An angle measurement system and method based on double whispering gallery microcavity structure

Abstract

The application relates to an angle measurement system and method based on a double echo-wall micro-cavity structure, wherein the system comprises a tunable laser, a polarization controller, a tapered fiber waveguide, crystal cavities, an angle displacement device, interference probes, rotating probes, a photodetector and a computer; the crystal cavities are located at the thinnest position of the tapered fiber waveguide and are used for coupling light waves into the crystal cavities; the crystal cavities are two, the standing wave mode numbers formed in the two crystal cavities are the same, and the standing wave nodes in the two crystal cavities are arranged in a staggered mode; each crystal cavity corresponds to an interference probe, a rotating probe and a tapered optical fiber; the axes of the two interference probes are not parallel; and the axes of the two rotating probes are parallel. The scheme can form stable standing waves in the double crystal cavities, realize angle sensing when the micro-cavity rotates, and solve the problem that the output spectrum cannot determine the angle turning due to the circumferential periodic distribution of the single micro-cavity standing wave mode field in the single-cavity evanescent wave coupling structure.

Description

Technical Field

[0001] The present invention relates to the field of optical sensing technology, and in particular to an angle measurement system and method based on a double-whispering gallery microcavity structure. Background Art

[0002] Angular displacement sensors are devices used to measure the angular changes of an object or system, and are typically used to monitor and control the angular information of rotating or pivoting objects. Existing, relatively mature and widely used angular displacement sensing devices include optical gratings, magnetic gratings, and capacitive gratings. These offer advantages such as high precision, high resolution, wide measurement range, ease of maintenance, and reliability, making them widely used in fields such as photoelectric theodolites, aerospace equipment, and CNC machine tools. While they can meet the measurement needs of many current high-precision applications, they also have certain limitations. For example, the measurement accuracy of traditional angular displacement measuring devices is limited by their size. High-precision angular displacement sensors are generally relatively large, making them difficult to miniaturize.

[0003] An optical whispering gallery microcavity is an optical system that can confine a light field to a very small spatial area. This confined light field typically has a high light energy density and a specific light field distribution. In optics, microcavities can be used to enhance the intensity of the interaction between light and matter, and are also commonly used to achieve miniature, high-sensitivity position information sensing. Attaching nanoparticles to the surface of an ordinary evanescent-wave-coupled microcavity can induce mode splitting of the field mode within the cavity, forming a stable standing wave mode field. Furthermore, by adding an interfering probe outside the standing wave field, the standing wave field distribution of the microcavity is disturbed, causing the output light signal to change as the probe rotates and interferes. Angular displacement sensing can also be achieved by analyzing the changing characteristics of the light signal.

[0004] However, in the evanescent wave coupling mode of the probe, since the formed mode field is periodically distributed in the circumferential direction of the microcavity, it is impossible to distinguish the direction of the microcavity by relying solely on a single signal. In the angle measurement of the direction change, it is impossible to accurately measure the angle change of the object and effectively distinguish the rotation direction. Summary of the Invention

[0005] To address the problem in existing solutions where the single-cavity evanescent wave coupling method of the probe is unable to effectively measure the angular changes of an object or effectively determine the direction of rotation, the present invention provides an angle measurement system and method based on a double-whispering gallery microcavity structure. This solution utilizes a double-whispering gallery mode to effectively measure the angular changes of an object and effectively determine the direction of rotation.

[0006] The technical scheme adopted by the present application is: an angle measurement system based on a double echo-wall microcavity structure, comprising a tunable laser, a polarization controller, a tapered fiber waveguide, a crystal cavity, an angular displacement device, an interference probe, a rotating probe, a photodetector, and a computer, the tunable laser, the polarization controller, the tapered fiber waveguide, the photodetector, and the computer are electrically connected in sequence, the crystal cavity is located at the thinnest position of the tapered fiber waveguide to couple the light wave in the tapered fiber waveguide into the crystal cavity, the crystal cavity and the interference probe are fixedly connected with the fixed end of the angular displacement device, and the rotating probe is fixedly connected with the rotating end of the angular displacement device. The crystal cavity has two, and the light waves in the two crystal cavities form standing wave mode electric fields with the same number of standing wave modes and mutually staggered arrangement of standing wave nodes, each crystal cavity has one interference probe, one rotating probe, and one tapered optical fiber corresponding thereto, the axes of the two interference probes are not parallel, and the axes of the two rotating probes are parallel.

