In-situ detection method and system for surface roughness of robotized dual-wavelength digital holography under complex scene

Abstract

This invention relates to a robotic dual-wavelength digital holographic in-situ detection method and system for surface roughness in complex scenarios. The method includes the following steps: S1: A robotic arm moves the detection system according to a pre-planned scanning path; S2: A plane measurement module locates the surface to be measured, ensuring that the object light energy in processes S3 and S4 is perpendicularly incident on the plane to be measured; S3: The detection system acquires a hologram of the region to be measured with wavelength λ1; S4: A hologram of the region to be measured with wavelength λ2 is acquired in the same environment; S5: The two holograms acquired in steps S3 and S4 are processed to obtain the phase difference; S6: Using λ 1、 The synthesized wavelength of λ2 and the phase distribution obtained in S5 enable the reconstruction of continuous height information and contour of the surface under test; S7: Based on the data obtained in S6, roughness parameters are calculated according to the definition of surface roughness to characterize the microscopic geometric features of the surface under test. Compared with existing roughness detection technologies, this invention has the advantages of full-field measurement, fast response, and non-contact in-situ online detection.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a robotic dual-wavelength digital holographic in-situ detection method and system for surface roughness in complex scenarios. Background Technology

[0002] Surface roughness is an important parameter reflecting the microscopic geometry of a workpiece surface, and its magnitude directly affects the assembly performance, service life, and overall machining quality of components. With the continuous development of intelligent manufacturing and automated production, rapid, non-contact, and online measurement of workpiece surface roughness has become a crucial research direction in the field of manufacturing inspection, especially in inspection scenarios involving complex curved surfaces or large-sized workpieces, which places higher demands on the spatial adaptability of the inspection system.

[0003] Digital holographic detection technology records the interference information between object light and reference light, and combines it with numerical diffraction reconstruction methods to simultaneously acquire the amplitude and phase information of the surface under test, thereby achieving non-contact, full-field measurement of the surface's three-dimensional morphology. Compared with traditional contour scanning methods, digital holographic detection has advantages such as fast measurement speed, complete information acquisition, and ease of digital processing, showing great application potential in the field of surface morphology and roughness detection. However, existing digital holographic detection methods are mostly based on single-wavelength interferometry, and their measurable height range is limited by the optical wavelength. When the height fluctuation of the surface under test exceeds one wavelength, phase wrapping is prone to occur, leading to ambiguity in the height inversion results and making it difficult to meet the measurement requirements of a large roughness range.

[0004] To extend the unambiguous height range of digital holographic measurements, existing research has proposed using a dual-wavelength interferometry method to achieve continuous measurement of large height variations by constructing equivalent synthetic wavelengths. For example, Chinese patent document CN112665524B discloses a three-dimensional topography detection method for a quartz vibrating beam accelerometer pendulum based on digital holography. This method uses a dual-wavelength digital holographic recording method to perform segmented measurements on a flexible support structure and completes three-dimensional reconstruction through digital extended depth-of-field technology.

[0005] However, existing dual-wavelength digital holographic systems typically rely on multiple light sources or complex beam splitting and combining structures, resulting in a large number of optical elements, complex optical path layouts, and large system size. This hinders overall integration and mobile applications, limiting their use in space-constrained scenarios. Secondly, existing digital holographic surface roughness detection systems are mostly fixed or platform-based structures, lacking effective integration methods with motion platforms such as robotic arms, making it difficult to achieve flexible deployment and attitude adjustment of the detection module in space. Furthermore, existing systems usually require manual adjustment of the position and attitude of the object under test before measurement to ensure that the object beam perpendicularly illuminates the surface. This process is time-consuming and dependent on the operator's experience, making it difficult to automate and standardize measurements.

[0006] Therefore, there is an urgent need for a dual-wavelength digital holographic surface roughness detection method and system that can be integrated with a robotic arm, has automatic adjustment function, and has a compact structure, in order to meet the demand for efficient and accurate measurement of surface roughness of a wide range of complex curved surfaces in modern industrial production. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing digital holographic detection methods, such as phase wrapping when measuring a large roughness range and the large size of dual-wavelength digital holographic systems which are not conducive to overall integration and mobile applications, and to provide a robotic dual-wavelength digital holographic in-situ detection method and system for surface roughness in complex scenarios.

