Polarization correction method and system for line structured light sensor based on reflected polarized light

Abstract

The present disclosure relates to a line structured light sensor polarization correction method and system based on reflected polarized light, the method comprising: obtaining the reflected light intensity of the object surface under different polarization angles, calculating the Stokes vector according to the reflected light intensity, establishing the mapping relationship between the reflected light intensity and the incident angle based on the Fresnel law, obtaining the maximum light intensity and the minimum light intensity; calculating the linear polarization degree based on the maximum light intensity and the minimum light intensity, obtaining the optimal laser incident angle based on the linear polarization degree and the refractive index of the object; constructing a polarization optimization model of the polarization angle and the incident angle by using the Stokes vector, and solving the optimal polarization angle; obtaining the light fringe image under the optimal polarization angle of the polarizer, performing polarization correction on the light fringe image based on the Stokes vector, and realizing three-dimensional measurement of the object. The present disclosure effectively reduces the errors caused by light intensity, incident angle, image quality and other factors, and greatly improves the measurement accuracy.

Description

Technical Field

[0001] This disclosure relates to the field of computer vision technology, and in particular to a polarization correction method and system for a line structured light sensor based on reflected polarized light. Background Technology

[0002] Due to their advantages of non-contact operation and simple structure, line structured light sensors (L-LVS) are widely used in reverse engineering, shape measurement, industrial inspection, identification, and positioning. A line structured light sensor mainly consists of a line structured laser source and a camera. The line structured laser source projects a light plane that intersects with the object's surface, forming a light stripe. The camera captures the image of the light stripe. Through calibration, the equation of the light plane in the camera coordinate system can be obtained, allowing the calculation of the object's three-dimensional (3D) coordinates from the pixel coordinates of the corresponding light stripe center.

[0003] Researchers have proposed numerous methods for calibrating the optical plane. Based on the target, these methods can be categorized into calibration methods based on one-dimensional, two-dimensional, and three-dimensional targets. Based on the principle, they can be categorized into calibration methods based on Plücker lines, uniformity constraints, and vanishing lines. While these methods can achieve optical plane calibration, measurement errors still exist in the calibrated sensor. Measurement errors consist of errors inherent in the calibration process and errors generated during measurement. Regarding measurement errors, some studies have analyzed measurement errors and optical plane calibration errors in line structured light measurement systems based on Taylor expansion and matrix perturbation principles, establishing error propagation models. However, these models only address the principle of invariant cross-ratio, exhibiting high limitations and computational costs. Other studies have established error models for line structured light measurement systems for applications such as pipe inner wall detection, but these models are only applicable to this scenario and lack versatility. Additionally, some studies have implemented metrological evaluation of line structured light scanning systems using standard gauges, but this method is inefficient and time-consuming. These methods can assess the systematic errors of line structured light scanning systems; however, most existing methods only independently evaluate single sources of system error in line structured light sensors and propose corresponding solutions, failing to integrate all major error sources in the system. This decentralized approach lacks systematicity and comprehensiveness, making it difficult to form a complete error assessment and measurement system. Therefore, its versatility and practicality in real-world applications are limited, and it cannot significantly improve measurement accuracy. Summary of the Invention

[0004] To address the limitations of existing methods in practical applications, such as limited versatility and low measurement accuracy, this disclosure proposes a polarization correction method for line structured light sensors based on reflected polarized light to solve these problems.

[0005] According to one aspect of this disclosure, a polarization correction method for a line structured optical sensor based on reflected polarized light is provided, comprising:

[0006] S10. Obtain the reflected light intensity of the object surface at different polarization angles, calculate the Stokes vector based on the reflected light intensity, establish the mapping relationship between the reflected light intensity and the incident angle based on Fresnel's law, and obtain the maximum and minimum light intensity values.

[0007] S20. The linear polarization degree is calculated based on the maximum and minimum light intensity values. The optimal laser incident angle is obtained based on the linear polarization degree and the refractive index of the object. The optimal laser incident angle is calculated using the following formula:

[0008] ,

[0009] Where n is the refractive index of the object, and θ is the optimal incident angle of the laser. DOLP Let be the degree of linear polarization, where

[0010] ,

[0011] and These represent the maximum and minimum light intensity, respectively.

[0012] S30. Based on the optimal laser incident angle, construct a polarization optimization model of polarization angle and incident angle using Stokes vector, and solve for the optimal polarization angle.

