High-precision small-angle generation device and method based on light path folding and amplification

Abstract

The invention relates to the technical field of metering and precision measurement, in particular to a high-precision small-angle generation device and method based on light path folding and amplification. Comprising a laser, a base, a sine arm, a hinge piece, a detector used for detecting the position of a light spot, an exciter used for generating infinitesimal displacement and a reflecting mirror. One end of the sine arm is rotationally connected with one end of the base through a hinge piece, the exciter is mounted at the other end of the base, the driving end of the exciter is in contact with the other end of the sine arm, the reflector is mounted on the sine arm, and the exciter drives the sine arm to rotate around the rotating center of the hinge piece so as to drive the reflector to generate angle change; two side walls, opposite to the sine arms, of the base are provided with plane light reflecting modules, one end, close to the hinge piece, of the base is provided with a light inlet through hole, and the detector is installed on the base or the first sine arm; the laser is located at the light inlet through hole. According to the invention, the complexity of the device is reduced, the operation is simple, and the measurement stability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metrology and precision measurement, and more specifically, to a high-precision small-angle generating device and method based on optical path folding and amplification. Background Art

[0002] A small-angle generator is a device used to generate precise small angles and is widely applied in fields such as metrology, optical measurement, aerospace, and precision machinery. Its main function is to provide a precise angle reference for various angle measuring instruments to ensure the accuracy and consistency of measurements. There are two mechanisms for small-angle generators. One is to subdivide a full circle, and the other is to define m / m according to the international unit of an angle and utilize the sine theorem to achieve angle generation.

[0003] The I2D-SAG small-angle calibration device developed by the National Metrology Institute of Finland measures the angular direction of a reference plane in space using three heterodyne interferometers. Before measurement, the reference plane is adjusted to be perpendicular to the beam of the interferometer. Then, by using an independent support frame with an air bearing and an electric angular movement, the rotation of the reference plane in the horizontal and vertical directions can be performed, and calibration with a standard uncertainty better than 0.01”≈50 nrad can be achieved within ±1000”. This device can achieve two-dimensional angle calibration with high precision, but the optical path and device are complex. A small-angle generator disclosed in an existing Chinese patent number includes a precision cylindrical rotating shaft, a precision electronic digital display indicator, a mechanical lifting device, a table board, a fastening device, etc. By using the mechanical lifting device, the sine arm is adjusted to rotate around the rotating shaft to achieve the generation of small angles. This small-angle generator has a complex device, high requirements for processing accuracy, and factors such as wear of the lifting device and thermal expansion and contraction of components caused by environmental temperature changes will affect the stability of measurement results.

[0004] Due to the limitations of complex structures and manufacturing processes, traditional small-angle generators often have difficulty achieving high-precision angle generation. Existing high-precision angle generators usually have complex optical paths or devices, requiring complex operation and calibration processes, which increase the time cost and operation difficulty for users. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the existing small-angle generator with a complex structure and difficult measurement and calibration, and provide a high-precision small-angle generating device and method based on optical path folding and amplification, which reduces the complexity of the device, is easy to operate, and improves the stability of measurement.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] Provided is a high-precision small-angle generating device based on optical path folding and amplification, including a laser, a base, a sine arm, a hinge, a detector for detecting the position of a light spot, an actuator for generating a small displacement, and a mirror; one end of the sine arm is rotatably connected to one end of the base through the hinge, the actuator is installed at the other end of the base, the driving end of the actuator contacts the other end of the sine arm, the mirror is installed on the sine arm, and the actuator drives the sine arm to rotate around the rotation center of the hinge, thereby driving the mirror to change its angle; plane reflecting modules are provided on both side walls of the base opposite to the sine arm, a light incident through-hole is opened at one end of the base close to the hinge, and the light spot detector is installed on the base or the sine arm; the laser is located at the light incident through-hole.

