Search system and method for the location of light spot target, and height measurement system and method

Abstract

This application discloses a system and method for searching the location of a light spot target, and a system and method for measuring height, relating to the field of measurement technology. The system for searching the location of a light spot target includes a light source, a reflector, a driving device, a photoelectric detection device, and a control device. The light source emits a detection beam to the object being measured. The reflector receives the detection beam reflected by the object and reflects it to a preset plane where the photoelectric detection device is located to form a light spot. The driving device is connected to the reflector and drives the reflector to rotate. The photoelectric detection device detects the light spot and includes multiple photodetectors arranged linearly. The control device is connected to both the driving device and the photoelectric detection device. This system for searching the location of a light spot target can improve upon the problem of the relatively complex structure of zero-plane adjustment devices in related technologies.

Description

Technical Field

[0001] This application relates to the field of height measurement technology, and in particular to a system and method for searching the location of a light spot target, and a height measurement system and method. Background Technology

[0002] In industries such as semiconductor manufacturing equipment and precision instruments, measurement systems are frequently used to measure the height of objects. To maintain measurement accuracy under different temperature conditions, the zero-plane position of the measurement system needs to be adjusted at different measurement locations. Therefore, a method for efficiently calibrating the zero-plane position is required.

[0003] Generally, the zero-plane adjustment device of a measurement system includes a light source, the object being measured, an adjuster, a probe slit, and a sensor. The light source generates a light beam and directs it toward the object being measured, causing the beam to be further reflected to the adjuster. The adjuster is used to adjust the reflection direction of the beam so that it passes through the probe slit and falls onto the sensor, thereby completing the zero-plane calibration process. However, this zero-plane adjustment device requires an additional slit mounting structure within the measurement system for installing the probe slit, which complicates the overall structure of the measurement system. Summary of the Invention

[0004] This application provides a system and method for searching the location of a light spot target, and a system and method for measuring height, aiming to improve the problem of the complex structure of zero-plane adjustment devices in related technologies.

[0005] Firstly, embodiments of this application provide a spot target location search system. This spot target location search system includes a light source, a reflector, a driving device, a photoelectric detection device, and a control device. The light source emits a detection beam to the object being measured. The reflector receives the detection beam reflected by the object and reflects it to a preset plane where the photoelectric detection device is located to form a spot. The driving device is connected to the reflector and drives the reflector to rotate. The photoelectric detection device detects the spot and includes multiple photodetectors arranged linearly. The control device is connected to both the driving device and the photoelectric detection device. In this embodiment, the boundary between two adjacent photodetectors (PDs) can be used as the spot target location; this boundary is equivalent to the aforementioned detection slit. The spot target location search system provided in this embodiment does not require additional detection slits and can correspondingly eliminate the need for a slit installation structure. Furthermore, since the spot target location search system itself requires PDs, this embodiment uses multiple PDs, eliminating the need for additional installation structures. Therefore, the spot target position search system provided in this application embodiment can improve the problem of the complex structure of the zero plane adjustment device in related technologies.

[0006] In some embodiments, the photoelectric detection device is configured such that when the object under test moves along a preset direction, the light spot moves along the arrangement direction of the plurality of photoelectric detectors, wherein the preset direction is the direction of movement of the object under test. In this embodiment, the direction of movement of the object under test is determined, i.e., the preset direction. Thus, the light spot can be reset simply by the driving device driving the reflector to rotate around the second axis, simplifying the movement process of the reflector.

[0007] In some embodiments, the driving device includes a first motor and a second motor; the first motor drives the reflector to rotate about a first axis, wherein the first axis is the axis that causes the light spot to move along a first direction when the reflector rotates; the second motor drives the reflector to rotate about a second axis, wherein the second axis is the axis that causes the light spot to move along a second direction when the reflector rotates; wherein the first direction is perpendicular to the arrangement direction of the plurality of photoelectric detection devices, and the second direction is parallel to the arrangement direction. In this embodiment, the first motor and the second motor of the driving device are respectively used to drive the reflector to rotate about the first axis and the second axis, so the light spot reflected by the reflector can move in two directions on the preset plane, that is, the movement trajectory of the light spot on the preset plane can be a two-dimensional trajectory, and the light spot can move in two dimensions within the neighborhood of the starting position.

[0008] Secondly, embodiments of this application provide a method for searching the location of a light spot target. This method is applied to the aforementioned light spot target location search system and includes: The driving device drives the reflector to perform a first rotation process, so that the light spot moves on the preset plane; During the movement of the light spot, the control device acquires the light intensity detection value of the photoelectric detection device; When the light intensity detected by the photoelectric detection device is greater than or equal to the first light intensity threshold, the driving device stops driving the reflector; and The driving device drives the reflector to perform a second rotation process, so that the light spot moves on the preset plane to the target position of the light spot, wherein the target position of the light spot is located on the preset plane and is within the coverage area of ​​the photoelectric detection device.

[0009] In related technologies, during the initial zero-plane calibration, the zero-plane adjustment device is unsure of the initial spot location, thus requiring manual adjustment of the adjuster until the spot passes through the detection slit. Subsequent changes in the zero plane allow for adjustment based on the distance of the zero-plane height change, such as translation distance or rotation angle. However, the initial zero-plane calibration process cannot be automated without manual intervention. In contrast, the spot target position search method provided in this application is applied to the aforementioned spot target position search system. The driving device drives the reflector to perform a first rotation process, causing the spot to move to the photoelectric detection device on a preset plane. Further movement stops when the light intensity detection value of the photoelectric detection device is greater than or equal to a first light intensity threshold, at which point at least a portion of the spot is located on the photoelectric detection device. Then, the driving device drives the reflector to perform a second rotation process, further moving the spot to the target position on the preset plane. Thus, regardless of whether it is the initial or subsequent zero-plane calibration, the spot can automatically move to the target position.

[0010] In some embodiments, the spot movement speed corresponding to the second rotation process is less than the spot movement speed corresponding to the first rotation process. In this embodiment, to quickly locate the photoelectric detection device on the preset plane, the spot movement speed corresponding to the first rotation process is relatively high, such as the motor speed being on the order of milliradians per second (mrad / s) when driving the reflector in the first rotation process. However, to accurately locate the spot target position after locating the photoelectric detection device, the spot movement speed corresponding to the second rotation process is relatively low, such as the motor speed being on the order of microradians per second (μrad / s) when driving the reflector in the second rotation process, so that the spot can move more precisely to the spot target position. Therefore, this embodiment can achieve both accurate positioning and high positioning efficiency.

[0011] In some embodiments, the driving device drives the reflector to perform a first rotation process to move the light spot on the preset plane, including: controlling the driving device to drive the reflector to rotate about a first axis and a second axis, so that the light spot moves along a spiral trajectory extending from the inside to the outside on the preset plane. When the reflector rotates about the first axis, the light spot moves along a first direction; when the reflector rotates about the second axis, the light spot moves along a second direction. The first direction is perpendicular to the arrangement direction of the plurality of photodetectors, and the second direction is parallel to the arrangement direction. In this embodiment, the light spot moves spirally within the neighborhood of the starting position on the preset plane in a manner that surrounds the starting position and gradually moves away from it. This method can reduce the risk of the light spot missing a photodetector in that neighborhood.

[0012] In some embodiments, the spiral trajectory is a spiral curve, or the spiral trajectory comprises multiple straight line segments connected sequentially to form the spiral trajectory. In this embodiment, the spiral trajectory can be a spiral curve; the spacing between adjacent turns of a spiral curve is the same in any direction, so it is less likely to miss photoelectric detection devices during the movement of the light spot along the spiral curve. The spiral trajectory can also be formed by connecting multiple straight line segments sequentially. This method not only reduces the risk of missing photoelectric detection devices in the neighborhood of the starting position, but also allows the reflector to rotate in one dimension each time it rotates. This method decouples the rotational motion of the reflector in two rotational dimensions, which helps to simplify the control of the reflector by the driving device.

[0013] In some embodiments, the light intensity detection value of the photoelectric detection device being greater than or equal to a first light intensity threshold includes: the light intensity detection value of any of the photodetectors being greater than or equal to the first light intensity threshold. In this embodiment, when determining whether a light spot falls on the photoelectric detection device, it is not necessary to sum the light intensity detection values ​​of two adjacent photodetectors or all photodetectors, which simplifies the judgment logic and computing power requirements of the control device, improves processing efficiency, and reduces equipment costs.