[0013] S40. Obtain a light stripe image of the polarizer at the optimal polarization angle, and perform polarization correction on the light stripe image based on the Stokes vector to achieve three-dimensional measurement of the object.

[0014] Preferably, the Stokes vector is calculated based on the reflected light intensity, and is expressed as:

[0015] ,

[0016] in, Indicates the total light intensity. This represents the variance of the intensity of horizontally polarized light relative to that of vertically polarized light. This represents the variance of light intensity at 45° polarization relative to 135° polarization. This represents the change in light intensity of right-handed circularly polarized flux relative to left-handed circularly polarized flux. , These are the horizontal and vertical components of the amplitude in the light vector, respectively. The phase of the light vector.

[0017] Preferably, the mapping relationship between the reflected light intensity and the incident angle is established based on Fresnel's law, expressed as:

[0018] ,

[0019] ,

[0020] in, and These are the components of the incident and reflected light parallel to the plane of incidence, respectively. and These are the components of the incident light and the reflected light perpendicular to the incident plane, respectively. The reflection coefficient of the parallel component. The reflection coefficient is the vertical component. Angle of incidence For the angle of refraction, Let be the refractive index of the medium before it reaches the incident surface. The refractive index of the medium after it is incident on the incident surface.

[0021] Preferably, a mapping relationship between reflected light intensity and incident angle is established based on Fresnel's law to obtain the maximum and minimum light intensity values, including:

[0022] The direction of light transmission is adjusted by rotating the polarizer in front of the camera. When the direction of light transmission of the polarizer is consistent with the polarization direction of the reflected light, the intensity of the detected reflected light reaches its maximum value, which is the component of the reflected light perpendicular to the incident plane. When the transmission direction of the polarizer is perpendicular to the polarization direction of the reflected light, the detected intensity of the reflected light reaches its minimum value, which is the component of the reflected light parallel to the plane of incidence. .

[0023] Preferably, a polarization optimization model for the polarization angle and incident angle is constructed using Stokes vectors, and the optimal polarization angle is solved, expressed as:

[0024] ,

[0025] ,

[0026] In the formula, For the optimal polarization angle, α represents the intensity of the emitted light, and α represents the polarization angle.

[0027] Preferably, polarization correction of the light stripe image based on the Stokes vector includes:

[0028] Extract the polarization phase distribution of the light stripe image and calculate the phase angle based on the Stokes vector;

[0029] Geometric correction of the light stripe image is performed using a pre-calibrated phase angle-pixel offset mapping table;

[0030] The sub-pixel center of the corrected light stripe image is located using the polarization-weighted gray-scale centroid method.

[0031] According to one aspect of this disclosure, a polarization correction system for a line structured optical sensor based on reflected polarized light is provided, comprising:

[0032] The mapping relationship establishment module obtains the reflected light intensity of the object surface under different polarization angles, calculates the Stokes vector based on the reflected light intensity, establishes the mapping relationship between the reflected light intensity and the incident angle based on Fresnel's law, and obtains the maximum and minimum light intensity values.

[0033] The optimal laser incident angle calculation module calculates the degree of linear polarization based on the maximum and minimum light intensity values, and then obtains the optimal laser incident angle based on the degree of linear polarization and the refractive index of the object; wherein, the optimal laser incident angle is calculated by the following formula:

[0034] ,

[0035] Where n is the refractive index of the object, and θ is the optimal incident angle of the laser. DOLP Let be the degree of linear polarization, where

[0036] ,

[0037] and These represent the maximum and minimum light intensity, respectively.

[0038] The optimal polarization angle calculation module, based on the optimal laser incident angle, uses Stokes vectors to construct a polarization optimization model of polarization angle and incident angle, and solves for the optimal polarization angle.

[0039] The three-dimensional measurement module acquires a light stripe image of the polarizer at the optimal polarization angle, and performs polarization correction on the light stripe image based on the Stokes vector to achieve three-dimensional measurement of the object.

[0040] According to one aspect of this disclosure, an electronic device is provided, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to: execute the above-described polarization correction method for a line structured light sensor based on reflected polarized light.

[0041] According to one aspect of this disclosure, a computer-readable storage medium is provided that stores computer program instructions thereon, which, when executed by a processor, implement the above-described polarization correction method for a line structured light sensor based on reflected polarized light.

