A laser scanning device, an angle measuring sensor based on laser scanning, and a method

Abstract

The object of the present invention is to improve the angle measurement accuracy and reduce the measurement cost, and relates to a laser scanning device, an angle measurement sensor and method based on laser scanning, including: a laser for emitting a laser with a fixed wavelength to a laser angle deflection device; a laser angle deflection device for changing the emission angle of the received laser and emitting the laser with the changed emission angle to a triangular prism; a triangular prism for expanding the angle of the laser emitted by the laser angle deflection device, so that the angle between two beams of laser before and after a fixed time interval is increased, that is, further amplifying the included angle of the laser emitted by the laser angle deflection device; a laser measurement device for receiving the laser with the expanded angle by the triangular prism and recording the positions where two beams of laser are incident before and after a fixed time interval T.

Description

Technical Field

[0001] The present invention relates to the technical field of angle measurement, and particularly relates to a laser scanning device, an angle measurement sensor based on laser scanning, and a method. Background Art

[0002] Currently, gratings are often used as measurement elements for high-precision angle measurement. However, the accuracy of gratings is limited by the grating line density and line accuracy, and it is difficult to further improve its measurement accuracy at present. The angle measurement sensor based on optical arm amplification proposed by the applicant also relies on high-precision position-sensitive detectors, and it is difficult for domestic manufacturers to manufacture such devices.

[0003] The time grating invented by Professor Peng Donglin of Chongqing University of Technology uses a rotating magnetic field as the motion reference system, and the uniformity and stability of the rotating magnetic field affect the measurement accuracy.

[0004] In the patent application with the application number 202110202949X and the name "A Novel Sensor Based on Time Angle Measurement and Its Angle Measurement Method", the optical waveguide array device used has a large laser deflection angle range, but its principle causes other stray light to be generated, which will affect the measurement results of the photodetector. When a conventional crystal is selected to achieve laser deflection, its deflection angle range is small, and it is difficult to meet the requirements of the angle deflection range in many application fields.

[0005] Therefore, it is very necessary to innovate from the measurement principle, reduce the accuracy requirements of the angle sensor for photoelectric detection devices, and develop a new type of high-precision and low-cost high-precision angle measurement sensor. Summary of the Invention

[0006] The purpose of the present invention is to improve the angle measurement accuracy and reduce the measurement cost, and provide a laser scanning device, an angle measurement sensor based on laser scanning, and a method.

[0007] In order to achieve the above invention purpose, the embodiments of the present invention provide the following technical solutions:

[0008] A laser scanning device, comprising:

[0009] A laser, configured to emit a laser with a fixed wavelength to a laser angle deflection device;

[0010] A laser angle deflection device, configured to change the emission angle of the laser emitted by the laser, and emit the laser with the changed emission angle to a triangular prism;

[0011] A triangular prism, configured to expand the angle of the laser emitted by the laser angle deflection device, so that the angle between two beams of laser before and after a fixed time interval T increases;

[0012] A laser measurement device is used to receive the laser with an enlarged angle by a triangular prism and record the incident positions of two laser beams before and after a fixed time interval T.

[0013] In the above solution, the laser angle deflection device continuously changes the emission angle of the laser, but the range of the changed emission angle is too small. Therefore, a triangular prism is arranged between the laser angle deflection device and the laser measurement device to increase the angle between two laser beams before and after a fixed time interval T, so that a large-angle change can be measured on the laser measurement device.

[0014] Furthermore, the angles of the two laser beams incident on the triangular prism before and after the fixed time interval T are smaller than the angles when they exit the triangular prism.

[0015] Furthermore, the laser angle deflection device is a potassium tantalate niobate crystal.

[0016] In the above solution, the laser angle deflection device is preferably a potassium tantalate niobate crystal, but other crystals can also be used.

[0017] An angle measuring sensor based on laser scanning includes a probe and a regular polygonal prism. The probe includes:

[0018] A laser for emitting a laser with a fixed wavelength to the laser angle deflection device;

[0019] A laser angle deflection device for changing the emission angle of the laser emitted by the laser and emitting the laser with the changed emission angle to the regular polygonal prism;

[0020] A first triangular prism for enlarging the angle of the laser reflected by the regular polygonal prism, so that the angle between two laser beams before and after a fixed time interval T is increased;

[0021] A measurement photodetector for receiving the laser with an enlarged angle by the first triangular prism and recording the incident positions of two laser beams before and after a fixed time interval T;

[0022] A processor for calculating the rotation angle of the regular polygonal prism according to the incident positions of two laser beams recorded by the measurement photodetector before and after the time interval T;

[0023] The regular polygonal prism is used to carry the object to be measured to rotate and reflect the laser with the changed emission angle emitted by the laser angle deflection device to the first triangular prism.

