calibrator can be moved to different positions and measured by controlling the movement of the image sensor itself. This reduces instrument errors introduced when manipulating the calibrator or calibration components, making image sensor calibration more convenient and accurate, and enabling it to serve precision measurements in various scenarios. Meanwhile, the calibrator is mounted on a lens that can move along the target direction, and the calibrator is placed on a stage that can move within the target plane. The target direction is perpendicular to the target plane, and the stage and lens do not interfere with each other when they move. Compared with the calibration method that only moves the lens, this method can further reduce the error introduced during the measurement process (for example, in the calibration method that only moves the lens, moving the calibrator (lens) along the horizontal direction may cause shaking and cause the position of the calibrator in the target direction to change).

[0007] Additionally, in the calibration method disclosed herein, optionally, any one of the plurality of gauge blocks is selected as the target gauge block. When the probe is moved between adjacent gauge blocks, the position and orientation of the calibrator are adjusted to align the probe with the target gauge block. The stage and lens are then controlled to move the probe between the target gauge block and the gauge blocks adjacent to it. In this case, the target gauge block can be used as a reference, and the distance between other gauge blocks and the target gauge block can be used as a reference distance. Since the distance between any gauge blocks can be accurately obtained based on the specifications or related data of the calibrator, errors that may be introduced when measuring the distance between gauge blocks on-site are reduced.

[0008] Additionally, in the calibration method disclosed herein, optionally, the specification parameters of the calibration component are input into the imager before obtaining the control scheme. In this case, the control scheme for the movement of the stage and lens can be refined based on the specification parameters. Thus, a control scheme matching the calibration component can be formulated according to the input specification parameters, and the imager can be precisely controlled to perform the corresponding calibration steps. Furthermore, corresponding control schemes can also be formulated using calibration components of different specifications.

[0009] Alternatively, in the calibration method disclosed herein, the imager may include a grating ruler, which records the distance the lens moves in the target direction when the probe contacts the gauge block. In this case, by recording the change in the position of the grating scale during lens movement using the grating ruler, the distance the imager's lens moves can be conveniently obtained.

[0010] Additionally, in the calibration method disclosed herein, optionally, the calibrator includes a connection line that transmits the signal generated by the probe to the imager. In this case, once the probe contacts a gauge block and generates a trigger signal, the signal can be quickly transmitted to the imager via the connection line, thereby enabling the imager to record the distance the lens moves in the target direction when the probe contacts the gauge block.

[0011] Additionally, in the calibration method disclosed herein, optionally, the calibration components include a plurality of gauge blocks arranged at equal intervals along the target direction. In this case, the calibration error of the imager can be conveniently obtained by comparing the positional relationship of the equally spaced gauge blocks with the position of the imager lens during movement.

[0012] Additionally, in the calibration method disclosed herein, optionally, the stage and the lens are moved based on the control scheme to bring the probe into contact with the plurality of gauge blocks. This allows for precise control of the stage to bring the probe into contact with the gauge blocks.

[0013] Furthermore, in the calibration method disclosed herein, optionally, if the calibration error is not less than a preset threshold, the calibration steps are repeated until the calibration error is less than the preset threshold. Thus, when a single calibration cannot meet the requirements, multiple calibrations can be performed to improve calibration accuracy, thereby improving the accuracy of the imager's height measurement.

[0014] Additionally, in the calibration method disclosed herein, optionally, the specification parameters include the distance between adjacent gauge blocks, the thickness of the gauge blocks along the target direction, and the number of gauge blocks. In this case, the image analyzer can obtain the distance the multiple gratings have moved along the target direction based on the distance between adjacent gauge blocks and the number of gauge blocks, and compare and analyze this distance with the standard distance between each adjacent gauge block to obtain the measurement error of the gratings more accurately.

[0015] In another aspect, this disclosure provides a calibration apparatus for an imager, comprising: a calibrator and a calibration element, wherein the calibrator is configured to calibrate the imager using the calibration method described in the first aspect of this disclosure, and the calibration element comprises a plurality of gauge blocks having predetermined specification parameters.

