High-precision and wide-range sensing device and method based on vortex interference

Abstract

The invention relates to the technical field of optical interference measurement, and discloses a high-precision and wide-range sensing device and method based on vortex interference, and the method comprises the steps: a light source outputs linear polarization laser, the linear polarization laser enters a light field regulation and control unit, and a pair of polarization orthogonal perfect vortex light beam arrays with triple concentric structures are generated; the two light beam arrays are separated by the polarization beam splitting unit and respectively enter the sensing unit and the compensation unit; the sensing parameter to be measured causes the optical path change of the sensing unit; the compensation unit compensates the optical path of the sensing unit when no sensing parameter to be measured exists; after passing through the sensing unit and the compensation unit, the light beam array is reflected back to the polarization beam splitting unit again for beam combination, and enters the detection unit; the detection unit detects the annular interference fringes of the triple concentric structure, and obtains the information of the to-be-detected sensing parameter according to the change of the interference fringes when the to-be-detected sensing parameter responds or not. A special light source and a complex system structure are not needed, and high detection sensitivity and a large detection range are achieved.

Description

Technical Field

[0001] This invention relates to the field of optical interferometry technology, and in particular to a high-precision, large-range sensing device and method based on vortex interferometry. Background Technology

[0002] Interferometry is a precision measurement method based on the principle of beam interference. It features high sensitivity, non-contact operation, and wide applicability, and can be used to detect characteristics such as refractive index, temperature, pressure, surface defects, and stress distribution. It has wide applications in sensing fields such as component identification, morphology detection, and defect detection. This method constructs the required interference fringes by superimposing two or more coherent beams carrying a certain phase difference. The distribution characteristics of the interference fringes reflect the phase information of the object under test. By analyzing the phase information introduced by the object, the characteristic information of the object can be obtained.

[0003] For detection phases exceeding 2π, the periodicity of the interference fringes makes it difficult to directly identify the corresponding phase based on their position. Furthermore, the accuracy of the refractive index detection is limited by the width of the interference fringes. Introducing multi-wavelength, multi-beam interference can improve the detection phase range and accuracy, but it places high demands on the light source and detection system, leading to increased measurement costs and system complexity.

[0004] Optical vortex beams possess unique optical effects. For example, their spiral phase structure causes interference fringes to exhibit spiral or ring patterns, which is helpful for studying the orbital angular momentum characteristics of vortex light. The interference between multiple vortex light fields can also present novel intensity and phase distribution characteristics, making their optical properties widely applicable in the field of precision sensing and measurement. For instance, application number CN202311505714.3, entitled "A High-Precision Angle Measurement Device and Method Based on Vortex Light Interference," utilizes a laser beam, which is split into a test beam and a reference beam by a beam splitter. These beams are then incident on an image acquisition unit to obtain a phase-shifted interferogram. By analyzing and demodulating the phase-shifted interferograms acquired before and after displacement, phase information can be obtained, and the displacement of the planar transmitting mirror can be calculated. Compared to traditional laser interference fringe counting, this method enables rapid and high-precision angle measurement. The structure of a linear guide rail meshing with a turntable allows for large-range angle measurements. However, this method is only used for angle measurement and requires coordination with a moving platform, gear rack, turntable, and translation guide rail, thus limiting its application scenarios. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a high-precision, large-range sensing device and method based on vortex interferometry, which can realize high-precision, large-range sensing parameter detection, and relies on only a single wavelength light source with a simple optical path structure.

[0006] This invention is achieved using the following technical solution: a high-precision, large-range sensing device based on vortex interferometry, comprising: a light source, an optical field modulation unit, a polarization beam splitting unit, a sensing unit, a compensation unit, and a detection unit. The light source is used to introduce linearly polarized laser light, which is incident on the optical field modulation unit. The optical field modulation unit is used to modulate the incident linearly polarized laser light into a first horizontally or vertically polarized vortex beam array and a second vertically or horizontally polarized vortex beam array, both propagating collinearly and with phase conjugation. Each vortex beam array consists of three perfect vortex beams with different radii. The topological charges of the first and second vortex beam arrays in different radial directions are l0, -l0, -l0 and -l0, l0, l0, respectively. The first and second vortex beam arrays are incident on the polarization beam splitting unit.

[0007] The polarization beam splitting unit includes a polarization beam splitter, which is used to separate the first vortex beam array and the second vortex beam array generated by the optical field modulation unit and respectively incident them onto the sensing unit and the compensation unit, and to combine the first vortex beam array and the second vortex beam array reflected back by the sensing unit and the compensation unit and incident them onto the detection unit.

[0008] The sensing unit is used to introduce optical path change related to the sensing parameter to be measured into the first vortex beam array, and to reflect the modulated first vortex beam array back to the polarization beam splitter.

[0009] The compensation unit is used to introduce a fixed compensation optical path to the second vortex beam array, reflect the second vortex beam array back to the polarization beam splitting unit, and combine it with the first vortex beam array reflected by the sensing unit, and then incident it onto the detection unit.

[0010] The detection unit is used to detect the vortex interference pattern of the triple concentric structure generated by the coherence of the first vortex beam array and the second vortex beam array. By comparing the change in the rotation angle of the interference pattern with and without the sensor parameter to be measured, the relevant information of the sensor parameter to be measured can be obtained. The detection sensitivity is improved by combining the changes of the innermost ring and the second outermost ring interference patterns, and the detection range is improved by combining the changes of the outermost ring and the second outermost ring interference patterns.