[0014] In some embodiments, a first direction is perpendicular to the arrangement direction of the plurality of photodetectors, a second direction is parallel to the arrangement direction, and the target position of the light spot is located at the center position of the photodetector along the first direction and the center position along the second direction. The driving device drives the reflector to perform a second rotation process to move the light spot to the target position on the preset plane, including: the driving device driving the reflector to rotate about a first axis to move the light spot to a first target position along the first direction, wherein when the reflector rotates about the first axis, the light spot moves along the first direction, and the first target position is located at the center position of the photodetector along the first direction; and the driving device driving the reflector to rotate about a second axis to move the light spot from the first target position to the target position along the second direction, wherein when the reflector rotates about the second axis, the light spot moves along the second direction. In this embodiment, the control device first drives the reflector to rotate, so that the light spot moves along the first direction to the first target position, and then drives the reflector to rotate, so that the light spot moves along the second direction to the target position of the light spot. Since the change of the light intensity detection value of the photoelectric detection device is regular when the light spot moves along the first direction and the second direction, controlling the light spot to move along the first direction first can make the light spot move to the center position of the photoelectric detection device along the first direction, and controlling the light spot to move along the second direction can make the light spot move to the center position of the photoelectric detection device along the second direction, thereby making the light spot move to the aforementioned target position of the light spot.

[0015] In some embodiments, the driving device drives the reflector to rotate about a first axis to move the light spot to a first target position along the first direction, comprising: the driving device driving the reflector to rotate about the first axis to move the light spot to one side of the photodetector along a first sub-direction, wherein the first direction includes a first sub-direction and a second sub-direction that are opposite to each other; the driving device driving the reflector to rotate about the first axis to move the light spot along the second sub-direction; the control device determining a first reference position and a second reference position where the light spot is located when the light intensity detection value of the photodetector is equal to a second light intensity threshold; the control device determining the first target position based on the first reference position and the second reference position; and the driving device driving the reflector to rotate about the first axis to move the light spot to the first target position.

[0016] In this embodiment, the driving device first drives the reflector to rotate around the first axis, causing the light spot to move along the first sub-direction and move out of the photoelectric detection device. Then, it drives the reflector to rotate around the first axis, causing the light spot to move along the second sub-direction and pass through the photoelectric detection device. After that, the first reference position and the second reference position with equal light intensity detection values ​​during the process are determined. Along the first direction, the two positions with equal light intensity are symmetrical about the midpoint of the photoelectric detection device along the first direction. Conversely, the first reference position and the second reference position are two positions symmetrical about the midpoint of the photoelectric detection device along the first direction. Therefore, the midpoint of the photoelectric detection device in the first direction, i.e., the first target position, can be determined based on the first reference position and the second reference position. Finally, the reflector is driven to rotate around the first axis, causing the light spot to move to the first target position.

[0017] In some embodiments, the plurality of photodetectors includes a first photodetector and a second photodetector; the driving device drives the reflector to rotate around a second axis to move the light spot from a first target position to the target position of the light spot along the second direction, including: the driving device drives the reflector to rotate around the second axis to move the light spot from the first target position to one side of the photodetector along a third sub-direction, wherein the second direction includes a third sub-direction and a fourth sub-direction that are opposite to each other, along the second direction; the driving device drives the reflector to rotate around the second axis to move the light spot along the fourth sub-direction until the first light intensity detection value of the first photodetector and the second light intensity detection value of the second photodetector satisfy a preset value condition; wherein the preset value condition is: the sum of the first light intensity detection value and the second light intensity detection value is greater than a third light intensity threshold, and the absolute value of the difference between the first light intensity detection value and the second light intensity detection value is less than a fourth light intensity threshold.

[0018] When the light spot moves to the center position of the photodetector along the second direction, the area of ​​the light spot on the first photodetector and the second photodetector should be the same, and the light intensity detection values ​​of the first photodetector and the second photodetector should be equal. The preset conditions include: the sum of the first light intensity detection value and the second light intensity detection value is greater than a third light intensity threshold, and the absolute value of the difference between the first light intensity detection value and the second light intensity detection value is less than a fourth light intensity threshold. The former condition constrains the light spot to be at least partially located on the photodetector, and the latter condition constrains the portion of the light spot located on the first photodetector to be the same as the portion located on the second photodetector. Therefore, when the above preset conditions are met, it can be determined that the light spot is located at the center position of the photodetector along the second direction.

[0019] Thirdly, this application also provides a method for searching the target position of a light spot. This method is applied to the aforementioned system for searching the target position of a light spot. The method includes: when the light spot is not at the target light spot position, the driving device drives the reflector to rotate around a second axis, so that the light spot is reset to the target light spot position along a second direction; wherein the target light spot position is located on the preset plane and within the coverage area of ​​the photoelectric detection device, the second direction is the arrangement direction of the plurality of photoelectric detectors, and the second axis is the axis along which the light spot moves along the second direction when the reflector rotates. After non-initial zero-plane adjustment, since the object being measured moves along the preset direction, and when the object being measured moves along the preset direction, the light spot moves along the second direction on the surface of the photoelectric detection device; therefore, during non-initial zero-plane adjustment, only the reflector needs to be controlled to rotate around the second axis to reset the light spot to the target light spot position along the second direction; thus, the non-initial zero-plane correction process is relatively simple.

[0020] In some embodiments, the plurality of photodetectors includes a first photodetector and a second photodetector; the driving device drives the reflector to rotate around a second axis to reset the light spot to the target light spot position along the second direction, including: the driving device drives the reflector to rotate around the second axis until the first light intensity detection value of the first photodetector and the second light intensity detection value of the second photodetector meet a preset value condition; wherein, the preset value condition is: the sum of the first light intensity detection value and the second light intensity detection value is greater than a third light intensity threshold, and the absolute value of the difference between the first light intensity detection value and the second light intensity detection value is less than a fourth light intensity threshold. When the light spot moves to the center position of the photodetector along the second direction, the area of ​​the light spot on the first photodetector and the second photodetector is the same size, and the light intensity detection values ​​of the first photodetector and the second photodetector should be equal. The preset value conditions include: the sum of the first light intensity detection value and the second light intensity detection value is greater than a third light intensity threshold, and the absolute value of the difference between the first light intensity detection value and the second light intensity detection value is less than a fourth light intensity threshold. The former condition constrains the light spot to be at least partially located within the photodetector, and the latter condition constrains the portion of the light spot located within the first photodetector to be the same as the portion located within the second photodetector. Therefore, when the above preset value conditions are met, it can be determined that the light spot has been reset to the center position of the photodetector along the second direction, i.e., the target position of the light spot.

[0021] Fourthly, this application also provides a height measurement system. This height measurement system includes a measured object, a driven component for the measured object, and a search system for the target position of the light spot. The driven component is connected to the measured object and is used to drive the measured object to move along a preset direction. When the height of the measured object needs to be measured, the height measurement system provided in this application moves the measured object to different height positions for measurement. At this time, the light spot moves along a second direction from the target position in the photoelectric detection device. The light intensity detection values ​​of multiple photodetectors in the photoelectric detection device will change because the size of the light spot in the photodetectors is different when the light spot moves to different positions. Therefore, the control device can determine the height of the measured object moving from the zero plane based on the light intensity detection values ​​of each photodetector corresponding to the moved light spot. That is to say, the search system for the target position of the light spot in this application can not only achieve zero plane correction but also height measurement.

[0022] Fifthly, this application also provides a height measurement method. This height measurement method is applied to the aforementioned height measurement system. The method includes: the object-to-measure drive unit driving the object to move along the preset direction; the control device acquiring the light intensity detection value of the photoelectric detection device; and the control device determining the height of the object based on the light intensity detection value of the photoelectric detection device. When the height of an object needs to be measured, the height measurement method provided in this application moves the object along the preset direction. At this time, the light spot moves along a second direction from the target position of the light spot in the photoelectric detection device. The light intensity detection values ​​of multiple photoelectric detectors in the photoelectric detection device will change because the size of the light spot in the photoelectric detector is different when the light spot moves to different positions. Therefore, after acquiring the light intensity detection value of the photoelectric detection device, the control device can determine the height of the object moving from the zero plane based on the light intensity detection value of the photoelectric detector. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating zero-plane adjustment using an adjustment method, as provided in an embodiment of this application. Figure 2 This is a schematic diagram of the architecture of a spot target location search system provided in an embodiment of this application; Figure 3 This is a flowchart illustrating a method for searching the location of a light spot target provided in an embodiment of this application; Figure 4 This is a schematic diagram of a light spot falling on a preset plane according to an embodiment of this application; Figure 5A This is a schematic diagram showing the movement of a light spot along a spiral curve on a preset plane during the first rotation process of the reflector provided in this application embodiment; Figure 5BThis is a side view of the reflector reflecting the light beam onto a preset plane in an embodiment of this application; Figure 5C This is a schematic diagram showing the movement of a light spot along a spiral trajectory composed of multiple straight lines on a preset plane during the first rotation process of the reflector provided in this application embodiment; Figure 6 This is a schematic diagram showing the location of the light spot at the target position provided in the embodiments of this application; Figures 7A-7B This is a schematic diagram of a movement trajectory of a light spot on a preset plane during the second rotation process of the reflector provided in this application embodiment; Figures 7C-7D This is a schematic diagram of another movement trajectory of the light spot on a preset plane during the second rotation process of the reflector provided in the embodiments of this application; Figure 8 This is a schematic diagram of the height measurement system provided in an embodiment of this application; Figure 9 This is a schematic diagram of the height measurement method provided in the embodiments of this application.

