A self-collimating angle measuring device and method with an absolute zero point

Abstract

A self-collimation angle measuring device and method with an absolute zero point are disclosed, relating to the field of self-collimation angle measurement technology. This invention addresses the problems of low measurement accuracy and complex structure in existing autocollimators. The device includes a self-collimation module, a target, a fiber optic weight module, a signal processing module, and a mechanical frame. The target and mechanical frame are placed on the object to be measured, and the mechanical frame also suspends the fiber optic weight module. The self-collimation module emits spatial light towards both the target and the fiber optic weight module. The target reflects the received incident light back to the self-collimation module. The fiber optic weight module converts the direction of the incident light to vertically downwards into the signal processing module. The signal processing module converts the received optical signal into an electrical signal to obtain the angle between the self-collimation module and the direction of gravity. Combined with the self-collimation relative angle obtained by the self-collimation module, the absolute angle value of the target is obtained. This invention is applicable to fields requiring high-precision absolute angle measurement, such as high-end equipment manufacturing, testing and measurement, and scientific experiments.

Description

Technical Field

[0001] This invention relates to the field of autocollimation angle measurement technology. Background Technology

[0002] The autocollimation angle measurement method utilizes the principle of optical autocollimation as a "self-reference" benchmark. That is, the zero point of the autocollimation angle measurement is when the optical axis incident on the target coincides with the optical axis emitted from the target. Using this zero point as a benchmark, and based on spatial optical relationships, high-precision angle measurements can be achieved over a small range using visual or photoelectric receiving devices.

[0003] Internationally, there are already mature methods and corresponding devices for measuring autocollimation angles. For example, the ELCOMAT 3000 dual-axis photoelectric autocollimator from Moeller-Wedel in Germany has a resolution of 0.01 and an accuracy of ±0.1.

[0004] Chinese researchers have also conducted in-depth research on autocollimators. For example, patent document CN106052548B, published on January 29, 2019, discloses a portable, high-precision, large-working-distance autocollimation device and method. Compared with traditional autocollimators, this device has the technical advantage of significantly increasing the autocollimation working range at the same working distance, or significantly increasing the working distance at the same autocollimation working range.

[0005] For example, patent document CN105783789A, published on July 20, 2016, discloses an autocollimator. This autocollimator is equipped with a blazed grating that can generate a real-time reference beam, which can realize automatic, real-time, and accurate correction of indication drift, greatly reducing the environmental requirements of high-precision autocollimators.

[0006] For example, patent document CN115523858A, published on October 28, 2022, discloses a high-precision coaxial autocollimator optical system that uses a PSD position sensor and a CCD image sensor to measure simultaneously and independently, and has the advantages of high frame rate, large measurement angle and high measurement accuracy.

[0007] For example, patent document CN218822210U, published on December 13, 2022, discloses a rapid aiming device for an autocollimator. It uses a positioning sleeve, a fixing plate, a laser pointer, and a gravity ring to achieve rapid aiming and adjustment of the autocollimator and its target. It has the advantages of convenient assembly and adjustment, light weight, simple structure, and low cost.

[0008] Due to the characteristics of the autocollimation angle measurement principle, the zero point of the aforementioned autocollimation angle measurement is a relative zero point, meaning that a high-precision angle value of the target attitude relative to the autocollimation optical axis can be measured. However, the issue of the absolute zero point of the autocollimation angle has not received sufficient attention. For example, the ELCOMAT 3000 dual-axis photoelectric autocollimator from Moeller-Wedel in Germany, with an accuracy within ±0.1″20″, integrates a level bubble in its body. Using only the visual observation of the level bubble as a measurement tool for adjusting the autocollimator's attitude presents a mismatch between high-precision relative measurement and low-precision absolute measurement, hindering the further application of autocollimators in the field of high-precision absolute angle measurement.

[0009] Another common approach is to develop an adjustable base for the autocollimator to allow for high-precision adjustment of its mounting posture. For example, patent document CN111365588A, published on July 3, 2020, discloses a vertically mounted adjustable base for the autocollimator and a method for aligning the horizontal reference mirror. This method requires adding an adjustable base to the autocollimator, but this overlaps with the function of the autocollimator's built-in adjustable legs, reducing its stability and increasing the size of the autocollimator in use.