[0016] Therefore, this disclosure provides a portable calibration method and apparatus for calibrating an image measuring instrument, thereby reducing the measurement error of the image measuring instrument. Attached Figure Description

[0017] Embodiments of this disclosure will now be explained in further detail by way of example only with reference to the accompanying drawings, in which:

[0018] Figure 1 This is a schematic diagram illustrating a scene of imager calibration according to an embodiment of the present disclosure.

[0019] Figure 2 This is an enlarged schematic diagram illustrating the calibration involved in the embodiments of this disclosure.

[0020] Figure 3 This is a schematic diagram illustrating the imager calibration process according to an embodiment of the present disclosure.

[0021] Figure 4 This is a schematic diagram illustrating the preparation state of calibration according to an embodiment of the present disclosure.

[0022] Figure 5 This is a schematic diagram illustrating the first state of calibration involved in an embodiment of this disclosure.

[0023] Figure 6 This is a schematic diagram illustrating the second state of calibration involved in the embodiments of this disclosure.

[0024] Figure 7 This is a schematic diagram illustrating the third state of calibration involved in the embodiments of this disclosure.

[0025] Figure 8 This is a schematic diagram illustrating the fourth state of calibration involved in the embodiments of this disclosure.

[0026] Figure 9 This is a schematic diagram illustrating the fifth state of calibration involved in the embodiments of this disclosure.

[0027] Figure 10 This is a schematic diagram illustrating the sixth state of calibration involved in the embodiments of this disclosure.

[0028] Figure 11 This is a schematic diagram illustrating the seventh state of calibration involved in the embodiments of this disclosure.

[0029] Explanation of reference numerals in the attached figures:

[0030] Imager…1, Lens…11, Stage…12, Calibrator…2, Calibrator…3. Detailed Implementation

[0031] All references cited in this disclosure are incorporated herein by reference in their entirety, as fully illustrated. Unless otherwise defined, the technical and scientific terms used in this disclosure have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure pertains. A general guide to the many terms used in this application is provided to those skilled in the art. Those skilled in the art will recognize many methods and materials similar to or equivalent to those described herein that can be used in the practice of this disclosure. In fact, this disclosure is by no means limited to the methods and materials described.

[0032] This disclosure relates to a calibration method for an image measuring instrument, which can be used for height calibration of the instrument. In some examples, the image measuring instrument typically includes a stage with a certain load-bearing capacity and a lens that moves in a direction perpendicular to the stage. The lens captures an image of the object to be measured placed on the stage, and the dimensional parameters of the object can be measured by analyzing and processing the image.

[0033] In some examples, the image measuring instrument can measure height as it moves along a direction extending the height. Typically, the image measuring instrument calculates height based on the position of the lens movement. In some examples, the lens movement can be determined by the image measuring instrument's Z-axis grating, thus ensuring the accuracy of height measurement by calibrating the grating. This disclosure relates to a calibration method for an image measuring instrument, which calibrates the lens movement of the image measuring instrument and consequently calibrates its Z-axis grating. In some examples, the calibration method for the image measuring instrument disclosed herein can be used to reduce errors in image measuring instrument height measurement.

[0034] In some examples, the calibration method for the imager disclosed herein may be simply referred to as the calibration method. In some examples, this calibration method allows for on-site calibration of the imager in multiple scenarios as much as possible. Therefore, portable calibration is possible.

[0035] This disclosure also relates to a calibration apparatus for an imager, which can calibrate the imager using the calibration method disclosed herein. In this case, the imager can be calibrated portablely without the aid of precision instruments (such as laser trackers). Furthermore, since the calibration apparatus is portable, it can be used to calibrate the imager in as many scenarios as possible.

[0036] In some examples, the calibration apparatus may include a calibrator and a calibration component. The calibrator may be a high-precision detector, and the calibration component may be a standard component with predetermined specifications. In this case, connecting the calibrator and the imager, and placing the calibration component on the imager's stage, allows for relatively simple calibration of the imager by controlling the imager itself. Furthermore, this reduces the introduction of errors from other instruments when manipulating the calibrator or calibration component.

[0037] The calibration method of the imaging instrument involved in this disclosure is described below with reference to the accompanying drawings.

