Multi-axis high-precision acceleration sensor based on monochromatic light interference

Abstract

The invention discloses a multi-axis high-precision acceleration sensor based on monochromatic light interference, which comprises an optical system unit, a sensing structure unit and an image sensor which are sequentially arranged in the X-axis direction, and further comprises a signal processing unit, the sensing structure unit comprises an outer frame and a mass block movably arranged in the outer frame; elastic pieces are connected between the two opposite sides of the mass block in the Y-axis direction and the outer frame and between the two opposite sides of the mass block in the Z-axis direction and the outer frame respectively. The mass block is provided with a first double-slit structure and a second double-slit structure. Two gaps of the first double-gap structure extend in the Y-axis direction; two gaps of the second double-gap structure extend in the Z-axis direction; the image sensor is used for collecting interference fringe images formed after monochromatic light passes through the first double-slit structure and the second double-slit structure; the signal processing unit is connected with the image sensor. According to the monochromatic light double-slit interference principle, the acceleration in the Y-axis direction and the Z-axis direction can be measured, and the measurement sensitivity is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a multi-axis high-precision acceleration sensor based on monochromatic light interference. BACKGROUND

[0002] As the core sensing unit of inertial measurement systems, acceleration sensors play an indispensable role in navigation and attitude control, earthquake monitoring and early warning, industrial automation equipment, aerospace and consumer electronics, etc. According to the different physical sensing mechanisms, traditional acceleration sensors can be mainly divided into several categories such as capacitive, piezoresistive, resonant and optical types. Among them, capacitive acceleration sensors have become the mainstream technology path in the medium and low precision market due to their good compatibility with standard CMOS process, relatively low manufacturing cost, and easy system integration. However, such sensors often face inherent problems such as large detection nonlinearity, mutual restriction between range and resolution in the design of sensitive structure, which limits their application potential in ultra-high precision measurement scenarios. Piezoresistive acceleration sensors rely on the resistance change of piezoresistive materials under stress to realize signal conversion, and have the advantages of simple structure and strong output signal. However, their sensitive elements are extremely sensitive to temperature changes, and there is a significant temperature drift phenomenon, which requires complex temperature compensation circuits or algorithms to maintain measurement stability, which greatly increases the complexity and cost of system design.

[0003] Resonant acceleration sensors use frequency as the output signal, have the characteristics of quasi-digital output, strong anti-interference ability, and can achieve extremely high measurement precision and long-term stability. However, such sensors usually require their mechanical resonators to work in a vacuum environment to maintain high mechanical quality factors, and must be vacuum packaged. This not only increases the process difficulty and manufacturing cost, but also faces not small problems in miniaturization and integration. In contrast, optical accelerometers based on optical heterodyne detection or fiber optic interference principles can achieve extremely high resolution and dynamic range, and have shown high research and application value in special fields such as precision earthquake monitoring and scientific experiments. The existing optical systems usually have complex structure, large volume, high energy consumption, and high manufacturing cost, which are difficult to meet the current development requirements of sensor miniaturization, low power consumption and low cost.

[0004] In recent years, with the continuous breakthrough of micro-electro-mechanical system and nanometer processing technology, and the rise of emerging applications such as Internet of Things, smart wear, micro unmanned aerial vehicle, implantable medical device, the market puts forward more stringent requirements on the performance indicators of acceleration sensor. The long-term stability, environmental adaptability and batch manufacturing cost of the sensor are also higher. In the face of the urgent needs of these high-end application scenarios, the acceleration sensor based on traditional physical principle has gradually encountered technical bottleneck in performance improvement. Its inherent material characteristics, structure limitation and working mechanism are difficult to realize fundamental breakthrough within the existing technical framework. Therefore, exploring new type of acceleration sensor based on new physical effect and innovative architecture has become an important research direction in the field of sensing technology and an urgent need of industrial development. It is not only the inevitable requirement to promote the inertial technology to a new stage, but also the key cornerstone to support the development of self-determination, miniaturization and high performance of next generation intelligent system and high-end equipment. SUMMARY

[0005] In view of the above technical problems, the purpose of the present application is to provide a multi-axis high-precision acceleration sensor based on monochromatic light interference, which can measure the acceleration in Y-axis direction and Z-axis direction by using the principle of monochromatic light double-slit interference, has high measurement sensitivity and strong practicality.