[0011] A high-precision, large-range sensing method based on vortex interferometry, using a high-precision, large-range sensing device based on vortex interferometry, includes the following steps:

[0012] Step 1: Turn on the light source so that the output linearly polarized laser passes through the optical field control unit to generate a first vortex beam array with collinear propagation, phase conjugation, and triple concentric structure, and a second vortex beam array with vertical or horizontal polarization, which are then incident on the polarization beam splitting unit.

[0013] Step 2: The polarization beam splitter separates the first vortex beam array and the second vortex beam array. The first vortex beam array is incident on the sensing unit, and the second vortex beam array is incident on the compensation unit.

[0014] Step 3: The first vortex beam array passes through the sensing unit and is then reflected back to the polarization beam splitting unit. The sensing unit has an optical path difference when there is no response from the sensing parameter to be measured and when there is a response from the sensing parameter to be measured. The optical path difference reflects the information of the sensing parameter to be measured.

[0015] Step 4: The second vortex beam array passes through the compensation unit and is then reflected back to the polarization beam splitter unit along the original path. The optical path of the compensation unit is equal to the optical path of the sensing unit when there are no sensing parameters to be measured.

[0016] Step 5: The reflected first and second vortex beam arrays are combined in the polarization beam splitter unit and incident on the detection unit;

[0017] Step 6: The detection unit records the interference fringe images of the triple concentric structure of the first vortex beam array and the second vortex beam array when there is no response of the sensor parameter to be measured in the sensing unit and when there is a response of the sensor parameter to be measured.

[0018] Step 7: By comparing the interference fringe images with and without the response of the sensor parameter to be measured, extract the optical path difference of the response of the sensor parameter to be measured, and obtain the corresponding sensor parameter magnitude based on the relationship between the sensor parameter to be measured and the optical path difference it causes.

[0019] Step 8: Improve the detection range by varying the relative rotation angles of the outermost and second outermost ring interference fringes in the interference fringe image of the triple concentric structure, and improve the detection sensitivity by varying the relative rotation angles of the innermost and second outermost ring interference fringes in the interference fringe image of the triple concentric structure.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The present invention provides a high-precision, large-range sensing device and method based on vortex interferometry, which can amplify the rotation angle of interference fringes caused by phase changes, thereby improving detection accuracy; it can identify the rotation period of a single interference fringe based on the relative rotation angle difference between the two interference fringes of the outermost and second outermost rings, thereby achieving phase magnitude detection of more than one period, improving detection range, and thus achieving high-precision, large-range sensing parameter detection, reducing the limitations of interferometric measurement technology in detection accuracy and detection range.

[0022] 2. The present invention provides a high-precision, large-range sensing device based on vortex interferometry, which relies on only a single-wavelength light source and a simple optical path structure, thereby reducing the limitations of interferometric measurement technology in detection accuracy and detection range. Compared with traditional multi-wavelength, multi-beam interferometric systems, it has lower cost and complexity.

[0023] 3. The present invention provides a high-precision, large-range sensing method based on vortex interferometry, which improves the detection range by varying the relative rotation angles of the outermost and second outermost ring interference fringes in a triple concentric interference fringe image, and improves the detection sensitivity by varying the relative rotation angles of the innermost and second outermost ring interference fringes in a triple concentric interference fringe image. It is simple to operate and convenient to use. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the high-precision, large-range sensing device based on vortex interferometry in this invention.

[0025] Figure 2 This is a connection diagram of the high-precision, large-range sensing device based on vortex interferometry in this invention;

[0026] Figure 3 This is a schematic diagram illustrating the implementation process of the high-precision, large-range sensing method based on vortex interferometry in this invention.

[0027] In the figure, 110-Optical field control unit; 111-Annular optical field generating device; 112-Composite vortex waveplate; 113-First quarter-wave plate; 120-Polarization beam splitter unit; 121-Polarization beam splitter; 130-Sensing unit; 131-Second quarter-wave plate; 132-Sensor device; 133-First reflector; 140-Compensation unit; 141-Third quarter-wave plate; 142-Second reflector; 150-Detection unit; 151-Polarizer; 152-Camera; 200-Light source. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0029] The purpose of this invention is to address the shortcomings of existing technologies by providing a high-precision, large-range sensing device and method based on vortex interferometry.

[0030] Example 1

[0031] A high-precision, large-range sensing device based on vortex interferometry, referring to... Figure 1 As shown, it includes: a light source 200, a light field control unit 110, a polarization beam splitting unit 120, a sensing unit 130, a compensation unit 140, and a detection unit 150. In this embodiment, the light source 200 can be a helium-neon laser, and the output laser is linearly polarized continuous light with a center wavelength of 632.8 nm. Linearly polarized laser output from light source 200 is incident on optical field control unit 110, generating a first and second linearly polarized vortex beam array with collinear propagation, phase conjugation, and triple concentric structure. Polarization beam splitting unit 120 separates the first and second vortex beam arrays. After separation, the first and second vortex beam arrays are incident on sensing unit 130 and compensation unit 140, respectively. Sensing unit 130 introduces optical path changes related to the measured sensing parameters for the first vortex beam array, and compensation unit 140 introduces a fixed compensation optical path for the second vortex beam array. After passing through sensing unit 130 and compensation unit 140, the first and second vortex beam arrays return along their original paths and are combined by polarization beam splitting unit 120 before being incident on detection unit 150. Detection unit 150 detects the interference fringe image of the triple concentric structure generated by the interference of the first and second vortex beam arrays. Based on the different radial interference fringe distributions, sensing parameter information with high precision and large range is extracted.