[0038] Figure 1 This is a schematic diagram illustrating a scene of imager 1 calibration according to an embodiment of the present disclosure. Figure 2 This is an enlarged schematic diagram illustrating the calibration involved in the embodiments of this disclosure.

[0039] In some examples, the imager 1 may include a stage 12 and a lens 11. In some examples, the stage 12 may be movable within the target plane (along such a plane). Figure 2 The lens 11 can move relative to the stage 12 along the target direction (as shown in the D3 or D4 direction). Figure 2 (Movement in the D1 or D2 direction as shown). In some examples, the target direction may be perpendicular to the target plane. In some examples, the stage 12 may include a support surface for carrying the item, and the target plane may be the plane containing the support surface.

[0040] In some examples, the imager 1 may also include a drive mechanism that can drive the lens 11 to move. In some examples, the drive mechanism may also drive the stage 12 to move.

[0041] In some examples, the stage 12 can be a two-dimensional stage. Specifically, the stage 12 can move along a first direction and a second direction. In some examples, the first direction and the second direction are orthogonal, and the plane formed by the intersection of the first direction and the second direction can be the target plane.

[0042] In some examples, such as Figure 2 As shown, the calibrator 2 can be mounted on the lens 11 of the imager 1, and the calibrator 3 can be placed on the stage 12. In this configuration, the calibrator 2 can move along with the lens 11 of the imager 1, and the calibrator 3 can move together with the stage 12. That is, when the lens 11 of the imager 1 moves along the target direction, the calibrator 2 can move along the target direction with the lens 11. When the stage 12 moves within the target plane, the calibrator 3 can move within the target plane with the stage 12. By continuously moving the lens 11 and the stage 12, and thus moving the calibrator 2 and the calibrator 3, the imager 1 can be calibrated.

[0043] In addition, since the calibrator 2 is mounted on the lens 11 and the calibrator 3 is placed on the stage, the calibrator 2 can be moved to different positions and measured by controlling the movement of the imager 1 itself, making the calibration of the imager 1 more convenient.

[0044] In some examples, the stage 12 may be equipped with a leveling device. In some examples, the leveling device can be used to determine the tilt of the stage 12 and adjust it to a horizontal position. In this case, calibrating the imager 1 when the stage 12 is horizontal reduces the possibility of positional changes in the calibration element 3 (changes in the position of the calibration element 3 along the target direction) that may occur when the stage 12 moves, thereby improving the accuracy of the calibration.

[0045] Figure 3 This is a schematic diagram illustrating the calibration process of the imager 1 according to an embodiment of the present disclosure.

[0046] In some examples, the calibration method for the imager 1 may include: controlling the lens 11 to be in the target position (S100), installing the calibrator 2 and placing the calibrator 3 (S200), forming a movement scheme for the lens 11 and the stage 12 (S300), and calibrating the imager 1 (S400).

[0047] In some examples, in step S100, the lens 11 can be controlled to be located at a target position. In some examples, the target position may refer to the closest position of the lens 11 to the stage 12 relative to the stage 12 along the target direction. In some examples, the target position may be the lowest position that the imager 1 can move along the Z-axis. In this case, after moving the lens 11 to the target position, the target position can be used as the initial position for subsequent calibration of the imager 1, thereby facilitating calibration to begin based on the target position.

[0048] In some examples, in step S200, the calibrator 2 can be mounted on the lens 11 of the imager 1, and the calibrator 3 can be placed on the stage 12. In some examples, the calibrator 2 can be detachably mounted on the imager 1. In this case, when the imager 1 needs calibration, the calibrator 2 can be quickly mounted on the imager 1 to calibrate it, and the calibrator 2 can be promptly removed from the imager 1 after calibration. Thus, calibration can be performed portablely.

[0049] In some examples, when installing the calibrator 2, the orientation of the calibrator 2's probe can be controlled and adjusted. Furthermore, when placing the calibrator 3, it can be adjusted to align it with the probe of the calibrator 2.

[0050] In some examples, the detection portion of the calibrator 2 can be referred to as a detection unit. In some examples, the detection unit may be equipped with a sensor, which generates a sensing signal in the calibrator 2 when it detects an object. In this case, if the calibrator 2 is connected to the image sensor 1, the sensing signal generated by the calibrator 2 can be transmitted to the image sensor 1.