[0007] The tunable laser generates light waves with adjustable wavelength and inputs them into the optical fiber, the polarization controller adjusts the polarization state of the light waves and sends them into the tapered fiber waveguide, the tapered fiber waveguide is close to the crystal cavity, the light waves are coupled into the crystal cavity through the tapered fiber waveguide and are bound in the crystal cavity, the crystal cavity binds the light waves input from the tapered fiber waveguide to enable them to form stable echo-wall modes in the crystal cavity. The angular displacement device is used to fix the position of the crystal cavity and adjust the relative angular position of the two rotating probes and the two crystal cavities, so that the two rotating probes can produce angular rotation with respect to the two crystal cavities. The two interference probes are used to interfere with the traveling wave mode electric field in the two crystal cavities, so that the light waves entering the crystal cavity will split due to the interference of the interference probe, and stable standing wave mode electric fields are formed in the crystal cavity. The photodetector is used to convert the received optical signal into an electrical signal and input it into the computer, the computer processes the electrical signal data to obtain a function curve of the effective reflectivity changing with the angle, and according to the curve, the rotation direction of the object can be judged and the angular change of the object can be measured.

[0008] The application adopts the double-probe of interference probe and rotating probe to interfere with the crystal cavity, so as to ensure the phase stability of the standing wave field in the crystal cavity when the rotating probe deflects. Meanwhile, two sets of coupling systems are adopted, the interference probes in the two sets of coupling systems are distributed in a staggered manner, and the axes of the rotating probes are parallel, so that the output end can collect two different sets of output data at the same time when the crystal cavity rotates. Since the standing wave nodes in the crystal cavity are uniformly distributed in the circumferential direction, when the rotating probe rotates along the circumferential direction of the crystal cavity, the interaction between the rotating probe and the standing wave in the crystal cavity changes, and the data of the output port changes. According to the output data of a single group, the corresponding change of the microcavity angle and the output data can be realized. When the two rotating probes deflect together, the interaction between them and the corresponding standing wave in the crystal cavity changes. Since the standing wave nodes in the two crystal cavities are distributed in a staggered manner, two different sets of output data can be obtained at the output port. By processing and analyzing the two sets of output spectra, the angle sensing of the microcavity can be realized. By comprehensively utilizing the single-group data and the double-group data for analysis, the angle measurement based on the double-back acoustic wall microcavity structure can be realized.

[0009] The scheme can form stable standing waves in the double crystal cavities, realize angle sensing when the microcavity angle rotates, and solve the problem that the output spectrum cannot determine the angle turning due to the periodic distribution of the single microcavity standing wave mode field in the single-cavity evanescent wave coupling structure. Moreover, the core component of the scheme, the double crystal cavity, has a small volume, is simple to manufacture, and is low in cost, and is suitable for microstructure measurement occasions.

[0010] Preferably, the fixed rod is fixedly connected with the fixed end of the angle displacement device, and the two crystal cavities are fixedly connected with the fixed rod and linearly arranged along the axis direction of the fixed rod. The two crystal cavities are fixed on the angle displacement device through the fixed rod. The fixed rod can be a silica rod, and the silica rod has stable shape. The silica rod can be obtained by using carbon dioxide laser and physical grinding on the uniform silica rod. The double crystal cavities can be manufactured on the same silica rod, so that the influence of the coaxiality deviation caused by assembly can be reduced to a certain extent. The sizes of the double crystal cavities can be inconsistent, and the wavelengths of the input light waves can be adjusted respectively to make the standing wave mode numbers in the two crystal cavities consistent.

