A tilt angle detection device of an optical angle magnification principle

Abstract

The application discloses a tilt angle detection device based on optical angle amplification principle and relates to the technical field of precise tilt angle measurement. The tilt angle detection device comprises a rotating shaft and an angle expansion assembly, characterized in that a swing assembly is rotatably arranged on the rotating shaft and always points to the vertical direction under the action of gravity; a laser is arranged on the swing assembly and used for emitting a detection beam; an incident convex lens and a reflecting element are sequentially arranged below the light path of the detection beam; the detection beam enters the reflecting element after passing through the incident convex lens; and the detection beam is deflected by 90 degrees and projected to the angle expansion assembly. The application significantly amplifies the micro angle change into measurable light spot displacement through the optical amplification mechanism, improves the detection sensitivity and resolution, is suitable for high-precision tilt angle measurement scenes such as engineering structure monitoring, geological disaster early warning and precise instrument leveling, and has the advantages of compact structure, strong anti-interference and fast response.

Description

Technical Field

[0001] This invention relates to the field of precision tilt measurement technology, specifically a tilt detection device based on the principle of optical angle magnification. Background Technology

[0002] Inclination measurement technology, as a core tool for engineering monitoring and precision measurement, is widely used in key areas such as high-speed rail track settlement monitoring, bridge structural health assessment, and precision instrument leveling. Its accuracy directly affects the safe operation of infrastructure and the quality of high-end equipment manufacturing. With the continuous improvement of the requirements for deformation monitoring accuracy in modern engineering, high-resolution inclination measurement at the sub-arcsecond level has become a technical bottleneck that the industry urgently needs to overcome.

[0003] Currently, MEMS (Micro-Electro-Mechanical Systems) tilt sensors have been widely used in civil engineering and industrial automation due to their advantages of small size, low cost, and ease of integration. However, their detection signals are easily overwhelmed by 1 / f noise, temperature drift, and residual stress from packaging. Even with complex signal processing techniques such as temperature compensation and Kalman filtering, the effective resolution is still difficult to exceed 15 bits, and the typical detection accuracy is only on the order of 0.01°, which is far from meeting the long-term micro-deformation monitoring needs of infrastructure such as high-speed railway seamless tracks and long-span bridges. On the other hand, electrolyte-based tiltmeters use the conductive liquid surface as a horizontal zero-point reference, and the static detection accuracy can reach 0.001°, which has certain advantages in laboratory environments. However, their high-resistance electrolyte-electrode interface impedance is as high as megaohms, requiring high-cost circuits such as chopper excitation and lock-in amplification to extract microvolt-level differential signals, which significantly increases system power consumption, PCB area, and manufacturing costs. More importantly, the problems of slow zero-point drift caused by long-term evaporation of electrolyte, bubble adsorption, and the difference in thermal expansion coefficient between electrolyte and container material are prominent. On-site use requires periodic disassembly, liquid filling, and recalibration, resulting in high maintenance costs and difficulty in achieving long-term stable monitoring.

[0004] Therefore, this invention proposes a tilt detection device based on the principle of optical angle magnification. Summary of the Invention

[0005] The purpose of this invention is to provide a tilt detection device based on the principle of optical angle magnification, so as to overcome the shortcomings of existing MEMS tilt measurement technology in terms of low sensitivity and low accuracy in detecting small angles, and to achieve high resolution and high stability detection of small tilt angle changes.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a tilt detection device based on the principle of optical angle magnification, comprising a rotating shaft and an angle expansion assembly, wherein a swing assembly is rotatably mounted on the rotating shaft, and the swing assembly always points in the vertical direction under the action of gravity; A laser is installed on the swing assembly to emit a detection beam. An incident convex lens and a reflector are arranged in sequence below the optical path of the detection beam. After passing through the incident convex lens, the detection beam enters the reflector. The detection beam is deflected by 90° and then projected onto the angle-expanding assembly. The deflected beam is parallel to the optical axis of the angle-expanding assembly and is located on the same side of the optical axis. The angle-expanding component is used to receive the light beam from the reflective element and amplify the angle. The amplified light beam enters the photosensitive element, which is used to detect the position of the light spot. In actual use, the laser follows the swing assembly to rotate relative to the incident convex lens, so that the detection beam forms an incident angle with respect to the optical axis of the incident convex lens, and the photosensitive element determines the tilt angle based on the detected spot displacement.

[0007] Furthermore, it also includes a housing, and the rotating shaft, incident convex lens, angle expanding assembly, photosensitive element and reflector are all fixedly installed inside the housing and tilt together with the housing.