[0051] In some examples, the calibrator 2 can be a trigger-type detection instrument. When the detection part of the calibrator 2 comes into contact with an object (e.g., a workpiece) during measurement, stress is generated during the contact process. If the stress when the detection part contacts the object reaches a predetermined threshold, an induction signal can be generated rapidly.

[0052] In some examples, the calibrator 2 may include a connecting cable for transmitting the sensing signal generated by the calibrator 2. In some examples, the connecting cable may be connected to the image sensor 1. In this case, if the calibrator 2 generates a sensing signal, it can be transmitted to the image sensor 1 via the connecting cable. In some examples, the sensing signal may be an edge signal. In other words, the signal output by the detector is not a continuous signal. In this case, since edge signals provide better real-time data transmission, the sensing signal can be quickly sent to the image sensor 1 when the detector contacts an object.

[0053] In some examples, the calibrator 2 can be fixed to the lens 11. In this case, the distance the calibrator 2 moves is equivalent to the distance of the lens 11 of the imager 1. That is, when the lens 11 of the imager 1 moves a certain distance along the target direction, the calibrator 2 on the lens 11 will also move a certain distance along the target direction. In this case, as long as the distance the calibrator 2 moves is determined, the distance the lens 11 moves can be determined, and thus the distance the imager 1 moves along the Z-axis can be determined.

[0054] In some examples, the distance the calibrator 2 moves can be determined by the calibrator 3 as the calibrator 2 moves in the target direction.

[0055] In some examples, the calibration element 3 may include multiple gauge blocks. These gauge blocks are arranged along the target direction. In this case, when the calibration element 3 is placed on the stage 12, since the gauge blocks are arranged along the target direction, the calibrator 2 can be successively aligned with each of the multiple gauge blocks by moving the lens 11 of the imager 1. Whenever the calibrator 2 contacts any gauge block, a trigger signal is generated and transmitted to the imager 1. The imager 1 can then record the position of the lens 11 when the probe generates the sensing signal. The distance the lens 11 moves can be further determined based on the change in the position of the probe when the calibrator 2 contacts each gauge block.

[0056] In some examples, the imager 1 may include a grating ruler. In some examples, the grating ruler may record the distance that the lens 11 moves along the target direction. In this case, if the actual distance moved by the lens 11 is obtained and compared with the distance moved by the lens 11 recorded by the imager 1, the deviation of the lens 11's moving distance can be obtained, and thus the deviation of the grating of the imager 1 can be obtained.

[0057] In some examples, steps S100 and S200 do not have a strict order. In other words, step S100 can be performed before step S200, or after step S200, or step S100 can be performed simultaneously with step S200. That is, the lens 11 can be positioned at the target location after the calibrator 2 is installed and the calibrator 3 is placed.

[0058] In some examples, in step S300, after the calibrator 2 and the calibrator 3 are in place, a control scheme for the imager 1 can be formed based on the positions of the calibrator 2 and the calibrator 3. In this case, precise control of the movement of parts of the imager 1 can be achieved under the control scheme.

[0059] In some examples, in step S400, the imager 1 can be started and calibrated. In some examples, the stage 12 and lens 11 can be moved according to a control scheme to bring the probe into contact with the gauge block. In some examples, when the probe contacts the gauge block, the movement distance of the lens 11 in the target direction is recorded, the calibration error is calculated based on the relationship between the movement distance and the position, and the imager 1 is calibrated based on the calibration error.

[0060] In some examples, the calibration element 3 may include multiple gauge blocks. These gauge blocks can be arranged at equal intervals along the target direction. In this case, when the lens 11 of the image sensor 1 moves along the target direction, the probe and the gauge blocks of the calibration element 3 can be controlled to contact each other sequentially. Each time the probe contacts a gauge block, the image sensor 1 receives a trigger signal and records the movement value via a grating ruler. The actual distance the lens 11 of the image sensor 1 moves along the target direction can then be represented by the distance it moves when contacting different gauge blocks. This distance is compared with the movement distance recorded by the grating ruler (the theoretical distance the image sensor 1 moves, reflected by the difference in the grating ruler's scale), thus obtaining the error in the movement of the lens 11 of the image sensor 1. That is, the grating deviation of the movement of the lens 11 of the image sensor 1 can be obtained based on the positional relationship between the gauge blocks and the movement of the grating of the image sensor 1.