[0042] Compared to the prior art, the beneficial effects of this disclosure are as follows:

[0043] 1) This disclosure analyzes the relationship between light intensity and incident angle by examining the polarization characteristics of light reflected from the surface of an object. It establishes a model for solving the optimal polarization angle of a polarizer using Stokes vectors and studies the relationship between polarization angle and incident angle, thereby improving the image quality of highly reflective objects and reducing calibration errors.

[0044] 2) This disclosure uses a polarization difference imaging model, which removes scattered light, effectively solves the influence of ambient light, improves the image quality of the measured object, reduces measurement error, and improves measurement accuracy.

[0045] 3) This disclosure constructs a complete polarization angle → incident angle → image processing error control chain, instead of simply using the Stokes vector to find the optimal polarization angle of the polarizer. This system integration has not appeared in previous technologies and can reduce errors by integrating minimum light intensity strategy, incident angle optimization and differential imaging.

[0046] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure.

[0047] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.

[0049] Figure 1 A flowchart of a polarization correction method for a line structured optical sensor based on reflected polarized light is shown.

[0050] Figure 2 A photograph of a highly reflective object being measured according to an embodiment of this disclosure is shown.

[0051] Figure 3 A schematic diagram of a polarization correction system for a line structured light sensor based on reflected polarized light, as shown in an example of this disclosure, is displayed. Detailed Implementation

[0052] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0053] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0054] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0055] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0057] Example 1

[0058] Based on the above ideas, this invention proposes a polarization correction method for line structured light sensors based on reflected polarized light. Figure 1 A flowchart illustrating a polarization correction method for a line-structured optical sensor based on reflected polarized light is shown. The method includes:

[0059] S10. Obtain the reflected light intensity of the object surface at different polarization angles, calculate the Stokes vector based on the reflected light intensity, establish the mapping relationship between the reflected light intensity and the incident angle based on Fresnel's law, and obtain the maximum and minimum light intensity values.

[0060] S20. The linear polarization degree is calculated based on the maximum and minimum light intensity values. The optimal laser incident angle is obtained based on the linear polarization degree and the refractive index of the object. The optimal laser incident angle is calculated using the following formula:

[0061] ,

[0062] Where n is the refractive index of the object, and θ is the optimal incident angle of the laser. DOLP Let be the degree of linear polarization, where

[0063] ,

[0064] and These represent the maximum and minimum light intensity, respectively.

[0065] S30. Based on the optimal laser incident angle, construct a polarization optimization model of polarization angle and incident angle using Stokes vector, and solve for the optimal polarization angle.

[0066] S40. Obtain a light stripe image of the polarizer at the optimal polarization angle, and perform polarization correction on the light stripe image based on the Stokes vector to achieve three-dimensional measurement of the object.

[0067] This disclosure constructs a complete error control chain: optimal laser incident angle → optimal polarization angle → polarization correction of the light fringe image based on Stokes vectors. It does not simply use Stokes vectors to determine the optimal polarization angle of the polarizer; instead, it integrates minimum light intensity strategies, incident angle optimization, and differential imaging to reduce errors. The specific steps of the polarization correction method for line structured light sensors based on reflected polarized light are as follows:

[0068] S10. Obtain the reflected light intensity of the object surface at different polarization angles, calculate the Stokes vector based on the reflected light intensity, establish the mapping relationship between the reflected light intensity and the incident angle based on Fresnel's law, and obtain the maximum and minimum light intensity values.

[0069] In this embodiment, the polarization state of light can be represented by the Stokes parameter. Based on the amplitude component of the light vector in the reflected light intensity , and phase The relationship with the Stokes vector yields the Stokes vector representation as follows:

[0070] ,

[0071] in, Indicates the total light intensity. This represents the variance of the intensity of horizontally polarized light relative to that of vertically polarized light. This represents the variance of light intensity at 45° polarization relative to 135° polarization. This represents the change in light intensity of right-handed circularly polarized flux relative to left-handed circularly polarized flux. , These are the horizontal and vertical components of the amplitude in the light vector, respectively. The phase of the light vector.