[0008] The objective of this invention can be achieved through the following technical solutions: This solution provides a robotic dual-wavelength digital holographic in-situ surface roughness detection method in complex scenarios, the method comprising the following steps: S1: The robotic arm moves the detection system along the pre-planned scanning path and stops in the area to be tested; S2: The plane to be measured is measured using the plane measurement module of the detection system based on the principle of triangulation. The robotic arm is then adjusted according to the measurement results so that the object light emitted by the dual-wavelength digital holographic detection module of the detection system is perpendicular to the plane to be measured. S3: The dual-wavelength digital holographic detection module emits an object light at wavelength λ1, acquires a hologram of the plane under test at wavelength λ1, and selects the hologram with the best effect. S4: The dual-wavelength digital holographic detection module emits an object light with wavelength λ2 to acquire a hologram of the plane under test with wavelength λ2 under the same conditions as wavelength λ1. S5: Process the two holograms from steps S3 and S4 and obtain the phase difference; S6: Utilizing λ 1、 The synthesized wavelength of λ2 and the phase distribution obtained in S5 are used to reconstruct the continuous height information and contour of the surface of the plane under test; S7: Based on the reconstructed data of the plane to be tested obtained from S6, calculate the roughness parameters according to the definition of surface roughness, and output the detection results.

[0009] Furthermore, in S3, based on Fourier transform, the real-time spectrogram corresponding to the hologram is obtained, and the hologram with the best effect is selected based on the quality of the spectrogram.

[0010] This solution also provides a robotic dual-wavelength digital holographic in-situ surface roughness detection system for complex scenarios, used to implement the aforementioned robotic dual-wavelength digital holographic in-situ surface roughness detection method for complex scenarios. The detection system includes a dual-wavelength digital holographic detection module and a plane measurement module. The dual-wavelength digital holographic detection module includes an optical path unit and a fixing unit. The optical path unit is used to emit object light of various wavelengths and receive reflected light from the plane to be measured. The fixing unit is used to fix the optical path unit. The plane measurement module is used to measure the perpendicular relationship between the object light and the plane to be measured, and to adjust the robotic arm according to the detection results.

[0011] Furthermore, the dual-wavelength digital holographic detection module includes three parallel optical path components. The first optical path component includes a laser source, a laser collimating lens, a zoom beam expander, and a first right-angle optical reflector arranged coaxially in sequence. The second optical path component includes a first beam splitter, a plano-convex lens, a second beam splitter, and a CCD camera arranged coaxially in sequence. The third optical path component includes a second right-angle optical reflector, a neutral density filter, and a third right-angle optical reflector arranged coaxially in sequence. The optical path of the dual-wavelength digital holographic detection module is as follows: the laser generated by the laser source passes through a collimating lens and a zoom beam expander, and is reflected by the first right-angle optical reflector to the first beam splitter, where it is split into two beams. One beam vertically illuminates the plane to be measured, and the reflected light from the plane to be measured passes through the first beam splitter, a plano-convex lens, and the second beam splitter in sequence before being acquired by the CCD camera. The other beam is continuously reflected by the second and third right-angle optical reflectors, and then passes through the second beam splitter before being acquired by the CCD camera.

[0012] Furthermore, the first right-angle optical reflector, the second right-angle optical reflector, and the third right-angle optical reflector have the same structure, each including a right-angle optical adjustment frame and a dielectric film plane mirror, wherein the dielectric film plane mirror is fixed on the inclined surface of the right-angle optical adjustment frame.

[0013] Furthermore, the first right-angle optical reflector is provided with a first adjustable aperture on the side facing the zoom beam expander, which is used to adjust the size of the output laser spot and filter the laser edge; the plano-convex lens is mounted on the coaxial base frame, and the coaxial base frame is provided with a second adjustable aperture on the side facing the second beam splitter, which is used to adjust the light intensity and NA value of the object light.

[0014] Furthermore, the fixing unit includes a base plate and a fixing base; the base plate has multiple parallel sliding grooves, the fixing base is snapped onto the base plate and fixed to the base plate by screws, and each component of the optical path unit is respectively installed on the corresponding fixing base.