[0024] Furthermore, the probe further includes a beam splitter and a reference photodetector, wherein,

[0025] The beam splitter reflects the laser emitted by the laser angle deflection device to the reference photodetector and transmits it to the regular polygonal prism;

[0026] The reference photodetector receives the laser reflected by the beam splitter and records the incident positions of two laser beams before and after a fixed time interval T, for real-time detection of the angle deflection amount of the laser changed by the laser angle deflection device.

[0027] Furthermore, the probe head further includes a second triangular prism for expanding the angle of the laser reflected by the beam splitter, so that the angle between two laser beams before and after the fixed time interval T increases.

[0028] Furthermore, the angles of two laser beams incident on the first triangular prism and the second triangular prism before and after the fixed time interval T are smaller than the angles when the two laser beams exit the first triangular prism and the second triangular prism.

[0029] An angle measurement method based on laser scanning includes the following steps:

[0030] Step S1: At any moment, the laser angle deflection device changes the exit angle of the laser emitted by the laser, and emits the laser with the changed exit angle to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the incident edge of the first triangular prism. The first triangular prism changes the angle of the laser and transmits it from its exit edge to the measurement photodetector. At this time, the measurement photodetector records the incident position x1 of the laser.

[0031] Step S2: After a fixed time interval T, the laser angle deflection device continuously changes the exit angle of the laser emitted by the laser, and emits the laser with the changed exit angle to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the incident edge of the first triangular prism. The first triangular prism changes the angle of the laser and transmits it from its exit edge to the measurement photodetector. At this time, the measurement photodetector records the incident position x2 of the laser.

[0032] Step S3: The processor calculates the position difference △x according to the positions x1 and x2 of the two laser beams incident on the measurement photodetector before and after the fixed time interval T, and obtains the rotation angle of the regular polygonal prism according to the position difference △x.

[0033] The step S1 further includes:

[0034] At any moment, the laser angle deflection device changes the exit angle of the laser emitted by the laser, and emits the laser with the changed exit angle to the beam splitter. The beam splitter transmits the laser to the regular polygonal prism and reflects it to the incident edge of the second triangular prism. The second triangular prism changes the angle of the laser and transmits it from its exit edge to the reference photodetector. At this time, the reference photodetector records the incident position y1 of the laser.

[0035] The step S2 further includes:

[0036] After a fixed time interval T, the laser angle deflection device continuously changes the exit angle of the laser emitted by the laser, and emits the laser with the changed exit angle to the beam splitter. The beam splitter transmits the laser to the regular polygonal prism and reflects it to the incident side of the second triangular prism. The second triangular prism changes the angle of the laser and transmits it from its exit side to the reference photodetector. At this time, the reference photodetector records the position y2 where the laser is incident.

[0037] The step S3 further includes:

[0038] The processor calculates the position difference △y based on the positions y1 and y2 of the laser incident on the reference photodetector before and after the fixed time interval T, and obtains the rotation angle of the regular polygonal prism according to the position differences △x and △y.

[0039] Furthermore, when the measurement photodetector or the reference photodetector detects that the laser has reached the edge position within the time interval T, the processor calculates the position difference between the two times the laser is incident on the measurement photodetector or the reference photodetector before and after the fixed time interval T as the distance traveled by the incident point, that is, the sum of the distance from the position incident before the fixed time interval to the edge position and the distance from the position incident after the fixed time interval to the edge position.

[0040] In the above solution, when the measurement photodetector or the reference photodetector detects that the laser has reached the edge position within the fixed time interval T, that is, the measurement photodetector has once appeared the maximum value or the minimum value Mx, or the detection value of the reference photodetector has once appeared the maximum value or the minimum value My, the processor calculates the position difference between the two times the laser is incident on the measurement photodetector as |Mx - x1| + |Mx - x2|, and the position difference of the reference photodetector is calculated as |My - y1| + |My - y2|.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] The deflection angle of the laser by the laser angle deflection device is enlarged by the triangular prism, and the deflection angle range of the laser angle deflection device is increased. At the same time, under the condition of a fixed deflection angle, the control requirements are greatly reduced. Taking the potassium tantalate niobate crystal as an example, under the same deflection angle requirements, the present invention greatly reduces the control voltage range.