[0072] The intensity of light reflected from an object's surface can be divided into two parts: specular reflection intensity and diffuse reflection intensity. When a laser beam strikes an object's surface, part of the light is directly reflected from the surface; this reflected light is called specular reflection intensity. The other part is transmitted into the object's interior, where it undergoes multiple reflections and is scattered back into the incident space; this part is called diffuse reflection intensity. For highly reflective, smooth objects, the intensity of light reflected from the surface is essentially only specular reflection intensity; diffuse reflection intensity is negligible. According to the electromagnetic theory of light, the relationship between the amplitude and phase of the incident and reflected light intensities can be obtained. Based on Fresnel's law, a mapping relationship between the reflected light intensity and the incident angle can be established, expressed as:

[0073] ,

[0074] ,

[0075] in, and These are the components of the incident and reflected light parallel to the plane of incidence, respectively. and These are the components of the incident light and the reflected light perpendicular to the incident plane, respectively. The reflection coefficient of the parallel component. The reflection coefficient is the vertical component. Angle of incidence For the angle of refraction, Let be the refractive index of the medium before it reaches the incident surface. The refractive index of the medium after it is incident on the incident surface.

[0076] In some embodiments, a mapping relationship between reflected light intensity and incident angle is established based on Fresnel's law to obtain the maximum and minimum light intensity values, including:

[0077] The light transmission direction can be adjusted by rotating the polarizer in front of the camera. When the light transmission direction of the polarizer is consistent with the polarization direction of the reflected light, the detected reflected light intensity reaches its maximum value. When the light transmission direction of the polarizer is perpendicular to the polarization direction of the reflected light, the detected reflected light intensity reaches its minimum value.

[0078] The direction of light transmission is adjusted by rotating the polarizer in front of the camera. When the direction of light transmission of the polarizer is consistent with the polarization direction of the reflected light, the intensity of the detected reflected light reaches its maximum value. The maximum light intensity The component of the reflected light perpendicular to the incident plane When the transmission direction of the polarizer is perpendicular to the polarization direction of the reflected light, the detected intensity of the reflected light reaches its minimum value. The minimum light intensity The component of the reflected light parallel to the plane of incidence. .

[0079] S20, Based on the maximum light intensity and minimum light intensity Calculate the degree of linear polarization DOLP Based on the linear polarization degree DOLP The optimal laser incident angle θ is obtained by combining the refractive index n of the object.

[0080] In this embodiment, a polarizer is placed in front of the camera, and the brightness changes as the polarizer is rotated. Assuming the incident plane is at 45°, the reflected light intensity is highest when perpendicular to the incident plane and lowest when parallel to it. This results in a sinusoidal waveform showing the maximum and minimum light intensities: the maximum and minimum light intensities detected during one rotation of the polarizer. The reflected light intensity is highest when the polarizer is aligned with the polarization angle, and lowest when the polarizer is 90° away from the polarization angle.

[0081] By recording the changes in reflected light intensity during one rotation of the polarizer, a sinusoidal waveform is fitted, and the degree of linear polarization is calculated by extracting the maximum and minimum values ​​of reflected light intensity. DOLP And based on the degree of linear polarization DOLP The optimal polarization angle is determined by the functional relationship between the polarization degree and the incident angle, wherein the degree of linear polarization is... DOLP Represented as:

[0082] ,

[0083] Where n is the refractive index of the object and the degree of linear polarization. DOLP That is, it is a function of n and θ; conversely, if the degree of linear polarization is known... DOLP The optimal incident angle θ of the laser can also be determined by the refractive index n of the object.

[0084] Among them, linear polarization degree DOLP It can also be expressed as:

[0085] ,

[0086] and These represent the maximum and minimum light intensity, respectively.

[0087] With the optimal polarization angle, the highlights on the object's surface are eliminated to the greatest extent possible, while the camera can also acquire image information to the maximum extent, greatly reducing errors caused by image quality issues.

[0088] S30. Based on the optimal laser incident angle, construct a polarization optimization model of polarization angle and incident angle using Stokes vectors, and solve for the optimal polarization angle.

[0089] Adjust the incident angle of the laser to the optimal laser incident angle, and then use the Stokes vector to construct a polarization optimization model of the polarization angle and the incident angle; , , Indicates light in , and The light intensities at three different angles can generally be ignored because the circularly polarized component of the light is very small. =0, the Stokes vector can be further expressed as:

[0090] ,

[0091] The Mueller matrix M can also be used to describe the effect of a polarizer. The Mueller matrix changes as the polarization angle α changes. Here, the polarization angle α is the angle at which the polarizer is located.

[0092] ,

[0093] The Mueller matrix M in the formula can also be used to describe the effect of the polarizer. When the polarization angle α changes, the Mueller matrix will also change accordingly.