[0032] Reference Figure 2As shown, specifically, the optical field modulation unit 110 includes a purely transmissive annular optical field generating device 111, a composite vortex waveplate 112, and a first quarter-wave plate 113 arranged opposite to each other. It is used to modulate the linearly polarized laser emitted by the light source 200 into a first vortex beam array with collinear propagation and phase conjugate horizontal or vertical polarization and a second vortex beam array with vertical or horizontal polarization. Each vortex beam array is composed of three perfect vortex beams with different radii, equal radial spacing, and narrow ring width. The topological charges corresponding to the first vortex beam array and the second vortex beam array are l0, -l0, -l0 and -l0, l0, l0, respectively.

[0033] The annular light field generating device 111 in this embodiment can be fabricated using quartz glass. A corresponding two-dimensional structure is etched using nanofabrication technology. It is used to introduce linearly polarized laser light emitted from the light source 200 into a two-dimensional modulation phase distribution, generating a triple concentric annular light field, which is then incident on the composite vortex waveplate 112. The modulation phase of the annular light field generating device is divided into three phase regions along the radial direction. Each radial phase region is used to modulate the incident linearly polarized laser light to generate an annular light field. The entire annular light field generating device 111 will generate a triple concentric annular light field, consisting of three annular light fields with different radii, equal radial spacing, and narrow ring widths.

[0034] The composite vortex waveplate 112 in this embodiment can be fabricated from a liquid crystal polymer device and is placed opposite to the annular light field generating device 111. The composite vortex waveplate 112 is divided into three phase modulation regions along the radial direction, corresponding one-to-one with the three phase regions of the annular light field generating device 111. These three phase modulation regions of the composite vortex waveplate 112 can introduce vortex phases with topological charges of l0, -l0, -l0 and -l0, l0, l0, respectively, into the left-hand and right-hand circularly polarized components of the incident laser. A first quarter-wave plate 113 is placed opposite the composite vortex waveplate 112, with its corresponding fast axis direction forming a 45-degree angle with the horizontal direction. This first quarter-wave plate is used to modulate the left-hand and right-hand circularly polarized components of the incident laser into horizontal and vertical polarizations.

[0035] Specifically, the polarization beam splitter 120 is composed of a polarization beam splitter 121, which can be a polarization beam splitter prism made of quartz glass. It is placed opposite to the first quarter-wave plate 113 to separate the first vortex beam array and the second vortex beam array generated by the optical field modulation unit 110 and respectively incident them onto the sensing unit 130 and the compensation unit 140. It also combines the first vortex beam array and the second vortex beam array reflected back from the sensing unit 130 and the compensation unit 140 and incident them onto the detection unit 150.

[0036] Specifically, the sensing unit 130 includes a second quarter-wave plate 131, a sensor element 132, and a first reflector 133. It is used to introduce optical path changes related to the measured sensing parameters into the first vortex beam array and reflect the modulated first vortex beam array back to the polarization beam splitting unit. The measured sensing parameters include temperature, pressure, etc. The second quarter-wave plate 131 is placed opposite the polarization beam splitting unit 120, with its corresponding fast axis forming a 45-degree angle with the horizontal direction. It is used to rotate the polarization direction of the first vortex beam array passing back and forth through the second quarter-wave plate 131 by 90 degrees. In this embodiment, the sensor element 132 is placed opposite the second quarter-wave plate 131, presenting a rectangular, sealed air chamber with light passing through both sides. One side is divided into two substructures along the radial direction. One substructure is a ring-shaped piston structure, which can change the gas volume inside the chamber by sensing parameters such as temperature and pressure, thereby adjusting the gas density inside the chamber. The other substructure is a light-transmitting region where the propagation path length of the light beam is fixed. This substructure has a ring-shaped recess that matches the size of the outermost perfect vortex beam in the first vortex beam array. This ring-shaped recess causes a difference in the path length of the outermost perfect vortex beam and the two inner perfect vortex beams through the chamber region. The first vortex beam array passes through sensor 132 and then enters the first reflector 133. The first reflector 133 is placed opposite sensor 132 to return the first vortex beam array along its original path, passing sequentially through sensor 132 and the second quarter-wave plate 131. At this point, the polarization direction of the first vortex beam array becomes either vertical or horizontal.