[0011] Preferably, the device further comprises a rotating probe mounting frame and an interference probe mounting frame, wherein the two rotating probes are fixedly connected to the rotating probe mounting frame, the line connecting the two rotating probes on the rotating probe mounting frame is parallel to the vertical direction, the bottom of the rotating probe mounting frame is fixedly connected to the rotating end of the angular displacement device, and the rotating probes are fixedly connected to the rotating end of the angular displacement device via the rotating probe mounting frame; the two interference probes are fixedly connected to the interference probe mounting frame, the bottom of the interference probe mounting frame is fixedly connected to the fixed end of the angular displacement device, and the interference probes are fixedly connected to the fixed end of the angular displacement device via the interference probe mounting frame. The two rotating probes are fixed to the rotating end of the angular displacement device via the rotating probe mounting frame, and the two interference probes are fixed to the fixed end of the angular displacement device via the interference probe mounting frame.

[0012] Preferably, the minimum distance between the tapered optical fiber waveguide and the crystal cavity is 0.2μm-0.4μm. The radius of the crystal cavity is greater than 2mm. The computer is also electrically connected to the tunable laser to control the tunable laser to emit laser light. The tapered optical fiber waveguide is at a distance from the crystal cavity rather than abutting it. This setting is to minimize coupling loss as much as possible, avoid the occurrence of over-coupling and under-coupling, and enhance the stability of the standing wave. Experiments have shown that when the minimum distance between the crystal cavity and the tapered optical fiber waveguide is 0.2μm-0.4μm, the evanescent wave coupling efficiency between the tapered optical fiber and the crystal cavity can be guaranteed to a certain extent, and a better coupling effect can be obtained. The minimum distance is preferably 0.3μm. The radius of the crystal cavity can be determined according to actual needs and is not limited. As the radius of the crystal cavity increases, the number of angular modes in the crystal cavity is expanded, and the resolution of the measurement results is improved. The computer is electrically connected to the tunable laser and can also control the laser wavelength generated by the tunable laser through the computer.

[0013] An angle measurement method based on a double-whispering gallery microcavity structure includes the following steps:

[0014] S1. Laser light emitted from a tunable laser is fed into two tapered fiber waveguides after being controlled by a polarization controller. After the light waves in the tapered fiber waveguides are coupled into the silica rods in the dual-crystal cavity, the light waves in the two crystal cavities, under the interference of two interfering probes with different axes, form stable standing waves with phase deviations but the same mode number. The rotating probes interact with the standing wave field in the crystal cavity, thereby affecting the signal output of the light field. The light wave signals generated at the output ends of the two tapered fiber waveguides are collected, converted into electrical signals by a photodetector, and sent to a computer for processing.

[0015] S2. When the rotating end of the angular displacement device rotates, the two rotating probes rotate accordingly and their angles change relative to the standing wave field in the crystal cavity. This changes the interaction between the rotating probes and the standing wave in the crystal cavity. Signals from the output ends of the two tapered fiber waveguides at different rotating probe angles are collected and processed.

[0016] S3. By processing and comparing the signal data from the output ends of the two tapered fiber waveguides, angle sensing based on the double whispering gallery microcavity can be realized.

[0017] This method sets two interference probes to interfere with the evanescent wave coupled dual crystal cavity, so that stable standing waves with phase deviation but the same mode number are formed in the two crystal cavities. Then, a rotating probe is used to perform rotational interference on the two standing wave fields. By collecting the output signal of the tapered optical fiber waveguide and processing and analyzing it in combination with the angle change, the rotation direction of the microcavity and angle sensing are realized. By adjusting the frequency of the input light wave, high-resolution angle measurement can be achieved.

[0018] Preferably, in S2, every time the two rotating probes rotate one angle, the light wave signals collected by the output ends of the two tapered optical fiber waveguides will change, and the light wave signals will show periodic changes with the standing wave phase angle. After the rotating probes rotate n angles, the output ends of the two tapered optical fiber waveguides will be able to collect n light wave signal change information respectively.