[0008] In the working process of the high-precision small-angle generating device based on optical path folding and amplification provided by the present invention, the actuator pushes the sine arm to rotate around the hinge, generating a small angle change. The light emitted by the laser is reflected back and forth multiple times on the reflecting modules between the sine arm and the base, and the detector captures the position of the light spot. By analyzing the displacement of the light spot, multiplying the coefficient by the change in the light spot displacement, the changed angle is obtained, realizing the measurement of the angle, and being able to accurately measure the generated small angle. The present invention can cleverly utilize the principle of multiple reflections of light. Through a simple combination of optical elements, it can amplify the change in the light spot position caused by a small angle change, greatly reducing the requirement for the detection accuracy of the light spot position and significantly lowering the accuracy requirement for the detector; before measuring the angle, coefficient calibration is first performed. When calibrating the coefficient, only the actuator needs to be replaced with standard gauge blocks of different thicknesses, and the position of the light spot is recorded to achieve the calibration of the coefficient. The present invention calibrates the coefficient through gauge blocks, without measuring the incident angle and the number of reflections of the optical path, and the calibration method is simpler, with extremely high repeatability and reliability. The present invention can achieve the measurement of the angle without relying on the accuracy of the actuator, has a low precision limit for the actuator, which makes the device more flexible and adaptable in practical applications, reduces the selection requirements for the actuator, and improves the feasibility of the measurement method.

[0009] Further, the emitted light of the laser penetrates into the space between the base and the sine arm at a certain angle through the light incident through-hole, and after being reflected several times between the reflecting module of the base and the reflecting module of the sine arm, it is detected by the detector. The present invention utilizes the principle of multiple reflections of light, enabling the incident light to be reflected multiple times between the base and the sine arm. Through a simple combination of optical elements, it can amplify the change in the light spot position generated by a small angle change, greatly reducing the requirement for the detection accuracy of the light spot position and significantly lowering the accuracy requirement for the detector.

[0010] Further, the surfaces of the base and the sine arm on which the reflective module is provided are both smooth planes; the reflective module includes a reflective film or a plane mirror. The reflective film can be formed by plating a reflective material on the surfaces of the base and the sine arm to form a thin film, realizing the function of light reflection.

[0011] Further, the hinge is a flexible hinge; the main body of the flexible hinge is a rectangular cube, and two opposite surfaces of the main body of the flexible hinge are respectively provided with grooves, the bottom end surfaces of the grooves are in an arc shape with a radius of R, the distance between the vertices of the two arcs is the flexible thickness d of the flexible hinge, and the central axes of the two arcs are perpendicular to the flexible thickness. The flexible hinge has high precision, good stability, and a simple motion equation, and can be applied to the flip adjustment of a small range of angles. At the same time, it has the advantages of no mechanical backlash, simple structure, and easy fabrication. The flexible hinge adopted by the present invention has a compact structure, is convenient to fabricate, has a simple shape, and has the advantages of a large stiffness range, high precision, and no friction; moreover, the flexible hinge adopting the structure of the present invention can ensure the stability of the rotation center during rotation, thereby improving the accuracy of angle measurement.

[0012] Further, the base, the flexible hinge, and the sine arm are integrally formed. The integrated design of the sine arm, the flexible hinge, and the base reduces the number of disassembly and assembly of parts, reduces the measurement error and the accumulation of errors; the integrated design adopted by the present invention can use fewer parts and a simpler structure, and has higher reliability compared with traditional instruments.

[0013] Further, the base, the flexible hinge, and the sine arm are made of a material with a coefficient of thermal expansion less than 10 -7 / K. Using a material with a low coefficient of thermal expansion or a zero coefficient of thermal expansion can avoid the influence of temperature fluctuations in the environment, enhance the measurement stability of the device, and improve the measurement accuracy.

[0014] Further, the base and the sine arm are arranged in parallel. The parallel arrangement of the base and the sine arm is a preferred embodiment of the present invention, which is convenient for the calibration of the initial coefficient and the installation of each component; the base and the sine arm can also be assembled at a certain angle.

[0015] Further, a spherical protrusion is provided on the sine arm, and the sine arm contacts the actuator through the spherical protrusion. The sine arm adopts a spherical protrusion to contact the actuator, ensuring that there is only one contact point.