[0024] Figure label: 110 - Light source; 120 - Object under test; 130 - Adjuster; 140 - Detection slit; 150 - Sensor; 210 - Light source; 220 - Driving device; 230 - Reflector; 240 - Photoelectric detection device; 250 - Control device; 400 - Height measurement system; 410 - Measured object; 420 - Measured object drive component. Detailed Implementation

[0025] It should be understood that the terms "first," "second," etc., used in the embodiments of this application are used to distinguish different objects, rather than to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, software, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may also include steps or units not listed, or may also include other steps or units inherent to these processes, methods, products, or devices.

[0026] The term "embodiment" as used in the embodiments of this application means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the embodiments of this application, "at least one" or "at least one item" refers to one or more, and "multiple" refers to two or more.

[0028] In this application's embodiments, "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three cases: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " can indicate that the preceding and following associated objects are in an "or" relationship. Additionally, the character " / " can represent a division sign, such as A / B, which means A divided by B.

[0029] In the embodiments of this application, "at least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent the following seven cases: a, b, c, a and b, a and c, b and c, a, b, and c. Each of a, b, and c can be an element or a set containing one or more elements.

[0030] In the embodiments of this application, the terms "of," "corresponding (relevant)," "corresponding," "associated (related)," and "mapped" may sometimes be used interchangeably. It should be noted that when no distinction is emphasized, the concepts or meanings expressed are consistent.

[0031] In the embodiments of this application, "connection" refers to various connection methods such as direct connection or indirect connection, and is not specifically limited thereto.

[0032] The technical solutions of the embodiments of this application will be described in detail below.

[0033] Photodetector (PD) A photoelectric device (PD) is a type of electronic device that uses the photoelectric effect to convert incident light radiation (photons) into measurable electrical signals (such as current and voltage).

[0034] [Light Spot] In an altitude measurement system, a light spot refers to the bright spot formed on the optical path by the beam of light emitted by the system.

[0035] Zero plane In the imaging system of semiconductor manufacturing equipment, the optimal focal plane refers to the imaging plane that achieves the best overall image quality across the entire field of view under given imaging conditions and evaluation criteria. In the height measurement system of semiconductor manufacturing equipment, the zero plane is a specific reference plane serving as the height measurement benchmark. It is generally configured to coincide with the optimal focal plane, meaning the zero plane and the optimal focal plane point to the same physical plane. The zero plane is a reference plane with a height value of 0, and the heights of other objects in the system are measured based on their relative positions to this plane. Because the optimal focal plane can change due to temperature drift, if the zero plane is not adjusted, there will be a deviation between the zero plane and the optimal focal plane, which will introduce measurement errors into the height measurement system. Methods for adjusting the zero plane position include adjustment methods, as detailed below.

[0036] Figure 1 This is a schematic diagram illustrating a related technique involving zero-plane adjustment using an adjustment method. For example... Figure 1 As shown, the zero-plane adjustment device includes a light source 110, a test object 120, an adjuster 130, a detection slit 140, and a sensor 150. The light source 110 generates a light beam and directs it toward the test object 120, so that the beam is further reflected by the test object to the adjuster 130. The adjuster 130 includes one or more movable components, which refer to devices capable of adjusting the path of the light beam. The adjuster 130 can be adjusted mechanically or electrically; for example, the adjuster 130 may include a reflector and its driving mechanism. The light beam reflected by the adjuster 130 further passes through the detection slit 140 and falls on the surface of the sensor 150. When the zero plane (i.e., the surface of the test object) changes, the light beam reflected by the adjuster 130 is deflected relative to the detection slit 140 and no longer passes through the detection slit 140 to fall on the surface of the sensor 150. In this case, it is necessary to first adjust the surface of the test object 120 to the updated zero plane (i.e., the optimal focal plane after the aforementioned temperature drift), and then configure the adjuster 130, for example, along... Figure 1 The vertical direction of the reflector is shifted or its orientation is adjusted so that the reflected light beam passes through the detection slit 140 again and falls on the sensor 150, thereby completing the correction of the adjusted zero plane.

[0037] [Target location of the light spot] The target position of the light spot is the location where the light beam, after being reflected by the zero plane, falls on the photosensitive surface of the PD. When the surface of the object under test moves to a new zero plane, causing the light spot to shift on the photosensitive surface of the PD, the light spot needs to be reset to the target position to achieve leveling. At this time, the focusing system (also known as the height measurement system) of the lithography equipment can measure the object under test and set the measurement result at this time as the zero position. After that, the height of the object under test can be dynamically measured.

[0038] Figure 2This is a schematic diagram of the architecture of a spot target location search system provided in an embodiment of this application, as shown below. Figure 2 As shown, the spot target location search system may include a light source 210, a driving device 220, a reflector 230, a photoelectric detection device 240, and a control device 250. The light source 210 emits a detection beam to the object being measured. The driving device 220 is connected to the reflector 230 and controls its rotation; the driving device 220 may be a motor assembly, an electromagnetic drive assembly, or other types of driving devices. The reflector 230 receives the detection beam reflected by the object being measured and reflects it to a preset plane where the photoelectric detection device 240 is located to form a spot; the reflector 230 may be a mechanical reflector, a MEMS reflector, or other types of reflectors. The photoelectric detection device 240 detects the light intensity of the spot and may include multiple linearly arranged photoelectric detectors (PDs); such as... Figure 2 As shown, the plurality of PDs may include two PDs, such as the first PD and the second PD shown in the figure. The control device 250 is connected to the drive device 220 and the photoelectric detection device 240 respectively. The control device 250 is used to control the operation of the drive device 220, thereby driving the reflector 230 to rotate according to the required trajectory. The control device 250 is also used to acquire the electrical signal obtained by the photoelectric conversion of the photoelectric detection device 240. The control device 250 may include a processor and a memory; the processor may be a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic device, discrete hardware component; or the memory may be volatile memory, non-volatile memory, static storage device, or dynamic storage device, etc., and the memory can store executable program code or instructions.

[0039] In this embodiment, the driving device 220 can drive the reflector 230 to rotate around two axes, so that the light spot can move in two directions on the surface of the photoelectric detection device 240. For example, the driving device 220 includes a motor assembly, specifically including a first motor and a second motor. The first motor is used to drive the reflector 230 to rotate around... Figure 2 The first axis RY is rotated to move the light spot along the first direction X shown in the figure on the photosensitive surface of the photodetector 240; wherein, the first direction X is perpendicular to the arrangement direction of the multiple PDs, and the first axis RY is the axis along which the light spot moves along the first direction X when the reflector 230 rotates. A second motor drives the reflector 230 to rotate around the second axis RX to move the light spot along the second direction Y shown in the figure on the photosensitive surface of the photodetector 240; wherein, the second direction Y is parallel to the arrangement direction of the multiple PDs, and the second axis RX is the axis along which the light spot moves along the second direction Y when the reflector 230 rotates.

[0040] In this embodiment, the photodetector 240 includes a plurality of photodiodes (PDs) arranged linearly. When a light spot is located at the boundary between two adjacent PDs, both adjacent PDs can receive the energy of the light spot. If the light spot is completely located on the first PD, completely located on the second PD, partially located on the first PD and partially located outside the photodetector 240, or partially located on the second PD and partially located outside the photodetector 240, the control device 250 cannot determine the specific location of the light spot within the photodetector 240. For example, when the light spot is completely located on the first PD, since the light intensity of the light spot is the same regardless of its location on the photosensitive surface of the first PD, the electrical signal generated by the first PD is also the same. Therefore, the control device 250 cannot distinguish the specific location of the light spot. In contrast, this embodiment can use the boundary between two adjacent PDs as the target location of the light spot. Thus, when the light spot moves to the boundary between two adjacent PDs, both adjacent PDs will generate corresponding electrical signals due to the light intensity of the light spot, and the control device 250 can know that the light spot is currently at the boundary position. During the zero-plane correction process, the light spot is moved to the target position.

[0041] Compared to the zero-plane adjustment devices in related technologies, the boundary position of two adjacent PDs in this embodiment is equivalent to the aforementioned detection slit. The spot target position search system provided in this embodiment does not require additional detection slits, and the slit mounting structure can be omitted accordingly. Furthermore, since the spot target position search system itself requires PDs, the use of multiple PDs in this embodiment eliminates the need for additional mounting structures. Therefore, the spot target position search system provided in this embodiment can improve upon the problem of the complex structure of zero-plane adjustment devices in related technologies.

[0042] The above is a brief description of the spot target location search system provided in the embodiments of this application. The following is an example of the spot target location search method provided in the embodiments of this application, which can be applied to the above-mentioned spot target location search system. Figure 3 This is a flowchart illustrating a method for searching the location of a light spot target provided in an embodiment of this application. The method includes the following steps S310 to S350.

[0043] In step S310, the driving device 220 drives the reflector 230 to perform a first rotation process so that the light spot moves on a preset plane.