[0061] In some examples, the gauge blocks on the calibration piece 3 may not be evenly spaced. In other examples, multiple gauge blocks may be arranged at predetermined intervals along the target direction. For example, the interval between the gauge block closest to the bottom of the calibration piece 3 (the target gauge block) and its adjacent first gauge block can be a first distance, the interval between the first gauge block and its adjacent second gauge block can be a second distance, ..., the interval between the (N-1)th gauge block and its adjacent Nth gauge block can be the Nth distance. It is understood that as long as the interval between any two adjacent gauge blocks on the calibration piece 3 is determined, when using the calibration piece 3 in conjunction with the calibrator 2 to calibrate the image instrument 1, the deviation of the grating movement can be obtained relatively accurately by the positional relationship between each gauge block (the distance between gauge blocks and the thickness of the gauge blocks) and the distance the grating moves when the probe contacts each gauge block.

[0062] In some examples, the specifications of the calibration component 3 can be input into the imager 1 before step S300. In this case, the control scheme for moving the stage 12 and lens 11 can be refined based on the specifications. Furthermore, a control scheme matching the calibration component 3 can be developed based on the input specifications, and the imager 1 can be precisely controlled to perform the corresponding calibration steps. Additionally, control schemes can be developed using calibration components 3 of different specifications.

[0063] In some examples, the specifications of the calibration component 3 may include the distance between adjacent gauge blocks, the thickness of the gauge blocks along the target direction, and the number of gauge blocks. By determining the distance between adjacent gauge blocks and the thickness of the gauge blocks, the distance the grating moves when it contacts the gauge blocks can be determined. By determining the number of gauge blocks and the positional relationship between them, the distance the lens 11 of the imager 1 needs to move along the target direction during calibration can be determined.

[0064] In some examples, the imager 1 may also have a display mechanism. In some examples, the display mechanism can be used to input the specifications of the calibration component 3. Additionally, the display mechanism can also output the raster deviation data of the imager 1 during calibration.

[0065] The calibration steps will be described below with reference to the accompanying drawings, but it should be understood that the descriptions should not be limiting.

[0066] Figure 4 This is a schematic diagram illustrating the preparation state of calibration according to an embodiment of the present disclosure. Figure 5 This is a schematic diagram illustrating the first state of calibration involved in an embodiment of this disclosure. Figure 6 This is a schematic diagram illustrating the second state of calibration involved in the embodiments of this disclosure. Figure 7This is a schematic diagram illustrating the third state of calibration involved in the embodiments of this disclosure. Figure 8 This is a schematic diagram illustrating the fourth state of calibration involved in the embodiments of this disclosure. Figure 9 This is a schematic diagram illustrating the fifth state of calibration involved in the embodiments of this disclosure. Figure 10 This is a schematic diagram illustrating the sixth state of calibration involved in the embodiments of this disclosure. Figure 11 This is a schematic diagram illustrating the seventh state of calibration involved in the embodiments of this disclosure.

[0067] In some examples, when calibrating the imager 1, any one of multiple gauge blocks can be selected as the target gauge block. While moving the probe between adjacent gauge blocks, the position and orientation of the calibrator 2 are adjusted to align the probe with the target gauge block, and the probe is controlled to move between the target gauge block and adjacent gauge blocks. In some examples, the probe can be moved between the target gauge block and adjacent gauge blocks by controlling the stage 12 and lens 11. In this case, the target gauge block can be used as a reference, and the distance between other gauge blocks and the target gauge block can be used as a reference distance. Since the distance between any gauge blocks can be obtained relatively accurately based on the specifications or data of the calibrator 3, errors that may be introduced when measuring the distance between gauge blocks on-site are reduced.

[0068] In some examples, the stage 12 and the lens 11 do not move simultaneously during calibration. In other words, the stage 12 and the lens 11 are controlled to move independently, and their movements do not interfere with each other.