[0016] Further, a cylinder protruding toward the base is provided on the sine arm, and the spherical protrusion is provided at the bottom of the cylinder; the cylinder, the spherical protrusion, and the sine arm are integrally formed.

[0017] Further, the mirror is arranged parallel to the rotation axis of the hinge and perpendicular to the sine arm. The mirror is disposed at the top of the sine arm, i.e., on the opposite side of the spherical protrusion. As the sine arm rotates, the mirror rotates coaxially with the sine arm, so that the angle of the mirror changes as the sine arm rotates.

[0018] The present invention also provides a high-precision small-angle generation method based on optical path folding and amplification. Using the high-precision small-angle generation device based on optical path folding and amplification described above, the sine arm is driven by the actuator to rotate a certain angle Δα around the hinge; the laser emits outgoing light, and the outgoing light enters between the base and the sine arm at a certain angle from the light incident through-hole, and is reflected several times between the light-reflecting module of the base and the light-reflecting module of the sine arm, and finally is detected by the detector; the generated angle Δα and the displacement change Δx of the light spot satisfy:

[0019] Δα = kΔx

[0020] In the formula, Δx represents the displacement change of the light spot on the detector when the actuator drives the sine arm to rotate around the hinge, and k represents a coefficient;

[0021] When using the high-precision small-angle generation device based on optical path folding and amplification, the following steps are included:

[0022] Calibrating the coefficient k: Replace the actuator with standard blocks of different models to achieve a height change Δh, and record the displacement change Δx of the light spot. Calculate the value of the coefficient k according to the following formula:

[0023]

[0024] In the formula, Δh represents the height difference between two standard blocks of different models; L represents the distance value between the contact point of the sine arm and the block and the rotation point of the hinge;

[0025] Angle measurement: Reinstall the actuator on the base, and measure the angle Δα generated by the actuator pushing the sine arm to rotate according to the displacement change Δx of the light spot detected by the detector.

[0026] A high-precision small-angle generation method based on optical path folding and amplification provided by the present invention, since it uses the high-precision small-angle generation device based on optical path folding and amplification provided by the present invention, when measuring an angle, first replace the actuator with standard gauge blocks of different sizes, record the displacement change of the light spot, and realize the calibration of the coefficient, avoiding the difficulty of accurately knowing parameters such as the incident angle and the number of reflections of the folded optical path in the traditional method. This calibration method is easy to operate and has extremely high repeatability and reliability. After the coefficient is calibrated, install the actuator again. During measurement, first turn on the laser, let the laser enter from the light incident through-hole at the base, the incident light will travel back and forth between the base and the sine arm, and finally the detector records the position of the light spot; adjust the actuator to make the actuator push the sine arm to rotate around the flexible hinge, so as to realize the generation of the angle, record the position of the changed light spot through the detector, multiply the coefficient by the displacement change of the light spot, and obtain the changed angle to realize the measurement of the angle. The present invention cleverly utilizes the principle of multiple reflections of light, and through a simple combination of optical elements, can amplify the change in the position of the light spot caused by a small angle change, greatly reducing the requirement for the detection accuracy of the light spot position and significantly reducing the accuracy requirement for the detector. The present invention can realize the measurement of the angle without relying on the accuracy of the actuator, has a low precision limit for the actuator, which makes the device more flexible and adaptable in practical applications, reduces the requirement for the selection of the actuator, and improves the feasibility of the measurement method.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The high-precision small-angle generation device and method based on optical path folding and amplification of the present invention cleverly utilize the principle of multiple reflections of light, and through a simple combination of optical elements, can amplify the change in the position of the light spot caused by a small angle change, greatly reducing the requirement for the detection accuracy of the light spot position and significantly reducing the accuracy requirement for the detector;

[0029] 2. The high-precision small-angle generation device and method based on optical path folding and amplification of the present invention can calibrate the amplification factor of the folded optical path for the angle through simple gauge block combination and measurement, avoiding the difficulty of accurately knowing parameters such as the incident angle and the number of reflections of the folded optical path in the traditional method. This calibration method is easy to operate and has extremely high repeatability and reliability;