[0006] The technical solution of the present application is as follows: a multi-axis high-precision acceleration sensor based on monochromatic light interference, comprising an optical system unit, a sensing structure unit and an image sensor arranged in sequence in the X-axis direction, and a signal processing unit; The sensing structure unit comprises an outer frame and a mass block movably arranged in the outer frame. A plurality of groups of elastic members are connected between the opposite sides of the mass block in the Y-axis direction and the outer frame, and between the opposite sides of the mass block in the Z-axis direction and the outer frame. A first double-slit structure and a second double-slit structure penetrating along the X-axis direction are arranged on the mass block; the two slits of the first double-slit structure extend along the Y-axis direction; the two slits of the second double-slit structure extend along the Z-axis direction. The optical system unit is used for delivering monochromatic light to the first double-slit structure and the second double-slit structure. The image sensor is used for collecting the interference fringe image formed after the monochromatic light passes through the first double-slit structure and the second double-slit structure. The signal processing unit is connected with the image sensor, and is used for extracting the phase change of the interference fringe according to the interference fringe image, and calculating the acceleration value according to the phase change. The calculation formula between the phase change of the interference fringe and the acceleration is as follows:

[0007] in, λ is the phase change value, d is the wavelength, d is the distance between the two gaps of the first double-slit structure or the second double-slit structure, m is the equivalent mass of the mass block, k is the equivalent elastic coefficient, and a is the acceleration value.

[0008] Furthermore, the optical system unit includes a laser source, an optical fiber, and a microlens arranged sequentially in the X-axis direction; the laser source is used to output a monochromatic coherent beam; the monochromatic coherent beam is collimated by the optical fiber and the microlens and then incident on the first double-slit structure and the second double-slit structure.

[0009] Furthermore, the two slits of the first double-slit structure and the two slits of the second double-slit structure are distributed on the four sides of a virtual rectangle, and the ends of the two slits of the first double-slit structure and the ends of the two slits of the second double-slit structure are far apart from each other.

[0010] Furthermore, the accelerometer includes a housing; the optical system unit, sensing structure unit, image sensor, and signal processing unit are all encapsulated within the housing; and the outer frame is fixedly connected to the housing.

[0011] Furthermore, two sets of elastic elements are arranged side by side on each side of the mass block.

[0012] Furthermore, the elastic element is a helical spring sheet.

[0013] Furthermore, the image sensor is a CCD sensor or a CMOS sensor.

[0014] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. This invention utilizes the cooperative use of sensing structural units. A mass block and an outer frame are connected by an elastic element, allowing the mass block to move relative to the outer frame in the Y-axis and Z-axis directions. A first double-slit structure and a second double-slit structure are arranged on the mass block. Utilizing the principle of monochromatic double-slit interference, when acceleration causes displacement of the mass block, it directly leads to a translation of the double-slit interference fringes. An image sensor captures the interference fringes and extracts the minute phase changes of these fringes. This allows for the calculation of acceleration values. The combination of these methods, utilizing the monochromatic double-slit interference principle, enables the measurement of acceleration in both the Y and Z axes, offering high sensitivity and strong practicality. Furthermore, the acceleration measurement process avoids the electrical noise and contact friction inherent in traditional capacitive or piezoresistive sensing, achieving nanometer-level high-resolution measurement with significantly higher accuracy than traditional techniques.

[0015] 2. This invention connects the mass block to the outer frame using several sets of elastic elements. By rationally designing the mechanical properties of these elastic elements, the mass block can be constrained to move only in the Y-axis and Z-axis directions, while suppressing unnecessary vibrations in the X-axis direction. This enables true multi-axis sensing and significantly reduces inter-axis crosstalk, ensuring the independence and accuracy of acceleration measurements in each direction, thus providing a guarantee for precise measurements in complex dynamic environments.