[0010] Another method, such as patent document CN1177240C published on November 24, 2004, discloses a method for processing fiber microlenses with center self-alignment function. This method involves suspending a plumb bob near the end of the fiber, with the fiber passing through the central micro-hole of the plumb bob, exposing a small portion of the fiber end and clamping it firmly, thus achieving center alignment function. However, it cannot guarantee that the center of mass of the plumb bob is collinear with the optical axis of the fiber, and therefore cannot guarantee the accuracy of the measurement. Summary of the Invention

[0011] This invention solves the problems of low accuracy in absolute angle measurement and complex structure of existing autocollimators.

[0012] To achieve the above objectives, the present invention provides the following solution:

[0013] This invention provides a self-collimation angle measuring device with an absolute zero point. The device includes a self-collimation module, a self-collimation target, an optical fiber counterweight module, a signal processing module, and a mechanical frame.

[0014] The autocollimation module is used to emit a beam of spatial light toward the autocollimation target;

[0015] The self-collimating target is set on the object to be tested and is used to reflect the received incident light back to the self-collimating module.

[0016] The fiber optic weight module is used to output a beam of vertically downward spatial light, which is then incident on the target component of the fiber optic weight module.

[0017] The signal processing module is used to convert the optical signal sent by the target component into an electrical signal to obtain the angle of the gravity direction of the fiber optic counterweight module. It is also used to combine the self-collimation relative angle obtained by the self-collimation module to calculate the absolute angle value of the self-collimated target relative to the gravity direction.

[0018] The mechanical frame is used to suspend the fiber optic weight module, fix the autocollimation module, and provide a clear assembly angle relationship between the two.

[0019] Furthermore, in a preferred embodiment, the self-collimation module includes a light source component, and the fiber optic counterweight module also includes a light source component. The light source components of the two modules can be independent of each other, or they can be shared and used as a single module.

[0020] Furthermore, in a preferred embodiment, the aforementioned fiber optic hammer module includes a light source, an optical fiber, a hammer, and a fiber optic hammer target.

[0021] One end of the optical fiber is fixed to the upper frame of the mechanical frame, and the other end of the optical fiber is connected to the counterweight.

[0022] The optical fiber is used to receive spatial light emitted by the light source, and under the action of the weight, the direction of the spatial light is converted to vertically downward and emitted to the optical fiber weight target.

[0023] Furthermore, in a preferred embodiment, the aforementioned fiber optic counterweight module further includes a photodetector;

[0024] The fiber optic hammer target is used to reflect the vertically downward spatial light output from the fiber back into the fiber; the reflected spatial light is transmitted in the opposite direction along the fiber and output at the upper end of the fiber, where it is converted into an electrical signal by a photodetector and then transmitted to the signal processing module.

[0025] Furthermore, in a preferred embodiment, the optical fiber is implemented using any one of single-mode fiber, single-mode polarization-maintaining fiber, and multimode fiber.

[0026] Furthermore, in a preferred embodiment, the aforementioned fiber optic hammer target includes optical elements and photoelectric conversion components;

[0027] The optical element is disposed between the optical fiber and the photoelectric conversion component, and is used to receive the spatial light emitted from the optical fiber, process the spatial light, and send it to the photoelectric conversion component;

[0028] The photoelectric conversion component is used to send the pose information of spatial light to the signal processing module.

[0029] Furthermore, in a preferred embodiment, the aforementioned fiber optic hammer target is implemented using a one-dimensional / two-dimensional position sensor or a one-dimensional / two-dimensional image sensor.

[0030] Furthermore, in a preferred embodiment, the optical element described above is implemented using a beam splitter prism;

[0031] Furthermore, in a preferred embodiment, the optical element may also be implemented using a converging lens.

[0032] Furthermore, in a preferred embodiment, the aforementioned optical elements and photoelectric conversion components can be integrated into a single module.

[0033] The present invention also provides a method for measuring self-collimation angle with an absolute zero point, the method being implemented based on a self-collimation angle measuring device with an absolute zero point as described in any one of the above claims, the method being as follows:

[0034] S1. Place the mechanical frame carrying the autocollimation module and fiber optic counterweight module on the rack and roughly adjust its horizontal angle; set the autocollimation target on the surface of the object to be measured and adjust the orientation of the autocollimation target and the mechanical frame to enter the range of autocollimation measurement.