[0037] Specifically, the compensation unit 140 includes a third quarter-wave plate and a second reflector, used to introduce a fixed compensation optical path for the second vortex beam array and reflect the second vortex beam array back to the polarization beam splitting unit 120. The reflected second vortex beam array and the first vortex beam array reflected back by the sensing unit 130 are combined in the polarization beam splitting unit 120 and incident on the detection unit 150; the third quarter-wave plate 141 is placed opposite to the polarization beam splitting unit 120, with its corresponding fast axis direction forming a 45-degree angle with the horizontal direction, used to rotate the polarization direction of the first vortex beam array passing through the third quarter-wave plate 141 by 90 degrees; the second reflector 142 is placed opposite to the third quarter-wave plate 141, and is composed of a ring-shaped reflector unit and a reflector unit with a ring-shaped aperture, introducing different delay amounts for the outermost ring beam and the two inner ring beams of the second vortex beam array. The second vortex beam array, after being reflected by the second reflector 142, returns along its original path and passes again through the third quarter-wave plate 141. At this point, the polarization direction of the second vortex beam array changes to horizontal or vertical polarization. The returning first and second vortex beam arrays are combined in the polarization beam splitting unit 120 and incident on the detection unit 150.

[0038] Specifically, the detection unit 150 includes a polarizer 151 and a camera 152, used to detect the interference patterns of the first vortex beam array and the second vortex beam array. By comparing the changes in the pattern rotation angle with and without the measured sensing parameter, information related to the measured sensing parameter is obtained. The detection sensitivity is improved by combining the changes in the innermost and second outermost ring interference patterns, and the detection range is improved by combining the changes in the outermost and second outermost ring interference patterns. The polarizer 151 can be an absorptive polarizer, placed opposite the polarization beam splitting unit 120, used to select the components of the first and second vortex beam arrays in the 45-degree polarization direction and incident them into the camera 152. In this embodiment, the camera 152 can be a CMOS camera in the prior art, such as Basler's acA1920-25gm / gc camera, used to record the interference images of the first and second vortex beam arrays. Based on the three annular interference fringes of different radial directions recorded by the camera 152, high-precision and large-range sensing parameter detection can be achieved.

[0039] Example 2

[0040] A high-precision, large-range sensing method based on vortex interferometry is proposed, using the high-precision, large-range sensing device based on vortex interferometry described in Embodiment 1, with reference to... Figure 3 As shown, the specific process includes the following:

[0041] Step 1: Turn on the light source 200 so that the output linearly polarized laser passes through the optical field control unit 110 to generate the first vortex beam array with horizontal or vertical polarization and the second vortex beam array with vertical or horizontal polarization, which have collinear propagation, phase conjugation and triple concentric structure, and are incident on the polarization beam splitting unit 120.

[0042] Step 2: The polarization beam splitter 120 separates the first vortex beam array and the second vortex beam array. The first vortex beam array is incident on the sensing unit 130, and the second vortex beam array is incident on the compensation unit 140.

[0043] Step 3: The first vortex beam array passes through the sensing unit 130 and is then reflected back to the polarization beam splitting unit 120. The sensing unit 130 has an optical path difference when there is no response from the sensing parameter to be measured and when there is a response from the sensing parameter to be measured. The optical path difference reflects the information of the sensing parameter to be measured.

[0044] Step 4: The second vortex beam array passes through the compensation unit 140 and is then reflected back to the polarization beam splitting unit 120. The optical path of the compensation unit 140 is equal to that of the sensing unit 130 when there are no sensing parameters to be measured.

[0045] Step 5: The reflected first and second vortex beam arrays are combined in the polarization beam splitter unit 120 and incident on the detector unit 150.

[0046] Step 6: The detection unit 150 records the interference fringe images of the triple concentric structure of the first vortex beam array and the second vortex beam array when there is no response of the sensor parameter to be measured in the sensing unit 130 and when there is a response of the sensor parameter to be measured.

[0047] Step 7: By comparing the interference fringe images with and without the response of the sensor parameter to be measured, the optical path difference of the response of the sensor parameter to be measured is extracted, and the magnitude of the corresponding sensor parameter is obtained according to the relationship between the sensor parameter to be measured and the optical path difference it causes.

[0048] Step 8: The detection range is increased by adjusting the relative rotation angle of the outermost and second outermost ring interference fringes in the triple concentric interference fringe image, and the detection sensitivity is increased by adjusting the relative rotation angle of the innermost and second outermost ring interference fringes in the triple concentric interference fringe image. This enables the detection of sensing parameters with a large range and high precision. The operation is simple and the measurement is convenient.

[0049] Example 3

[0050] A high-precision, large-range sensing device based on vortex interferometry, wherein the linearly polarized laser output by the light source 200 first passes through the optical field control unit 110; the optical field control unit 110 includes a ring optical field generating device 111, a composite vortex waveplate 112, and a first quarter-wave plate 113 whose fast axis forms a 45-degree angle with the horizontal direction.

[0051] The modulation phase of the ring-shaped optical field generating device 111 is divided into three phase regions along the radial direction. Each radial phase region is used to modulate the incident ray-polarized laser to generate a ring-shaped optical field. The entire ring-shaped optical field generating device 111 will generate a ring-shaped optical field array consisting of three ring-shaped optical fields with different radii, equal radial spacing, and narrow ring widths. The modulation phase distribution corresponding to the ring-shaped optical field generating device 111 can be expressed as:

[0052] , (1a)

[0053] in,

[0054] , (1b)

[0055] Where r and θ correspond to radial and angular polar coordinates, respectively, k0 is the incident light wave vector, f is the device focal length, and a i R represents the distance from the center of different annular regions. i Let be the outer diameter of the i-th annular region.

[0056] The incident light field (linearly polarized laser output from light source 200) will generate a triple concentric annular light field after passing through the annular light field generating device 111 and propagating a distance f, that is:

[0057] , (2)

[0058] Where A is the amplitude, r1, r2, and r3 correspond to the radii of the three ring components of the ring light field, and R0 is the ring width of each ring component in the ring light field.