[0019] Preferably, in S3, the periodically changing standing wave phase angle data is processed to obtain a function curve of effective reflectivity changing with angle, wherein a plurality of small intervals are provided within one angular period of the function curve, and the function within each small interval changes monotonically.

[0020] Compared with the prior art, the beneficial effect of the present invention lies in that: this scheme interferes with the evanescent wave coupled dual crystal cavity by setting two interference probes, so that stable standing waves with phase deviation but the same mode number are formed in the two crystal cavities respectively, and then the two standing wave fields are subjected to rotational interference by using a rotating probe. By collecting the output signal of the tapered optical fiber waveguide and processing and analyzing it in combination with the angle change, the rotation direction of the microcavity and angle sensing are realized. By adjusting the frequency of the input light wave, high-resolution angle measurement can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of an angle measurement system based on a double whispering gallery microcavity structure according to the present invention;

[0022] Figure 2 It is a schematic diagram of the working state of the tapered optical fiber waveguide, crystal cavity, interference probe and rotation probe in the light wave coupling state of the present invention;

[0023] Figure 3 This is a schematic diagram of the working state of the rotating probe when it rotates along the circumference of the crystal cavity after the waveguide coupling forms a standing wave in the present invention;

[0024] Figure 4 This is a flow chart of an angle measurement method based on a double whispering gallery microcavity structure according to the present invention;

[0025] Figure 5 is a curve chart of the effective reflectivity of the two rotating probes of the present application along the two crystal cavities respectively, and the reflectivity of the two tapered fiber waveguides output changes with the angle of the rotating probe;

[0026] Figure 6 is a curve chart of the angle position of the two rotating probes of the present application and the effective reflectivity in a single periodic interval in Figure 4 . DETAILED DESCRIPTION

[0027] The drawings are only used for illustrative description, and cannot be understood as a limitation of the present patent; in order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the actual product size; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationship described in the drawings is only used for illustrative description, and cannot be understood as a limitation of the present patent.

[0028] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar parts; in the description of the present application, it is understood that if the terms "upper", "lower", "left", "right", "long", "short" and the like indicate the orientation or positional relationship shown in the drawings, they are only used for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for illustrative description, and cannot be understood as a limitation of the present patent, and for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0029] The technical solutions of the present application will be further described in detail below through specific embodiments, and in conjunction with the drawings:

[0030] Embodiment 1

[0031] An angle measurement system based on a double echo wall microcavity structure, as shown in Figure 1-Figure 3As shown, it includes a tunable laser 1 capable of generating a tunable laser with a wavelength of approximately 1550 nm and a linewidth of 300 kHz, a polarization controller 2, a tapered optical fiber waveguide with a thin end diameter of 0.2 μm, a crystal cavity with a diameter of 6 μm, an angular displacement device 8, an interference probe, a rotation probe, a photodetector 13, and a computer 14. The tunable laser 1, the polarization controller 2, the tapered optical fiber waveguide, the photodetector 13, and the computer 14 are electrically connected in sequence. The crystal cavity is located at the thinnest position on the tapered optical fiber waveguide to couple the light wave in the tapered optical fiber waveguide into the crystal cavity. The crystal cavity and the interference probe are fixedly connected to the fixed end of the angular displacement device 8, and the rotation probe is fixedly connected to the rotating end of the angular displacement device 8. There are two tapered fiber waveguides, two crystal cavities, two interference probes, and two rotating probes. The first tapered fiber waveguide 3 is coupled to the first crystal cavity 5, and the first rotating probe 10 and the first interference probe 9 both interfere with the first crystal cavity 5. The second tapered fiber waveguide 4 is coupled to the second crystal cavity 6, and the second rotating probe 12 and the second interference probe 11 both interfere with the second crystal cavity 6. A standing wave mode electric field is formed in the two crystal cavities, with the same number of standing wave modes and standing wave nodes arranged in a staggered manner. When the interference probe does not change, the standing wave nodes in the cavity do not shift. The number of standing wave nodes is related to the radius of the crystal cavity and the corresponding mode resonance wavelength. The angle between each two standing wave nodes is defined as a standing wave phase angle. The relative deviation angle between the first interference probe 9 and the second interference probe 11 is 1 / 4 of the standing wave phase angle.