[0044] The preset plane refers to the plane on which the photosensitive surface of the photodetector 240 is located. For example, if the photodetector 240 includes one or more PDs, the preset plane refers to the plane on which the photosensitive surface of the PD is located. For example, when the photodetector 240 includes multiple PDs arranged in an array, the photosensitive surfaces of the multiple PDs are coplanar, and the plane on which the photosensitive surfaces of the multiple PDs are located is the aforementioned preset plane.

[0045] The movement of the light spot on the preset plane can be achieved by the light spot moving along a spiral trajectory extending from the inside to the outside of the preset plane. Figure 4 This is a schematic diagram of the light spot falling on a preset plane. The photoelectric detection device 240 includes two PDs, namely a first PD and a second PD, and the light spot falls outside the first PD and the second PD at this time; Figure 5A and Figure 5C This is a schematic diagram of the trajectory of the light spot moving on a preset plane during the first rotation of the reflector 230. The trajectory is a spiral extending from the center to the edge, which can be clockwise or counterclockwise. To ensure that the light spot falls on the PD when moving on the preset plane in a spiral trajectory extending from the center to the edge, the interval between two adjacent turns of the spiral trajectory cannot be greater than the smaller of the length or width of the photoelectric detection device 240. If the length of the PD is L and the width is W, then the length of the photoelectric detection device 240 is L and the width is approximately 2W, and min(L, 2W) represents the smaller of L and 2W. Therefore, the interval d between two adjacent turns of the spiral trajectory is less than or equal to min(L, 2W), thus ensuring that the light spot does not miss the PD during its movement. Preferably, the interval d between two adjacent turns of the spiral trajectory remains constant so that the light spot can spiral away from the starting position at uniform intervals.

[0046] As mentioned above, the number of photodetectors 240 is not limited to two. For example, photodetector 240 may include three, four, or even more photodetectors. When photodetector 240 includes three photodetectors, the interval d between two adjacent turns of the spiral trajectory is less than or equal to min(L, 3W), so that the light spot will not miss a photodetector during movement; when photodetector 240 includes four photodetectors, the interval d between two adjacent turns of the spiral trajectory is less than or equal to min(L, 4W), so that the light spot will not miss a photodetector during movement.

[0047] Optionally, such as Figure 5A As shown, the spiral trajectory is a spiral curve; thus, the light spot moves spirally within the neighborhood of the starting point in the preset plane, gradually moving away from the starting point. This reduces the risk of missing the PD (Distribution Point) in that neighborhood. The "starting point" is the position of the light spot on the preset plane before the reflector 230 rotates. Here, when the light spot travels in a spiral curve on the preset plane, as... Figure 2 As shown, the driving equations for the driving device 220 to drive the reflector 230 to rotate around the first axis RY and the second axis RX are explained. The trajectory equations of the spiral curve are as follows (1)~(2): (1) (2) Where A is the distance between two adjacent turns of the spiral, ω is the angular velocity of the light spot moving along the spiral curve, and t is time. and These are the x-axis and y-axis coordinates of the starting position of the light spot on the preset plane, respectively.

[0048] Combination Figure 5B Taking the example where the normal of the reflector 230 at the midpoint of its rotation around the first axis RY is perpendicular to the preset plane, the distance between the reflector 230 and the preset plane is the preset height H, and the angle between the light beam and the normal of the reflector 230 is the first angle α. When the first motor drives the reflector 230 to rotate around the first axis RY by a first rotation angle β, since the direction of the incident light beam remains unchanged, and the normal rotates by the first rotation angle β, the angle between the light beam and the normal of the preset plane when the beam hits the preset plane is the first target angle α + 2β. Therefore, the position of the light spot on the preset plane is: (3) For ease of explanation and calculation, taking the coordinates of the projection of the center of the reflector 230 onto the preset plane as (0,0) as an example, substituting the parameters t=0 and β=0 when the light spot has not yet started moving into equations (1) and (3) above, we can obtain And further, we obtain the following equation (4): (4) Furthermore, the curve of the first rotation angle β of the first motor-driven reflector 230 rotating around the first axis RY as a function of time t can be obtained as follows: (5) Similarly, taking the example where the normal of the reflector 230 at the midpoint of its rotation around the second axis RX is perpendicular to the preset plane, the distance between the reflector 230 and the preset plane remains the preset height H, and the angle between the beam and the normal of the reflector 230 is the second angle γ. When the second motor drives the reflector 230 to rotate around the second axis RX by a second rotation angle δ, the angle between the beam and the normal of the preset plane when the beam hits the preset plane is the second target angle γ+2δ. Therefore, the position of the light spot on the preset plane is: (6) For ease of explanation and calculation, taking the coordinates of the projection of the center of the reflector 230 onto the preset plane as (0,0) as an example, and setting the parameter t=0 before the light spot begins to move, =0, substituting into equations (2) and (6) above, we can obtain And further, we obtain the following equation (7): (7) Furthermore, the curve of the second rotation angle δ of the second motor driving the reflector 230 to rotate around the second axis RX as a function of time t can be obtained as follows: (8) In summary, equations (5) and (8) can be used as driving equations to drive the reflector 230 to rotate around the first axis RY and the second axis RX, thereby obtaining the aforementioned spiral curve. The spacing between adjacent turns of the spiral curve is the same in any direction, so the photoelectric detection device is less likely to be missed during the movement of the light spot along the spiral curve.

[0049] Optionally, such as Figure 5C As shown, the spiral trajectory can also include multiple straight line segments, which are connected sequentially to form the spiral trajectory. This method not only reduces the risk of missing the PD (photodetector point) in the neighborhood of the starting position, but also allows the reflector 230 to rotate in one dimension each time. For example, the driving device 220 first drives the reflector 230 to rotate around the first axis RY, then drives the reflector 230 to rotate around the second axis RX, and then drives the reflector 230 to rotate around the first axis RY, and so on. In this way, the rotation axes of any two adjacent rotation processes are perpendicular to each other. This method can decouple the rotational motion of the reflector 230 in two rotational dimensions, which helps to simplify the control of the reflector 230 by the driving device 220. Specifically, when the spiral trajectory includes multiple straight line segments, different straight line segments can be connected sequentially according to specific angles and lengths to present a spiral trajectory.

[0050] In step S320, during the movement of the light spot, the control device 250 acquires the light intensity detection value of the photoelectric detection device 240.

[0051] It should be noted that the light intensity detection value of the PD in the preset plane refers to the quantized light intensity result obtained by each independent PD in the preset plane after receiving light radiation energy, converting the light signal into a quantifiable electrical signal through its own photoelectric conversion effect, and then converting it through signal processing circuits (such as amplification, filtering, and analog-to-digital conversion). For example, in a typical indoor ambient light scenario, the light intensity detection value of the PD in the preset plane can be 100 lux (lx), 200 lx, or 300 lx.

[0052] The control device 250 may acquire the light intensity detection value of the photoelectric detection device 240 by: acquiring the sum of the light intensity detection values ​​of all PDs; or, forming a PD group by any two adjacent PDs and acquiring the sum of the light intensity detection values ​​of the two PDs in each PD group; or, acquiring the light intensity detection value of each PD itself.

[0053] For example, when the photodetector 240 includes a first PD and a second PD, obtaining the light intensity detection value of the photodetector 240 can specifically refer to: obtaining the sum of the light intensity detection values ​​of the first PD and the second PD; or, obtaining the light intensity detection values ​​of the first PD and the second PD separately. When the photodetector 240 includes a first PD, a second PD, and a third PD arranged sequentially, obtaining the light intensity detection value of the photodetector 240 can specifically refer to: obtaining the sum of the light intensity detection values ​​of the three PDs; or, obtaining the sum of the light intensity detection values ​​of the first PD and the second PD, and obtaining the sum of the light intensity detection values ​​of the second PD and the third PD; or, obtaining the light intensity detection values ​​of the first PD, the second PD, and the third PD separately. When the photoelectric detection device 240 includes a first PD, a second PD, a third PD, and a fourth PD arranged sequentially, obtaining the light intensity detection value of the photoelectric detection device 240 can specifically refer to: obtaining the sum of the light intensity detection values ​​of the four PDs; or, obtaining the sum of the light intensity detection values ​​of the first PD and the second PD, obtaining the sum of the light intensity detection values ​​of the second PD and the third PD, and obtaining the sum of the light intensity detection values ​​of the third PD and the fourth PD; or, obtaining the light intensity detection values ​​of the first PD, the second PD, the third PD, and the fourth PD respectively.

[0054] In step S330, when the light intensity detection value of the photoelectric detection device 240 is greater than or equal to the first light intensity threshold, the driving device 220 stops driving the reflector 230.