[0094] Calculate the intensity of the emitted light The optimal polarization angle can be determined as follows:

[0095] ,

[0096] ,

[0097] In the formula, For the optimal polarization angle, α represents the intensity of the emitted light, and α represents the polarization angle.

[0098] S40. Obtain a light stripe image of the polarizer at the optimal polarization angle, and perform polarization correction on the light stripe image based on the Stokes vector to achieve three-dimensional measurement of the object.

[0099] Polarization correction of the light stripe image based on Stokes vectors includes: extracting the polarization phase distribution of the light stripe image and calculating the phase angle based on the Stokes vectors; applying a pre-calibrated phase angle-pixel offset mapping table to perform geometric correction on the light stripe image; and locating the sub-pixel center of the corrected light stripe image using a polarization degree-weighted gray-scale centroid method.

[0100] In this embodiment, multiple light stripe images with different polarization directions are acquired by rotating a polarizer, and the polarization state of each pixel is calculated using Stokes vectors. The polarization phase angle is further calculated using Stokes vectors. The light stripe images are geometrically corrected by combining the polarization phase angle with a pre-calibrated phase angle-pixel offset mapping table. The sub-pixel center of the corrected light stripe image is located using the gray-scale centroid method weighted by linear polarization degree (DOLP). The coordinates of the corrected light stripe center are combined with the pre-calibrated camera parameters and light plane equations, and the three-dimensional coordinates of the object surface are calculated using the principle of triangulation.

[0101] Specifically, the polarization phase angle is established through experimental calibration. α With pixel offset , The mapping relationship is used to correct image distortion caused by polarized light reflection.

[0102] The correction formula is:

[0103] ,

[0104] in, The original image coordinates, For the corrected coordinates, α It is the polarization phase angle.

[0105] By analyzing the polarization phase distribution using Stokes vector analysis, the image distortion problem caused by the polarization characteristics of highly reflective object surfaces was resolved. Combining a phase angle-pixel offset mapping table with the DOLP weighted algorithm significantly improved the sub-pixel accuracy of light stripe center localization.

[0106] To verify the effectiveness of the method in this embodiment, the experimental system was set up mainly consisting of a Daheng camera (1920×1200 pixels resolution), a polarizer, and a laser (wavelength 650mm). The camera measurement distance was approximately 1100mm. The measured objects were metal cylinders and metal blocks with relatively smooth surfaces to ensure strong stability of polarized light. The distance from the laser to the camera to the object was set to less than 1000mm to ensure the accuracy of the results. A polarizer was added in front of the laser, and the polarization angle was adjusted to 0° to ensure that the laser light emitted from the laser was completely horizontally polarized and retained its original polarization state after reflection. This embodiment studies the characteristics of reflected polarized light and optimal polarization differential imaging, focusing on using the characteristics of polarized light to optimize the performance of the line structured light sensor, analyze errors, and reduce errors. The lens focal length mounted on the camera was set to 16mm, the camera aperture was f / 8 (where f represents the aperture number, and f / 8 in this art means an aperture number of 8), and the exposure time was set to 2000ms.

[0107] The method in this embodiment is compared with the method in the literature (Zhu Z, Liu H, Zhang JZ Y. Calibration method of line-structured light sensors based on a hinge-connected target with arbitrary pinch angles[J]. Applied optics, 2023, 62(7): 1695-1703. DOI:10.1364 / ao. 483595.) to measure a 70mm high metal block and a 150mm high metal cylinder. Laser beams are projected onto the measured objects, generating four feature points D1, D2, D3, and D4, as shown below. Figure 2 As shown. Therefore, the measured height of the metal block is:

[0108] ,

[0109] The measured height of the metal cylinder is:

[0110] ,

[0111] The measurement error value (∆d) is calculated based on the actual value of the workpiece. The measured values ​​of the part dimensions are shown in the table below:

[0112]

[0113] The table shows that, compared with the methods in the literature, the root mean square error (RMSE) of the method in this embodiment is reduced to 0.0353 mm and 0.0458 mm, respectively, in the measurement of metal blocks and cylinders, demonstrating smaller measurement errors and higher accuracy. Furthermore, the method in this embodiment also performs better in reducing ambient light interference and improving image quality, thereby effectively reducing errors in the calibration process and improving the reliability of the measurement results.

[0114] The experiments described above validated the effectiveness of the method proposed in this embodiment in achieving high measurement accuracy. Through precise line structure cursor positioning and polarization differential imaging technology, the accuracy and reliability of the measurement were significantly improved. Experimental results demonstrate that this method not only improves measurement accuracy but also enhances the robustness of the system.