[0032] The working principle or working process of this embodiment: The present application uses a dual-probe interference probe and a rotating probe to interfere with the crystal cavity, ensuring the phase stability of the standing wave field in the crystal cavity when the rotating probe is deflected. At the same time, two sets of coupling systems are used, and the first interference probe 9 and the second interference probe 11 in the two sets of coupling systems are staggered. The axes of the first rotating probe 10 and the second rotating probe 12 are parallel, so that when the first crystal cavity 5 and the second crystal cavity 6 rotate, the output end can simultaneously collect two sets of different output data. Since the standing wave nodes in the first crystal cavity 5 and the second crystal cavity 6 are uniformly distributed along the circumference, when the first rotating probe 10 and the second rotating probe 12 rotate along the circumference of the microcavity, the interaction between the first rotating probe 10 and the standing wave in the first crystal cavity 5 and the interaction between the second rotating probe 12 and the standing wave in the second crystal cavity 6 change, and the data at the corresponding output port changes. The two sets of output spectra are processed and analyzed to realize the angle sensing of the microcavity. By comprehensively utilizing the single set of data and the double set of data for analysis, angle measurement based on the double echo gallery microcavity structure can be realized.

[0033] The tunable laser generated by the tunable laser 1 is input into the optical fiber. The polarization controller 2 adjusts the polarization state of the light wave and sends the light wave into the first tapered optical fiber waveguide 3 and the second tapered optical fiber waveguide 4. The light wave entering the first tapered optical fiber waveguide 3 is coupled into the first crystal cavity 5 and is confined within the first crystal cavity 5. The first crystal cavity 5 confines the light wave input from the first tapered optical fiber waveguide 3 so that it can form a stable whispering gallery mode within the first crystal cavity 5. The first interference probe 9 interferes with the traveling wave mode electric field within the first crystal cavity 5, causing the light wave to undergo mode splitting after entering the first crystal cavity 5 due to the interference of the first interference probe 9, forming a stable standing wave mode electric field within the first crystal cavity 5. Figure 2 Similarly, the light wave coupled from the second tapered optical fiber waveguide 4 into the second crystal cavity 6 forms a stable standing wave mode electric field in the second crystal cavity 6 under the interference of the second interference probe 11, as shown in FIG. Figure 2 As shown in b.

[0034] The rotating part of the angular displacement device 8 starts to work, and the first rotating probe 10 on the rotating part produces an angular rotation with respect to the first crystal cavity 5. The first rotating probe 10 interacts with the standing wave field in the first crystal cavity 5, as shown in FIG. Figure 3 As shown in c in the figure, the optical signal in the first crystal cavity 5 changes periodically. Similarly, when the second rotating probe 12 rotates, it interacts with the standing wave field in the second crystal cavity 6, as shown in FIG. Figure 3 As shown in d in the figure, the optical signal in the second crystal cavity 6 changes periodically. The photodetector 13 converts the optical signals received from the first and second crystal cavities 5 and 6 into electrical signals and inputs them into the computer 14. The computer 14 processes the electrical signal data to obtain a function curve of the effective reflectivity changing with angle. Based on this curve, the rotation direction of the object can be determined and the angular change of the object can be measured.

[0035] The beneficial effects of this embodiment are as follows: This solution can form a stable standing wave within the dual-crystal cavity, enabling angle sensing during microcavity rotation. This solves the problem in single-cavity evanescent wave coupling structures where the output spectrum cannot determine angular rotation due to the circumferential periodicity of the single microcavity standing wave mode field. Furthermore, the dual-crystal cavity, the core component of this solution, is small, simple to manufacture, and low-cost, making it suitable for microstructure measurement applications.

[0036] Example 2

[0037] Embodiment 2 of an angle measurement system based on a double whispering gallery microcavity structure, as Figure 1 As shown, based on Example 1, the structure of the system is further limited.