[0043] The reflection angle of the regular polygonal prism is enlarged by the triangular prism, that is, the small angle change of the regular polygonal prism is enlarged, and the angle measurement accuracy of the regular polygonal prism is improved.

[0044] Through the setting of the spectroscope, the deflected laser of the laser deflection device is detected by two groups of photodetectors respectively. The reference photodetector realizes the measurement of the change in the laser angle incident on the regular polygonal prism, and the measurement photodetector realizes the measurement of the change in the laser angle after being reflected by the regular polygonal prism. Taking the angle measured by the reference photodetector as the benchmark, the angle measurement accuracy of the regular polygonal prism is improved. Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0046] Figure 1 Structural schematic diagram of a laser scanning device according to Embodiment 1 of the present invention;

[0047] Figure 2 Angle comparison schematic diagram of a laser scanning device according to Embodiment 1 of the present invention;

[0048] Figure 3 Structural schematic diagram of an angle measuring sensor based on scanning laser according to Embodiment 2 of the present invention;

[0049] Figure 4 Structural schematic diagram of another embodiment of an angle measuring sensor based on scanning laser according to Embodiment 2 of the present invention;

[0050] Figure 5 Schematic diagram for calculating the position difference of an angle measuring method based on scanning laser according to Embodiment 3 of the present invention.

[0051] Figure 6 Schematic diagram of the deflection curve of a triangular prism for lasers with different incident angles according to Embodiment 1 of the present invention.

[0052] Description of the main component symbols

[0053] Laser 1, laser angle deflection device 2, first triangular prism (triangular prism) 3, measurement photodetector (laser measurement device) 4, regular polygonal prism 5, spectroscope 6, second triangular prism 7, reference photodetector 8. Detailed implementation manners

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0055] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance, or implying any such actual relationship or order between these entities or operations.

[0056] Embodiment 1:

[0057] The present invention is implemented through the following technical solutions. As Figure 1 shown, a laser scanning device is proposed, including a laser, a laser angle deflection device, a triangular prism, and a laser measurement device, where:

[0058] The laser is used to emit laser with a fixed wavelength to the laser angle deflection device;

[0059] The laser angle deflection device is used to change the exit angle of the laser emitted by the laser and emit the laser with the changed exit angle to the triangular prism;

[0060] The triangular prism is used to expand the angle of the laser emitted by the laser angle deflection device, so that the angle between two beams of laser before and after a fixed time interval T increases;

[0061] The laser measurement device is used to receive the laser with the expanded angle by the triangular prism and record the incident positions of two beams of laser before and after a fixed time interval T.

[0062] Please refer to Figure 1, where the solid line represents the laser emitted by the laser angle deflection device before a fixed time interval, and the dashed line represents the laser emitted by the laser angle deflection device after the fixed time interval. For example, at time t0, the laser emitter emits laser light towards the laser angle deflection device, which changes the emission angle of the laser and emits the laser with the changed emission angle to the laser measurement device. A triangular prism is arranged between the laser angle deflection device and the laser measurement device to expand the deflection angle of the laser. After a fixed time interval T, at time t0+T, the laser angle deflection device continuously changes the emission angle of the laser, and after the deflection angle of the laser is expanded by the triangular prism, it is transmitted to the laser measurement device.

[0063] It can be seen that after the triangular prism is arranged between the laser angle deflection device and the laser measurement device, the position difference between the two times when the laser enters the laser measurement device before and after the fixed time interval T becomes larger. For example, when the triangular prism is not arranged, the position where the laser enters the laser measurement device before the fixed time interval is a, and the position where the laser enters the laser measurement device after the fixed time interval is b; but after the triangular prism is arranged, the triangular prism expands the deflection angle of the laser, the position where the laser enters the laser measurement device before the fixed time interval is a`, and the position where the laser enters the laser measurement device after the fixed time interval is b`; through measurement, it is found that the position difference |a - b| is less than |a` - b`|. The range of the incident angle of the laser on the triangular prism needs to be determined by calculation to ensure that the angle between the two incident laser beams is less than the angle between the laser beams emerging from the triangular prism.

[0064] Therefore, after the triangular prism is arranged, the laser angle emitted by the laser angle deflection device changes from a small angle to a large angle. According to the known refractive index of the triangular prism and the measured position difference of the laser incident on the laser measurement device, the angle deflection amount of the laser emission by the laser angle deflection device before and after the fixed time interval T can be obtained. In this solution, the angle deflection amount of the laser by the laser angle deflection device can be further corrected and improved.