[0115] This disclosure proposes a polarization correction method for a line structured light sensor based on reflected polarized light. This method analyzes the relationship between light intensity and incident angle by examining the polarization characteristics of light reflected from an object's surface. Furthermore, a model for determining the optimal polarization angle of the polarizer is established using Stokes vectors, and the relationship between the polarization angle and the incident angle is studied. The optimal laser incident angle is calculated under the optimal polarization angle. Light stripe images are acquired, and the light plane is calibrated. Based on the calibration results, three-dimensional measurements are performed on highly reflective objects. This method effectively integrates the influencing factors of the main error sources of line structured light sensors, allowing them to interact and forming a complete error assessment and measurement system. It effectively reduces errors caused by physical factors such as light intensity, incident angle, and image quality, thereby significantly improving measurement accuracy.

[0116] Example 2

[0117] As another aspect of this disclosure, a polarization correction system 100 for a line structured light sensor based on reflected polarized light is also provided, such as... Figure 3 As shown, it includes:

[0118] The mapping relationship establishment module 1 obtains the reflected light intensity of the object surface under different polarization angles, calculates the Stokes vector based on the reflected light intensity, establishes the mapping relationship between the reflected light intensity and the incident angle based on Fresnel's law, and obtains the maximum and minimum light intensity values.

[0119] The optimal laser incident angle calculation module 2 calculates the degree of linear polarization based on the maximum and minimum light intensity values, and obtains the optimal laser incident angle based on the degree of linear polarization and the refractive index of the object; wherein, the optimal laser incident angle is calculated by the following formula:

[0120] ,

[0121] Where n is the refractive index of the object, and θ is the optimal incident angle of the laser. DOLP Let be the degree of linear polarization, where

[0122] ,

[0123] and These represent the maximum and minimum light intensity, respectively.

[0124] The optimal polarization angle calculation module 3, based on the optimal laser incident angle, uses the Stokes vector to construct a polarization optimization model of the polarization angle and the incident angle, and solves for the optimal polarization angle;

[0125] The three-dimensional measurement module 4 acquires a light stripe image of the polarizer at the optimal polarization angle, performs polarization correction on the light stripe image based on the Stokes vector, and realizes the three-dimensional measurement of the object.

[0126] Without causing contradictions, the above-described modules in the system of the present disclosure embodiments can implement any of the above-described methods.

[0127] Based on the description of the above embodiments, it can be seen that the embodiments of this disclosure can achieve the following technical effects:

[0128] 1) This embodiment of the present disclosure analyzes the relationship between light intensity and incident angle by the polarization characteristics of light reflected from the surface of an object, establishes a solution model for the optimal polarization angle of a polarizer using Stokes vectors, and studies the relationship between polarization angle and incident angle, thereby improving the image quality of highly reflective objects and reducing calibration error.

[0129] 2) The optimal polarization angle calculation module used in this embodiment removes scattered light, effectively solves the influence of ambient light, improves the image quality of the measured object, reduces measurement error, and improves measurement accuracy.

[0130] This disclosure also proposes an electronic device, including: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to perform the aforementioned polarization correction method for a line structured light sensor based on reflected polarized light. The electronic device can be provided as a terminal, a server, or other type of device.

[0131] This disclosure also proposes a computer-readable storage medium storing computer program instructions that, when executed by a processor, implement the aforementioned polarization correction method for a line-structured optical sensor based on reflected polarized light. The computer-readable storage medium may be a non-volatile computer-readable storage medium.

[0132] Those skilled in the art will understand that, in the above-described polarization correction method and system for a linear structured optical sensor based on reflected polarized light in specific embodiments, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0133] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0134] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A polarization correction method for a line structured light sensor based on reflected polarized light, characterized in that, Includes the following steps: S10. Obtain the reflected light intensity of the object surface at different polarization angles, calculate the Stokes vector based on the reflected light intensity, establish the mapping relationship between the reflected light intensity and the incident angle based on Fresnel's law, and obtain the maximum and minimum light intensity values. S20. The degree of linear polarization is calculated based on the maximum and minimum light intensity values. The optimal laser incident angle is then obtained based on the degree of linear polarization and the refractive index of the object. The optimal laser incident angle is calculated using the following formula: ， where n is the refractive index of the object, and θ is the optimal laser incidence angle, DOLP is the degree of linear polarization, where ， and respectively the maximum and minimum light intensity; S30. Based on the optimal laser incident angle, construct a polarization optimization model of polarization angle and incident angle using Stokes vector, and solve for the optimal polarization angle; S40. Obtain a light stripe image of the polarizer at the optimal polarization angle, and perform polarization correction on the light stripe image based on the Stokes vector to achieve three-dimensional measurement of the object. Polarization correction of the light stripe image based on Stokes vectors includes: Extract the polarization phase distribution of the light stripe image and calculate the phase angle based on the Stokes vector; Geometric correction of the light stripe image is performed using a pre-calibrated phase angle-pixel offset mapping table; The sub-pixel center of the corrected light stripe image is located using the polarization-weighted gray-scale centroid method.