[0055] The first light intensity threshold Thr1 is a threshold used to determine whether the light spot falls on the photodetector 240. Since the PD will also output a noise signal when the light spot does not fall on the photodetector 240, the first light intensity threshold Thr1 should be higher than the amplitude of the noise signal. For example, taking the case where the entire light spot falls completely on the photosensitive surface of a PD, and the light intensity detection value of the PD is the first value, the value of the first light intensity threshold Thr1 should be less than the first value. It can be obtained based on a preset multiple of the first value; for example, the preset multiple can be one-tenth, one-fifth, etc., and the first light intensity threshold Thr1 obtained based on the first value of the preset multiple should be greater than the noise amplitude. For example, when the first value is 100 lx, the value of the first light intensity threshold Thr1 can be 20 lx.

[0056] When the light detection value obtained by the control device 250 from the photoelectric detection device 240 is greater than or equal to the first light intensity threshold Thr1, it can be determined that the corresponding light spot partially or completely falls on the PD. At this time, the driving device 220 stops driving the reflector 230 and ends the first rotation process described above. For ease of explanation in the embodiment, the position of the light spot here is defined as the first position P1.

[0057] The representation of the light intensity detection value of the photoelectric detection device 240 can be roughly divided into three categories: the sum of the light intensity detection values ​​of all PDs, the sum of the light intensity detection values ​​of two adjacent PDs, and the light intensity detection value of each PD itself. In this embodiment, obtaining the light intensity detection value of the photoelectric detection device 240 may include obtaining the light intensity detection value of each PD itself. Correspondingly, the light intensity detection value of the photoelectric detection device 240 being greater than or equal to the first light intensity threshold Thr1 includes: the light intensity detection value of any PD being greater than or equal to the first light intensity threshold Thr1. Thus, when determining whether the light spot falls on the photoelectric detection device 240, it is not necessary to sum the light intensity detection values ​​of two adjacent PDs or sum the light intensity detection values ​​of all PDs, which helps to simplify the judgment logic and computing power requirements of the control device 250, improve processing efficiency, and reduce equipment costs.

[0058] S340, the driving device 220 drives the reflector 230 to perform a second rotation process, so that the light spot moves on the preset plane to the target position P of the light spot. r .

[0059] Among them, the target position of the light spot P r Located on a preset plane and within the coverage area of ​​the photoelectric detection device 240, specifically, located between the boundaries of both ends of the photoelectric detection device 240 along the first direction X and the boundaries of both ends along the second direction Y. For example, please refer to... Figure 6 Target position of light spot P r The light spot can be located at the center of the photoelectric detection device 240 along the first direction X and the center of the second direction Y, that is, the geometric center of the array formed by the arrangement of the first PD and the second PD. The light spot movement speed corresponding to the second rotation process is less than the light spot movement speed corresponding to the first rotation process. In order to quickly locate the PD on the preset plane, when the driving device 220 drives the reflector 230 to perform the first rotation process, the light spot movement speed corresponding to the first rotation process is relatively large, such as the motor speed on the order of milliradians per second (mrad / s) when driving the reflector 230 to perform the first rotation process; and in order to accurately determine the target position P of the light spot after locating the PD. r For positioning, when the driving device 220 drives the reflector 230 to perform the second rotation process, the movement speed of the light spot corresponding to the second rotation process is relatively small. For example, when the driving device 220 drives the reflector 230 to perform the second rotation process, the speed of the motor is on the order of microradians per second (μrad / s), so that the light spot can be moved to the target position P more accurately. r .

[0060] The above step S340 may include steps S341 and S342, as detailed below.

[0061] Step S341: The driving device 220 drives the reflector 230 to rotate, so that the light spot moves along the first direction X to the first target position P.t1 Wherein, the first target position P t1 It is located at the center of the photoelectric detection device 240 along the first direction X.

[0062] Specifically, please combine Figure 7A , Figure 7A This is a schematic diagram of the trajectory of a light spot moving on a preset plane during the second rotation process of a reflector 230 provided in this application embodiment. Taking the photoelectric detection device 240 including a first PD and a second PD as an example, step S341 may further include steps S341a~S341e.

[0063] Step S341a: The driving device 220 drives the reflector 230 to rotate around the first axis RY, so that the light spot is along the first sub-direction X. d1 Move to one side of the photoelectric detection device 240; wherein, the first direction X includes first sub-directions X that are opposite to each other. d1 With the second sub-direction X d2 For ease of explanation of the embodiments, the position to which the light spot moves in step S341a is defined as the second position P2.

[0064] like Figure 7A As shown, when performing steps S310~S330, since the first position P1 is on the photoelectric detection device 240, it is necessary to first move the light spot from the first position P1 out of the photoelectric detection device 240, and then move the light spot from outside the photoelectric detection device 240 to inside the photoelectric detection device 240. At this time, the light spot can be moved from the first position P1 along the first sub-direction X. d1 The light spot moves to the second position P2. In order to ensure that the second position P2 is outside the photoelectric detection device 240, in this embodiment, when the light spot is at the second position P2, the sum of the light intensity detection values ​​of the first PD and the second PD in the photoelectric detection device 240 is close to 0 and no longer attenuates further.

[0065] Step S341b: The driving device 220 drives the reflector 230 to rotate around the first axis RY, so that the light spot is along the second sub-direction X. d2 move.

[0066] Please continue reading. Figure 7A For ease of explanation, this example uses the movement of the light spot to the other side of the photodetector 240 in step S341b as an example, and defines the position to which the light spot moves as the third position P3. To ensure that the third position P3 is outside the photodetector PD and not on the same side of the PD as the second position P2, the sum of the light intensity detection values ​​of the first and second photodetectors must undergo a process of first increasing and then decreasing, and the sum of the light intensity detection values ​​of the first and second photodetectors corresponding to the third position P3 must be close to 0 and no longer decrease further. During this process, the change curve of the light intensity detection value of the photodetector 240 is as follows: Figure 7A The curve in the diagram represents the sum of the light intensity detection values ​​of the first PD and the second PD detected by the photoelectric detection device 240 on the ordinate, and the coordinates of the light spot's location in the first direction X on the abscissa. This abscissa can be determined by an angle sensor inside the drive device 220. For example, the drive device 220 includes the aforementioned first motor, and the angle indicated by the encoder of the first motor has a first mapping relationship with the coordinates of the light spot in the first direction X. This first mapping relationship can be obtained in advance. Thus, during the rotation of the reflector 230 around the first axis RY to move the light spot along the first direction X, the coordinates of the light spot in the first direction X can be determined by the angle corresponding to the encoder of the first motor.

[0067] Taking the example of the light spot falling on the first PD, the trend of the light intensity detection value obtained by the photoelectric detection device 240 during the process of the light spot moving from the second position P2 to the third position P3 is as follows: In the first stage, the light spot gradually enters the left edge of the first PD from the outside. At this time, the energy of the light spot received by the first PD gradually increases, so the light intensity detection value of the first PD in the curve gradually rises from a low value to a peak value; In the second stage, the light spot moves inside the first PD but does not reach the right edge of the first PD. At this time, the light spot completely enters the first PD, the area of ​​the first PD covered by the light spot remains basically unchanged, the received energy is stable, so the light intensity detection value of the first PD remains at the peak value; In the third stage, the light spot gradually moves out of the first PD from the inside to the right edge of the first PD. At this time, the area of ​​the first PD covered by the light spot gradually decreases, the received energy gradually decreases, and the light intensity detection value of the first PD gradually decreases from the plateau period to close to zero.

[0068] Step S341c: When the light intensity detection value of the photoelectric detection device 240 is equal to the second light intensity threshold Thr2, the control device 250 determines the first reference position X1 and the second reference position X2 where the light spot is located.

[0069] Since the light intensity detection value of the photoelectric detection device 240 goes through the first to third stages during the process of the light spot moving from the second position P2 to the third position P3, the position of the light spot with a light intensity detection value equal to the second light intensity threshold Thr2 can be determined in the first stage, namely the first reference position X1. The horizontal coordinate of the first reference position X1 can be determined based on the angle indicated by the first motor encoder and the first mapping relationship. Similarly, the position of the light spot with a light intensity detection value equal to the second light intensity threshold Thr2 can also be determined in the third stage, namely the second reference position X2. The horizontal coordinate of the second reference position X2 can be determined based on the angle indicated by the first motor encoder and the aforementioned first mapping relationship. Please refer to... Figure 7A The curves of the second light intensity threshold Thr2 and the change of the light intensity detection value intersect at two points, which correspond to the first reference position X1 and the second reference position X2 mentioned above, respectively.

[0070] It is worth mentioning that, despite Figure 7A The diagram illustrates the process of the light spot moving from the second position P2 to the third position P3, but this application does not impose specific limitations on this. For example, the light spot may move along the second sub-direction X. d2 During the movement, the photoelectric detection device 240 may not be completely removed, as long as the process can obtain a position (first reference position and second reference position) where the light intensity detection value is equal to the second light intensity threshold in the first and third stages respectively.

[0071] Step S341d: The control device 250 determines the first target position P based on the first reference position X1 and the second reference position X2. t1 .