[0008] Furthermore, the swing assembly includes a bushing rotatably mounted on a rotating shaft, a swing rod fixedly mounted at the bottom of the bushing, and a weight fixedly mounted at the bottom end of the swing rod. The entire swing assembly rotates around the rotating shaft and always points in the direction of the plumb bob under the action of the weight.

[0009] Furthermore, the laser is fixedly mounted on the bushing and swings around the shaft together with the bushing. The detection beam emitted by the laser always passes through the axis of the shaft, which is also the focal point of the incident convex lens. The laser light passes through the focal point and is projected onto the incident convex lens, so that the detection beam forms a parallel beam parallel to the optical axis of the incident convex lens after passing through the incident convex lens.

[0010] Furthermore, the reflective element is configured as a plane mirror or a right-angle total reflection mirror. The reflective element is located in the optical path between the incident convex lens and the expanding assembly, and is used to rotate the parallel beam from the incident convex lens by 90° and project it onto the expanding assembly. The emitted light rays from the reflective element are all parallel to the optical axis of the expansion component, and within the tilt angle measurement range, the light rays are all on the same side of the optical axis.

[0011] Furthermore, the angle-expanding component is used to increase the distance between the off-axis incident light ray parallel to the optical axis of the angle-expanding component and the optical axis, or to increase the angle between the oblique incident light ray and the optical axis of the angle-expanding component; The expanding angle assembly includes multiple coaxial convex and concave lenses, which are arranged alternately in pairs, and each convex lens and its adjacent concave lenses on the same side share the same focal point.

[0012] Furthermore, it also includes a convex mirror, which is fixed inside the housing and is located on the exit side of the expanding assembly. Its optical axis is collinear with the optical axis of the expanding assembly, and its focal point is the same as the focal point of the last convex lens of the expanding assembly. The detection beam, amplified by the angle-expanding component, is projected onto the convex mirror and then reflected back to the angle-expanding component. After being amplified a second time, it exits from the incident side of the angle-expanding component to the photosensitive element.

[0013] Furthermore, the photosensitive element is configured as a CCD line scan camera or a CMOS line scan camera, with a pixel size of less than 5μm.

[0014] Furthermore, the reflective element is a shared reflective element, with one part placed between the incident convex lens and the expanding component, and the other part extending into the outgoing light path of the expanding component, for projecting the outgoing light beam of the expanding component onto the photosensitive element after secondary deflection.

[0015] Furthermore, the mounting position of the shared reflective element satisfies the following: Within the maximum positive and negative tilt angle measurement range, the beam projection area from the incident convex lens does not overlap with the beam projection area from the expanding assembly.

[0016] This invention has at least the following beneficial effects: 1. This invention employs a multi-stage optical amplification structure, which sequentially amplifies the minute angular changes of the pendulum through collimation by an incident convex lens, transmission amplification by an expansion component, and secondary amplification by reflection by a convex mirror, ultimately converting them into a significant spot displacement on the photosensitive element. This successfully achieves high resolution, long-term stability, compact structure, and fast response simultaneously, effectively overcoming the technical defects of existing MEMS and electrolyte-based tilt sensors. It is suitable for high-precision tilt measurement scenarios such as high-speed rail track monitoring and bridge health.

[0017] 2. The oscillating component of this invention uses gravity as the sole reference, and is unaffected by temperature drift, electromagnetic interference, and 1 / f noise, fundamentally avoiding the temperature drift defects of MEMS sensors and the slow zero-point drift problem of electrolyte-based inclinometers. The combination of mechanical pendulum and optical detection eliminates the need for complex temperature compensation or periodic liquid filling calibration, significantly reducing maintenance costs.

[0018] 3. This invention introduces a reflective element to fold the optical path, and arranges the incident optical path and the outgoing optical path in space to overlap, which greatly reduces the size of the device. In particular, by adopting a shared reflective element design, the optical path is folded by utilizing the vertical space while ensuring that the optical path does not overlap. The equivalent optical path length exceeds the physical size, which has the advantages of high sensitivity and miniaturization, and is easy to install and deploy in narrow spaces.