2. The method of claim 1, wherein, The Stokes vector is calculated based on the reflected light intensity and is expressed as: ， wherein, represents the total light intensity, represents the variance of the light intensity of the horizontal polarization relative to the vertical polarization, represents the variance of the light intensity of the 45° polarization relative to the 135° polarization, represents the change in the light intensity of the right-handed circular polarization flux relative to the left-handed circular polarization flux, , are the horizontal, vertical components of the amplitude in the light vector, respectively, is the phase of the light vector.

3. The method of claim 2, wherein, Based on Fresnel's law, the mapping relationship between reflected light intensity and incident angle is established as follows: ， ， in, and These are the components of the incident and reflected light parallel to the plane of incidence, respectively. and These are the components of the incident light and the reflected light perpendicular to the incident plane, respectively. The reflection coefficient of the parallel component. The reflection coefficient is the vertical component. Angle of incidence For the angle of refraction, Let be the refractive index of the medium before it reaches the incident surface. The refractive index of the medium after it is incident on the incident surface.

4. The method according to claim 3, characterized in that, Based on Fresnel's law, a mapping relationship between reflected light intensity and incident angle is established, yielding the maximum and minimum light intensity values, including: The direction of light transmission is adjusted by rotating the polarizer in front of the camera. When the direction of light transmission of the polarizer is consistent with the polarization direction of the reflected light, the intensity of the detected reflected light reaches its maximum value, which is the component of the reflected light perpendicular to the incident plane. When the transmission direction of the polarizer is perpendicular to the polarization direction of the reflected light, the detected intensity of the reflected light reaches its minimum value, which is the component of the reflected light parallel to the plane of incidence. .

5. The method according to claim 4, characterized in that, A polarization optimization model for the polarization angle and incident angle is constructed using Stokes vectors, and the optimal polarization angle is solved, expressed as: ， ， In the formula, For the optimal polarization angle, α represents the intensity of the emitted light, and α represents the polarization angle.

6. A polarization correction system for a linear structured optical sensor based on reflected polarized light, characterized in that, include: The mapping relationship establishment module obtains the reflected light intensity of the object surface under different polarization angles, calculates the Stokes vector based on the reflected light intensity, establishes the mapping relationship between the reflected light intensity and the incident angle based on Fresnel's law, and obtains the maximum and minimum light intensity values. The optimal laser incident angle calculation module calculates the degree of linear polarization based on the maximum and minimum light intensity values, and then obtains the optimal laser incident angle based on the degree of linear polarization and the refractive index of the object; wherein, the optimal laser incident angle is calculated by the following formula: ， Where n is the refractive index of the object, and θ is the optimal incident angle of the laser. DOLP Let be the degree of linear polarization, where ， and These represent the maximum and minimum light intensity, respectively. The optimal polarization angle calculation module, based on the optimal laser incident angle, uses Stokes vectors to construct a polarization optimization model of polarization angle and incident angle, and solves for the optimal polarization angle; The three-dimensional measurement module acquires an image of light stripes when the polarizer is located at the optimal polarization angle, and performs polarization correction on the light stripe image based on the Stokes vector to achieve three-dimensional measurement of the object. Polarization correction of the light stripe image based on Stokes vectors includes: Extract the polarization phase distribution of the light stripe image and calculate the phase angle based on the Stokes vector; Geometric correction of the light stripe image is performed using a pre-calibrated phase angle-pixel offset mapping table; The sub-pixel center of the corrected light stripe image is located using the polarization-weighted gray-scale centroid method.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the polarization correction method for a line structured light sensor based on reflected polarized light as described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the polarization correction method for a line structured light sensor based on reflected polarized light as described in any one of claims 1 to 5.

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