[0015] Furthermore, the lower end of the fixed base is provided with a groove, and a slider that cooperates with the sliding groove is provided in the groove. The slider can be slidably engaged in the sliding groove. The fixed base is provided with a fixing waist hole for installing screws. The fixed base is provided with an optical element mounting hole.

[0016] Furthermore, the fixing unit also includes a beam splitter holder, one side of which is provided with a beam splitter placement groove, and both ends of the beam splitter placement groove are respectively covered with fixing tabs. The beam splitter is inserted into the beam splitter placement groove from one end. The bottom end of the beam splitter holder is provided with a mounting hole, and the beam splitter is installed on the fixing base through the mounting hole.

[0017] Furthermore, the planar measurement module includes a system housing, which covers the dual-wavelength digital holographic detection module. The front end of the system housing has three rectangular holes and one light-transmitting hole. Laser displacement sensors are installed in the rectangular holes respectively, and the light-transmitting hole corresponds to the laser emission position of the dual-wavelength digital holographic detection module.

[0018] Compared with the prior art, the present invention has the following advantages: (1) This solution integrates the dual-wavelength digital holographic detection module and the planar measurement module and installs them at the end of the robotic arm. Combined with the multi-degree-of-freedom motion characteristics of the robotic arm, it can achieve high-precision adjustment of the detection area and posture, thereby realizing real-time, non-contact online detection of the roughness of complex curved surfaces. Moreover, the planar measurement module and the robotic arm form a closed-loop feedback control, which can monitor the detection distance and angle in real time and automatically adjust the posture of the robotic arm according to the feedback information to maintain consistent interference conditions, thereby improving the repeatability of the detection results and the stability of the system operation.

[0019] (2) This scheme adopts a compact off-axis optical path structure. By using shared optical elements, optical path folding design, and wavelength sequential switching, dual-wavelength interferometry is achieved, which reduces the system structural complexity and optical path length, improves the stability of optical interference, and reduces the system volume, thus facilitating the mounting of the detection system on a robotic arm. The optical elements adopt an integrated base pad mounting scheme, replacing the traditional column-telescopic rod structure. Through slider adjustment and screw fixing, the miniaturization, compactness, and high stability of the optical path system are achieved, effectively improving the system's vibration resistance and long-term operational reliability.

[0020] (3) Based on the principle of dual-wavelength interference, this scheme uses the synthesized wavelength to convert the phase difference information into a continuous surface height distribution, which effectively solves the problem of height inversion ambiguity caused by the phase wrapping phenomenon in single-wavelength interferometry, significantly expands the measurable height range, and can meet the measurement needs of a large roughness range. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the dual-wavelength digital holographic detection module provided by the present invention; Figure 2 This is a schematic diagram of the structure of the base plate provided by the present invention; Figure 3 This is a schematic diagram of the structure of the fixed base provided by the present invention; Figure 4 This is a schematic diagram of the beam splitter clamping frame structure provided by the present invention; Figure 5 This is a schematic diagram of the planar measurement module structure provided by the present invention; Figure 6 A schematic diagram of the external structure of the system housing provided by the present invention; Figure 7 A schematic diagram of the detection system provided by the present invention mounted on a robotic arm; Figure 8 A flowchart of the detection method provided by the present invention; Explanation of reference numerals in the attached figures: 101. Laser source; 102. Laser collimating lens; 103. Coaxial base frame; 104. Variable magnification beam expander; 105a. First adjustable aperture; 105b. Second adjustable aperture; 106. Right-angle optical adjustment frame; 107a. First dielectric film plane mirror; 107b. Second dielectric film plane mirror; 107c. Third dielectric film plane mirror; 108a. First beam splitter; 108b. Second beam splitter; 109. Plano-convex lens; 110. Neutral density filter; 111. CCD camera; 201, Base plate; 201a, Sliding groove; 201b, Array of fixed threaded holes; 202, Fixed base; 202a, Fixed waist hole; 202b, Groove; 202c, Optical component mounting hole; 202d, Slider; 203, Beam splitter holder; 203a, Beam splitter placement slot; 203b, Fixed lever; 203c, Mounting hole; 301. System housing; 302. Sensor fixture; 303. Laser displacement sensor. Detailed Implementation

[0022] 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 only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] Example 1 like Figure 8 As shown, this embodiment provides a robotic dual-wavelength digital holographic in-situ surface roughness detection method in complex scenarios, including the following steps: S1: The robotic arm moves the detection system along the pre-planned scanning path and stops in the area to be tested; In this step, the robotic arm moves the detection system to the designated area according to a pre-planned scanning path and automatically stops in the area to be tested. The robotic arm can achieve high-precision adjustment of the detection area and posture, thereby realizing real-time, non-contact online detection of the roughness of complex curved surfaces.