[0069] In some examples, the gauge block closest to the stage 12 can be set as the target gauge block. After completing the preparatory steps before calibration, the calibrator 2 is installed, and the position of the calibration component 3 is adjusted. At this time, the lens 11 of the image sensor 1 can be located at the target position, and the probe of the calibrator 2 can be roughly aligned with the target gauge block of the calibration component 3 (see...). Figure 4 In this case, by recording the reading of the grating ruler when the lens 11 is in the target position using the imager 1, and then recording the reading of the grating ruler and the change in reading when it is in contact with each gauge block during calibration, the actual movement error of the grating can be obtained.

[0070] In some examples, since the target direction and the target plane are perpendicular to each other, the paths of the stage 12 and the lens 11 do not interfere with each other. Compared with moving the stage 12 and the lens 11 at the same time in the calibration step, moving only the stage 12 or only the lens 11 can reduce the error caused during the measurement process (for example, in the calibration method of moving only the lens 11, moving the calibrator 2 (or lens 11) in the horizontal direction may cause jitter and cause the position of the calibrator 2 in the target direction to change).

[0071] In some examples, after entering the calibration step, the first state of calibration can begin. At this time, the lens 11 can move along the D1 direction to move away from the stage 12. When the calibrator 2 fixed on the lens 11 is at a height approximately between the target gauge block and the gauge block adjacent to the target gauge block, the lens 11 stops moving. At this time, the probe of the calibrator 2 is located on one side of the target gauge block.

[0072] In some examples, the target gauge block can be set as the first gauge block, and the gauge block adjacent to the target gauge block can be set as the second gauge block, the other gauge block adjacent to the second gauge block as the third gauge block, the other gauge block adjacent to the third gauge block as the fourth gauge block, and so on. Similarly, when the calibrator 3 has N gauge blocks, the target gauge block, second gauge block, third gauge block, ..., Nth gauge block can be set along the target direction (understandably, N is a finite positive integer). In this case, if the calibrator 2... Figure 4 The state shown is roughly aligned with the target gauge block. As the calibrator 2 moves along the target direction, the calibrator 2 can gradually approach the target gauge block, the second gauge block, the third gauge block, ..., the Nth gauge block along the target direction.

[0073] In some examples, the stage 12 can move along the target platform (along the D3 or D4 direction). In some examples, when the probe of the calibrator 2 is located outside the target gauge block (first gauge block), it can enter the second calibration state, at which point the lens 11 moves along the D1 direction and gradually approaches the second gauge block. When the height of the probe of the calibrator 2 is as shown... Figure 5 When the lens 11 is at the height between the target gauge block and the second gauge block, as shown, it stops moving and begins calibration.

[0074] In some examples, when calibration enters the first state, the stage 12 can move along the D3 direction in the target plane. When the probe of the calibrator 2 is between the target gauge block and the second gauge block, and the probe of the calibrator 2 is observed along the target direction, if the probe of the calibrator can be blocked by the gauge block of the calibrator 3, the stage 12 stops moving and enters the second state of calibration.

[0075] In some examples, such as Figure 6As shown, when calibration enters the second state, the lens 11 can move along the D2 direction closer to the stage 12. Since the probe is blocked by the gauge block along the target direction, as the lens 11 moves closer to the stage 12, the probe can change from a suspended state to a state of touching the target gauge block. In this case, since only the lens 11 moves along the target direction while the stage 12 remains stationary, compared to simultaneously moving both the lens 11 and the stage 12 to allow the calibrator 2 and the calibrator 3 to touch and measure, the possibility of the stage 12 vibrating during the measurement process and causing a change in the position of the calibrator 2 in the target direction can be reduced. Therefore, the accuracy of the lens 11 movement measurement can be improved.

[0076] In some examples, the probe of calibrator 2 can gradually approach the target gauge block as lens 11 moves along direction D2. When the probe of calibrator 2 contacts the target gauge block, it enters the third state of calibration (see...). Figure 7 In this case, since the detector can contact the target block to generate a sensing signal, the image unit 1 can receive the sensing signal and record the instantaneous grating position and calculate the scale of grating movement (the grating position when the lens 11 is in the target position and the grating position when the detector contacts the target block).