[0072] Since the first reference position X1 and the second reference position X2 are symmetrical about the center position of the photoelectric detection device 240 along the first direction X, the first target position P can be determined based on the average of the abscissas of the first reference position X1 and the second reference position X2. t1 The coordinates along the first direction X; as the light spot moves along the first direction X, its coordinates along the second direction Y remain unchanged, i.e., the first target position P. t1 The coordinates along the second direction Y are the same as the first reference position X1 and the second reference position X2 mentioned above.

[0073] Step S341e: The driving device 220 drives the reflector 230 to rotate around the first axis RY, so that the light spot moves to the first target position P. t1 .

[0074] After obtaining the first target position P t1 After determining the coordinates along the first direction X, the first target position P corresponding to the first motor can be determined again based on the aforementioned first mapping relationship. t1 The encoder angle; the first motor drives the reflector 230 to rotate until the angle indicated by the encoder of the first motor is the first angle, then the light spot moves from the third position P3 to the first target position P. t1 .

[0075] Step S342: The driving device 220 drives the reflector 230 to rotate, so that the light spot moves along the second direction Y from the first target position Pt1 to the target position P. r .

[0076] Specifically, please combine Figure 7B , Figure 7B This is another schematic diagram of the trajectory of the light spot moving on a preset plane during the second rotation process of the reflector 230 provided in the embodiment of this application. Step S342 may further include steps S342a~S342b.

[0077] Step S342a: The driving device 220 drives the reflector 230 to rotate around the second axis RX, so that the light spot moves from the first target position P. t1 Along the third sub-direction Y d1 Move to one side of the photoelectric detection device 240; wherein, the second direction Y includes a third sub-direction Y that is opposite to the second direction. d1 With the fourth sub-direction Y d2 .

[0078] For ease of explanation, the position to which the light spot moves is defined as the fourth position P4. In order for the fourth position P4 to be outside the photodetector 240, it is required that when the light spot is at the fourth position P4, the sum of the light intensity detection values ​​of the first PD and the second PD of the photodetector 240 is close to 0, and no further attenuation occurs.

[0079] like Figure 7B As shown, the light spot is moved to the first target position P through the above step S341. t1 At that time, due to the first target position P t1 Therefore, on the photoelectric detection device 240, the light spot needs to be moved from the first target position P first. t1 Remove the photoelectric detection device 240, and then move the light spot from outside the photoelectric detection device 240 to inside the photoelectric detection device 240. At this time, the light spot can be moved from the first target position P. t1 Along the third sub-direction Y d1 Move to position P4.

[0080] Step S342b: The driving device 220 drives the reflector 230 to rotate around the second axis RX, so that the light spot moves from the fourth position P4 along the fourth sub-direction Y. d2 The movement continues until the first light intensity detection value of the first PD and the second light intensity detection value of the second PD meet the preset value conditions; wherein, the preset value conditions are: the sum of the first light intensity detection value and the second light intensity detection value is greater than the third light intensity threshold Thr3, and the absolute value of the difference between the first light intensity detection value and the second light intensity detection value is less than the fourth light intensity threshold Thr4.

[0081] Please see Figure 7B The light spot starts from the fourth position P4 along the fourth sub-direction Y. d2 During the movement, the curves showing the changes in the light intensity detection values ​​of each PD in the photoelectric detection device 240 are as follows: Figure 7BThe curve in the diagram represents the position of the light spot in the second direction Y. This coordinate can be determined by an angle sensor inside the drive device 220. For example, the drive device 220 includes a second motor, and the angle indicated by the encoder of the second motor has a second mapping relationship with the coordinate of the light spot in the Y-axis direction. This second mapping relationship can be obtained in advance. Thus, during the rotation of the reflector 230 around the second axis RX to move the light spot along the second direction Y, the coordinate of the light spot in the second direction Y can be determined by the angle corresponding to the encoder of the second motor. The vertical axis of the curve represents the light intensity detection values ​​of the first PD and the second PD obtained by the photoelectric detection device 240.

[0082] by Figure 7B The first target position P shown t1 Taking the first PD as an example, and the fourth position P4 being close to the first PD, the light spot moves from the fourth position P4 along the fourth sub-direction Y. d2 During the movement, the light intensity detection value of the photoelectric detection device 240 changes as follows: In the first stage, the light spot gradually enters the upper edge of the first PD from the outside. At this time, the light spot energy received by the first PD gradually increases, so the light intensity detection value of the first PD in the curve gradually rises from a low value, while the light intensity detection value of the second PD approaches zero. In the second stage, the light spot moves inside the first PD. At this time, the light intensity detection value of the first PD remains at its peak, while the light intensity detection value of the second PD approaches zero. In the third stage, the light spot crosses the boundary between the first PD and the second PD. At this time, the light spot begins to move from the first PD towards... As the second PD moves, the area covered by the light spot on the first PD gradually decreases, resulting in reduced received energy. Simultaneously, the area covered by the light spot on the second PD gradually increases, increasing received energy. Thus, the light intensity detection value of the first PD gradually decreases to near zero, while the light intensity detection value of the second PD gradually rises to its peak value. In the fourth stage, the light spot moves inside the second PD. At this point, the light intensity detection value of the first PD approaches zero, while the light intensity detection value of the second PD remains at its peak value. In the fifth stage, the light spot gradually moves out of the second PD. At this point, the light intensity detection value of the first PD approaches zero, while the light intensity detection value of the second PD gradually decreases to near zero.

[0083] The third light intensity threshold Thr3 is used to determine whether the light spot is located on the photosensitive surface of the PD. The third light intensity threshold Thr3 can be obtained in a similar way to obtaining the first light intensity threshold Thr1. Optionally, the third light intensity threshold Thr3 is equal to the first light intensity threshold Thr1, that is, the third light intensity threshold Thr3 reuses the same value as the first light intensity threshold Thr1; of course, the third light intensity threshold Thr3 can also be different from the first light intensity threshold Thr1. The preset value conditions include that the sum of the first light intensity detection value and the second light intensity detection value is greater than the third light intensity threshold Thr3, which aims to filter out the case where the light spot does not fall on the photodetector 240; for example, when the light spot does not fall on the photodetector 240, both the first light intensity detection value and the second light intensity detection value are noise values ​​of the PD, and the first light intensity detection value and the second light intensity detection value are also very close.

[0084] The fourth light intensity threshold Thr4 is the threshold for determining whether the light intensity detection values ​​of two PDs are equal. The fourth light intensity threshold Thr4 needs to be close to zero. Specifically, the fourth light intensity threshold Thr4 is another preset multiple (such as one-thirtieth, one-fortieth, or one-fiftieth) of the light intensity when the entire light spot falls on the photosensitive surface of the PD. The fourth light intensity threshold Thr4 is used to define the acceptable range of the light intensity difference between the two PDs. When the first light intensity detection value and the second light intensity detection value meet the preset value conditions, it means that the energy of the light spot distributed in the first PD and the second PD is basically the same, and the light spot is located at the center position of the array formed by the first PD and the second PD along the second direction Y.

[0085] Combination Figure 7B It is known that when the light spot moves to the center position of the photoelectric detection device 240 along the second direction Y, the area of ​​the light spot located on the first PD and the second PD is the same, and the light intensity detection values ​​of the first PD and the second PD should be equal. Therefore, the above-mentioned preset value conditions can be configured, and when the first light intensity detection value and the second light intensity detection value satisfy the above-mentioned preset value conditions, it is determined that the light spot is located at the center position of the photoelectric detection device 240 along the second direction Y. Figure 7B As shown, the intersection of curve 1 and curve 2 indicates the location of the light spot that meets the above-mentioned preset value conditions, i.e., the target light spot position P. r It is worth noting that, Figure 7B The fifth position P5 shown is intended to indicate that the light spot moves from the fourth position P4 to the fifth position P5, but the light spot does not necessarily need to move to the fifth position P5, because the light spot moves to the target light spot position P. r When the time is right, step S340 can be ended.

[0086] Optionally, the driving device 220 drives the reflector 230 to perform a second rotation process, causing the light spot to move from the first position P1 to the target position P on the preset plane. rIn addition to moving the light spot first along the first direction X and then along the second direction Y, it is also possible to move the light spot first along the second direction Y and then along the first direction X. For ease of explanation, the process of the driving device 220 driving the reflector 230 will not be repeated here; only the movement of the light spot will be described. For example, please refer to [reference needed]. Figure 7C and Figure 7D The light spot starts from the first position P1 and moves along the third sub-direction Y. d1 Move to the fourth position P4; then, the light spot moves from the fourth position P4 along the fourth sub-direction Y. d2 Move until the preset value conditions are met, at which point the light spot reaches the second target position P. t2 Afterwards, the light spot moved from the second target position P. t2 Along the first sub-direction X d1 Move to the second position P2; next, the light spot moves from the second position P2 along the second sub-direction X. d2 Move to the third position P3; finally, determine the center position of the first reference position X1 and the second reference position X2 during the process of the light spot moving from the second position P2 to the third position P3 as the target position P of the light spot. r The light spot moves to the target position P. r .

