Time-difference-based displacement sensors and their measurement methods

Abstract

This invention provides a time-difference-based displacement sensor and its measurement method. The time-difference-based displacement sensor includes: a reflector for receiving a laser beam reflected by a first reflecting surface of a triangular wave reflector, and ensuring that the laser beam is reflected along the same path to a second reflecting surface of the triangular wave reflector during measurement; an optical deflector for uniformly deflecting the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflector within a set angle range; photodetectors one and two, both for receiving the deflected laser beam twice within one deflection cycle of the optical deflector; and a processing system for calculating the displacement change of the measured object based on the time difference between the laser beams received by photodetectors one and two, and the deflection speed of the optical deflector. This invention can improve the measurement accuracy of the displacement sensor.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and in particular to a displacement sensor based on time difference and its measurement method. Background Technology

[0002] The novel displacement measurement principle based on optical triangulation amplification combines triangular wave optics with a high-precision phototransistor (position-sensitive device, also known as a photodetector). Chinese patent number 2018207451284 provides a tracking displacement sensor that uses an optical deflector to drive the photodetector's movement, ensuring that the reflected laser beam from the triangular wave mirror remains at a constant position on the photodetector. This improves the measurement accuracy of the time-difference-based displacement sensor and increases its amplification. However, all motion has inertia, and the inertia of mechanical structures reduces the measurement speed, making it unsuitable for high-speed motion measurement. Summary of the Invention

[0003] The purpose of this invention is to provide a time-difference-based displacement sensor that can improve measurement accuracy.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A time-difference-based displacement sensor, comprising:

[0006] A triangular wave reflector, comprising a first reflecting surface and a second reflecting surface;

[0007] Laser beam one is incident on the first reflecting surface of the triangular wave reflector;

[0008] A reflector is used to receive a laser beam reflected by the first reflecting surface of a triangular wave reflector, and to reflect the laser beam along the same path to the second reflecting surface of the triangular wave reflector during the measurement process in which the laser beam is incident on the same first reflecting surface.

[0009] Optical deflector one is used to deflect the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflector at a uniform speed within a set angle range.

[0010] Both photodetector one and photodetector two are used to receive the laser beam deflected by optical deflector one.

[0011] The processing system is used to calculate the displacement change of the measured object based on the time difference between the laser beams received by photodetector 1 and photodetector 2, and the deflection speed of optical deflector 1.

[0012] In one possible implementation, the first and second reflecting surfaces of the triangular wave reflector are at an angle of 150 degrees to the horizontal plane, the incident angle of the laser beam to the first reflecting surface is 30 degrees, and the reflector is parallel to the first reflecting surface.

[0013] Preferably, the above-mentioned displacement sensor based on time difference further includes:

[0014] Laser beam two is incident on the first reflecting surface of the triangular wave reflector, and the initial incident points of laser beam one and laser beam two on the first reflecting surface are different.

[0015] The second reflector is used to receive the laser beam reflected by the first reflecting surface of the second laser beam and to reflect the laser beam along the same path to the second reflecting surface of the second laser beam during the measurement process when the second laser beam is incident on the same first reflecting surface.

[0016] Optical deflector 2 is used to deflect the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflector at a uniform speed within a set angle range.

[0017] Photodetector 3 and photodetector 4 are used to receive the laser beam deflected by optical deflector 2;

[0018] The processing system is specifically used to calculate the displacement change of the object under test based on the time difference between the laser beams received by photodetector one and photodetector two, and the deflection speed of optical deflector one; or, it is used to calculate the displacement change of the object under test based on the time difference between the laser beams received by photodetector three and photodetector four, and the deflection speed of optical deflector two.

[0019] The method for displacement measurement using the aforementioned time-difference-based displacement sensor includes the following steps:

[0020] Step 1: Fix the object to be measured on the triangular wave reflector or the probe;

[0021] Step 2: Adjust the positional relationship of laser beam 1, triangular wave reflector, reflector 1, optical deflector 1, photodetector 1, and photodetector 2 so that reflector 1 receives the laser beam reflected by the first reflecting surface of the triangular wave reflector 1, and the laser beam is reflected along the same path to the second reflecting surface of the triangular wave reflector 1 during the measurement process when the laser beam 1 is incident on the same first reflecting surface, and photodetector 1 and photodetector 2 are within the deflection range of optical deflector 1.