[0030] 3. The high-precision small-angle generation device and method based on optical path folding and amplification of the present invention can realize the measurement of the angle without relying on the accuracy of the actuator, has a low precision limit for the actuator, which makes the device more flexible and adaptable in practical applications, reduces the requirement for the selection of the actuator, and improves the feasibility of the measurement method;

[0031] 4. The high-precision small-angle generating device and method based on optical path folding and amplification of the present invention adopt an integrated structure of a base, a reed, and a sine arm. Compared with the commonly used high-precision small-angle generators, the complexity of the system is reduced, the measurement operation is simple, and the stability of the measurement results is increased. Description of the Drawings

[0032] Figure 1 It is a schematic structural diagram of the high-precision small-angle generating device based on optical path folding and amplification of the present invention; the arrows in the figure indicate the incident light reflection routes;

[0033] Figure 2 It is a schematic structural diagram of the hinge member of the present invention;

[0034] Figure 3 It is a schematic principle diagram of the angle generating device in the first embodiment;

[0035] Figure 4 It is a schematic principle diagram of the optical path turning back in the first embodiment, and the arrows in the figure indicate the optical path.

[0036] In the drawings: 1. Laser; 2. Base; 3. Sine arm; 4. Hinge member; 5. Detector; 6. Exciter; 7. Reflecting mirror; 8. Light incident through hole; 9. Spherical protrusion; 10. Groove. Detailed Embodiments

[0037] The following further describes the present invention in conjunction with the detailed embodiments. Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as limiting the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, and do not represent the actual size of the product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0038] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0039] Embodiment 1

[0040] This embodiment is an embodiment of a high-precision small-angle generating device based on optical path folding and amplification. As Figure 1As shown, it includes a laser 1, a base 2, a sine arm 3, a hinge 4, a detector 5 for detecting the position of the light spot, an actuator 6 for generating a small displacement, and a mirror 7; one end of the sine arm 3 is rotatably connected to one end of the base 2 through the hinge 4, the actuator 6 is installed at the other end of the base 2, the driving end of the actuator 6 contacts the other end of the sine arm 3, the mirror 7 is installed on the sine arm 3, and the actuator 6 drives the sine arm 3 to rotate around the rotation center of the hinge 4, thereby driving the mirror 7 to change its angle; planar reflective modules are provided on both opposite side walls of the base 2 and the sine arm 3, a light incident through-hole 8 is opened at one end of the base 2 close to the hinge 4, and the light spot detector 5 is installed on the base 2 or the sine arm 3; the laser 1 is located at the light incident through-hole 8.

[0041] In this embodiment, the emitted light of the laser 1 enters between the base 2 and the sine arm 3 at a certain angle through the light incident through-hole 8, and the emitted light is detected by the detector 5 after being reflected several times between the reflective module of the base 2 and the reflective module of the sine arm 3. The present invention utilizes the principle of multiple reflections of light, enables the incident light to be reflected multiple times between the base 2 and the sine arm 3, and through a simple combination of optical elements, can amplify the change in the position of the light spot caused by a small angular change, greatly reducing the requirement for the detection accuracy of the light spot position and significantly reducing the accuracy requirement for the detector 5.

[0042] In this embodiment, the surfaces of the base 2 and the sine arm 3 provided with the reflective modules are both smooth planes; the reflective module includes a reflective film or a plane mirror. The reflective film can be formed by plating a reflective material on the surfaces of the base 2 and the sine arm 3 to form a thin film to achieve the function of light reflection.