[0087] When the photoelectric detection device 240 includes three or more photodiodes (PDs), such as a first PD, a second PD, ..., an Nth PD, where N ≥ 3, the driving device 220 can perform step S341 in the same way as in the case where the photoelectric detection device includes two PDs. Since the photoelectric detection device 240 includes only one PD in the first direction X, steps S341a~S341e can also be used to move the light spot to the first target position P. t1 .

[0088] After determining the first target location P t1 Subsequently, the execution of step S342 by the drive device 220 will differ from the case where the photoelectric detection device includes two PDs.

[0089] Specifically, when the photoelectric detection device 240 includes an odd number of photodetectors (PDs), the PD in the middle of the multiple PDs can be identified as the target PD. Step S342 may include: the driving device 220 driving the reflector 230 to rotate around the second axis RX, so that the light spot moves from the first target position P. t1 Along the third sub-direction Y d1 Move to one side of the photoelectric detection device 240; drive device 220 drives reflector 230 to rotate around the second axis RX, so that the light spot is along the fourth sub-direction Y. d2Move the light source; determine the third and fourth reference positions where the light intensity detection value of the target PD is equal to the second light intensity threshold Thr2; determine the target spot position P based on the third and fourth reference positions. r For example, the target position P of the light spot is determined based on the average of the second direction Y coordinates of the third and fourth reference positions. r The driving device 220 drives the reflector 230 to rotate around the second axis RX, so that the light spot moves to the target position P. r .

[0090] When the photoelectric detection device 240 includes an even number of photodetectors (PDs), two PDs in the middle of the multiple PDs can be identified as the target PD. Step S342 may include: the driving device 220 driving the reflector 230 to rotate around the second axis RX, so that the light spot moves from the first target position P. t1 Along the third sub-direction Y d1 Move to one side of the photoelectric detection device 240; drive device 220 drives reflector 230 to rotate around the second axis RX, so that the light spot is along the fourth sub-direction Y. d2 The light spot is moved until the light intensity detection values ​​of the two target PDs meet the above preset value conditions, then the light spot moves to the target position P. r .

[0091] In step S350, when the displacement of the light spot relative to the starting position is greater than the distance threshold and the light intensity detection value of the photoelectric detection device 240 is always less than the first light intensity threshold Thr1, the driving device 220 stops driving the reflector 230.

[0092] The displacement of the light spot relative to the starting position represents the radius of the light spot's search on the preset plane. When the displacement of the light spot relative to the starting position is greater than a distance threshold, it indicates that the light spot is already far from the starting position. If the light intensity detection value of the photoelectric detection device 240 is consistently less than the first light intensity threshold Thr1, it means that the distance between the starting position of the light spot and the photoelectric detection device 240 exceeds expectations, and the search has failed to locate the photoelectric detection device 240 despite spending a significant amount of time. Therefore, it can be determined that the search for the target position of the light spot has failed. The drive device 220 stops driving the reflector, issues an alarm, and / or re-adjusts the components in the light spot target position search system. This reduces the time wasted due to the light spot continuing to move ineffectively. Afterward, the above steps S310~S340 are repeated until the light spot moves to the target position. The displacement of the light spot relative to the starting point can be determined by a sensor in the drive device 220. For example, when the drive device 220 includes a first motor and a second motor, it can be determined based on the rotation angle indicated by the encoders of the first motor and the second motor. The distance threshold can be obtained based on experience. For example, the distance threshold can be a multiple of the length of the photoelectric detection device 240, such as 10 times the length of the photoelectric detection device 240.

[0093] Steps S310 to S350 above are for when the object being measured is located in the zero plane position, and the starting position of the light spot is outside the photoelectric detection device 240, so that the light spot is moved to the target position P. r The process is explained below. This process often occurs when the zero plane is set for the first time (leveling process). Since the movement direction of the object being measured is unidirectional, when the zero plane is adjusted to change the position of the light spot on the preset plane, the light spot can also be moved in a unidirectional direction to reset to the target position of the light spot.

[0094] Specifically, the above-mentioned spot target position search system can be further improved. The photoelectric detection device 240 can be configured such that when the object being measured moves along a preset direction, the spot moves along a second direction Y, that is, along the arrangement direction of multiple PDs; wherein, the movement direction of the object being measured is unidirectional, and the preset direction is the movement direction of the object being measured. In this way, the driving device 220 can drive the reflector 230 to rotate around the second axis RX to reset the spot, which can eliminate the process of rotating the reflector 230 around the first axis RY, and the movement process of the reflector 230 is simpler. Based on this improved solution of the photoelectric detection device 240, this application embodiment also provides another spot target position search method for adjustment of non-first zero plane, the spot target position search method includes: When the light spot is not at the target light spot position P r At that time, the driving device 220 drives the reflector 230 to rotate around the second axis RX, so that the light spot is reset to the target light spot position P along the second direction Y.r .

[0095] Since the zero plane is established based on the surface of the object being measured, the direction of change of the zero plane is consistent with the direction of movement of the object being measured (preset direction). Therefore, when the change of the zero plane causes the light spot to no longer be at the target light spot position, the light spot moves along the second direction Y. At this time, the driving device 220 drives the reflector 230 to rotate around the second axis RX until the first light intensity detection value of the first PD and the second light intensity detection value of the second PD satisfy the above-mentioned preset value condition; then, the light spot will be reset to the above-mentioned target light spot position.

[0096] Please see Figure 8 This application also provides a height measurement system 400, which includes a measured object 410, a measured object driving component 420, and a spot target position search system described in the above embodiments. The measured object 410 can be a workpiece stage or a wafer mounted on the workpiece stage. The measured object driving component 420 is connected to the measured object 410 and is used to drive the measured object 410 to move along a preset direction. For example, the preset direction can be a vertical direction, in which case the measured object 410 moves along the vertical direction. The measured object driving component 420 can be a linear motor or a motor screw, or other structure capable of linear motion output. The photoelectric detection device 240 in the spot target position search system is configured such that when the measured object 410 moves along the preset direction, the spot moves along the second direction Y.

[0097] Thus, when it is necessary to measure the height of the object 410, the object 410 is moved to different height positions for height measurement. At this time, the light spot moves from the target position of the light spot along the second direction Y in the photoelectric detection device 240, and the light intensity detection values ​​of multiple PDs in the photoelectric detection device 240 will change. The control device 250 can determine the height of the object moving from the zero plane based on the difference between the light intensity detection values ​​of each PD corresponding to the moved light spot and the light intensity detection values ​​of each PD corresponding to the light spot when the light spot is located at the target position.

[0098] Please see Figure 9 This application also provides a height measurement method, which is applied to the height measurement system in the above embodiments. The height measurement method includes the following steps S510 to S530.

[0099] Step S510: The test object driving component 420 drives the test object 410 to move along a preset direction.

[0100] Once the zero plane is set and the light spot is located at the target position, the height of the object under test 410 can be measured. For example, the object under test drive 420 moves the object under test 410 along a preset direction to perform the height measurement process.

[0101] Step S520: Control device 250 acquires the light intensity detection value of photoelectric detection device 240.

[0102] After the object being measured is moved, the height at which the detection beam falls on the surface of the object changes, causing the light spot to shift in the second direction Y. For example, when the photodetector 240 includes a first PD and a second PD, the light spot moves along the aforementioned third sub-direction Y. d1 As the light moves, more of the light spot falls on the first photodetector (PD) and less on the second photodetector (PD). At this time, the control device 250 acquires the light intensity detection value output by the photodetector 240; for example, the control device 250 acquires the light intensity detection values ​​of the first PD and the second PD.

[0103] Step S530: The control device 250 determines the height of the object 410 to be measured based on the light intensity detection value of the photoelectric detection device 240.

[0104] After obtaining the light intensity detection values ​​of the first PD and the second PD, the height of the object being measured can be determined based on the light intensity detection values ​​of the first PD and / or the second PD.

[0105] In one optional implementation, a third mapping relationship can be established in advance between the light intensity detection value of the first PD and the angle indicated by the second motor encoder. Thus, after obtaining the light intensity detection value of the first PD, the angular position indicated by the second motor encoder can be determined based on this third mapping relationship. Then, the angular change can be determined based on the angular position indicated by the second motor encoder and a reference angle, where the reference angle position refers to the angular position indicated by the second motor encoder when the light spot is at the target position. Finally, based on the incident angle of the detection beam to the object under test and the aforementioned angular change, combined with mathematical calculations, the height change of the object under test can be determined.

[0106] In another optional implementation, a third mapping relationship can be established beforehand between the difference in light intensity detection values ​​of the first PD and the second PD and the angle indicated by the second motor encoder. Thus, after acquiring the light intensity detection values ​​of the first PD and the second PD, the angular position indicated by the second motor encoder can be determined by combining the third mapping relationship. Then, the angular change can be determined based on the angular position indicated by the second motor encoder and a reference angular position, where the reference angular position refers to the angular position indicated by the second motor encoder when the light spot is at the target position. Finally, based on the incident angle of the detection beam to the object under test and the aforementioned angular change, the height change of the object under test can be determined by mathematical calculation.