[0022] Step 3: Start the optical deflector to rotate at a constant speed and emit laser beam 1. After passing through the first reflecting surface of the triangular wave reflector, reflector 1, and the second reflecting surface of the triangular wave reflector, the laser beam 1 is detected twice by photodetector 1 and photodetector 2 within one deflection cycle, and the time of detection of the laser beam is recorded.

[0023] Step 4: Displacement of the object being measured. During the displacement process, record the time when photodetector 1 and photodetector 2 detect the laser beam twice.

[0024] Step 5: The processing system calculates the displacement value of the object under test based on the time difference between the laser beams received by photodetector 1 and photodetector 2, and the deflection speed of optical deflector 1.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention discloses a time-difference-based displacement sensor. It utilizes an optical deflector to deflect a reflected laser beam, creating a time difference between the two receptions within one deflection cycle. As movement continues, the time difference between the receptions of the reflected laser beam by one photodetector increases, while the time difference between the receptions by the other photodetector decreases. The displacement can be calculated based on the time difference and the deflection angle. The time measurement results from the two photodetectors achieve differential amplification measurement, further improving measurement accuracy.

[0027] This invention utilizes an optical deflector to eliminate the influence of motion inertia on the measurement speed when the driver drives the photodetector for tracking measurement, thereby improving the speed of displacement measurement.

[0028] Meanwhile, this invention achieves displacement measurement through time difference. High-precision displacement measurement can be achieved through high-precision time measurement, transforming displacement measurement into time measurement, which makes it easier to achieve higher precision displacement measurement than traditional displacement measurement sensors. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used 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 a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The diagram shown is a schematic diagram of the measurement principle of a time-difference-based displacement sensor provided in Embodiment 1.

[0031] Figure 2The diagram shows the principle that there is a time difference in the reception of the reflected laser beam by the photodetector before and after displacement.

[0032] Figure 3 The diagram shown is a schematic diagram of the measurement principle of a time difference-based displacement sensor with another structure provided in Embodiment 2.

[0033] Figure 4 The diagram shows the calculation principle of displacement measurement based on time difference.

[0034] Explanation of the labels in the diagram:

[0035] Laser source 1, laser source 2, laser beam 1, laser beam 2, triangular wave reflector 5, housing 6, photodetector 1, photodetector 2 8, reflector 1 9, light deflector 1 10, reflector 2 11, light deflector 2 12, photodetector 3 13; photodetector 4 14; first reflecting surface 51, second reflecting surface 52. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the protection scope of the present invention.

[0037] Example 1

[0038] Please see Figure 1 This embodiment provides a displacement sensor based on time difference, including a laser source 1, a triangular wave reflector 5, a reflector 9, a photodetector 7, and a photodetector 8. The triangular wave reflector 5 includes multiple reflecting surfaces. For ease of understanding, the reflecting surface used to receive the laser beam emitted by the laser source 1 (or 2) is defined as the first reflecting surface, and the reflecting surface used to receive the laser beam reflected by the reflector 1 (or 2) is defined as the second reflecting surface.

[0039] In the time-difference-based displacement sensor described in this embodiment:

[0040] Laser source 1 is used to emit laser beam 3 and direct it toward the first reflecting surface 51 of triangular wave reflector 5;

[0041] The reflector 9 is used to receive the laser beam 3 reflected by the first reflecting surface 51 of the triangular wave reflector 5, and to make the laser beam reflect along the same path to the second reflecting surface 52 of the triangular wave reflector 5 during the measurement process in which the laser beam 3 is incident on the same first reflecting surface 51.

[0042] Optical deflector 10 is used to make the angle of the laser reflected by the second reflecting surface 52 of the triangular wave reflector 5 deflect at a constant speed within a set angle range.

[0043] Photodetector 7 and photodetector 8 are used to receive the laser beam deflected by optical deflector 10 twice within one deflection cycle of optical deflector 10; that is, photodetector 7 and photodetector 8 are both within the set angle range of optical deflector 10, thereby ensuring that the laser beam deflected by optical deflector 10 can be received.

[0044] The processing system is used to calculate the displacement change of the measured object based on the time difference between the laser beams received by photodetector 7 and photodetector 8, respectively, and the deflection speed of optical deflector 10.