[0029] S2: The plane to be measured is measured using the plane measurement module of the detection system based on the principle of triangulation. The robotic arm is then adjusted according to the measurement results so that the object light emitted by the dual-wavelength digital holographic detection module of the detection system is perpendicular to the plane to be measured. In this step, the detection system uses a plane measurement module to accurately locate the plane of the surface to be measured based on the principle of triangulation. The plane measurement module includes a laser displacement sensor, which is fixed inside the system housing by a sensor clamp. Three rectangular holes are opened on the front of the system housing as working holes for the laser displacement sensor. The position and posture of the robotic arm are adjusted based on the measurement results to ensure that the laser beam is perpendicularly incident on the area to be measured during subsequent measurements, thereby improving measurement accuracy.

[0030] S3: The dual-wavelength digital holographic detection module emits an object light at wavelength λ1, acquires a hologram of the plane under test at wavelength λ1, and selects the hologram with the best effect. In this step, the laser source in the dual-wavelength digital holographic detection module generates a laser beam with wavelength λ1. After passing through a collimating lens and a zoom beam expander, the laser beam is reflected by a plane mirror and split into two beams by a beam splitter. One beam illuminates the surface of the area to be measured, while the other beam, after passing through the beam splitter, illuminates a mirror and is reflected to another mirror. Finally, the light reflected by the area to be measured and the mirror is captured by a CCD camera after passing through the beam splitter, forming a hologram. The size of the output laser spot can be changed by adjusting the adjustable aperture, while filtering out areas of uneven laser intensity at the edges. The intensity of the object beam and the NA value can be changed by adjusting another adjustable aperture. The detection range of the system and the magnification of the area to be measured can be changed by moving the plano-convex lens.

[0031] In a preferred embodiment, a real-time spectrogram corresponding to the hologram is obtained based on Fourier transform, and the hologram with the best performance is selected based on the quality of the spectrogram. Specifically, the best performance in the real-time spectrogram is characterized by: weak zero-order spectrum, clear and complete separation of +1 and -1 order spectra with high signal-to-noise ratio, no obvious aliasing or noise, concentrated spectral energy, rich high-frequency components, and sharp edges, ensuring accurate analysis of the subsequent hologram.

[0032] S4: The dual-wavelength digital holographic detection module emits an object light with wavelength λ2 to acquire a hologram of the plane under test with wavelength λ2 under the same conditions as wavelength λ1. In this step, by adjusting the output voltage of the PZT piezoelectric ceramic controller connected to the laser source and replacing it with a light source of wavelength λ2, the process in S3 is repeated to acquire another hologram under the same environmental conditions. The optical path of the dual-wavelength digital holographic detection module is the same as in step S3, except that the wavelength of the laser source has changed.

[0033] S5: Process the two holograms from steps S3 and S4 and obtain the phase difference; In this step, complex conjugate calculations are performed on the two holograms acquired at wavelengths λ1 and λ2 to obtain phase difference information. Digital holography is then used to digitally reconstruct the two holograms, and the phase difference is calculated to provide basic data for subsequent surface contour reconstruction.

[0034] S6: Utilizing λ 1、 The synthesized wavelength of λ2 and the phase distribution obtained in S5 are used to reconstruct the continuous height information and contour of the surface of the plane under test; In this step, based on the principle of dual-wavelength interference, the phase difference information is converted into a continuous surface height distribution using the synthesized wavelengths λ1 and λ2, thereby achieving three-dimensional reconstruction of the measured surface profile. The synthesized wavelengths significantly improve the measurement range and overcome the 2π phase ambiguity problem in single-wavelength digital holographic measurements.