[0077] In some examples, after the probe and target gauge block come into contact and the imager 1 records the grating position, the fourth calibration state is entered. The stage 12 can move along the D4 direction in the target plane to move the probe away from the calibration element 3. When the stage 12 moves a predetermined distance, the probe is not obstructed by any gauge block of the calibration element 3 along the target direction (see [reference]). Figure 8 In this case, the probe of the subsequent calibrator 2 can move along the target direction without being obstructed by the next gauge block.

[0078] In some examples, after the probe contacts the target gauge block, the imager 1 can control the probe to lift away from the surface of the target gauge block. In this case, since the probe is free from the surface of the target gauge block, when the stage 12 moves along the D4 direction and moves the calibration element 3 away from the probe, it can effectively prevent the probe from sliding on the surface of the target gauge block as the calibration element 3 moves. If the probe slides on the surface of the target gauge block, significant friction will be formed at the point of contact between the probe and the surface of the target gauge block, which can easily damage the calibrator 2 and the calibration element 3, and thus easily reduce the accuracy of the imager 1 calibrated by the calibration device (calibrator 2 and calibration element 3).

[0079] In some examples, such as Figure 9 As shown, the stage 12 can be controlled to move the calibration piece 3 along the D3 direction closer to the calibrator 2 until it reaches the desired position. Figure 10 The state shown.

[0080] In some examples, such as Figure 10 As shown, the imager 1 can be controlled to perform similar functions. Figure 6 As shown in the operation, when the probe of calibrator 2 moves along the D1 direction to between the second and third gauge blocks, the movement of lens 11 stops, and calibration enters the seventh state. Then, lens 11 is moved along the D2 direction until... Figure 11 The state shown.

[0081] In some examples, such as Figure 11 As shown, the stage 12 can be controlled to perform similar actions. Figure 7 The operation shown is that when the probe of the calibrator 2 contacts the second gauge block, the data of the grating is recorded.

[0082] Repeat the above operation, controlling the movement paths of lens 11 and stage 12 until the calibrator 2 contacts each gauge block of the calibration component 3, and record the distance the grating moves when the calibrator 2 contacts each gauge block. Then process the data to obtain the deviation of the grating movement. In this case, by collecting data such as the position of the grating and the distance the grating moves when the calibrator 2 contacts the gauge blocks, the movement error of the grating of the image instrument 1 can be obtained. At the same time, the calibration operation steps are simple, and the data collection and processing are also relatively simple, thus greatly improving the calibration efficiency.

[0083] In some examples, the calibration component 3 may be configured with ten gauge blocks. In this case, the grating position when the calibrator 2 and each of the ten gauge blocks are in contact is obtained, and the initial position of the grating before calibration is recorded. Then, the deviation of the grating movement is calculated and analyzed based on the distance between each gauge block and the scale corresponding to the grating movement between each gauge block.

[0084] In some examples, after calibration, the error in the movement distance can be obtained based on the actual movement distance of the lens 11 of the imager 1 and the movement distance recorded by the grating. This error is then used to compensate the grating of the imager 1. The compensated imager 1 is then measured again using the calibrator 2 and the calibration component 3. If the grating error of the imager 1 at this point is less than a preset threshold, it indicates that the imager 1 has completed calibration. Therefore, when a single calibration is insufficient, multiple calibrations can improve the calibration accuracy, thereby improving the measurement accuracy of the imager 1.

[0085] In some examples, if the calibration error obtained by imager 1 is not less than a preset threshold, the calibration steps are repeated until the final calibration error obtained by imager 1 is less than the preset threshold. This improves the accuracy of the grating measurement by imager 1.

[0086] This embodiment also discloses a calibration apparatus for an image sensor 1. The calibration apparatus may include a calibrator 2 and a calibration component 3. The calibrator 2 can calibrate the image sensor 1 using the calibration method described above. The calibration component 3 may include a plurality of gauge blocks having predetermined specifications.

[0087] According to this disclosure, a calibration method and calibration apparatus for calibrating an imager 1 in a portable manner can be provided.