[0059] The composite vortex waveplate 112 is divided into three phase modulation regions along the radial direction, corresponding one-to-one with the three phase regions of the ring light field generating device 111. These three phase modulation regions of the composite vortex waveplate 112 can introduce vortex phases with topological charges of l0, -l0, l0 and -l0, l0, -l0, respectively, into the left-hand and right-hand circularly polarized components of the incident laser. The modulation phase distribution carried by the linearly polarized beam after passing through the composite vortex waveplate 112 can be represented by a Jones matrix as follows:

[0060] (3a)

[0061] in,

[0062] , (3b)

[0063] Here, β represents the fast axis distribution of each pixel unit in the composite vortex waveplate 112, and mod represents the remainder operation. According to equations (3a) and (3b), the composite vortex waveplate 112 can introduce conjugate vortex phases for different circular polarization components, and the topological charge of the corresponding vortex phase has three different discrete values ​​along the radial direction.

[0064] The first quarter-wave plate 113, whose fast axis direction forms a 45-degree angle with the horizontal direction, is used to modulate the left-hand and right-hand circular polarization components of the incident laser into horizontal and vertical polarization.

[0065] The linearly polarized laser output from light source 200, after passing through optical field modulation unit 110, generates a collinear propagating, phase-conjugated horizontally or vertically polarized first vortex beam array and a vertically or horizontally polarized second vortex beam array, namely:

[0066] , (4a)

[0067] , (4b)

[0068] Where θ is the azimuth angle, l1, l2, and l3 are the topological charges of different annular components in the vortex beam array, l1 = -l2 = l3 = l0, and l0 is a set topological charge value.

[0069] The first vortex beam array and the second vortex beam array are separated after passing through the polarization beam splitter 120.

[0070] The separated first vortex beam array is incident on the sensing unit 130 composed of the second quarter-wave plate 131, the sensor 132, and the first reflector 133;

[0071] The second quarter-wave plate 131 modulates the polarization direction of the incident horizontally or vertically polarized first vortex beam array into left-hand or right-hand circular polarization, after which the first vortex beam array is incident on the sensor device 132.

[0072] The sensor 132 introduces different optical paths to the outermost ring of the perfect vortex beam and the two inner rings of the incident first vortex beam array. The first vortex beam array passes through the sensor 132 and is then incident on the first reflector 133.

[0073] The first reflecting mirror 133 returns the first vortex beam array along its original path, passing sequentially through the sensor 132 and the second quarter-wave plate 131. At this point, the polarization direction of the first vortex beam array becomes either vertical or horizontal. The total optical path lengths of the outermost, second outermost, and innermost perfect vortex beams of the first vortex beam array when passing through the sensing unit 132 under conditions of no sensing parameter response and with sensing parameter response are L, (α-1)L / α, (α-1)L / α and nL, (α-1)nL / α, (α-1)nL / α, respectively. Where α is a proportionality coefficient and n is the air refractive index with sensing parameter response.

[0074] The separated second vortex beam array is incident into the compensation unit 140, which is composed of a third quarter-wave plate 141 and a second reflector 142;

[0075] The third quarter-wave plate 141 modulates the polarization direction of the incident vertically or horizontally polarized second vortex beam array into right-hand or left-hand circular polarization, and then incident it onto the second reflecting mirror 142.

[0076] The second reflector 142, composed of a ring-shaped reflector unit and a reflector unit with a ring-shaped aperture, introduces different delays to the outermost ring beam and the two inner ring beams of the second vortex beam array. After being reflected by the second reflector 142, the second vortex beam array returns along its original path and passes through the third quarter-wave plate 141 again. At this time, the polarization direction of the second vortex beam array becomes horizontal or vertical polarization. The total optical path lengths of the outermost, second outermost, and innermost perfect vortex beams of the second vortex beam array in the compensation unit 140 are L, (α-1)L / α, and (α-1)L / α, respectively. The returning first and second vortex beam arrays will be combined in the polarization beam splitting unit 120 and incident on the detection unit 150.

[0077] The detection unit 150 includes a polarizer 151 and a camera 152; the polarizer 151 extracts the components of the first vortex beam array and the second vortex beam array in the 45-degree polarization direction, and then directs the first vortex beam array and the second vortex beam array into the camera 152.

[0078] Camera 152 acquires interference images of the first vortex beam array and the second vortex beam array, namely:

[0079] (5)

[0080] Where A is the amplitude, r1, r2, and r3 correspond to the radii of the three perfect annular vortex beams from the inside out, R is the ring width of the perfect vortex beam, k0 is the wave vector, n is the air refractive index caused by the sensor parameter to be measured, (n-1)L is the optical path difference change of the inner two annular interference modes of the first and second vortex beam arrays caused by the sensor parameter to be measured, and (α-1)nL / α is the optical path difference change of the outer annular interference modes of the first and second vortex beam arrays caused by the sensor parameter to be measured.