[0016] 3. This invention integrates the optical system unit, sensing structure unit, and image sensor into a compact structure with a small size. Furthermore, the changes in interference fringes, as an intermediate signal, are a quasi-digital quantity, less susceptible to analog circuit noise and temperature drift. The signal processing unit directly decodes the fringe image, converting physical displacement into precise phase information, giving the entire system outstanding advantages such as strong anti-interference capability and good long-term stability. Attached Figure Description

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a three-dimensional structural diagram of the sensing structure unit of the present invention; Figure 3 for Figure 1 A three-dimensional structural diagram from another perspective; The components include: 1. Optical system unit; 11. Laser source; 12. Optical fiber; 13. Microlens; 2. Sensing structure unit; 21. Outer frame; 22. Mass block; 221. First double-slit structure; 222. Second double-slit structure; 23. Elastic element; 3. Image sensor; 4. Signal processing unit; 5. Housing. Detailed Implementation

[0018] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0019] like Figures 1-3 The illustration shows a multi-axis high-precision accelerometer based on monochromatic light interferometry as described in this embodiment. The accelerometer includes an optical system unit 1, a sensing structure unit 2, and an image sensor 3 arranged sequentially along the X-axis, as well as a signal processing unit 4. The optical system unit 1 includes a laser source 11, an optical fiber 12, and a microlens 13 arranged sequentially along the X-axis. The microlens 13 is positioned closer to the sensing structure unit 2 than the optical fiber 12. The laser source 11 generates a monochromatic coherent beam. This monochromatic coherent beam is directed towards the sensing structure unit 2 via the optical fiber 12 and the microlens 13.

[0020] The aforementioned sensing structure unit 2 includes an outer frame 21 and a mass block 22. The outer frame 21 is an annular structure with an inner cavity extending along the X-axis. The mass block 22 is arranged within the inner cavity of the outer frame 21, having a front facing the optical system unit 1 and a back facing the image sensor 3. Several sets of elastic members 23 are connected between the mass block 22 and the outer frame 21 on opposite sides in the Y-axis direction, and between the mass block 22 and the outer frame 21 on opposite sides in the Z-axis direction. These elastic members 23 provide elastic force in the Y-axis and Z-axis directions, allowing the mass block 22 to move relative to the outer frame 21 in the Y-axis and Z-axis directions. Two sets of elastic members 23 are arranged side-by-side on each side of the mass block 22. The elastic members 23 are helical spring sheets as used in the prior art. Several sets of helical springs connect the mass block 22 to the outer frame 21. By rationally designing the mechanical properties of the elastic element 23, the mass block 22 can be constrained to move only in the Y-axis and Z-axis directions, while suppressing unnecessary vibrations in the X-axis direction. This enables true multi-axis sensing, greatly reduces inter-axis crosstalk, ensures the independence and accuracy of acceleration measurements in each direction, and provides a guarantee for precise measurements in complex dynamic environments.

[0021] In this embodiment, a first double-slit structure 221 and a second double-slit structure 222 are machined on the aforementioned mass block 22. The first double-slit structure 221 and the second double-slit structure 222 penetrate the front and back surfaces of the mass block 22 along the X-axis. The two slits of the first double-slit structure 221 extend along the Y-axis. The two slits of the second double-slit structure 222 extend along the Z-axis. Specifically, the front or back surface of the mass block 22 forms a virtual rectangle. The two slits of the first double-slit structure 221 and the two slits of the second double-slit structure 222 are distributed on the four sides of the virtual rectangle, and the ends of the two slits of the first double-slit structure 221 and the two slits of the second double-slit structure 222 are far apart from each other.

[0022] The aforementioned optical system unit 1 is used to deliver monochromatic light to the first double-slit structure 221 and the second double-slit structure 222. Specifically, the laser source 11 generates a monochromatic coherent beam. This monochromatic coherent beam is collimated by the optical fiber 12 and the microlens 13 and then incident on the first double-slit structure 221 and the second double-slit structure 222, thereby forming interference fringes on the back side of the mass block 22. The aforementioned image sensor 3 is used to acquire the image of the interference fringes formed after the monochromatic light passes through the first double-slit structure 221 and the second double-slit structure 222. The image sensor 3 is a CCD sensor or a CMOS sensor in the prior art.

[0023] The aforementioned signal processing unit 4 is connected to the image sensor 3 and is used to extract the phase change of the interference fringes based on the interference fringe image using a sub-pixel level image processing algorithm, and to calculate the acceleration value based on the phase change. The formula for calculating the relationship between the phase change of the interference fringes and the acceleration is as follows: ; in, λ is the phase change value, d is the wavelength, d is the distance between the two gaps of the first double-slit structure 221 or the second double-slit structure 222, m is the equivalent mass of the mass block 22, k is the equivalent elastic coefficient, and a is the acceleration value.