[0045] The processing system can be an arithmetic circuit composed of components. Different implementation methods result in different circuit structures, but those skilled in the art can easily implement this arithmetic circuit based on the calculation process of the processing system; therefore, a specific arithmetic circuit diagram is not provided here. The processing system can also be a processor that integrates arithmetic circuits, such as the STM32 series microcontroller.

[0046] The purpose of the optical deflector 10 is to deflect the incident laser beam. The simplest implementation is to install a reflector (or multifaceted reflector) on a rotating platform. The rotation of the platform will change the incident angle of the laser beam incident on the reflector, thereby achieving the purpose of deflection.

[0047] Preferably, the optical deflector can be a potassium tantalate niobate crystal to achieve high-frequency angle deflection.

[0048] In this embodiment, the deflection range of the optical deflector 10 is less than 15 degrees, that is, the set angle range is less than 15 degrees. The time it takes for the optical deflector 10 to rotate from the initial position to the end position and then return from the end position to the initial position is one deflection cycle.

[0049] To ensure the amplification performance of the time-difference-based displacement sensor, the angle between the laser beam incident on photodetector 7 and photodetector 7 should be less than 45 degrees.

[0050] like Figure 1 As shown, photodetector 7 uses a phototransistor. The laser beam 3 before displacement is represented by a solid line, and the laser beam 3 after displacement is represented by a dashed line. The transmission path of laser beam 3 is as follows:

[0051] Before displacement, laser source 1 emits laser beam 3 to the first reflecting surface 51 of triangular wave reflector 5. The first reflecting surface 51 of triangular wave reflector 5 reflects laser beam 3 to reflector 9. Reflector 9 reflects the laser beam reflected by the first reflecting surface 51 to the second reflecting surface 52. The second reflecting surface 52 then reflects the incident laser beam to optical deflector 10.

[0052] In the first half of the deflection cycle, the optical deflector 10 deflects the incident laser beam to the photodetector 7 (assuming that the photodetector 7 receives the laser beam first). Let t1 be the moment when the photodetector 7 receives the laser beam. As the optical deflector 10 rotates at a constant speed, it reaches the deflection limit angle of the beam after rotating to a certain angle, and then the laser beam deflects towards another deflection limit angle. With the deflection of the laser beam, the optical deflector 10 deflects the incident laser beam to the photodetector 7 again. Let t2 be the moment when the photodetector 7 receives the laser beam again.

[0053] In the latter half of the deflection cycle, optical deflector 10 first deflects the incident laser beam to photodetector 8. The moment photodetector 8 receives the laser beam is t3. As optical deflector 10 rotates at a constant speed, it reaches the deflection limit angle of the beam after rotating to a certain angle. Then, the laser beam deflects towards another deflection limit angle. With the deflection of the laser beam, optical deflector 10 deflects the incident laser beam to photodetector 8 again. The moment photodetector 8 receives the laser beam again is t4.

[0054] Let δT1 = t2 - t1 be the time difference in which photodetector 10 receives the laser beam within one deflection period before displacement, and let δT2 = t4 - t3 be the time difference in which photodetector 8 receives the laser beam within one deflection period.

[0055] After displacement ( Figure 1 The image shows a leftward displacement, during which laser source 1, reflector 9, optical deflector 10, photodetector 7, and photodetector 8 simultaneously move to the left. Laser source 1 emits laser beam 3 to the first reflecting surface 51 of the triangular wave reflector 5 (a different position point compared to the same reflecting surface before the displacement). The first reflecting surface 51 of the triangular wave reflector 5 reflects laser beam 3 to reflector 9. Reflector 9 reflects the laser beam reflected by the first reflecting surface 51 along the same path as before the displacement to the second reflecting surface 52. The second reflecting surface 52 then reflects the incident laser beam along the same path as before the displacement to optical deflector 10.

[0056] After being deflected by optical deflector 10, the laser beam enters photodetectors 7 and 8 in the same way as before the displacement. During the first half of the deflection period, the time when photodetector 7 first receives the laser beam is t5, and the time when it receives it for the second time is t6. During the second half of the deflection period, the time when photodetector 8 first receives the laser beam is t7, and the time when it receives it for the second time is t8. The time difference between the laser beam received by photodetector 7 within one deflection period after the displacement is denoted as δT3 = t6 - t5, and the time difference between the laser beam received by photodetector 8 within one deflection period is denoted as δT4 = t8 - t7.