[0107] In another optional implementation, a third mapping relationship can be established beforehand between the light intensity detection value of the first PD and the displacement of the light spot from the target position. Thus, after obtaining the light intensity detection value of the first PD, the displacement of the light spot can be determined by combining the third mapping relationship. Then, based on the incident angle of the detection beam onto the object under test, the reference angle position indicated by the second motor encoder, and the aforementioned displacement, the height change of the object under test can be determined by mathematical calculation. The reference angle position refers to the angle position indicated by the second motor encoder when the light spot is at the target position.

[0108] It should be noted that the height measurement method provided in this application embodiment relies on the light intensity detection values ​​of the first PD and / or the second PD. Given a fixed beam energy, this light intensity detection value should have a unique mapping to the location of the light spot to ensure that the location of the light spot can be distinguished. Based on this principle, the height measurement method provided in this application embodiment needs to ensure that the light spot does not completely detach from the second PD or the first PD; that is, the light spot must be located at the boundary between the first PD and the second PD. When a larger height measurement range is required, the actual height measurement range can be increased by adjusting the zero plane.

[0109] Although the technical solutions of this application have been described herein in conjunction with various embodiments, those skilled in the art can understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims during the implementation of the claimed application. In the claims, the words "comprising," "having," and any variations thereof are intended to cover non-exclusive inclusion; "at least one" or "at least one item" refers to one or more; and "multiple" refers to two or more. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0110] For the sake of simplicity, each of the aforementioned embodiments of the spot target location search method is described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to this application.

[0111] Furthermore, those skilled in the art can make various modifications and variations to the spot target location search system and method, and height measurement system and method provided in this application without departing from the spirit and scope of this application. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A search system for a light spot target position, characterized by, Includes light source, reflector, drive unit, photoelectric detection device and control unit; The light source is used to emit a detection beam to the object under test. The reflector is used to receive the detection beam reflected by the object under test and reflect it to a preset plane where the photoelectric detection device is located to form a light spot. The driving device is connected to the reflector and is used to drive the reflector to rotate. The photoelectric detection device is used to detect the light spot. The photoelectric detection device includes multiple photoelectric detectors arranged in a linear fashion. The control device is connected to the driving device and the photoelectric detection device respectively. The plurality of photodetectors is an even number. When the light spot is located at the boundary between two adjacent photodetectors in the middle of the plurality of photodetectors, the two adjacent photodetectors generate corresponding electrical signals.

2. The search system for a target position of a light spot according to claim 1, characterized by The photoelectric detection device is configured such that when the object being tested moves along a preset direction, the light spot moves along the arrangement direction of the plurality of photoelectric detectors, wherein the preset direction is the moving direction of the object being tested.

3. The search system for a target position of a light spot according to claim 2, characterized by The drive device includes a first motor and a second motor; The first motor is used to drive the reflector to rotate around a first axis, wherein the first axis is the axis that causes the light spot to move along a first direction when the reflector rotates; The second motor is used to drive the reflector to rotate around the second axis, wherein the second axis is the axis that causes the light spot to move along the second direction when the reflector rotates; Wherein, the first direction is perpendicular to the arrangement direction of the plurality of photodetectors, and the second direction is parallel to the arrangement direction.

4. A method of searching for a light spot target position, characterized by, The method is applied to the spot target location search system as described in claim 1, and the method includes: The driving device drives the reflector to perform a first rotation process, so that the light spot moves on the preset plane; During the movement of the light spot, the control device acquires the light intensity detection value of the photoelectric detection device; When the light intensity detected by the photoelectric detection device is greater than or equal to a first light intensity threshold, the driving device stops driving the reflector; and The driving device drives the reflector to perform a second rotation process, so that the light spot moves on the preset plane to the target position of the light spot, wherein the target position of the light spot is located on the preset plane and is within the coverage area of ​​the photoelectric detection device.

5. The method of claim 4, wherein, The spot movement speed corresponding to the second rotation process is less than the spot movement speed corresponding to the first rotation process.

6. The method of claim 4, wherein, The driving device drives the reflector to perform a first rotation process, so that the light spot moves on the preset plane, including: The driving device is controlled to drive the reflector to rotate around a first axis and a second axis, so that the light spot moves along a spiral trajectory extending from the inside to the outside on the preset plane. When the reflector rotates around the first axis, the light spot moves along a first direction. When the reflector rotates around the second axis, the light spot moves along a second direction. The first direction is perpendicular to the arrangement direction of the multiple photodetectors, and the second direction is parallel to the arrangement direction.

7. The method of claim 6, wherein, The spiral trajectory is a spiral curve, or the spiral trajectory includes multiple straight line segments, which are connected sequentially to form the spiral trajectory.

8. The method as described in claim 4, characterized in that, The light intensity detection value of the photoelectric detection device is greater than or equal to a first light intensity threshold, including: The light intensity detection value of any of the photodetectors is greater than or equal to the first light intensity threshold.

9. The method according to any one of claims 4 to 8, characterized in that, The first direction is perpendicular to the arrangement direction of the plurality of photodetectors, the second direction is parallel to the arrangement direction, and the target position of the light spot is located at the center position of the photodetector along the first direction and the center position along the second direction; The driving device drives the reflector to perform a second rotation process, so that the light spot moves on the preset plane to the target position of the light spot, including: The driving device drives the reflector to rotate around a first axis, so that the light spot moves along the first direction to a first target position, wherein when the reflector rotates around the first axis, the light spot moves along the first direction, and the first target position is located at the center position of the photoelectric detection device along the first direction; and The driving device drives the reflector to rotate around the second axis, so that the light spot moves from the first target position to the target position of the light spot along the second direction, wherein the light spot moves along the second direction when the reflector rotates around the second axis.

10. The method as described in claim 9, characterized in that, The driving device drives the reflector to rotate around a first axis, so that the light spot moves along the first direction to a first target position, including: The driving device drives the reflector to rotate around the first axis, causing the light spot to move along the first sub-direction to one side of the photoelectric detection device, wherein the first direction includes a first sub-direction and a second sub-direction that are opposite to each other; The driving device drives the reflector to rotate around the first axis, causing the light spot to move along the second sub-direction; When the control device determines that the light intensity detection value of the photoelectric detection device is equal to the second light intensity threshold, the first reference position and the second reference position where the light spot is located are determined. The control device determines the first target position based on the first reference position and the second reference position; and The driving device drives the reflector to rotate around the first axis, so that the light spot moves to the first target position.

11. The method as described in claim 9, characterized in that, The plurality of photodetectors includes a first photodetector and a second photodetector; The driving device drives the reflector to rotate around the second axis, so that the light spot moves from the first target position to the target position of the light spot along the second direction, including: The driving device drives the reflector to rotate around the second axis, so that the light spot moves from the first target position along the third sub-direction to one side of the photoelectric detection device, wherein the second direction includes the third sub-direction and the fourth sub-direction, which are opposite to each other, along the second direction; The driving device drives the reflector to rotate around the second axis, causing the light spot to move along the fourth sub-direction until the first light intensity detection value of the first photodetector and the second light intensity detection value of the second photodetector meet the preset value conditions; wherein, the preset value conditions are: the sum of the first light intensity detection value and the second light intensity detection value is greater than the third light intensity threshold, and the absolute value of the difference between the first light intensity detection value and the second light intensity detection value is less than the fourth light intensity threshold.

12. A method for searching the location of a light spot target, characterized in that, The method is applied to the spot target location search system as described in claim 2 or 3, and the method includes: When the light spot is not at the target light spot position, the driving device drives the reflector to rotate around the second axis, so that the light spot is reset to the target light spot position along the second direction; The target position of the light spot is located on the preset plane and within the coverage area of ​​the photoelectric detection device. The second direction is the arrangement direction of the plurality of photoelectric detectors. The second axis is the axis along which the light spot moves when the reflector rotates.

13. The search method according to claim 12, characterized in that, The plurality of photodetectors includes a first photodetector and a second photodetector; The driving device drives the reflector to rotate around the second axis to reset the light spot to the target light spot position along the second direction, including: The driving device drives the reflector to rotate around the second axis until the first light intensity detection value of the first photodetector and the second light intensity detection value of the second photodetector meet the preset value conditions. The preset value conditions are as follows: the sum of the first light intensity detection value and the second light intensity detection value is greater than the third light intensity threshold, and the absolute value of the difference between the first light intensity detection value and the second light intensity detection value is less than the fourth light intensity threshold.

14. A height measurement system, characterized in that, include: The object being tested; A test object driving component, connected to the test object, is used to drive the test object to move along a preset direction; as well as The spot target location search system as described in claim 2 or 3.

15. A height measurement method, characterized in that, Applied to the height measurement system of claim 14, the method includes: The test object driving component drives the test object to move along the preset direction; The control device acquires the light intensity detection value of the photoelectric detection device; and The control device determines the height of the object being measured based on the light intensity detection value of the photoelectric detection device.

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