[0024] In this embodiment, to meet the requirements for acceleration measurement and practical application, the aforementioned optical system unit 1, sensing structure unit 2, image sensor 3, and signal processing unit 4 are all encapsulated within the housing 5. The aforementioned outer frame 21 is fixedly connected to the housing 5, or the outer frame 21 and the housing 5 can be designed as an integral structure to save costs.

[0025] In practical application, utilizing the principle of monochromatic double-slit interference, when acceleration causes displacement of mass block 22 in the Y-axis and Z-axis directions, it directly leads to translation of the double-slit interference fringes. The interference fringes are captured using image sensor 3, and a sub-pixel-level image processing algorithm is used to extract the minute phase changes of these interference fringes. The acceleration value is calculated according to the formula. In the above method, the principle of monochromatic double-slit interference is used to measure acceleration in both the Y and Z axes, achieving high sensitivity and practicality. Furthermore, the acceleration measurement process avoids the electrical noise and contact friction of traditional capacitive or piezoresistive sensing, achieving nanometer-level high-resolution measurement with significantly higher accuracy than traditional techniques. The optical system unit 1, sensing structure unit 2, and image sensor 3 are integrated together, resulting in a compact structure and small size. Moreover, the changes in interference fringes, as an intermediate signal, are a quasi-digital quantity, less susceptible to analog circuit noise and temperature drift. The signal processing unit 4 directly decodes the fringe image, converting physical displacement into precise phase information, giving the entire system strong anti-interference capabilities and excellent long-term stability.

[0026] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A multi-axis high-precision accelerometer based on monochromatic light interferometry, comprising an optical system unit, a sensing structure unit, an image sensor, and a signal processing unit arranged sequentially along the X-axis; characterized in that: The sensing structure unit includes an outer frame and a mass block movably disposed within the outer frame; Several sets of elastic elements are connected between the opposite sides of the mass block in the Y-axis direction and the outer frame, and between the opposite sides of the mass block in the Z-axis direction and the outer frame. The mass block is provided with a first double-slit structure and a second double-slit structure that extend through the X-axis; the two slits of the first double-slit structure extend along the Y-axis; the two slits of the second double-slit structure extend along the Z-axis. The optical system unit is used to deliver monochromatic light to the first double-slit structure and the second double-slit structure; The image sensor is used to acquire interference fringe images formed after monochromatic light passes through the first double-slit structure and the second double-slit structure; The signal processing unit is connected to the image sensor and is used to extract the phase change of the interference fringes from the interference fringe image and calculate the acceleration value based on the phase change. The formula for calculating the relationship between the phase change of the interference fringes and the acceleration is as follows: ； in, λ is the phase change value, d is the wavelength, d is the distance between the two gaps of the first double-slit structure or the second double-slit structure, m is the equivalent mass of the mass block, k is the equivalent elastic coefficient, and a is the acceleration value.

2. The multi-axis high-precision accelerometer based on monochromatic light interferometry according to claim 1, characterized in that: The optical system unit includes a laser source, an optical fiber, and a microlens arranged sequentially along the X-axis; the laser source is used to output a monochromatic coherent beam; the monochromatic coherent beam is collimated by the optical fiber and the microlens and then incident on the first double-slit structure and the second double-slit structure.

3. The multi-axis high-precision accelerometer based on monochromatic light interferometry according to claim 1, characterized in that: The two slits of the first double-slit structure and the two slits of the second double-slit structure are distributed on the four sides of a virtual rectangle, and the ends of the two slits of the first double-slit structure and the ends of the two slits of the second double-slit structure are far apart from each other.

4. The multi-axis high-precision accelerometer based on monochromatic light interference according to claim 1, characterized in that: The accelerometer includes a housing; the optical system unit, sensing structure unit, image sensor, and signal processing unit are all encapsulated within the housing; the outer frame is fixedly connected to the housing.

5. The multi-axis high-precision accelerometer based on monochromatic light interferometry according to claim 1, characterized in that: The elastic element is arranged in two sets on each side of the mass block.

6. The multi-axis high-precision accelerometer based on monochromatic light interferometry according to claim 1, characterized in that: The elastic element is a helical spring sheet.

7. The multi-axis high-precision accelerometer based on monochromatic light interferometry according to claim 1, characterized in that: The image sensor is either a CCD sensor or a CMOS sensor.

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