[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the tilt state of the tilt angle detection device described in this invention. Figure 2 This is a schematic diagram of the structure and optical path of the tilt angle detection device according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the optical path of a first embodiment of the tilt angle detection device of the present invention; Figure 4 This is a schematic diagram illustrating the working principle of the expanding component in Embodiment 1 of the tilt detection device of the present invention; Figure 5 This is a schematic diagram of the structure and optical path of the tilt angle detection device according to Embodiment 2 of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0022] Example 1: Please see Figures 1-4 The present invention provides a technical solution: a tilt detection device based on the principle of optical angle magnification, comprising a rotating shaft and an angle expansion assembly, wherein a swing assembly is rotatably mounted on the rotating shaft, and the swing assembly always points in the vertical direction under the action of gravity; A laser is installed on the swing assembly to emit a detection beam. An incident convex lens and a reflector are arranged in sequence below the optical path of the detection beam. After passing through the incident convex lens, the detection beam enters the reflector. The detection beam is deflected by about 90° and then projected onto the expanding assembly. The deflected beam is parallel to the optical axis of the expanding assembly and is located on the same side of the optical axis. The angle-expanding component is used to receive the light beam from the reflector and amplify the angle. The amplified light beam then enters the photosensitive element, which is used to detect the position of the light spot. In actual use, the laser follows the swing assembly to rotate relative to the incident convex lens, so that the detection beam forms an incident angle with respect to the optical axis of the incident convex lens, and the photosensitive element determines the tilt angle based on the detected spot displacement.

[0023] The technical solution of this embodiment also includes a housing, and the rotating shaft, incident convex lens, angle expanding assembly, photosensitive element and reflective element are all fixedly installed in the housing and tilt together with the housing; like Figure 1As shown, when the outer casing is not tilted, the detection beam emitted by the laser is projected vertically downwards onto the incident convex lens. At this time, the incident light ray coincides with the optical axis of the incident convex lens. When the outer casing is tilted, the incident convex lens tilts along with the outer casing, and the incident light ray remains vertically downwards, forming an angle with the optical axis of the incident convex lens. α After exiting, the light is projected along the parallel optical axis onto the expanding assembly. If the focal length of the incident convex lens is... f If the distance between the emitted ray and the optical axis is 0, then the distance between the emitted ray and the optical axis is 0. h 0 is: It should be noted that the laser is fixedly mounted on the bushing and swings around the shaft together with the bushing. The detection beam emitted by the laser always passes through the axis of the shaft, which is also the focal point of the incident convex lens. The laser light passes through the focal point and is projected onto the incident convex lens, so that the detection beam forms a parallel beam parallel to the optical axis of the incident convex lens after passing through the incident convex lens.

[0024] Regarding the technical solution of this embodiment, the swing assembly includes a bushing rotatably mounted on a rotating shaft, a swing rod fixedly mounted at the bottom of the bushing, and a weight fixedly mounted at the bottom end of the swing rod. The entire swing assembly rotates around the rotating shaft and always points in the direction of the plumb line under the action of the weight. This structure utilizes the gravity of the weight to form a naturally stable vertical reference benchmark, which is not affected by temperature drift, electromagnetic interference, or electronic noise. This fundamentally ensures the long-term stability and reliability of the measurement system. Compared with the temperature drift problem of MEMS sensors and the liquid evaporation defect of electrolyte inclinometers, the physical characteristics of the mechanical pendulum are more stable and durable.

[0025] Regarding the technical solution of this embodiment, such as Figure 2 and Figure 3 As shown, the reflector is set as a plane mirror or a right-angle total reflection mirror. The reflector is independently located in the optical path between the incident convex lens and the expansion assembly. It is used to rotate the parallel beam from the incident convex lens by 90° and project it onto the expansion assembly. The outgoing light rays of the reflector are all parallel to the optical axis of the expansion assembly, and within the tilt angle measurement range, the light rays are all on the same side of the optical axis. Specifically, such as Figure 2 As shown, after the light rays pass through the optical axis of the incident convex lens and are reflected by the reflector, the distance between the light rays and the optical axis of the expanding assembly is d. After passing through the expanding assembly, the light rays are projected from the left side parallel to the optical axis onto the convex mirror, and then reflected again onto the convex lens 2 of the expanding assembly. The light rays then exit from the right side of the expanding assembly, and the off-axis angle further increases, finally projecting onto the photosensitive element. like Figure 3 As shown, within the range of tilt angle measurement, the light beam emitted from the right side of the expansion component will not illuminate the independently set reflector element, but will be projected entirely onto the photosensitive element.