[0081] The variation of the rotation angle of different radial regions of the interference fringes recorded by camera 152 with optical path difference can be expressed by the following formula:

[0082] (6)

[0083] Equation (6) shows that the two interference fringes of the innermost and second outermost rings rotate in opposite directions, and the corresponding rotation angle difference Δθ is k0(n-1)L / l0, which is twice the rotation angle of a single interference fringe (θ1 or θ2). Therefore, the overall change characteristics of the two interference fringes of the innermost and second outermost rings can amplify the magnitude of the interference fringe rotation angle caused by the phase change, thereby achieving a twofold improvement in detection accuracy. The two interference fringes of the outermost and second outermost rings rotate in the same direction, but there is a difference in rotation speed. The corresponding rotation angle difference is k0(n-1)L / (2αl0), which is 1 / α times the rotation angle of a single interference fringe (θ1 or θ2). When a single interference fringe rotates by 2απ, the rotation angle difference between the two interference fringes of the outermost and second outermost rings changes by 2π. Therefore, the rotation period of a single interference fringe can be identified based on the relative rotation angle difference between the two interference fringes of the outermost and second outermost rings, thus enabling phase magnitude detection exceeding one period and achieving an α-fold increase in detection range. This allows for high-precision, large-range sensing parameter detection, reducing the limitations of interferometry technology in detection accuracy and range.

[0084] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-precision, large-range sensing device based on vortex interferometry, characterized in that, include: The light source (200), the light field control unit (110), the polarization beam splitting unit (120), the sensing unit (130), the compensation unit (140), and the detection unit (150) are included. The light source (200) is used to introduce linearly polarized laser light, which is incident on the light field control unit (110). The optical field modulation unit (110) is used to modulate the incident linearly polarized laser into a first vortex beam array and a second vortex beam array with collinear propagation and phase conjugate horizontal or vertical polarization. Each vortex beam array consists of three perfect vortex beams with different radii. The topological charges of the first vortex beam array and the second vortex beam array in different radial directions are l0, -l0, -l0 and -l0, l0, l0, respectively. The first vortex beam array and the second vortex beam array are incident on the polarization beam splitting unit (120). The polarization beam splitting unit (120) includes a polarization beam splitter 121, which is used to separate the first vortex beam array and the second vortex beam array generated by the optical field modulation unit (110) and respectively incident them onto the sensing unit (130) and the compensation unit (140), and combine the first vortex beam array and the second vortex beam array reflected back from the sensing unit (130) and the compensation unit (140) and incident them onto the detection unit (150). The sensing unit (130) is used to introduce optical path change related to the sensing parameter to be measured into the first vortex beam array and reflect the modulated first vortex beam array back to the polarization beam splitter (120). The compensation unit (140) is used to introduce a fixed compensation optical path to the second vortex beam array, reflect the second vortex beam array back to the polarization beam splitting unit (120), and combine it with the first vortex beam array reflected by the sensing unit (130) and incident it onto the detection unit (150). The detection unit (150) is used to detect the vortex interference pattern of the triple concentric structure generated by the coherence of the first vortex beam array and the second vortex beam array. By comparing the change in the rotation angle of the interference pattern with and without the sensor parameter to be measured, the relevant information of the sensor parameter to be measured can be obtained. The detection sensitivity is improved by combining the changes of the innermost ring and the second outermost ring interference patterns, and the detection range is improved by combining the changes of the outermost ring and the second outermost ring interference patterns.

2. The high-precision, large-range sensing device based on vortex interferometry according to claim 1, characterized in that: The light field control unit (110) includes a ring light field generating device (111), a composite vortex waveplate (112), and a first quarter-wave plate (113). The ring light field generating device (111) is used to modulate the linearly polarized laser emitted by the light source (200) into a ring light field array with a linearly polarized triple concentric structure, and the ring light field with the triple concentric structure is incident on the composite vortex wave plate (112). The composite vortex waveplate (112) is used to introduce conjugate modulation phases to different circularly polarized components of the annular optical field of the triple concentric structure, and to introduce different vortex phase modulations to different radial regions of each circularly polarized component, thereby generating a first vortex beam array with collinear propagation, phase conjugation, and triple concentric structure with left-hand or right-hand circular polarization and a second vortex beam array with right-hand or left-hand circular polarization. The first vortex beam array and the second vortex beam array are incident on the first quarter-wave plate (113). The first quarter-wave plate (113) has its fast axis at a 45-degree angle to the horizontal direction, and is used to modulate the left-handed or right-handed circularly polarized first vortex beam array and the right-handed or left-handed circularly polarized second vortex beam array into a horizontally or vertically polarized first vortex beam array and a vertically or horizontally polarized second vortex beam array, which are then incident on the polarization beam splitting unit (120).

3. The high-precision, large-range sensing device based on vortex interferometry according to claim 2, characterized in that: The sensing unit (130) includes a second quarter-wave plate (131), a sensor element (132), and a first reflector (133). The second quarter-wave plate (131) has a fast axis direction at a 45-degree angle to the horizontal direction, and is used to change the polarization direction of the incident horizontally or vertically polarized first vortex beam array to left-handed or right-handed circular polarization, and the left-handed or right-handed circularly polarized first vortex beam array is incident on the sensor device (132). The sensor (132) has a rectangular sealed air chamber with light passing through both sides. One side is divided into two substructures along the radial direction. One substructure is an annular piston structure, which can adjust the gas density of the air chamber by sensing parameters such as temperature and pressure. The other substructure is a light-passing area with a fixed path length. This substructure has an annular depression that matches the size of the outermost perfect vortex beam in the first vortex beam array. The existence of this annular depression causes a difference in the path length of the outermost perfect vortex beam in the first vortex beam array and the two inner perfect vortex beams through the air chamber area. The first vortex beam array is incident on the first reflector (133) after passing through the sensor (132). The first reflector (133) returns the incident first vortex beam array along its original path and passes through the sensor (132) and the second quarter-wave plate (131) in sequence. At this time, the polarization direction of the first vortex beam array is modulated by the second quarter-wave plate (131) to be vertical or horizontal polarization and is incident on the polarization beam splitting unit (120).