[0057] Please see Figure 2 The thick solid line (the rightmost solid line) represents the deflection limit boundary of the optical deflector. Before the displacement, the angle between the laser beam incident on photodetector 7 and the deflection limit boundary is b. After the displacement, the angle between the laser beam incident on photodetector 7 and the deflection limit boundary is a. b is less than a, meaning the incident angle after the displacement is larger. Therefore, the time difference between the two laser beams received by photodetector 7 before and after the displacement will increase accordingly, i.e., δT3 is greater than δT1.

[0058] Similarly, after displacement, the angle between the laser beam incident on photodetector 28 and the deflection limit boundary will decrease. Therefore, the time difference between the laser beam received by photodetector 28 before and after displacement will decrease accordingly, i.e., δT4 is less than δT2.

[0059] The optical deflector-10 deflects the incident laser at a constant angle, and the angle of rotation per unit time is known. The displacement of the object under test can be calculated based on the deflection speed of the optical deflector-10 and the time difference between the two photodetectors before and after the displacement.

[0060] For reference Figure 4The calculation process is as follows: Let the angle deflection speed of the optical deflector-10 to the incident laser be α degrees / second, the distance from the angle deflector-10 to the receiving surface of the photodetector-7 be h, and the maximum deflection angle of the angle deflector-10 be β degrees. Then the angle corresponding to the time difference δT3 is (α×δT3) / 2. Then the current displacement X = h×tg(β-(α×δT3) / 2). The two displacements X can be calculated based on the two different time differences before and after the displacement, and the relative displacement ΔX can be calculated accurately. The formula is as follows: ΔX=h×tg(β-(α×δT3) / 2)-h×tg(β-(α×δT1) / 2); When the structural parameters of photodetector 28 are the same as those of photodetector 17, the displacement difference principle can be used to obtain 2ΔX=h×tg(β-(α×δT3) / 2)-h×tg(β-(α×δT1) / 2)+h×tg(β-(α×δT2) / 2)-h×tg(β-(α×δT4) / 2). When the structural parameters of photodetector 28 are inconsistent with those of photodetector 17, the distance from angle deflector 10 to the receiving surface of photodetector 28 is h', and the maximum deflection angle of angle deflector 10 is β' degrees. Then, 2ΔX = h×tg(β-(α×δT3) / 2)-h×tg(β-(α×δT1) / 2)+h'×tg(β'-(α×δT2) / 2)-h'×tg(β'-(α×δT4) / 2).

[0061] To further improve measurement accuracy, a standard displacement calibration experiment can be conducted to obtain the relationship curve between time difference and displacement. After moving the device by a fixed interval ΔX, a time difference δT is obtained. The displacement corresponding to any given time difference can then be obtained through interpolation.

[0062] To achieve the goal of reflecting the laser beam from mirror 9 along the same path before and after displacement to the second reflecting surface 52 of the triangular wave mirror 5, it can be achieved, for example, by having mirror 9 parallel to the first reflecting surface and the second reflecting surface, and the acute angle between the laser beam and the first reflecting surface being equal to twice the angle between the first reflecting surface and the horizontal plane.

[0063] For example, as a preferred implementation, the first reflecting surface 51 and the second reflecting surface 52 of the triangular wave reflector 5 each make an angle of 150 degrees with the horizontal plane (taking the horizontal to the right as the positive direction and rotating counterclockwise as an example only). The incident angle of the laser beam 3 emitted by the laser source 1 onto the first reflecting surface 51 is 30 degrees, and the reflector 9 is parallel to the first reflecting surface 51. Other different configurations are also possible, provided that during the measurement process, the emitted laser beam 3 is incident on the same first reflecting surface and reflected along the same path to the second reflecting surface 52 of the triangular wave reflector 5.

[0064] A triangular wave does not necessarily have to be an isosceles triangular wave; that is, the acute angles between the two reflecting surfaces forming the triangular wave and the horizontal plane can be equal or unequal. In the time-difference-based displacement sensor provided in this embodiment, for the triangular wave reflector 5, there are no restrictions on its specific structure, provided that the first reflecting surface 51 is parallel to the second reflecting surface 52. In other words, there are no restrictions on the angles between the two reflecting surfaces forming the triangular wave.