[0065] Furthermore, in the traditional technology, since the refractive index of the triangular prism for different wavelengths of light is different, the triangular prism is used to disperse the mixed light to separate the monochromatic lights. In the present invention, the laser emitted by the laser emitter is a beam of light with a fixed wavelength. Therefore, when this laser enters the triangular prism at different positions on the incident surface of the triangular prism, different results may occur. That is to say, when the incident angle of the triangular prism is not selected appropriately, the angle between the two non-parallel laser beams will be narrowed after the laser enters the triangular prism.

[0066] Taking a prism with a refractive index of 1.5 and a vertex angle of 60 degrees as an example, the relationship between the incident angle and the exit angle is as Figure 6As shown. When the incident angle is selected to be between 28 degrees and 33 degrees, the triangular prism has an obvious deflection and amplification effect on the incident laser. However, when the incident angle is not appropriate, the triangular prism has a shrinking effect on the deflection of the incident laser.

[0067] Therefore, this solution limits that the angle between two laser beams incident on the triangular prism before and after the fixed time interval T is smaller than the angle when they exit the triangular prism. Please refer to Figure 2 , where the angle α refers to the angle between two laser beams incident on the triangular prism before and after the fixed time interval, and the angle β refers to the angle between two laser beams exiting the triangular prism before and after the fixed time interval.

[0068] Embodiment 2:

[0069] The present invention also proposes an angle measuring sensor based on laser scanning, including a probe head and a regular polygonal prism. The probe head includes a laser, a laser angle deflection device, a first triangular prism, and a measurement photodetector, where:

[0070] The laser is used to emit laser with a fixed wavelength to the laser angle deflection device;

[0071] The laser angle deflection device is used to change the exit angle of the laser emitted by the laser and emit the laser with the changed exit angle to the regular polygonal prism;

[0072] The first triangular prism is used to expand the angle of the laser reflected by the regular polygonal prism, so that the angle between two laser beams before and after the fixed time interval T increases;

[0073] The measurement photodetector is used to receive the laser with the expanded angle by the first triangular prism and record the positions where two laser beams are incident before and after the fixed time interval T; the measurement photodetector in this embodiment is equivalent to the laser measurement device in Embodiment 1;

[0074] The processor calculates the rotation angle of the regular polygonal prism according to the positions where two laser beams are incident before and after the fixed time interval T recorded by the measurement photodetector;

[0075] The regular polygonal prism is used to carry the object to be measured to rotate and reflect the laser with the changed exit angle emitted by the laser angle deflection device to the first triangular prism.

[0076] Please refer to Figure 3, the solid line represents the laser before the fixed time interval, and the dashed line represents the laser after the fixed time interval. Before the fixed time interval, for example, at time t0, the laser is incident on the laser angle deflection device. Under the action of the control signal, the output laser angle of the laser angle deflection device will change, and the laser is output to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the measurement photodetector. The first triangular prism is arranged between the regular polygonal prism and the measurement photodetector to expand the deflection angle of the laser. Its function is the same as that of the triangular prism described in Embodiment 1, so it will not be elaborated here. After the expansion of the first triangular prism, the laser enters the measurement photodetector, and the measurement photodetector records the position x1 where the laser is incident at this time.

[0077] After the fixed time interval T, that is, at time t0 + T, the laser is incident on the laser angle deflection device. Under the action of the control signal, the output laser angle of the laser angle deflection device will continue to change, and the laser is output to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the measurement photodetector. Similarly, after the expansion of the first triangular prism, it enters the measurement photodetector, and the measurement photodetector records the position x2 where the laser is incident at this time.

[0078] The processor can calculate the position difference △x before and after the fixed time interval T according to the positions x1 and x2 recorded by the measurement photodetector. Since the laser deflection amounts changed by the laser angle deflection device before and after the fixed time interval T are known, the processor can obtain the rotation angle of the regular polygonal prism according to the position difference △x and the laser deflection amount.

[0079] It should be noted that before the measurement, the position difference △x, the laser deflection amount, and the rotation angle of the regular polygonal prism are made into a table in the form of marks in advance. During the measurement, by looking up the table, that is, a position difference △x and a laser deflection amount correspond to a unique rotation angle, and this rotation angle is the rotation angle of the regular polygonal prism, that is, the rotation angle of the object to be measured.