[0035] S7: Based on the reconstructed data of the plane to be tested obtained from S6, calculate the roughness parameters according to the definition of surface roughness, and output the detection results.

[0036] In this step, based on the reconstructed height data, roughness parameters such as Ra are calculated according to the definition of surface roughness to quantitatively characterize the microscopic geometric features of the tested surface. The system can calculate various roughness parameters according to international standards, including arithmetic mean deviation Ra, root mean square deviation Rq, and maximum profile height Rz, providing a quantitative basis for surface quality assessment.

[0037] This method utilizes a dual-wavelength digital holographic detection system mounted on a robotic arm to achieve non-contact, high-precision surface roughness detection, suitable for online inspection of complex curved surfaces in industrial production. By replacing the beam-splitting prism in the traditional optical path with a beam splitter, the size of the detection system is significantly reduced, improving its integration and portability.

[0038] Example 2 like Figure 1 and Figure 7 As shown, this embodiment provides a robotic dual-wavelength digital holographic in-situ surface roughness detection system for complex scenarios, used to implement the detection method in Embodiment 1. The detection system includes a dual-wavelength digital holographic detection module and a plane measurement module. The dual-wavelength digital holographic detection module consists of an optical path unit and a fixing unit. The optical path unit emits object light of various wavelengths and receives reflected light from the plane to be measured, while the fixing unit is used to fix the optical path unit. The plane measurement module measures the perpendicular relationship between the object light and the plane to be measured and adjusts the robotic arm according to the detection results.

[0039] In this embodiment, the dual-wavelength digital holographic detection module includes an optical path unit: a tunable narrow-linewidth laser source 101, a laser collimating lens 102, a coaxial base frame 103, a zoom beam expander 104, an adjustable aperture, a right-angle optical adjustment frame 106, three dielectric film plane mirrors respectively installed in the right-angle optical adjustment frame, a beam splitter, a plano-convex lens 109 installed in the coaxial base frame, a neutral density filter 110 installed in the coaxial base frame 103, and a CCD camera 111; and a fixing unit: a fixing plate 201, a fixing base 202, and a beam splitter clamping frame 203. The planar measurement module includes: a system housing 301, a sensor fixture 302, and a laser displacement sensor 303.

[0040] Furthermore, the dual-wavelength digital holographic detection module can be divided into three parallel optical path components. The first optical path component includes a laser source 101, a laser collimating lens 102, a zoom beam expander 104, and a first right-angle optical reflector arranged coaxially in sequence. The second optical path component includes a first beam splitter 108a, a plano-convex lens 109, a second beam splitter 108b, and a CCD camera 111 arranged coaxially in sequence. The third optical path component includes a second right-angle optical reflector, a neutral density filter 110, and a third right-angle optical reflector arranged coaxially in sequence. The second optical path component is located between the first and third optical path components.

[0041] In this embodiment, the laser collimating lens 102, the second adjustable aperture 105b, the plano-convex lens 109, and the neutral density filter 110 are respectively fixedly mounted on the coaxial base lens frame 103; the first adjustable aperture 105a and the three dielectric film plane mirrors are respectively fixedly mounted on the right-angle optical adjustment frame 106; and the two beam splitters 108 are respectively fixedly mounted in the beam splitter clamping frame 203.

[0042] Furthermore, such as Figure 2 and Figure 3 As shown, based on the coaxial distribution of the optical path, a fixing base is provided for each optical element that needs to be fixed. Each fixing base is mounted on a base plate, and the base plate has a sliding groove for guiding fibers to ensure the coaxial distribution of the corresponding optical elements. Among them, the coaxial base frame 103, the zoom beam expander 104, the right-angle optical adjustment frame 106, the CCD camera 111, and the beam splitter holder 203 are all designed with a fixing base 202. The optical elements are fixed by countersunk screws passing through the countersunk holes 202c of the fixing base. The bottom of the fixing base 202 has a groove 202b, and a slider 202d is installed in the groove 202b. By limiting the sliding of the slider 202d in the sliding groove 201c on the base plate 201, the distance between the optical elements can be adjusted. After the optical path is adjusted, a flat-head screw is passed through the waist-shaped hole 202a on the fixing base and screwed into the corresponding fixing thread hole 201b on the base plate and tightened to achieve reliable fixation of the optical path elements.