[0038] Specifically, the device further includes a fixed rod 7, which is fixedly connected to the fixed end of the angular displacement device 8. The first crystal cavity 5 and the second crystal cavity 6 are both fixedly connected to the fixed rod 7 and arranged linearly along the axis of the fixed rod 7. The fixed rod 7 can be a silicon oxide rod. The silicon oxide rod is obtained by using a carbon dioxide laser, physical grinding, or the like to uniformly form the silicon oxide rod.

[0039] Specifically, it also includes a rotating probe mounting frame 15 and an interference probe mounting frame 16. The first rotating probe 10 and the second rotating probe 12 are both fixedly connected to the rotating probe mounting frame 15. The connecting line of the first rotating probe 10 and the second rotating probe 12 on the rotating probe mounting frame 15 is parallel to the vertical direction. The bottom of the rotating probe mounting frame 15 is fixedly connected to the rotating end of the angular displacement device 8, and the two rotating probes are fixedly connected to the rotating end of the angular displacement device 8 through the rotating probe mounting frame 15; the first interference probe 9 and the second interference probe 11 are both fixedly connected to the interference probe mounting frame 16. The bottom of the interference probe mounting frame 16 is fixedly connected to the fixed end of the angular displacement device 8, and the two interference probes are fixedly connected to the fixed end of the angular displacement device 8 through the interference probe mounting frame 16.

[0040] Specifically, the minimum distance between the tapered optical fiber waveguide and the crystal cavity is 0.3 μm. The computer 14 is also electrically connected to the tunable laser 1 to control the tunable laser 1 to emit laser light.

[0041] The beneficial effects of this embodiment include: the first and second crystal cavities 5 and 6 are secured to the angular displacement device 8 via a silica rod. The silica shape is stable, and the first and second crystal cavities 5 and 6 can be fabricated on the same silica rod, which can somewhat reduce the impact of coaxiality deviation caused by assembly. The first and second crystal cavities 5 and 6 can be sized differently; the wavelengths of the input light waves can subsequently be adjusted to ensure the same number of standing wave modes formed within the first and second crystal cavities 5 and 6. The first and second rotating probes 10 and 12 are secured to the rotating end of the angular displacement device 8 via a rotating probe mounting bracket 15, while the first and second interfering probes 9 and 11 are secured to the fixed end of the angular displacement device 8 via an interfering probe mounting bracket 16. When the minimum distance between the crystal cavity and the tapered fiber waveguide is 0.3 μm, the evanescent wave coupling efficiency between the tapered fiber and the crystal cavity can be guaranteed to a certain extent, achieving a good coupling effect. The computer 14 is electrically connected to the tunable laser 1 and can also be used to control the laser wavelength generated by the tunable laser 1.

[0042] Example 3

[0043] Example 3 of an angle measurement method based on a double whispering gallery microcavity structure, as shown in FIG. Figure 4-Figure 6 As shown, based on the system of Example 1 or Example 2, a method for angle measurement based on a double whispering gallery microcavity structure is performed.

[0044] Specifically, the following steps are included:

[0045] S1. Laser light emitted from a tunable laser 1 is fed into two tapered fiber waveguides after being acted upon by a polarization controller 2. After the light waves in the tapered fiber waveguides are coupled into the silica rods in the dual-crystal cavity, the light waves in the two crystal cavities are interfered with by an interfering probe having a standing wave phase angle deviation of 1 / 4 on both axes, forming stable standing waves with phase deviations but the same number of modes. The rotating probe interacts with the standing wave field in the crystal cavity, thereby affecting the signal output of the light field. The light wave signals generated at the output ends of the two tapered fiber waveguides are collected, converted into electrical signals by a photodetector 13, and sent to a computer 14 for processing.

[0046] S2. When the rotating end of the angular displacement device 8 rotates along the circumference of the crystal cavity, the two rotating probes rotate accordingly and their angles change relative to the standing wave field in the crystal cavity. This changes the interaction between the rotating probes and the standing wave in the crystal cavity. The signals at the output ends of the two tapered optical fiber waveguides at different rotating probe angles are collected and processed.