[0026] Regarding the technical solution of this embodiment, the angle expanding component is used to increase the distance between the off-axis incident light ray parallel to the optical axis of the angle expanding component and the optical axis, or to increase the angle between the oblique incident light ray and the optical axis of the angle expanding component; The widening assembly includes multiple coaxial convex and concave lenses, which are arranged alternately in pairs, and each convex lens and its adjacent concave lenses on the same side have the same focal point. Specifically, such as Figure 4 As shown, the expanding lens assembly, from right to left, consists of concave lens 1, convex lens 1, concave lens 2, and convex lens 2, with equal spacing. All four lenses share a common optical axis, which is the optical axis of the expanding lens assembly. The focal points of the convex lens and the adjacent concave lens on the same side are at the same point. The focal lengths of the two concave lenses are... f 1. The focal lengths of the two convex lenses are f 2. For example Figure 4 In the image, the focal point on the same side of concave lens 1 and convex lens 1 is the right focal point 1. Therefore, ray 1 parallel to the optical axis is projected onto concave lens 1 at a distance from the optical axis. h After point 1, light ray 2 is scattered and projected onto concave lens 2. h At point 2, the backward extension of ray 2 passes through focal point 1 on the right, indicating that: Similarly, the off-axis distance of the beam 3 emitted from the left side of the expanding component can be obtained. h 3 is: The convex mirror, located to the left of the expanding assembly, has a focal length of f1 and shares a focal point 2 with the convex lens 2. Light rays 3, parallel to the optical axis, are reflected by the convex mirror, and light rays 4 are projected onto the off-axis... h 4 o'clock. It can be known that... h 4 is: Similarly, we can obtain h 5 is: The distance between the photosensitive element and the concave lens 1 is l Then the distance between the projection point of ray 5 and the optical axis is... h y for: The following is a typical size: f 0 = 50mm; f 1 = 50mm; f 2 = 70mm; d =5mm; l =80mm; αThe range is -3° to 3°; Calculated h y The range is 23.768mm - 76.114mm. h y The minimum value is greater than h The maximum value of 1 is 7.620mm, and light 5 will not shine on the reflector. When the minimum change in tilt angle is 0.001°, h y The change in light spot size is 8.7 μm, therefore the pixel size of the photosensitive element must be less than 8.7 μm. In this embodiment, the photosensitive element is a CCD line scan camera or a CMOS line scan camera, with a pixel size of less than 5 μm. The core advantage of using a CCD or CMOS line scan camera with a pixel size of less than 5 μm as the photosensitive element is its ability to accurately capture the minute spot displacement after optical magnification. According to calculations in this embodiment, when the tilt resolution reaches 0.001°, the change in spot displacement is only 8.7 μm. The small pixel size ensures that this minute change can be effectively detected, thereby achieving sub-arcsecond high-resolution measurement. Simultaneously, the digital output characteristics of the line scan camera facilitate signal processing and precise quantization. Combined with the optical magnification system, this fully leverages the overall detection accuracy, preventing the sensor's own resolution from becoming a bottleneck in system performance.

[0027] The technical solution of this embodiment also includes a convex mirror, which is fixed inside the housing and disposed on the exit side of the expanding assembly. Its optical axis is collinear with the optical axis of the expanding assembly, and its focal point is the same as the focal point of the last convex lens of the expanding assembly. In this design, the detection beam amplified by the angle expander is projected onto the convex mirror and reflected back to the angle expander. After a second amplification, it exits from the incident side of the angle expander to the photosensitive element. This design achieves a "secondary amplification" effect in the optical path. The small change in the incident angle is amplified by the angle expander for the first time, then the beam is projected onto the convex mirror and reflected, and then passes back through the angle expander in the opposite direction. This process is equivalent to the light undergoing two angle amplification actions by the angle expander, which increases the proportionality (i.e., the magnification factor) between the offset distance of the final outgoing light and the initial angle α by a factor of two. This makes the response of the light spot displacement on the photosensitive element to small changes in angle extremely significant, greatly improving the resolution of the entire device.

[0028] Example 2: like Figure 5 As shown, the fundamental difference between this embodiment and Embodiment 1 is that the reflective element is set as a common reflective element, one part of which is placed between the incident convex lens and the expanding component, and the other part extends to the outgoing light path of the expanding component to reflect and fold the light and project it upward. The photosensitive element is placed on the upper part of the expanding component to receive the light.

[0029] Furthermore, the installation position of the shared reflector element satisfies: Within the maximum positive and negative tilt angle measurement range, the beam projection area from the incident convex lens does not overlap with the beam projection area from the expanding assembly.

[0030] In this embodiment, the equivalent distance from the angle-expanding component to the photosensitive element is: l 1+ l 2. The size is much larger than that in Example 1, which can further improve the sensitivity within the effective size space, while ensuring the compactness of the detection device.