[0035] S2. The device is powered on, and the self-collimation module and the fiber optic counterweight module each emit spatial light.

[0036] S3. The self-collimating target reflects the incident light back to the self-collimating module;

[0037] S4. The fiber optic counterweight module converts the incident light direction to vertically downward and sends it to the signal processing module.

[0038] S5. The signal processing module converts the optical signal received from the fiber optic weight module into an electrical signal to obtain the angle between the autocollimation module and the direction of gravity; it converts the relative angle obtained from the autocollimation module into the absolute angle value of the target.

[0039] The beneficial effects of this invention are as follows:

[0040] 1. This invention provides a self-collimation angle measuring device with an absolute zero point. Addressing the issue that the angle measured by a traditional autocollimator relative to the target is only relative to the autocollimator itself, this invention measures the absolute angle of the autocollimator relative to gravity using an optical fiber weight module, and then calculates the absolute angle of the target relative to gravity using a signal processing module. This solves the problem that existing autocollimators cannot measure absolute angle values.

[0041] This invention is applicable to self-collimation angle measurement with an absolute zero point of an optical fiber weight, and is suitable for fields such as high-end equipment manufacturing, testing and measurement, and scientific experiments that require high-precision absolute angle measurement. Attached Figure Description

[0042] Figure 1This is a schematic diagram of a self-collimating angle measuring device with an absolute zero point as described in this invention;

[0043] Figure 2 This is a schematic diagram of the structure of a self-collimation angle measuring device with an absolute zero point according to the present invention;

[0044] Figure 3 This is a schematic diagram of the structure of the self-collimation angle measuring device with an absolute zero point that adds a photodetector according to the present invention;

[0045] Figure 4 This is a schematic diagram of the structure of the self-collimation angle measuring device of the fiber optic hammer target described in this invention, which includes optical elements and photoelectric conversion components;

[0046] Figure 5 This is a schematic diagram of the structure of the hammer described in this invention;

[0047] Figure 6 This is a schematic diagram of the center of gravity of the hammer described in this invention in the three directions of x, y, and z axes in the spatial coordinate system;

[0048] Figure 7 This is a cross-sectional view of the optical fiber counterweight described in this invention;

[0049] Figure 8 This is a schematic diagram of the structure described in this invention, which uses a mass block for center of gravity adjustment and compensation.

[0050] Among them, 1-autocollimation module, 2-autocollimation target, 3-fiber optic weight module, 31-light source, 32-fiber optic, 33-weight, 34-fiber optic weight target, 35-photodetector, 341-optical element, 342-photoelectric conversion component, 4-signal processing module, and 5-mechanical frame. Detailed Implementation

[0051] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0052] Implementation Method 1, see [link] Figure 1 and Figure 2 This embodiment describes a self-collimation angle measuring device with an absolute zero point. The device includes a self-collimation module 1, a self-collimation target 2, an optical fiber counterweight module 3, a signal processing module 4, and a mechanical frame 5.

[0053] The autocollimation module 1 is used to emit a beam of spatial light toward the autocollimation target 2;

[0054] The self-collimating target 2 is set on the object to be tested and is used to reflect the received incident light to the self-collimating module 1;

[0055] The fiber optic counterweight module 3 is used to output a beam of vertically downward spatial light, which is then incident on the target component of the fiber optic counterweight module 3.

[0056] The signal processing module 4 is used to convert the optical signal sent by the target component into an electrical signal to obtain the angle of gravity direction of the fiber optic weight module 3. It is also used to calculate the absolute angle value of the self-collimated target 2 relative to the gravity direction by combining the self-collimation relative angle obtained by the self-collimation module 1.

[0057] The mechanical frame 5 is used to suspend the fiber optic weight module 3 and fix the autocollimation module 1, and provides a clear assembly angle relationship between the two.