[0088] Various embodiments of this disclosure have been described above in the detailed description. Although these descriptions directly depict the above embodiments, it should be understood that modifications and / or variations to the specific embodiments shown and described herein will occur to those skilled in the art. Any such modifications or variations falling within the scope of this specification are also intended to be included herein. Unless specifically indicated, the inventors intend that the words and phrases in the specification and claims be given the common and customary meaning to those skilled in the art.

[0089] The foregoing description of various embodiments of this disclosure, known to the applicant at the time of filing this application, is intended for illustrative and descriptive purposes. This description is not intended to be exhaustive, nor does it limit the disclosure to the exact forms disclosed, and many modifications and variations can be made in accordance with the foregoing teachings. The described embodiments are intended to explain the principles of this disclosure and its practical application, and to enable others skilled in the art to utilize this disclosure in various embodiments and with various modifications suitable for the particular intended use. Therefore, this disclosure is not intended to be limited to the specific embodiments disclosed for implementing this disclosure.

[0090] While specific embodiments of this disclosure have been shown and described, it will be apparent to those skilled in the art that variations and modifications can be made based on the teachings of this disclosure without departing from the disclosure and its broader aspects, and therefore the appended claims are intended to cover all such changes and modifications within the true spirit and scope of this disclosure. Those skilled in the art will understand that, in general, the terminology used in this disclosure is intended to be “open” terminology (e.g., the term “comprising” should be interpreted as “including but not limited to”, the term “having” should be interpreted as “at least having”, the term “comprising” should be interpreted as “including but not limited to”, etc.).

Claims

1. A calibration method for an imager, the imager comprising a stage movable within a target plane and a lens movable relative to the stage along a target direction, the target direction being perpendicular to the target plane, characterized in that, The calibration method includes a preparation step and a calibration step. The preparation step includes: controlling the lens to move closer to the stage so that the lens is in a target position; installing a calibrator on the image instrument, the calibrator including a probe fixed to the lens; placing a calibration component on the stage, the calibration component including multiple gauge blocks arranged at equal intervals along the target direction; moving the probe between adjacent gauge blocks; and forming a control scheme for the image instrument based on the positional relationship of the multiple gauge blocks. The calibration step includes: controlling the stage and the lens to move based on the control scheme so that the probe contacts each of the multiple gauge blocks; the probe contacts the gauge blocks and generates stress during measurement; when the stress reaches a predetermined threshold, the probe generates a sensing signal; the calibrator transmits the sensing signal to the image instrument; recording the movement distance of the lens in the target direction when the probe contacts each gauge block; calculating the calibration error based on the movement distance and the positional relationship; and calibrating the image instrument based on the calibration error; the stage remains stationary while the lens moves along the target direction. Before obtaining the control scheme, the specification parameters of the calibration component are input into the image instrument, and the control scheme matching the calibration component is formulated according to the specification parameters. The specification parameters include the distance between adjacent gauge blocks, the thickness of the gauge blocks along the target direction, and the number of the plurality of gauge blocks.

2. The calibration method according to claim 1, characterized in that: Select any one of the plurality of gauge blocks as the target gauge block. When the probe is moved between the adjacent gauge blocks, adjust the position and orientation of the calibrator so that the probe is aligned with the target gauge block. Control the stage and the lens to move so that the probe is moved between the target gauge block and the gauge block adjacent to the target gauge block.

3. The calibration method according to claim 1, characterized in that: The imaging device includes a grating ruler, which records the movement distance of the lens in the target direction when the probe contacts the gauge block.

4. The calibration method according to claim 1, characterized in that: The calibrator includes a connection line that transmits the signal generated by the detector to the imager.

5. The calibration method according to claim 1, characterized in that: Based on the control scheme, the stage and the lens are moved to make the probe contact the plurality of gauge blocks.

6. The calibration method according to claim 1, characterized in that: If the calibration error is not less than a preset threshold, the calibration steps are repeated until the calibration error is less than the preset threshold.

7. A calibration device for an imager, characterized in that, include: A calibrator and calibration components, the calibrator being configured to calibrate the imager using the calibration method according to any one of claims 1-6, the calibration components comprising a plurality of gauge blocks having predetermined specification parameters.

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