[0065] Please refer to Figure 1 The aforementioned time-difference-based displacement sensor may further include a housing 6. A laser source 1, a reflector 9, an optical deflector 10, a photodetector 7, and a photodetector 8 are all fixedly disposed within the housing 6, forming a probe. The laser beam 3 emitted by the laser source 1 and its reflected beam can both pass through the transceiver end face of the probe. The fixed placement of the laser source 1, reflector 9, optical deflector 10, photodetector 7, and photodetector 8 within the housing 6 ensures that their relative positions are fixed and that they maintain synchronous displacement.

[0066] During measurement, depending on the actual application, the triangular wave reflector 5 can be fixed to the object being measured, while the probe remains stationary. When the object moves, the triangular wave reflector 5 and the probe move relative to each other, allowing the probe to measure the displacement of the triangular wave reflector 5, which corresponds to the displacement of the object. Alternatively, the probe can be fixed to the object being measured, while the triangular wave reflector 5 remains stationary. When the object moves, the probe moves, causing a relative displacement between the probe and the triangular wave reflector 5. The probe can then measure this relative displacement to obtain the displacement value of the object.

[0067] The measurement method uses a triangular wave reflector 5 or a probe to fix itself on the object being measured, which improves the convenience of measurement.

[0068] When using the time-difference-based displacement sensor described above for displacement measurement, the steps are as follows:

[0069] Step 1: Fix the object to be measured on the triangular wave reflector or the probe;

[0070] Step 2: Adjust the positional relationship of laser beam 1 (i.e., laser source 1), triangular wave reflector, reflector 1, optical deflector 1, photodetector 1, and photodetector 2, so that reflector 1 receives the laser beam reflected by the first reflecting surface of the triangular wave reflector, and during the measurement process of laser beam 1 incident on the same first reflecting surface, the laser beam is reflected along the same path to the second reflecting surface of the triangular wave reflector, and photodetector 1 and photodetector 2 are within the deflection range of optical deflector 1, that is, during the rotation of optical deflector 1, photodetector 1 and photodetector 2 can receive the laser beam reflected by the second reflecting surface of the triangular wave reflector.

[0071] Step 3: Start the optical deflector to rotate at a constant speed and emit laser beam 1. After passing through the first reflecting surface of the triangular wave reflector, reflector 1, and the second reflecting surface of the triangular wave reflector, the laser beam 1 is detected twice by photodetector 1 and photodetector 2 within one deflection cycle, and the time of detection of the laser beam is recorded.

[0072] Step 4: Displacement of the object being measured. During the displacement process, record the time when photodetector 1 and photodetector 2 detect the laser beam twice.

[0073] Step 5: The processing system calculates the displacement value of the object under test based on the time difference between the laser beams received by photodetector 1 and photodetector 2, and the deflection speed of optical deflector 1.

[0074] Example 2

[0075] Please refer to Figure 3 Compared with the time-difference-based displacement sensor described in Embodiment 1, the time-difference-based displacement sensor provided in this embodiment further includes a laser beam 4 incident on another first reflecting surface 51 of the triangular wave reflector 5; and the following components:

[0076] Reflector 2 11 is used to receive the laser beam 2 4 reflected by the other first reflecting surface 51 of the triangular wave reflector 5, and to reflect the laser beam along the same path to the other second reflecting surface 52 of the triangular wave reflector 5 during the measurement process in which the laser beam 2 4 is incident on the same other first reflecting surface 51.

[0077] Optical deflector 12 is used to deflect the incident angle of the laser beam reflected by the second reflecting surface 52 of the triangular wave reflector 5 at a constant speed within a set angle range.

[0078] Photodetector 3 13 and photodetector 4 14 are used to receive the laser beam deflected by optical deflector 2 twice within one deflection cycle of optical deflector 2.

[0079] In the time-difference-based displacement sensor described in this embodiment, the processing system calculates the displacement change of the measured object based on the time difference between the laser beams received by photodetector 7 and photodetector 8, and the deflection speed of optical deflector 10; or, it calculates the displacement change of the measured object based on the time difference between the laser beams received by photodetector 3 and photodetector 4, and the deflection speed of optical deflector 12.