[0047] S3. By processing and comparing the signal data from the output ends of the two tapered fiber waveguides, angle sensing based on the double whispering gallery microcavity can be realized.

[0048] Specifically, in S2, every time the two rotating probes rotate an angle, the light wave signals collected by the output ends of the two tapered optical fiber waveguides will change, and the change in the light wave signal shows a periodic change with the standing wave phase angle. By changing the position of the rotating probe and the crystal cavity, it can be obtained that the output light wave signal shows a relatively stable periodic change with the deflection of the rotating probe, such as Figure 5 As shown, curve e corresponds to the interference probe no phase deviation model, curve f corresponds to the interference probe deflection 1 / 4 standing wave phase angle model, the reflectivity R1 in the curve graph is used as the dividing threshold, and the intersection of curve e, curve f and y=R1 is recorded as An, n≥0, it can be found that the interval between An and An+1 is periodically repeated.

[0049] Specifically, in S3, the periodically changing standing wave phase angle data is processed. Figure 5 In the example, the periodic interval between A0 and A1 is a periodic interval. Perpendicular lines Li (i=1, 2, 3, 4, 5) are drawn through the five points A0, f=R1, e=f, ​​e=R1, and A1 in the periodic interval. The five perpendicular lines divide the periodic interval into four smaller intervals. The following judgment is made in each smaller interval:

[0050] ①.e <f,且e<R1,f> R1; then R(A)=Re2(A), the interval code is 01;

[0051] ②.e <f,且e<R1,f<R1;则R(A)=Rf2(A),区间编码为00;

[0052] ③.e>f, and e>R1, f <R1;则R(A)=Re1(A),区间编码为00;

[0053] ④.e>f, and e>R1, f <R1;则R(A)=Rf1(A),并记区间编码为10。

[0054] Where A is the angle within each small interval, R(A) is the relationship function between the small interval angle and reflectivity, Re1,2(A) and Rf1,2(A) are the reflectivities of curves e and f corresponding to angle A respectively.

[0055] The function curve of the effective reflectivity changing with angle in the periodic interval is obtained, and the following is obtained: Figure 6 The effective reflectivity is shown as a function of angle.

[0056] When the interval code changes from 10 to 01, the probe rotation angle is recorded as crossing a periodic interval and a forward count is performed; conversely, when the interval code changes from 01 to 10, a reverse count is performed; two identical 00 intervals are distinguished based on the magnitude relationship between the two signals e and f; and the angle measurement within the small interval can be calculated based on the functional correspondence of the selected monotonic curve.

[0057] The beneficial effects of this embodiment are as follows: by setting two interference probes to interfere with the evanescent wave coupled dual crystal cavity, stable standing waves with phase deviation but the same mode number are formed in the two crystal cavities respectively, and then a rotating probe is used to perform rotational interference on the two standing wave fields. By collecting the output signal of the tapered optical fiber waveguide and processing and analyzing it in combination with the angle change, the rotation direction of the microcavity and angle sensing are realized. By adjusting the frequency of the input light wave, high-resolution angle measurement can be achieved.

[0058] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. An angle measurement system based on a double whispering gallery microcavity structure, characterized in that: The invention comprises a tunable laser (1), a polarization controller (2), a tapered optical fiber waveguide, a crystal cavity, an angular displacement device (8), an interference probe, a rotation probe, a photodetector (13) and a computer (14); The tunable laser (1), the polarization controller (2), the tapered optical fiber waveguide, the photodetector (13) and the computer (14) are electrically connected in sequence; the crystal cavity is located at the thinnest position on the tapered optical fiber waveguide to couple light waves into the crystal cavity; the crystal cavity and the interference probe are fixedly connected to the fixed end of the angular displacement device (8); and the rotating probe is fixedly connected to the rotating end of the angular displacement device (8); There are two crystal cavities, and the light waves in the two crystal cavities form a standing wave mode electric field with the same number of standing wave modes and standing wave nodes arranged in a staggered manner. Each crystal cavity is provided with an interference probe, a rotation probe, and a tapered optical fiber waveguide corresponding thereto. The axes of the two interference probes are not parallel, and the axes of the two rotation probes are parallel. It also includes a fixed rod (7), the fixed rod (7) is fixedly connected to the fixed end of the angular displacement device (8), and the two crystal cavities are fixedly connected to the fixed rod (7) and are linearly arranged along the axis direction of the fixed rod (7).