[0031] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on," "mounted on," "fixed to," or "set on" another element, it may be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0034] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A tilt detection device based on the principle of optical angle magnification, comprising a rotating shaft and an angle-expanding assembly, characterized in that, A swing assembly is rotatably mounted on the shaft, and the swing assembly always points in the vertical direction under the action of gravity. A laser is installed on the swing assembly to emit a detection beam. An incident convex lens and a reflector are arranged in sequence below the optical path of the detection beam. After passing through the incident convex lens, the detection beam enters the reflector. The detection beam is deflected by 90° and then projected onto the angle-expanding assembly. The deflected beam is parallel to the optical axis of the angle-expanding assembly and is located on the same side of the optical axis. The angle-expanding component is used to receive the light beam from the reflective element and amplify the angle. The amplified light beam enters the photosensitive element, which is used to detect the position of the light spot. In actual use, the laser follows the swing assembly to rotate relative to the incident convex lens, so that the detection beam forms an incident angle with respect to the optical axis of the incident convex lens, and the photosensitive element determines the tilt angle based on the detected spot displacement.

2. The tilt detection device based on the optical angle magnification principle according to claim 1, characterized in that, It also includes a housing, and the rotating shaft, incident convex lens, angle expansion assembly, photosensitive element and reflector are all fixedly installed inside the housing and tilt together with the housing.

3. The tilt detection device based on the optical angle magnification principle according to claim 2, characterized in that: The swing assembly includes a bushing rotatably mounted on a rotating shaft, a swing rod fixedly mounted at the bottom of the bushing, and a weight fixedly mounted at the bottom end of the swing rod. The entire swing assembly rotates around the rotating shaft and always points in the direction of the plumb bob under the action of the weight.

4. The tilt detection device based on the optical angle magnification principle according to claim 3, characterized in that: The laser is fixedly mounted on the bushing and swings around the shaft together with the bushing. The detection beam emitted by the laser always passes through the axis of the shaft, which is also the focal point of the incident convex lens. The laser light passes through the focal point and is projected onto the incident convex lens, so that the detection beam forms a parallel beam parallel to the optical axis of the incident convex lens after passing through the incident convex lens.

5. The tilt detection device based on the optical angle magnification principle according to claim 4, characterized in that: The reflective element is configured as a plane mirror or a right-angle total reflection mirror. The reflective element is located in the optical path between the incident convex lens and the expanding component, and is used to rotate the parallel beam from the incident convex lens by 90° and project it onto the expanding component. The emitted light rays from the reflective element are all parallel to the optical axis of the expansion component, and within the tilt angle measurement range, the light rays are all on the same side of the optical axis.

6. The tilt detection device based on the optical angle magnification principle according to claim 4, characterized in that: The expanding component is used to increase the distance between the off-axis incident light ray parallel to the optical axis of the expanding component and the optical axis, or to increase the angle between the oblique incident light ray and the optical axis of the expanding component. The expanding angle assembly includes multiple coaxial convex and concave lenses, which are arranged alternately in pairs, and each convex lens and its adjacent concave lenses on the same side share the same focal point.

7. The tilt detection device based on the optical angle magnification principle according to claim 6, characterized in that, It also includes a convex mirror, which is fixed inside the housing and is located on the exit side of the expanding assembly. Its optical axis is collinear with the optical axis of the expanding assembly, and its focal point is the same as the focal point of the last convex lens of the expanding assembly. The detection beam, amplified by the angle-expanding component, is projected onto the convex mirror and then reflected back to the angle-expanding component. After being amplified a second time, it exits from the incident side of the angle-expanding component to the photosensitive element.

8. The tilt detection device based on the optical angle magnification principle according to claim 7, characterized in that: The photosensitive element is configured as a CCD linear array camera or a CMOS linear array camera, with a pixel size of less than 5μm.

9. The tilt detection device based on the optical angle magnification principle according to claim 4, characterized in that: The reflective element is a shared reflective element, with one part placed between the incident convex lens and the expanding angle assembly, and the other part extending into the outgoing light path of the expanding angle assembly, for projecting the outgoing light beam from the expanding angle assembly onto the photosensitive element after secondary deflection.

10. The tilt detection device based on the optical angle magnification principle according to claim 9, characterized in that: The installation position of the shared reflective element satisfies: Within the maximum positive and negative tilt angle measurement range, the beam projection area from the incident convex lens does not overlap with the beam projection area from the expanding assembly.

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