[0080] The time-difference-based displacement sensor described in this embodiment can achieve continuous displacement measurement. Specifically, one of two laser beams can be selected for measurement. When the reflection point of one laser beam is located at certain positions on the reflecting surface, such as the top of the reflecting surface or the intersection of two reflecting surfaces, the reflected laser beam path changes and may not be reflected to the corresponding photodetector. However, the reflection point of the other laser beam is located at other positions on another reflecting surface and can be reflected to the corresponding photodetector. This allows for the measurement of at least one laser beam reflected by each of the second reflecting surfaces 52 on the triangular wave reflector 5 at every moment of the measured object's movement, which can then be reflected to the corresponding photodetector. At this time, the processing system can switch back and forth to calculate the time difference between the two sets of photodetectors and perform superposition and accumulation to achieve the measurement of the one-time change or continuous incremental change of the displacement of the measured object. The measurement method is simple, reliable, easy to operate, and can improve measurement accuracy.

[0081] like Figure 3 As shown, laser beam 3 and laser beam 4 are obtained by laser source 1 and laser source 2, respectively.

[0082] The two measurement systems can be housed within a single housing to form one probe, or they can be housed separately within a housing to form two probes. Specifically, laser source one, laser source two, reflector one, reflector two, optical deflector one, optical deflector two, photodetector one, photodetector two, photodetector three, and photodetector four are all fixedly housed within the housing to form one probe. Alternatively, laser source one, reflector one, optical deflector one, photodetector one, and photodetector two are all fixedly housed within one housing to form one probe; laser source two, reflector two, optical deflector two, photodetector three, and photodetector four are all fixedly housed within another housing to form another probe.

[0083] It is easy to understand that in this embodiment, the purpose of setting up laser source one and laser source two is to avoid the situation where one set of photodetectors cannot receive the laser beam, so that the other set of photodetectors can receive the laser beam to achieve displacement measurement. Therefore, in addition to... Figure 3 Besides the setup shown, there are other setups, as long as laser source one and laser source two are staggered so that the initial incident points of laser beam one and laser beam two are different on the first reflecting surface. For example, laser beam two can also be incident on another first reflecting surface on the same side of the first reflecting surface where laser beam one is incident, or it can be incident on the same reflecting surface where laser beam one is incident, but the incident point positions are different.

[0084] The photodetectors (one to four) can be position-sensitive detectors such as phototransistors, or devices such as photodiodes and photovoltaic cells.

[0085] When using the time-difference-based displacement sensor in this embodiment for displacement measurement, the steps are as follows:

[0086] Step 1: Fix the object to be measured on the triangular wave reflector or the probe;

[0087] Step 2: Adjust the positional relationship of laser beam 1, triangular wave reflector, reflector 1, optical deflector 1, photodetector 1, and photodetector 2, so that reflector 1 receives the laser beam reflected by the first reflecting surface of the triangular wave reflector, and during the measurement process where laser beam 1 is incident on the same first reflecting surface, the laser beam is reflected along the same path to the second reflecting surface of the triangular wave reflector, and photodetector 1 and photodetector 2 are within the deflection range of optical deflector 1; Adjust the positional relationship of laser beam 2, triangular wave reflector, reflector 2, optical deflector 2, photodetector 3, and photodetector 4, so that reflector 2 receives the laser beam reflected by the first reflecting surface of the triangular wave reflector, and during the measurement process where laser beam 2 is incident on the same first reflecting surface, the laser beam is reflected along the same path to the second reflecting surface of the triangular wave reflector, and photodetector 3 and photodetector 4 are within the deflection range of optical deflector 2;

[0088] Step 3: Start the optical deflector 1 to rotate at a constant speed and emit laser beam 1. After passing through the first reflecting surface of the triangular wave reflector, reflector 1, and the second reflecting surface of the triangular wave reflector, the laser beam 1 is detected twice by photodetector 1 and photodetector 2 respectively within one deflection cycle, and the time of detection is recorded. Alternatively, start the optical deflector 2 to rotate at a constant speed and emit laser beam 2. After passing through the first reflecting surface of the triangular wave reflector, reflector 2, and the second reflecting surface of the triangular wave reflector, the laser beam 2 is detected twice by photodetector 3 and photodetector 4 respectively within one deflection cycle, and the time of detection is recorded.

[0089] Step 4: Displacement of the object being measured. During the displacement process, record the time when photodetector 1 and photodetector 2 detect the laser beam twice, or record the time when photodetector 3 and photodetector 4 detect the laser beam twice.