2. The angle measurement system based on a double whispering gallery microcavity structure according to claim 1, characterized in that: The invention also includes a rotating probe mounting frame (15), wherein the two rotating probes are fixedly connected to the rotating probe mounting frame (15), and the connecting line of the two rotating probes on the rotating probe mounting frame (15) is parallel to the vertical direction. The bottom of the rotating probe mounting frame (15) is fixedly connected to the rotating end of the angular displacement device (8), and the rotating probe is fixedly connected to the rotating end of the angular displacement device (8) through the rotating probe mounting frame (15).

3. The angle measurement system based on a double whispering gallery microcavity structure according to claim 1, characterized in that: It also includes an interference probe mounting frame (16), the two interference probes are fixedly connected to the interference probe mounting frame (16), the bottom of the interference probe mounting frame (16) is fixedly connected to the fixed end of the angular displacement device (8), and the interference probe is fixedly connected to the fixed end of the angular displacement device (8) through the interference probe mounting frame (16).

4. The angle measurement system based on a double whispering gallery microcavity structure according to claim 1, characterized in that: The minimum distance between the tapered optical fiber waveguide and the crystal cavity is 0.2 μm-0.4 μm.

5. The angle measurement system based on a double whispering gallery microcavity structure according to claim 1, characterized in that: The radius of the crystal cavity is greater than 2 mm.

6. The angle measurement system based on a double whispering gallery microcavity structure according to claim 1, characterized in that: The computer (14) is also electrically connected to the tunable laser (1) to control the tunable laser (1) to emit laser light.

7. An angle measurement method based on a double whispering gallery microcavity structure, characterized in that: An angle measurement system based on a double-whispering gallery microcavity structure as described in any one of claims 1 to 6 comprises the following steps: S1. The laser light emitted from the tunable laser (1) is input into two tapered optical fiber waveguides after being acted upon by a polarization controller (2). After the light waves in the tapered optical fiber waveguides are coupled into the fixed rod (7) of the dual crystal cavity, the light waves in the two crystal cavities are interfered by interference probes with two axes having an angle, and form stable standing waves with phase deviation but the same mode number. The rotating probe interacts with the standing wave field in the crystal cavity, thereby affecting the signal output of the light field. The light wave signals generated at the output ends of the two tapered optical fiber waveguides are collected, and the collected light wave signals are converted into electrical signals by a photoelectric detector (13) and sent to a computer (14) for processing. S2. When the rotating end on the angular displacement device (8) rotates, the two rotating probes rotate accordingly and the deflection angle relative to the standing wave field in the crystal cavity changes, and the interaction between the rotating probes and the standing wave in the crystal cavity changes. The signals at the output ends of the two tapered optical fiber waveguides at different rotating probe angles are collected and processed; S3. Process and compare the signal data from the output ends of the two tapered fiber waveguides to realize angle sensing based on the double whispering gallery microcavity.

8. The angle measurement method based on a double whispering gallery microcavity structure according to claim 7, characterized in that: In S2, every time the two rotating probes rotate an angle, the light wave signals collected by the output ends of the two tapered optical fiber waveguides will change, and the light wave signals will show periodic changes with the standing wave phase angle. After the rotating probes rotate n angles, the two tapered optical fiber waveguide output ends will be able to collect n light wave signal change information respectively.

9. The angle measurement method based on a double whispering gallery microcavity structure according to claim 7, characterized in that: In said S3, the periodically changing standing wave phase angle data is processed to obtain a function curve of effective reflectivity changing with angle. A plurality of small intervals are provided within one angular period of the function curve, and the function within each small interval changes monotonically.

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