4. The high-precision, large-range sensing device based on vortex interferometry according to claim 3, characterized in that: The compensation unit (140) includes a third quarter-wave plate (141) and a second reflector (142). The third quarter-wave plate (141) has its fast axis at a 45-degree angle to the horizontal direction, and is used to modulate the incident vertically or horizontally polarized second vortex beam array into right-hand or left-hand circular polarization. The second vortex beam array is incident on the second reflector (142) after passing through the quarter-wave plate. The second reflector (142) is composed of a ring-shaped reflector unit and a reflector unit with a ring-shaped aperture. It introduces different delays to the outermost ring beam and the two inner ring beams in the second vortex beam array. After being reflected by the second reflector (142), the second vortex beam array returns along the original path and passes through the third quarter-wave plate (141) again. At this time, the polarization direction of the second vortex beam array becomes horizontal or vertical polarization.

5. The high-precision, large-range sensing device based on vortex interferometry according to claim 4, characterized in that: The detection unit (150) includes a polarizer (151) and a camera (152). The polarizer (151) has a polarization direction at a 45-degree angle to the horizontal direction, allowing only the 45-degree polarization components of the first and second vortex beam arrays after being combined by the polarization beam splitting unit (120) to pass through, and the first and second vortex beam arrays of the polarizer (151) are incident on the camera (152). The camera (152) records the interference patterns of the first vortex beam array and the second vortex beam array.

6. A high-precision, large-range sensing method based on vortex interferometry, using the high-precision, large-range sensing device based on vortex interferometry as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Turn on the light source (200) so that the output linearly polarized laser passes through the optical field control unit (110) to generate a first vortex beam array with horizontal or vertical polarization and a second vortex beam array with vertical or horizontal polarization, which are collinearly propagated, phase conjugate, and triple concentric structure, and are incident on the polarization beam splitting unit (120). Step 2: The polarization beam splitter (120) separates the first vortex beam array and the second vortex beam array. The first vortex beam array is incident on the sensing unit (130), and the second vortex beam array is incident on the compensation unit (140). Step 3: The first vortex beam array passes through the sensing unit (130) and is then reflected back to the polarization beam splitting unit (120) along the original path. The sensing unit (130) has an optical path difference when there is no response from the sensing parameter to be measured and when there is a response from the sensing parameter to be measured. The optical path difference reflects the information of the sensing parameter to be measured. Step 4: The second vortex beam array passes through the compensation unit (140) and is then reflected back to the polarization beam splitter unit (120) along the original path. The optical path of the compensation unit (140) is equal to that of the sensing unit (130) when there are no sensing parameters to be measured. Step 5: The reflected first and second vortex beam arrays are combined in the polarization beam splitting unit (120) and incident on the detection unit (150). Step 6: The detection unit (150) records the interference fringe images of the triple concentric structure of the first vortex beam array and the second vortex beam array when there is no response of the sensor parameter to be measured in the sensing unit (130) and when there is a response of the sensor parameter to be measured. Step 7: By comparing the interference fringe images with and without the response of the sensor parameter to be measured, the optical path difference of the response of the sensor parameter to be measured is extracted, and the magnitude of the corresponding sensor parameter is obtained according to the relationship between the sensor parameter to be measured and the optical path difference it causes. Step 8: Improve the detection range by varying the relative rotation angles of the outermost and second outermost ring interference fringes in the triple concentric interference fringe image, and improve the detection sensitivity by varying the relative rotation angles of the innermost and second outermost ring interference fringes in the triple concentric interference fringe image.

7. The high-precision, large-range sensing device based on vortex interferometry according to claim 2, characterized in that: The ring light field generating device (111) is used to generate a ring light field with a triple concentric structure, and the corresponding modulation phase distribution can be expressed as follows: ， （1a） in, ， （1b） Where r and θ correspond to radial and angular polar coordinates, respectively, k0 is the incident light wave vector, f is the device focal length, and a i R represents the distance from the center of different annular regions. i Let be the outer diameter of the i-th annular region; the linearly polarized laser output from the light source 200 will generate a triple concentric annular light field after passing through the annular light field generating device (111) and propagating a distance f, that is: ， （2） Where A is the amplitude, r1, r2, and r3 correspond to the radii of the three ring components of the ring light field, and R0 is the ring width of each ring component in the ring light field. The composite vortex waveplate (112) can introduce conjugate modulation phases to different circularly polarized components of the incident triple concentric ring light field, and introduce different vortex phase modulations to different radial ring light spot regions of different circularly polarized components of the ring light field, thereby generating a first vortex beam array with collinear propagation, phase conjugation, triple concentric structure, and left-hand or right-hand circularly polarized vortex beam array and a second vortex beam array with right-hand or left-hand circularly polarized vortex beam array. The modulation phase distribution carried by the linearly polarized beam after passing through the composite vortex waveplate (112) can be represented by a Jones matrix as follows: （3a） in, ， （3b） Where β is the fast axis distribution of each pixel unit in the composite vortex wave plate (112), and mod is the modulo operation; According to equations (3a) and (3b), the composite vortex waveplate (112) can introduce conjugate vortex phases for different circular polarization components, and the topological charge of the corresponding vortex phase has three different discrete values ​​along the radial direction. The first quarter-wave plate (113) is controlled to modulate the left-handed or right-handed circularly polarized first vortex beam array and the right-handed or left-handed circularly polarized second vortex beam array into a horizontally or vertically polarized first vortex beam array and a vertically or horizontally polarized second vortex beam array. The output first vortex beam array and second vortex beam array can be represented as follows: ， （4a） ， （4b） Where θ is the azimuth angle, l1, l2, and l3 are the topological charges of different annular components in the vortex beam array, l1 = -l2 = l3 = l0, and l0 is a set topological charge value.