[0043] In this embodiment, as Figure 2 shown, the hinge 4 is a flexible hinge; the main body of the flexible hinge is a rectangular cube, grooves 10 are respectively formed on two opposite surfaces of the main body of the flexible hinge, the bottom end surface of the groove 10 is in an arc shape with a radius of R, the distance between the vertices of the two arcs is the flexible thickness d of the flexible hinge, and the central axes of the two arcs are perpendicular to the flexible thickness. The flexible hinge has high precision, good stability, and a simple motion equation, can be applied to the flipping adjustment of a small range of angles, and has the advantages of no mechanical backlash, simple structure, and easy manufacturing. The flexible hinge structure adopted by the present invention is compact, easy to manufacture, simple in shape, and has the advantages of a large stiffness range, high precision, and no friction; moreover, the flexible hinge adopting this structure of the present invention can ensure the stability of the rotation center during rotation, thereby improving the accuracy of angle measurement.

[0044] In this embodiment, the base 2, the flexible hinge, and the sine arm 3 are integrally formed. The integrated design of the sine arm 3, the flexible hinge, and the base 2 reduces the number of disassembly and assembly of components, and reduces the measurement error and the accumulation of errors; the integrated design of the present invention can use fewer components and a simpler structure, and has higher reliability compared with traditional instruments.

[0045] In this embodiment, the base 2, the flexible hinge, and the sine arm 3 are made of a material with a coefficient of thermal expansion less than 10 -7 / K. Using a material with a low coefficient of thermal expansion or a zero coefficient of thermal expansion can avoid the influence of temperature fluctuations in the environment, enhance the measurement stability of the device, and improve the measurement accuracy.

[0046] In this embodiment, the base 2 is arranged parallel to the sine arm 3. The parallel arrangement of the base 2 and the sine arm 3 is the preferred embodiment of the present invention, which is convenient for the calibration of the initial coefficient and the installation of each component; the base 2 and the sine arm 3 can also be assembled at a certain angle.

[0047] In this embodiment, a spherical protrusion 9 is provided on the sine arm 3, and the sine arm 3 contacts the actuator 6 through the spherical protrusion 9. The sine arm 3 uses the spherical protrusion 9 to contact the actuator 6 to ensure that there is only one contact point. A column protruding toward the base 2 is provided on the sine arm 3, and the spherical protrusion 9 is provided at the bottom of the column; the column, the spherical protrusion 9, and the sine arm 3 are integrally formed.

[0048] In this embodiment, the mirror 7 is arranged parallel to the rotation axis of the hinge 4 and perpendicular to the sine arm 3. The mirror 7 is arranged at the top of the sine arm 3, that is, on the opposite side of the spherical protrusion 9. When the sine arm 3 rotates, the mirror 7 rotates coaxially with the sine arm 3, so that the angle of the mirror 7 changes with the rotation of the sine arm 3.

[0049] Working principle:

[0050] As Figure 3 shown, point O is the rotation point, |OB| is the length of the sine arm (in this embodiment, it is actually the distance value between the contact point of the sine arm and the gauge block and the rotation point of the hinge), |AB| is the height of the sine arm from the reference plane. According to the sine theorem, we can get:

[0051]

[0052] According to the arcsine operation, the angle α generated by the small angle generator is:

[0053]

[0054] In the actual use scenario of the high-precision small angle generator, the generated angle α is generally very small. Therefore, formula (2) can be simplified as:

[0055]

[0056] Changing the height h can achieve the generation of a small angle. In this process, the length L needs to be kept stable, so as to achieve the precise generation of a small angle.

[0057] The schematic diagram of the optical path folding and amplification technology is as Figure 4 shown. The distance from the incident point C to the rotation axis O is |OC|, and the distance from the spot position D to the rotation axis O is |OD|. The angle between the incident light and the bottom surface is θ, and the angle between the light ray shooting towards point D and the bottom surface detector plane is The angle between the bottom surface and the upper reflecting mirror is α, and n is the total number of spots on the upper and lower surfaces. According to the geometric relationship, it can be calculated that:

[0058]

[0059] where n represents the number of reflections on the lower bottom surface. In the case of a small angle, it can be approximated as:

[0060]

[0061] When changing within a small range, the relationship between the angle change Δα and the spot displacement change Δx is:

[0062]

[0063] Through formula (6), the measurement of the angle change can be realized by converting it into the measurement of the spot position.