[0058] In practical applications, this implementation method, such as Figure 1 As shown, the self-collimation angle measuring device includes a self-collimation module 1, a self-collimation target 2, a fiber optic weight module 3, a signal processing module 4, and a mechanical frame 5;

[0059] Among them, such as Figure 2 As shown, the autocollimating target 2 is placed on the object to be measured. During application, the autocollimating module 1 emits a beam of spatial light towards the autocollimating target 2; the autocollimating target 2 reflects the received incident light back to the autocollimating module 1, which then transmits the photoelectric signal to the signal processing module 4 to measure the angle between the autocollimating target 2 and the autocollimating module 1. Because the autocollimating module 1 may become skewed during actual operation, the angle measured by the autocollimating module 1 is only a relative value. Therefore, in this embodiment, the fiber optic weight module 3 is suspended on the mechanical frame 5. The fiber optic weight module 3 includes a light source 31, an optical fiber 32, a weight 33, and a fiber optic weight target 34. The light emitted from the light source 31 enters the optical fiber 32, which is straightened by the weight 33, converting the outgoing light from the optical fiber 32 into a vertically downward beam before it enters the fiber optic weight target 34. Figure 2 In the illustrated embodiment, the fiber optic weighted target 34 is a photoelectric sensor. The signal it collects is transmitted to the signal processing module 4, which calculates the absolute angle value of the fiber optic weighted target 34 relative to gravity, thereby reflecting the absolute angle value of the autocollimation module 1. The signal processing module 4 calculates the absolute angle value of the autocollimation target 2 based on the angle value between the autocollimation target 2 and the autocollimation module 1 measured by the autocollimation module 1, and the absolute angle value of the autocollimation module 1 measured by the fiber optic weighted target 3, thus solving the problem that existing autocollimation measuring devices cannot measure absolute angle values.

[0060] In application, the self-collimation module 1 contains a light source component, and the fiber optic counterweight module 3 also contains a light source component. The light source components of the two modules can be independent of each other, or they can be shared and used as a single module.

[0061] Implementation Method 2, see below Figure 3 This embodiment is described by way of example, illustrating the fiber optic counterweight module 3 in the autocollimation angle measuring device with an absolute zero point as described in Embodiment 1.

[0062] The fiber optic hammer module 3 includes a light source 31, an optical fiber 32, a hammer 33, a fiber optic hammer target 34, and a photodetector 35.

[0063] One end of the optical fiber 32 is fixed to the upper frame of the mechanical frame 5, and the other end of the optical fiber 32 is connected to the counterweight 33.

[0064] The optical fiber 32 is used to receive the spatial light emitted by the light source 31, and under the action of the weight 32, the direction of the spatial light is converted to vertically downward and emitted to the optical fiber weight target 34.

[0065] exist Figure 3 In the illustrated embodiment, the fiber optic hammer target 34 is a planar reflector, which reflects the vertically downward spatial light output from the fiber optic 32 back to the fiber optic 32. The spatial light reflected back to the fiber optic 32 is transmitted in the reverse direction along the fiber and output at the upper end of the fiber. It is then converted into an electrical signal by the photodetector 35 and transmitted to the signal processing module 4 to calculate the absolute angle value of the autocollimation module 1.

[0066] The photoelectric sensor 35 and the light source module 31 can be independent components or integrated into the same photoelectric module.

[0067] This embodiment provides a self-collimating angle measuring device with an absolute zero point. The fiber optic weight module 3 is connected to the mechanical frame 5 only through the fiber optic cable 32, serving as a "free end" unaffected by gravity. In application, the weight 33 has a through-hole for inserting the fiber optic cable 32 and connecting to the lower end of the fiber optic cable 32, i.e., the "working end" affected by gravity. Specifically, it can be connected to the sheath, cladding, or outer wall of the fiber core of the fiber optic cable 31. The center of mass of the weight 32 coincides with the axis of the portion of the fiber optic cable 31 inserted into the through-hole. The center of mass of the weight 32 can be adjustable.

[0068] In practical applications, the mechanical frame 5 can be placed on an adjustable or non-adjustable rack. The mechanical frame 5 can be equipped with vibration isolation devices to isolate the interference of ground vibrations on the fiber optic weight.

[0069] In a preferred embodiment, the connection between the optical fiber 31 and the counterweight 32 is achieved by adhesive bonding, which neither generates lateral force affecting the light output of the optical fiber nor introduces a complex connection mechanism.