8. The high-precision, large-range sensing device based on vortex interferometry according to claim 3, characterized in that: The second quarter-wave plate (131) is controlled to modulate the polarization direction of the incident horizontally or vertically polarized first vortex beam array to left-hand or right-hand circular polarization, and the first vortex beam array is incident on the sensor device (132). The sensor (132) introduces different optical paths to the outermost ring of the perfect vortex beam and the two inner rings of the incident first vortex beam array. The first vortex beam array is then incident on the first reflector (133) after passing through the sensor (132). The first reflector (133) returns the first vortex beam array along its original path, passing sequentially through the sensor (132) and the second quarter-wave plate (131). At this time, the polarization direction of the first vortex beam array becomes vertical or horizontal polarization. The total optical path lengths of the perfect vortex beams of the outermost ring, the second outermost ring, and the innermost ring of the first vortex beam array when passing through the sensing unit (130) under the conditions of no sensing parameter response and with sensing parameter response are L, (α-1)L / α, (α-1)L / α and nL, (α-1)nL / α, (α-1)nL / α, respectively, where α is a proportionality coefficient and n is the air refractive index with sensing parameter response.

9. The high-precision, large-range sensing device based on vortex interferometry according to claim 4, characterized in that: The third quarter-wave plate (141) is controlled to modulate the polarization direction of the incident vertically or horizontally polarized second vortex beam array to right-hand or left-hand circular polarization, and the second vortex beam array is incident on the second reflector (142). The second reflector (142) is composed of a ring-shaped reflector unit and a reflector unit with a ring-shaped aperture. It introduces different delays to the outermost ring beam and the two inner ring beams of the second vortex beam array. After being reflected by the second reflector (142), the second vortex beam array returns along the original path and passes through the third quarter-wave plate (141) again. At this time, the polarization direction of the second vortex beam array becomes horizontal or vertical polarization. The total optical path of the outermost ring, the second outermost ring, and the innermost ring perfect vortex beams of the second vortex beam array in the compensation unit (140) is L, (α-1)L / α, and (α-1)L / α, respectively. The returning first vortex beam array and the second vortex beam array will be combined in the polarization beam splitting unit (120) and incident on the detection unit (150).

10. The high-precision, large-range sensing device based on vortex interferometry according to claim 5, characterized in that: The polarizer (151) is controlled to extract the components of the first vortex beam array and the second vortex beam array in the 45-degree polarization direction, and the first vortex beam array and the second vortex beam array are incident on the camera (152). The camera (152) is controlled to acquire interference images of the first vortex beam array and the second vortex beam array, i.e. (5) Where A is the amplitude, r1, r2, and r3 correspond to the radii of the three perfect vortex beams from the inside out, R is the ring width of the perfect vortex beam, k0 is the wave vector, n is the air refractive index caused by the sensor parameter to be measured, (n-1)L is the optical path difference change of the inner two ring interference modes of the first and second vortex beam arrays caused by the sensor parameter to be measured, and (α-1)nL / α is the optical path difference change of the outer ring interference modes of the first and second vortex beam arrays caused by the sensor parameter to be measured. The rotation angle of different radial regions of the interference fringes recorded by the camera (152) varies with the optical path difference, which can be expressed by the following formula: (6) Equation (6) shows that the two interference fringes of the innermost ring and the second outermost ring rotate in opposite directions, and the corresponding rotation angle difference Δθ is k0(n-1)L / l0, which is twice the rotation angle of a single interference fringe. Therefore, the overall change characteristics of the two interference fringes of the innermost ring and the second outermost ring can amplify the rotation angle of the interference fringes caused by the phase change. The two interference fringes of the outermost ring and the second outermost ring rotate in the same direction, and there is a difference in rotation speed. The corresponding rotation angle difference is k0(n-1)L / (2αl0), which is 1 / α times the rotation angle of a single interference fringe (θ1 or θ2). When a single interference fringe rotates by 2απ, the rotation angle difference between the two interference fringes of the outermost ring and the second outermost ring changes by 2π. Therefore, the rotation period of a single interference fringe can be identified based on the relative rotation angle difference between the two interference fringes of the outermost ring and the second outermost ring, thereby realizing the detection of phase size exceeding one period and achieving an α-fold increase in detection range.

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