[0064] According to formula (6), it can be known that when changing within a small angle range, the generated angle Δα and the spot displacement change Δx satisfy:

[0065] Δα = kΔx (7)

[0066] According to formula (7), when using the device provided in this embodiment, in order to avoid accurately measuring parameters such as the number of reflections, the optical path length, and the incident angle, only the coefficient k needs to be calibrated first, and then the measurement of the angle transformation can be realized by converting it into the measurement of the spot position change.

[0067] According to the calculation, when the laser incident position is determined, n < 300, and Δα is a small angle, k is basically a constant. Therefore, k can be calibrated. The calibration method is as follows. Replace the actuator 6 with a standard gauge block, change the gauge blocks with different thicknesses to achieve the height change Δh, measure the length L between the contact point of the sine arm and the gauge block and the rotation point of the hinge, record the spot displacement change Δx, and according to formula (3) and formula (7), it can be obtained that:

[0068]

[0069] According to formula (8), the calibrated coefficient k is obtained. Then, after the actuator 6 is installed, the angle measurement generated by the actuator 6 pushing the sine arm 3 can be realized according to the spot displacement Δx of the detector.

[0070] A high-precision small-angle generating device based on optical path folding and amplification provided by this embodiment, during the working process, the actuator 6 pushes the sine arm 3 to rotate around the hinge 4, generating a small angle change. The light emitted by the laser 1 is reflected back and forth multiple times on the reflective module between the sine arm 3 and the base 2. The position of the spot is captured by the detector 5. By analyzing the displacement of the spot, multiplying the coefficient by the change in the spot displacement, the changed angle is obtained, realizing the angle measurement, and being able to accurately measure the generated small angle. The present invention can cleverly utilize the principle of multiple reflections of light. Through a simple combination of optical elements, it can amplify the change in the spot position caused by a small angle change, greatly reducing the requirement for the detection accuracy of the spot position and significantly lowering the accuracy requirement for the detector 5; before measuring the angle, coefficient calibration is first performed. When calibrating the coefficient, only the actuator 6 needs to be replaced with standard blocks of different thicknesses, and the position of the spot is recorded to achieve coefficient calibration. The present invention calibrates the coefficient through the gauge block, without measuring the incident angle and the number of reflections of the optical path. The calibration method is simpler and has extremely high repeatability and reliability. The present invention can realize the measurement of the angle without depending on the accuracy of the actuator 6, with a lower accuracy limit for the actuator 6, which makes the device more flexible and adaptable in practical applications, reduces the selection requirements for the actuator 6, and improves the feasibility of the measurement method.

[0071] Embodiment 2

[0072] This embodiment is the first embodiment of a high-precision small-angle generating method based on optical path folding and amplification. This embodiment uses the high-precision small-angle generating device based on optical path folding and amplification provided by Embodiment 1. The actuator 6 drives the sine arm 3 to rotate a certain angle around the hinge 4; the laser 1 emits an outgoing light, and the outgoing light enters between the base 2 and the sine arm 3 at a certain angle from the light incident through-hole 8 and is reflected several times between the reflective module of the base 2 and the reflective module of the sine arm 3, and finally is detected by the detector 5; the generated angle Δα and the change in the spot displacement Δx satisfy:

[0073] Δα = kΔx

[0074] In the formula, Δx represents the change in the spot displacement on the detector 5 when the actuator 6 drives the sine arm 3 to rotate around the hinge 4; k represents the coefficient;

[0075] When using the high-precision small-angle generating device based on optical path folding and amplification, it includes the following steps:

[0076] Calibration coefficient k: Replace the actuator 6 with standard blocks of different models to achieve a height change Δh, and record the displacement change Δx of the light spot. Calculate the value of the coefficient k according to the following formula:

[0077]

[0078] In the formula, Δh represents the height difference between two different models; L represents the distance value between the contact point of the sine arm 3 and the measuring block and the rotation point of the hinge 4, that is Figure 3 the length value of |OB| in

[0079] Angle measurement: Reinstall the actuator on the base. According to the displacement change Δx of the light spot detected by the detector, measure the angle Δα generated by the actuator pushing the sine arm to rotate.