[0070] In this embodiment, the weight is connected to the optical fiber. To ensure that the center of mass of the weight is collinear with the optical axis of the optical fiber, and that the fixing method does not cause deformation of the light, this embodiment sets the weight as a rotating body structure. Based on the principle of center of gravity compensation, by adding mass blocks, a new, relatively more uniform and controllable mass distribution area is formed around the weight of the optical fiber. This minimizes the offset between the line of action of gravity passing through the center of gravity of the weight and the optical fiber axis. At the same time, according to the actual offset position of the center of gravity, mass blocks are reasonably distributed in a ring at different positions, and their embedding distance is controlled. This allows the sum of the torques generated by these counterweights to balance the torques caused by the offset of the center of gravity, thereby gradually pulling the center of gravity back to the position of the optical axis center, ensuring that the center of mass of the weight is collinear with the optical axis of the optical fiber, so that the emitted light is completely perpendicular to the horizontal plane. At the same time, the optical fiber is bonded to the weight to ensure that it will not affect the optical fiber.

[0071] Specifically:

[0072] In this embodiment, to ensure that the center of mass of the weight is collinear with the optical axis of the optical fiber, the weight is configured as a rotating body structure, such as... Figure 5 As shown, since the weight is made of a single material, there may be subtle density variations during manufacturing; that is, the material density is not absolutely uniform but spatially dependent. Furthermore, the weight is a toroidal body of revolution, and its outer cylindrical profile and inner hole are not ideal cylindrical surfaces, and their positions are not absolutely coaxial. Therefore, the actual center of gravity of the weight is necessarily not on its ideal axis. Figure 6 As shown, for a cylindrical hammer, this embodiment focuses on the x, y, and z axes in the spatial coordinate system. For objects with continuously distributed mass, this embodiment uses integration to calculate the position of the center of gravity.

[0073]

[0074] in, The coordinates of the centroid are represented by ρ(x,y,z), the density at position (x,y,z), and dv is the volume element.

[0075] In practical applications, material density often requires complex testing methods to determine, and calculating the micro-elements at various points is quite tedious. This embodiment provides a simple and effective compensation method, specifically:

[0076] The principle of center of gravity compensation is employed to minimize the offset between the line of action of gravity passing through the center of gravity of the weight and the fiber optic axis. Assuming a geodetic coordinate system exists in space, with the z-axis parallel to the direction of gravity, and the fiber optic axis coinciding with the z-axis, it is desirable for the center of gravity to be at any position along the z-axis. Due to factors such as material inhomogeneity, cylindricity errors, and internal hole position errors, it is difficult for the center of gravity of a directly machined weight to be at its geometric center; therefore, center of gravity compensation is necessary. Since the position of the center of gravity along the z-axis does not affect the effectiveness of this invention, the compensation process can be simplified to a planar problem, such as... Figure 7 As shown, a cross-sectional view of the fiber optic counterweight is directly presented. The origin of the coordinate system is at the center of the fiber axis, i.e., the desired center of gravity. The x-axis and y-axis are defined as two mutually perpendicular directions passing through the origin. Multiple uniformly distributed mass blocks with adjustable axial directions are used for center of gravity adjustment and compensation. One typical implementation example is... Figure 8 As shown, mass blocks 1, 2, and 3 are evenly distributed in a ring at different positions along the axial direction of the fiber optic counterweight.

[0077] Let the mass of the fiber optic counterweight be m0, and the masses of the newly added mass blocks 1, 2, and 3 be m1, m2, and m3, respectively, with distances from the centroid of the optical axis of d1, d2, and d3, respectively. The distance of the original centroid from the center of the optical axis is d. In the x and y coordinate system of the fiber optic counterweight profile, the position coordinates of the centroids of the three newly added mass blocks can be simplified to (x1, y1), (x2, y2), and (x3, y3), while the original centroid is located at (x0, y0).

[0078] The components of the resultant torque generated by the newly added mass block on the x-axis and y-axis are:

[0079]

[0080] The new centroid coordinates (x', y') of the fiber optic counterweight after the addition of the new mass block can be expressed by the following formula:

[0081]

[0082] The distance d' between the new centroid coordinates and the optical axis center (i.e., the origin) can be expressed as:

[0083]

[0084] As can be seen, due to the ring-shaped distribution of the newly added mass blocks, the overall center of gravity is affected by the newly added, position-adjustable mass blocks. The overall center of gravity can be adjusted to coincide with the desired optical axis, or the deviation value can be kept from affecting the implementation effect of the present invention.