[0090] Step 5: The processing system calculates the displacement value of the object under test based on the time difference between the laser beams received by photodetector 1 and photodetector 2, and the deflection speed of optical deflector 1; or it calculates the displacement value of the object under test based on the time difference between the laser beams received by photodetector 3 and photodetector 4, and the deflection speed of optical deflector 2.

[0091] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A displacement sensor based on time difference, characterized in that, include: A triangular wave reflector, comprising a first reflecting surface and a second reflecting surface; Laser beam one is incident on the first reflecting surface of the triangular wave reflector; A reflector is used to receive a laser beam reflected by the first reflecting surface of a triangular wave reflector, and to reflect the laser beam along the same path to the second reflecting surface of the triangular wave reflector during the measurement process in which the laser beam is incident on the same first reflecting surface. Optical deflector one is used to deflect the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflector at a uniform speed within a set angle range. Both photodetector one and photodetector two are used to receive the laser beam deflected by optical deflector one twice within one deflection cycle of optical deflector one. The processing system is used to calculate the displacement change of the measured object based on the time difference between the laser beams received by photodetector 1 and photodetector 2 and the deflection speed of optical deflector 1. The time difference between the laser beam received by photodetector 1 and photodetector 2 is the time difference between two laser beam detections by photodetector 1 within one deflection period, and the time difference between two laser beam detections by photodetector 2 within one deflection period. The first reflector is parallel to the first reflecting surface and also parallel to the second reflecting surface. The acute angle between the first laser beam and the first reflecting surface is equal to twice the angle between the first reflecting surface and the horizontal plane. The housing contains a laser beam emitted from a laser source. The laser source, mirror, photodetector, and photodetector are all fixedly installed inside the housing, forming the probe.

2. The displacement sensor based on time difference according to claim 1, characterized in that, The first and second reflecting surfaces of the triangular wave reflector are at an angle of 150 degrees to the horizontal plane, and the incident angle of the laser beam to the first reflecting surface is 30 degrees.

3. The time-difference-based displacement sensor according to claim 1 or 2, characterized in that, Also includes: Laser beam two is incident on the first reflecting surface of the triangular wave reflector, and the initial incident points of laser beam one and laser beam two on the first reflecting surface are different. The second reflector is used to receive the laser beam reflected by the first reflecting surface of the second laser beam and to reflect the laser beam along the same path to the second reflecting surface of the second laser beam during the measurement process when the second laser beam is incident on the same first reflecting surface. Optical deflector 2 is used to deflect the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflector at a uniform speed within a set angle range. Photodetector 3 and photodetector 4 are used to receive the laser beam deflected by optical deflector 2 twice within one deflection cycle of optical deflector 2. The processing system is specifically used to calculate the displacement change of the object under test based on the time difference between the laser beams received by photodetector one and photodetector two, and the deflection speed of optical deflector one; or, based on the time difference between the laser beams received by photodetector three and photodetector four, and the deflection speed of optical deflector two, to calculate the displacement change of the object under test. The time difference between the laser beam received by photodetector 1 and photodetector 2 is the time difference between two laser beam detections by photodetector 1 within one deflection period, and the time difference between two laser beam detections by photodetector 2 within one deflection period. The time difference between the laser beam received by photodetector three and photodetector four is the time difference between two laser beam detections by photodetector three within one deflection period and the time difference between two laser beam detections by photodetector four within one deflection period.

4. The displacement sensor based on time difference according to claim 3, characterized in that, Laser beam one and laser beam two are respectively incident on two different first reflecting surfaces of the triangular wave reflector.

5. The displacement sensor based on time difference according to claim 3, characterized in that, It also includes a housing. The laser beam one and laser beam two are emitted by laser source one and laser source two, respectively. Laser source one, laser source two, reflector one, reflector two, optical deflector one, optical deflector two, photodetector one, photodetector two, photodetector three, and photodetector four are all fixedly installed inside the housing to form a probe.

6. The displacement sensor based on time difference according to claim 3, characterized in that, It also includes two housings. The first laser beam and the second laser beam are emitted by the first laser source and the second laser source, respectively. The first laser source, the first reflector, the first optical deflector, the first photodetector and the second photodetector are all fixedly installed in one housing to form a probe. The second laser source, the second reflector, the second optical deflector, the third photodetector and the fourth photodetector are all fixedly installed in the other housing to form another probe.