[0080] However, although the laser angle deflection amounts of the laser angle deflection device before and after the fixed time interval T are known, since the deflection amount is small, the first triangular prism is set. In order to more accurately measure the laser angle deflection amount of the laser angle deflection device, a beam splitter, a second triangular prism, and a reference photodetector are also provided in this solution.

[0081] Please refer to Figure 4, the beam splitter reflects the laser emitted by the laser angle deflection device to the reference photodetector and transmits it to the regular polygonal prism. The laser path transmitted to the regular polygonal prism is the same as the path before the beam splitter is set. A second triangular prism is arranged between the beam splitter and the reference photodetector to expand the deflection angle of the laser. Its function is the same as that of the triangular prism in Embodiment 1 and the first triangular prism in this embodiment, so it will not be elaborated here.

[0082] At time t0, the beam splitter reflects the laser to the reference photodetector. After being expanded by the second triangular prism, it enters the reference photodetector. The reference photodetector records the position y1 where the laser is incident at this time. After a fixed time interval T, that is, at time t0 + T, the reference photodetector records the position y2 where the laser is incident at this time. The processor can calculate the position difference △y based on the positions y1 and y2 recorded by the reference photodetector. Based on the position difference △y, the deflection amount of the laser by the laser angle deflection device before and after the fixed time interval T can be calculated more accurately.

[0083] Therefore, in this embodiment, a reference photodetector is set to detect the deflection amount of the laser by the laser angle deflection device in real time, reducing the error in obtaining the deflection amount and improving the measurement accuracy.

[0084] Similarly, the angles of the two laser beams incident on the first triangular prism and the second triangular prism before and after the fixed time interval T are smaller than the angles when they exit the first triangular prism and the second triangular prism. The principle has been explained in Embodiment 1, so it will not be elaborated here.

[0085] Other contents of this embodiment are the same as those of Embodiment 1. Please refer to Embodiment 1.

[0086] Embodiment 3:

[0087] The present invention also proposes an angle measurement method based on laser scanning, including the following steps:

[0088] Step S1: At any time, the laser angle deflection device changes the emission angle of the laser emitted by the laser device and emits the laser with the changed emission angle to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the incident side of the first triangular prism. The first triangular prism changes the angle of the laser and transmits it from its exit side to the measurement photodetector. At this time, the measurement photodetector records the position x1 where the laser is incident.

[0089] At this moment, the laser angle deflection device changes the emission angle of the laser emitted by the laser device and emits the laser with the changed emission angle to the beam splitter. The beam splitter transmits the laser to the regular polygonal prism and reflects it to the incident side of the second triangular prism. The second triangular prism changes the angle of the laser and transmits it from its exit side to the reference photodetector. At this time, the reference photodetector records the position y1 where the laser is incident.

[0090] Step S2: After a fixed time interval T, the laser angle deflection device continuously changes the exit angle of the laser emitted by the laser, and emits the laser with the changed exit angle to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the incident side of the first triangular prism. The first triangular prism changes the angle of the laser and transmits it from its exit side to the measurement photodetector. At this time, the measurement photodetector records the position x2 where the laser is incident.

[0091] At this moment, the laser angle deflection device continuously changes the exit angle of the laser emitted by the laser, and emits the laser with the changed exit angle to the beam splitter. The beam splitter transmits the laser to the regular polygonal prism and reflects it to the incident side of the second triangular prism. The second triangular prism changes the angle of the laser and transmits it from its exit side to the reference photodetector. At this time, the reference photodetector records the position y2 where the laser is incident.

[0092] Step S3: The processor calculates the position difference △x based on the positions x1 and x2 where the laser enters the measurement photodetector before and after the fixed time interval T; calculates the position difference △y based on the positions y1 and y2 where the laser enters the reference photodetector before and after the fixed time interval T, and obtains the rotation angle of the regular polygonal prism according to the position differences △x and △y.

[0093] It should be noted that when the laser angle deflection device deflects the laser angle, it can be continuously changed. For example, like a pendulum, it keeps swinging after being powered on and is measured every fixed time interval T. Therefore, it is very likely that within the fixed time interval T, the laser has scanned to the edge position of the measurement photodetector or the reference photodetector. Please refer to Figure 5 , taking the measurement photodetector as an example, point A is the edge position at one end of the measurement photodetector, and point B is the edge position at the other end. However, the edge position will change. It is not always points A and B for each edge position. Therefore, as the regular polygonal prism rotates, the edge position will change. But whenever the laser scans to a certain position and then returns, this position is the edge position of this time. The measurement photodetector in this solution has the function of detecting the edge position.