[0085] In practice, the precise location of the center of gravity of a fiber optic counterweight structure is difficult to determine, requiring gradual approximation to obtain a reasonable mass and distribution. Specifically, with a certain level of machining accuracy, the center of gravity offset is relatively small. The evenly distributed holes can be designed as threaded holes, using screws or threaded structures. The holes and mass blocks are considered as an adjustment unit (containing at least two or more non-coaxial adjustment units). Simple yet effective fine-tuning is achieved by varying the position of homogeneous counterweights of different masses. That is, based on the principle of torque balance, let the mass be m... i The distance from the mass block to the desired center of gravity is d i The torque generated by the mass block at its center of gravity is:

[0086] M = m i ·d i

[0087] From this formula, it can be seen that when the mass is constant, embedding a mass block near the desired center of gravity results in a smaller torque M due to the shorter lever arm d, thus having a weaker effect on correcting the center of gravity. Conversely, embedding a mass block far from the desired center of gravity results in a larger lever arm d, leading to a larger torque M and a stronger effect on correcting the center of gravity. Furthermore, a mass block with a larger mass m has a stronger effect on correcting the center of gravity. By rationally distributing mass blocks in a ring at different positions according to the actual center of gravity offset and controlling their embedding distance, the total torque generated by these counterweights can balance the torque caused by the center of gravity deviation, thereby gradually pulling the center of gravity back to the center of the optical axis.

[0088] Finally, after adjusting with screws, a torque analysis can be performed again to verify whether the center of gravity has been correctly adjusted. Torque balance means that the sum of the torques in all directions is zero. Simultaneously, dynamic tests, such as rotation or tilting, can be used to check stability and balance. If the center of gravity is not in the expected position, i.e., it is offset from the fiber optic axis, then additional or repositioned counterweight screws are needed.

[0089] Furthermore, in this embodiment, by connecting a weight to an optical fiber, with the optical fiber serving as the connecting line for the weight, gravity acts directly on the optical axis of the fiber, straightening it and pointing it perpendicularly to the Earth's center. This forms a ray of light parallel to the direction of gravity, serving as a horizontal measurement reference. This breaks away from the conventional approach of using lasers for horizontal measurement, which requires both a measuring ray component and a reference ray component in the horizontal measurement device, obtaining the horizontal measurement result by measuring the angle change between the reference ray and the measuring ray. This embodiment, however, eliminates the need for a separate reference ray component to achieve horizontal measurement, overcoming the biases of existing technologies. Since the component generating the reference ray is eliminated, yet horizontal measurement is still achieved with more accurate results, this is an invention that saves on resource consumption.

[0090] Existing technologies typically integrate a semiconductor laser with a counterweight, creating a vertical line parallel to the direction of gravity between the counterweight's center of mass and a thin wire. This forms an optical axis parallel to gravity, serving as a measurement reference. However, achieving parallelism between the vertical line and the optical axis requires high-precision machining and adjustment between the counterweight and the thin wire, and this precision directly affects the optical axis direction. This embodiment addresses the problem in existing technologies where the precision of machining and adjustment between the counterweight and the thin wire affects the optical axis direction. Although both methods employ a suspension system, the "suspension" differs fundamentally. Existing technologies apply gravity to the laser's center of mass, straightening the thin wire suspending the laser to ensure the emitted light is vertically downward. This requires that the suspension point and center of mass of the thin wire be collinear with the laser's optical axis, meaning the suspension point and center of mass pass through the reverse extension of the laser's optical axis. Because lasers contain light-emitting diodes or chips, driver circuit boards, heat dissipation structures, and even optical components and fans, their center of mass is difficult to estimate, thus requiring high-precision assembly and adjustment. However, the technical solution used in this embodiment only involves the optical fiber and a counterweight. Gravity acts on the center of mass of the counterweight, straightening the optical fiber. The counterweight can be a rotating body precision-machined, with uniform material and ideal mass; gravity directly straightens the optical fiber axis, eliminating the need for high-precision assembly and adjustment between the thin wire and the optical axis. Furthermore, apart from the counterweight, no other components are installed at the end of the optical fiber in this solution, thus avoiding the impact of non-ideal assembly and adjustment of multiple components on measurement accuracy.