7. A method for displacement measurement using a time-difference-based displacement sensor as described in claim 1, characterized in that, Includes the following steps: Step 1: Fix the object to be measured on the triangular wave reflector or the probe; Step 2: Adjust the positional relationship of laser beam 1, triangular wave reflector, reflector 1, optical deflector 1, photodetector 1, and photodetector 2 so that reflector 1 receives the laser beam reflected by the first reflecting surface of the triangular wave reflector 1, and the laser beam is reflected along the same path to the second reflecting surface of the triangular wave reflector 1 during the measurement process when the laser beam 1 is incident on the same first reflecting surface, and photodetector 1 and photodetector 2 are within the deflection range of optical deflector 1. Step 3: Start the optical deflector to rotate at a constant speed and emit laser beam 1. After passing through the first reflecting surface of the triangular wave reflector, reflector 1, and the second reflecting surface of the triangular wave reflector, the laser beam 1 is detected twice by photodetector 1 and photodetector 2 within one deflection cycle, and the time of detection of the laser beam is recorded. Step 4: Displacement of the object being measured. During the displacement process, record the time when photodetector 1 and photodetector 2 detect the laser beam twice. Step 5: The processing system calculates the displacement value of the object under test based on the time difference between the laser beams received by photodetector 1 and photodetector 2, and the deflection speed of optical deflector 1. The time difference between the laser beam received by photodetector 1 and photodetector 2 is the time difference between two laser beam detections by photodetector 1 within one deflection period, and the time difference between two laser beam detections by photodetector 2 within one deflection period.

8. The method for displacement measurement using the time-difference-based displacement sensor as described in claim 3, characterized in that, Includes the following steps: Step 1: Fix the object to be measured on the triangular wave reflector or the probe; Step 2: Adjust the positional relationship of laser beam 1, triangular wave reflector, reflector 1, optical deflector 1, photodetector 1, and photodetector 2, so that reflector 1 receives the laser beam reflected by the first reflecting surface of the triangular wave reflector, and during the measurement process where laser beam 1 is incident on the same first reflecting surface, the laser beam is reflected along the same path to the second reflecting surface of the triangular wave reflector, and photodetector 1 and photodetector 2 are within the deflection range of optical deflector 1; Adjust the positional relationship of laser beam 2, triangular wave reflector, reflector 2, optical deflector 2, photodetector 3, and photodetector 4, so that reflector 2 receives the laser beam reflected by the first reflecting surface of the triangular wave reflector, and during the measurement process where laser beam 2 is incident on the same first reflecting surface, the laser beam is reflected along the same path to the second reflecting surface of the triangular wave reflector, and photodetector 3 and photodetector 4 are within the deflection range of optical deflector 2; Step 3: Start the optical deflector 1 to rotate at a constant speed and emit laser beam 1. After passing through the first reflecting surface of the triangular wave reflector, reflector 1, and the second reflecting surface of the triangular wave reflector, the laser beam 1 is detected twice by photodetector 1 and photodetector 2 within one deflection cycle, and the time of detection is recorded. Alternatively, start the optical deflector 2 to rotate at a constant speed and emit laser beam 2. After passing through the first reflecting surface of the triangular wave reflector, reflector 2, and the second reflecting surface of the triangular wave reflector, the laser beam 2 is detected twice by photodetector 3 and photodetector 4 within one deflection cycle, and the time of detection is recorded. Step 4: Displacement of the object being measured. During the displacement process, record the time when photodetector 1 and photodetector 2 detect the laser beam twice, or record the time when photodetector 3 and photodetector 4 detect the laser beam twice. Step 5: The processing system calculates the displacement value of the object under test based on the time difference between the laser beams received by photodetector 1 and photodetector 2, and the deflection speed of optical deflector 1; or it calculates the displacement value of the object under test based on the time difference between the laser beams received by photodetector 3 and photodetector 4, and the deflection speed of optical deflector 2. The time difference between the laser beam received by photodetector 1 and photodetector 2 is the time difference between two laser beam detections by photodetector 1 within one deflection period, and the time difference between two laser beam detections by photodetector 2 within one deflection period. The time difference between the laser beam received by photodetector three and photodetector four is the time difference between two laser beam detections by photodetector three within one deflection period and the time difference between two laser beam detections by photodetector four within one deflection period.

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