[0080] The working principle of this embodiment is similar to that of the first embodiment and will not be elaborated here.

[0081] A high-precision small-angle generation method based on optical path folding and amplification provided by this embodiment. Since the high-precision small-angle generation device based on optical path folding and amplification provided by the present invention is adopted, during angle measurement, first replace the actuator 6 with standard blocks of different sizes, record the displacement change of the light spot, and realize the calibration of the coefficient, avoiding the difficulties of accurately knowing parameters such as the incident angle and the number of reflections of the folded optical path in the traditional method. This calibration method is simple to operate and has extremely high repeatability and reliability. After the coefficient is calibrated, reinstall the actuator 6. During measurement, first turn on the laser 1, and let the laser enter through the light incident through-hole 8 of the base 2. The incident light will travel back and forth between the base 2 and the sine arm 3, and finally the detector 5 records the position of the light spot; adjust the actuator 6 to make the actuator 6 push the sine arm 3 to rotate around the rotation point of the flexible hinge, so as to generate an angle. Record the changed position of the light spot through the detector 5, multiply the coefficient by the displacement change of the light spot, and obtain the changed angle to realize angle measurement. The present invention ingeniously utilizes the principle of multiple reflections of light, and through simple combinations of optical elements, can amplify the position change of the light spot generated by tiny angle changes, greatly reducing the requirement for the detection accuracy of the light spot position and significantly reducing the accuracy requirement for the detector 5. The present invention can realize angle measurement without relying on the accuracy of the actuator 6, has a low accuracy limit for the actuator 6, which makes the device more flexible and adaptable in practical applications, reduces the selection requirements for the actuator 6, and improves the feasibility of the measurement method.

[0082] Embodiment Three

[0083] This embodiment is the second embodiment of the high-precision small-angle generation method based on optical path folding and amplification. This embodiment is similar to Embodiment 2. In this embodiment, it is assumed that the angle to be changed is Δα = 1000 μrad. It is assumed that the distance value L from the contact point of the sine arm 3 with the gauge block to the rotation point of the hinge 4 is 400.0 mm. Then the height difference Δh between the front and rear gauge blocks needs to be 400 μm. The standard uncertainty of a typical high-precision gauge block is 0.02 μm, and the uncertainty of the introduced angle change Δα is 0.05 μrad. Taking the uncertainty of L as 0.2 mm, the uncertainty of the introduced angle change Δα is 0.5 μrad. At this time, the error introduced by the gauge block can be ignored compared with the error introduced by the length L. Through reasonable design, the spot displacement Δx = 5 mm on the detector 5 can be realized. The position-sensitive detector 5 (PSD) is used to detect the spot position. The typical detection accuracy of the position-sensitive detector 5 is 1.0 μm, so the calibration coefficient k = 0.2 rad / m can be obtained, and the corresponding standard uncertainty is 100 μrad / m. After replacing the gauge block with the actuator 6 and measuring the spot displacement, substituting it into Formula (7) in Embodiment 1 can realize the measurement of small-angle changes with an uncertainty better than 0.05 μrad within 100 μrad and the measurement of small-angle changes with an uncertainty better than 0.5 μrad within 1000 μrad. According to different requirements for angle measurement, gauge blocks can be used for calibration in different ranges to meet the measurement requirements.

[0084] In the specific content of the above specific implementation manner, each technical feature can be combined arbitrarily without contradiction. For the sake of concise description, not all possible combinations of the above technical features are described. However, as long as the combinations of these technical features do not exist in contradiction, they should be considered as the scope described in this specification.