[0091] Implementation Method 3: This implementation method is an example of the optical fiber 32 in the self-collimating angle measuring device with an absolute zero point described in Implementation Method 2.

[0092] The optical fiber 32 is implemented using any one of single-mode fiber, single-mode polarization-maintaining fiber, and multimode fiber.

[0093] Implementation Method Four, see below Figure 4 This embodiment is described by way of example, illustrating the fiber optic counterweight module 3 in the autocollimation angle measuring device with an absolute zero point as described in Embodiment 1.

[0094] The fiber optic hammer target 34 includes an optical component 341 and a photoelectric conversion component 342;

[0095] The optical component 341 is disposed below the optical fiber 32 and is used to receive the spatial light emitted by the optical fiber 32 and to transmit the spatial light to the photoelectric conversion component 342.

[0096] The photoelectric conversion component 342 is used to convert the optical signal of spatial light into an electrical signal and send it to the signal processing module 4.

[0097] The optical component 341 may be an optical plate, an optical thin film, a prism, a lens, a superlens, or a combination of the above-mentioned optical elements.

[0098] Implementation Method 5: This implementation method is an example of the fiber optic weighted target 34 in the self-collimating angle measuring device with an absolute zero point described in Implementation Method 2.

[0099] The fiber optic hammer target 34 is implemented using a one-dimensional position sensor or a one-dimensional image sensor.

[0100] In practical applications of this embodiment, when the fiber optic hammer target 34 uses a one-dimensional position sensor (PSD), the object under test forms an angle with the horizontal plane along the PSD direction, creating a light spot at a distance x from the midpoint of the photosensitive surface. The two output electrodes on the photosensitive surface generate a current signal I related to the position of the light spot. x1 I x2 Based on the positioning principle of PSD, the position of the center of the light spot is derived as follows: In the formula, L x Where is the side length of the PSD photosensitive surface, and K is a proportionality coefficient related to the PSD load resistance. The angle between the vertically downward spatial light and the target can be derived geometrically based on the center position of the light spot.

[0101] The fiber optic plumb bob target 34 can also be a two-dimensional device. When the fiber optic plumb bob target 34 is a two-dimensional device, the tilt angle of the object under test in two planes can be measured simultaneously. In application, the fiber optic plumb bob target 34 can be a position-sensitive detector (PSD), a four-quadrant detector (QPD), an image sensor (CCD or CMOS), or an array formed by multiple photodiodes (PDs).

[0102] Implementation Method Six: This implementation method provides a self-collimation angle measurement method with an absolute zero point. The measurement method is implemented based on a self-collimation angle measurement device with an absolute zero point as described in any one of Implementation Methods One to Five. The method of use is as follows:

[0103] S1. Place the mechanical frame carrying the autocollimation module and the fiber optic counterweight module on the machine frame or machine platform, and roughly adjust its horizontal angle; set the autocollimation target on the surface of the object to be measured, and adjust the orientation of the autocollimation target and the mechanical frame to enter the range of autocollimation measurement.

[0104] S2. The device is powered on, and the self-collimation module emits spatial light towards the self-collimation target; the light source of the fiber optic weight module emits vertically downward spatial light towards the fiber optic weight target.

[0105] S3. The self-collimating target reflects the spatial light of the incident target to the self-collimating module, obtains a photoelectric signal, sends it to the signal processing module, and calculates the relative angle between the self-collimating target and the self-collimating module.

[0106] S4. The fiber optic hammer target sends vertically downward spatial light to the signal processing module, which calculates the absolute horizontal angle of the collimation module.

[0107] S5. The signal processing module uses the angle value of the autocollimating target relative to the autocollimating module and the absolute horizontal angle value of the autocollimating module to calculate the absolute angle value of the autocollimating target.