[0094] Suppose that in this measurement, the measurement photodetector detects that the laser enters point C at time t0. After scanning to point A within the fixed time interval T and then returning, at time t0 + T, the laser enters point D. Therefore, when calculating the time difference △x at this time, the position difference between the laser entering the measurement photodetector before and after the fixed time interval should be calculated as the distance traveled by the incident point, that is, the sum of the distance from the position where it entered before the fixed time interval to the edge position and the distance from the position where it entered after the fixed time interval to the edge position, that is, the sum of the distance from point C to point A and the distance from point A to point D, △x = |CA| + |AD|. The same principle applies to the reference photodetector, so it will not be elaborated here.

[0095] The other content of this embodiment is the same as that of Embodiment 1 and Embodiment 2. Please refer to Embodiment 1 and Embodiment 2.

[0096] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for measuring angles based on laser scanning, characterized in that: Based on an angle measuring sensor, the angle measuring sensor includes a probe head and a regular polygonal prism. The probe head includes: A laser for emitting laser with a fixed wavelength to a laser angle deflection device; A laser angle deflection device for changing the emission angle of the laser emitted by the laser and emitting the laser with the changed emission angle to the regular polygonal prism; A first triangular prism for expanding the angle of the laser reflected by the regular polygonal prism, so that the angle between two beams of laser before and after a fixed time interval T increases; A measuring photodetector for receiving the laser with the expanded angle by the first triangular prism and recording the incident positions of two beams of laser before and after the fixed time interval T; A processor for calculating the rotation angle of the regular polygonal prism according to the incident positions of two beams of laser recorded by the measuring photodetector before and after the time interval T; The regular polygonal prism is used to carry the object to be measured for rotation and reflect the laser with the changed emission angle emitted by the laser angle deflection device to the first triangular prism; The angle measuring method includes the following steps: Step S1: At any moment, the laser angle deflection device changes the emission angle of the laser emitted by the laser and emits the laser with the changed emission angle to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the incident edge of the first triangular prism. The first triangular prism changes the angle of the laser and transmits it from its exit edge to the measuring photodetector. At this time, the measuring photodetector records the incident position x1 of the laser; Step S2: After a fixed time interval T, the laser angle deflection device continuously changes the emission angle of the laser emitted by the laser and emits the laser with the changed emission angle to the regular polygonal prism. The laser is reflected by the regular polygonal prism to the incident edge of the first triangular prism. The first triangular prism changes the angle of the laser and transmits it from its exit edge to the measuring photodetector. At this time, the measuring photodetector records the incident position x2 of the laser; Step S3: The processor calculates the position difference △x according to the positions x1 and x2 of the two beams of laser incident on the measuring photodetector before and after the fixed time interval T, and obtains the rotation angle of the regular polygonal prism according to the position difference △x.

2. The angle measuring method based on laser scanning according to claim 1, wherein: Step S1 further includes: At any moment, the laser angle deflection device changes the emission angle of the laser emitted by the laser and emits the laser with the changed emission angle to a beam splitter. The beam splitter transmits the laser to the regular polygonal prism and reflects it to the incident edge of the second triangular prism. The second triangular prism changes the angle of the laser and transmits it from its exit edge to the reference photodetector. At this time, the reference photodetector records the incident position y1 of the laser; Step S2 further includes: After a fixed time interval T, the laser angle deflection device continuously changes the emission angle of the laser emitted by the laser and emits the laser with the changed emission angle to the beam splitter. The beam splitter transmits the laser to the regular polygonal prism and reflects it to the incident edge of the second triangular prism. The second triangular prism changes the angle of the laser and transmits it from its exit edge to the reference photodetector. At this time, the reference photodetector records the incident position y2 of the laser; Step S3 further includes: The processor calculates the position difference △y based on the positions y1 and y2 of the laser beam entering the reference photodetector twice before and after a fixed time interval T, and obtains the rotation angle of the regular polygonal prism based on the position differences △x and △y.

3. The angular measurement method based on laser scanning according to claim 2, characterized in that: When the measurement photodetector or the reference photodetector detects that the laser beam has reached the edge position within the time interval T, the processor calculates the position difference between the two times the laser beam enters the measurement photodetector or the reference photodetector before and after the fixed time interval T as the distance traveled by the incident point, that is, the sum of the distance from the position where the laser beam entered before the fixed time interval to the edge position and the distance from the position where the laser beam entered after the fixed time interval to the edge position.

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