[0085] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A high-precision small-angle generating device based on optical path folding and amplification, characterized in that It includes a laser (1), a base (2), a sine arm (3), a hinge (4), a detector (5) for detecting the position of the light spot, an actuator (6) for generating a small displacement, and a mirror (7); one end of the sine arm (3) is rotatably connected to one end of the base (2) through the hinge (4), the actuator (6) is installed at the other end of the base (2), the driving end of the actuator (6) contacts the other end of the sine arm (3), the mirror (7) is installed on the sine arm (3), and the actuator (6) drives the sine arm (3) to rotate around the rotation center of the hinge (4), thereby driving the mirror (7) to change its angle; planar reflective modules are provided on both side walls of the base (2) opposite to the sine arm (3), a light incident through-hole (8) is opened at one end of the base (2) close to the hinge (4), and the detector (5) is installed on the base (2) or the sine arm (3); the laser (1) is located at the light incident through-hole (8).

2. The high-precision small-angle generating device based on optical path folding and amplification according to claim 1, wherein The emitted light of the laser (1) penetrates into the space between the base (2) and the sine arm (3) at a certain angle from the light incident through-hole (8), and after being reflected several times between the reflective module of the base (2) and the reflective module of the sine arm (3), the emitted light is detected by the detector (5).

3. The high-precision small-angle generating device based on optical path folding and amplification according to claim 2, wherein, The surfaces of the base (2) and the sine arm (3) provided with the reflective modules are both smooth planes; the reflective module includes a reflective film or a plane mirror.

4. The high-precision small-angle generating device based on optical path folding and amplification according to claim 2, characterized in that, The hinge (4) is a flexible hinge; the main body of the flexible hinge is a rectangular cube, grooves (10) are respectively made on two opposite surfaces of the main body of the flexible hinge, the bottom surface of the groove (10) is in an arc shape with a radius of R, the distance between the vertices of the two arcs is the flexible thickness d of the flexible hinge, and the central axes of the two arcs are perpendicular to the flexible thickness.

5. The high-precision small-angle generating device based on optical path folding and amplification according to claim 4, characterized in that, The base (2), the flexible hinge, and the sine arm (3) are integrally formed.

6. The high-precision small-angle generating device based on optical path folding and amplification according to claim 4, characterized in that The base (2), the flexible hinge, and the sine arm (3) are made of a material with a coefficient of thermal expansion less than 10 -7 / K.

7. The high-precision small-angle generating device based on optical path folding and amplification according to claim 4, characterized in that The base (2) and the sine arm (3) are arranged in parallel.

8. The high-precision small-angle generating device based on optical path folding and amplification according to any one of claims 1 to 7, characterized in that A spherical protrusion (9) is provided on the sine arm (3), and the sine arm (3) contacts the actuator (6) through the spherical protrusion (9).

9. The high-precision small-angle generating device based on optical path folding and amplification according to any one of claims 1 to 7, characterized in that The mirror (7) is arranged parallel to the rotation axis of the hinge (4) and perpendicular to the sine arm (3).

10. A high-precision small-angle generation method based on optical path folding and amplification, characterized in that, When using the high-precision small-angle generating device based on optical path folding and amplification according to any one of claims 1 to 9, the actuator (6) is used to drive the sine arm (3) to rotate a certain angle Δα around the hinge (4); the laser (1) is used to emit emitted light, the emitted light penetrates into the space between the base (2) and the sine arm (3) at a certain angle from the light incident through-hole (8), and is reflected several times between the reflective module of the base (2) and the reflective module of the sine arm (3), and finally is detected by the detector (5); the generated angle Δα and the displacement change Δx of the light spot satisfy: Δα = kΔx Wherein, Δx represents the displacement change of the light spot on the detector (5) when the exciter (6) drives the sine arm (3) to rotate around the hinge (4), and k represents the coefficient; When using a high-precision small-angle generating device based on optical path folding and amplification, the following steps are included: Calibrating the coefficient k: Replace the exciter (6) with standard blocks of different models to achieve the height change Δh, and record the displacement change Δx of the light spot. Calculate the value of the coefficient k according to the following formula: Wherein, Δh represents the height difference between two standard blocks of different models; L represents the distance value between the contact point of the sine arm (3) and the block and the rotation point of the hinge (4); Angle measurement: Reinstall the exciter (6) on the base (2). According to the displacement change Δx of the light spot detected by the detector (5), measure the angle Δα generated by the exciter (6) pushing the sine arm (3) to rotate.

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