[0108] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0109] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0110] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A self-collimating angle measuring device with an absolute zero point, characterized in that, The device includes a self-collimation module (1), a self-collimation target (2), a fiber optic weight module (3), a signal processing module (4), and a mechanical frame (5); The self-collimation module (1) is used to emit a beam of spatial light toward the self-collimation target (2); The self-collimating target (2) is set on the object to be tested and is used to reflect the received incident light to the self-collimating module (1); The fiber optic hammer module (3) is used to output a beam of vertically downward spatial light and to be incident on the target component of the fiber optic hammer module (3); The signal processing module (4) is used to convert the optical signal sent by the target component into an electrical signal to obtain the angle of gravity direction of the fiber optic hammer module (3). It is also used to calculate the absolute angle value of the self-collimated target (2) relative to the gravity direction by combining the self-collimation relative angle obtained by the self-collimation module (1). The mechanical frame (5) is used to suspend the fiber optic weight module (3) and fix the autocollimation module (1), and provides a clear assembly angle relationship between the two.

2. The self-collimating angle measuring device with an absolute zero point according to claim 1, characterized in that, Both the self-collimation module (1) and the fiber optic counterweight module (3) include a light source component; The two light source components can be used independently or shared as a single module.

3. The self-collimating angle measuring device with an absolute zero point according to claim 1, characterized in that, The fiber optic hammer module (3) includes a light source (31), an optical fiber (32), a hammer (33), and a fiber optic hammer target (34); One end of the optical fiber (32) is fixed to the upper frame of the mechanical frame (5), and the other end of the optical fiber (32) is connected to the counterweight (33). The optical fiber (32) is used to receive spatial light emitted by the light source (31), and under the action of the weight (33), the direction of the spatial light is converted to vertically downward and emitted to the optical fiber weight target (34).

4. The autocollimation angle measuring device with an absolute zero point according to claim 3, characterized in that, The fiber optic counterweight module (3) also includes a photodetector (35); The fiber optic hammer target (34) is used to reflect the vertically downward spatial light output from the fiber optic (32) back to the fiber optic (32); the spatial light reflected back to the fiber optic (32) is transmitted in the opposite direction along the fiber optic and output at the upper end of the fiber optic and converted into an electrical signal by the photodetector (35), and then transmitted to the signal processing module (4).

5. The autocollimation angle measuring device with an absolute zero point according to claim 3, characterized in that, The optical fiber (32) is implemented using any one of single-mode fiber, single-mode polarization-maintaining fiber, and multimode fiber.

6. The autocollimation angle measuring device with an absolute zero point according to claim 3, characterized in that, The fiber optic hammer target (34) includes an optical element (341) and a photoelectric conversion component (342); The optical element (341) is disposed between the optical fiber (32) and the photoelectric conversion component (342) for receiving spatial light emitted from the optical fiber (32), processing the spatial light, and sending it to the photoelectric conversion component (342); the photoelectric conversion component (342) is used to send the pose information of the spatial light to the signal processing module (4).

7. The autocollimation angle measuring device with an absolute zero point according to claim 3, characterized in that, The fiber optic hammer target (34) is implemented using a one-dimensional / two-dimensional position sensor or a one-dimensional / two-dimensional image sensor.

8. A self-collimating angle measuring device with an absolute zero point according to claim 6, characterized in that, The optical element (341) is implemented using a beam splitter prism; The optical element (341) can also be implemented using a converging lens.

9. A self-collimating angle measuring device with an absolute zero point according to claim 6, characterized in that, The optical element (341) and photoelectric conversion component (342) can be an integrated module.

10. A method for measuring the self-collimation angle with an absolute zero point, characterized in that, The method is implemented based on the self-collimation angle measuring device with an absolute zero point as described in any one of claims 1-9, and the method is as follows: S1. Place the mechanical frame carrying the autocollimation module and fiber optic counterweight module on the rack and roughly adjust its horizontal angle; set the autocollimation target on the surface of the object to be measured and adjust the orientation of the autocollimation target and the mechanical frame to enter the range of autocollimation measurement. S2. The device is powered on, and the self-collimation module and the fiber optic counterweight module each emit spatial light. S3. The self-collimating target reflects the incident light back to the self-collimating module; S4. The fiber optic counterweight module converts the incident light direction to vertically downward and sends it to the signal processing module. S5. The signal processing module converts the optical signal received from the fiber optic weight module into an electrical signal to obtain the angle between the autocollimation module and the direction of gravity; it converts the relative angle obtained from the autocollimation module into the absolute angle value of the target.

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