[0043] In this embodiment, the optical path of the dual-wavelength digital holographic detection module is as follows: the laser generated by the laser source 101 passes through the collimating lens 102 and the zoom beam expander 104, and is reflected by the first dielectric film plane mirror 107a of the first right-angle optical reflector to the first beam splitter 108a, where it is split into two beams; one beam vertically illuminates the plane to be measured, and the reflected light from the plane to be measured returns along the original path, passing sequentially through the first beam splitter 108a, the plano-convex lens 109, and the second beam splitter 108b before being acquired by the CCD camera 111; the other beam is continuously reflected by the second dielectric film plane mirror 107b of the second right-angle optical reflector and the third dielectric film plane mirror 107c of the third right-angle optical reflector, and is then acquired by the CCD camera 111 after passing through the second beam splitter 108b.

[0044] In this embodiment, the first right-angle optical reflector, the second right-angle optical reflector and the third right-angle optical reflector have the same structure, each including a right-angle optical adjustment frame 106 and a dielectric film plane mirror, with the dielectric film plane mirror fixed on the inclined surface of the right-angle optical adjustment frame 106.

[0045] Preferred implementation methods, such as Figure 1 As shown, the first right-angle optical reflector has a first adjustable aperture 105a on the side facing the zoom beam expander 104, which is used to adjust the size of the output laser spot and filter the laser edge; the plano-convex lens 109 is mounted on the coaxial base frame 103, and the coaxial base frame 103 has a second adjustable aperture 105b on the side facing the second beam splitter 108b, which is used to adjust the light intensity and NA value of the object light.

[0046] In this embodiment, as Figure 2 As shown, the fixing unit includes a base plate 201 and a fixing base 202; the base plate 201 has multiple parallel sliding grooves 201a; the fixing base 202 is snapped onto the base plate 201 and fixed onto the base plate 201 by screws; and each component of the optical path unit is installed on the corresponding fixing base 202.

[0047] In this embodiment, as Figure 3 As shown, the lower end of the fixed base 202 is provided with a groove 202b, and a slider 202d that cooperates with the sliding groove 201a is provided in the groove 202b. The slider 202d can be slidably engaged in the sliding groove 201a. The fixed base 202 is provided with a fixing waist hole 202a for installing screws. The fixed base 202 is provided with an optical element mounting hole 203c.

[0048] In this embodiment, as Figure 4As shown, the fixing unit also includes a beam splitter holder 203. One side of the beam splitter holder 203 has a beam splitter placement groove 203a. Both ends of the beam splitter placement groove 203a are respectively covered with fixing tabs 203b. The two ends of the fixing tabs 203b are mounted on the beam splitter holder 203 with screws to limit the beam splitter's position. The beam splitter is inserted into the beam splitter placement groove 203a from one end. The bottom end of the beam splitter holder 203 has a mounting hole 203c, through which it is mounted to the fixing base 202.

[0049] In this embodiment, as Figure 5 and Figure 6 As shown, the planar measurement module includes a system housing 301, which covers the dual-wavelength digital holographic detection module. The front end of the system housing 301 has three rectangular holes and one light-transmitting hole. The rectangular holes are the working holes of the laser displacement sensor 303. At the same time, a sensor clamp 302 is designed according to the size of the laser displacement sensor 303. The laser displacement sensor 303 is fixed inside the system housing by nuts and screws through the sensor clamp 302. The light-transmitting hole corresponds to the laser emission position of the dual-wavelength digital holographic detection module.

[0050] In this embodiment, the entire integrated and fixed detection system is secured to the end effector of the robotic arm via a flange, enabling high-precision adjustment of the detection area and posture. This allows for real-time, non-contact online detection of the roughness of complex curved surfaces. The planar measurement module and the robotic arm form a closed-loop feedback control system, which can monitor the detection distance and angle in real time and automatically adjust the robotic arm posture based on the feedback information to maintain consistent interference conditions, thereby improving the repeatability of the detection results and the stability of the system operation.

[0051] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A robotic dual-wavelength digital holographic in-situ surface roughness detection method in complex scenarios, characterized in that, The method includes the following steps: S1: The robotic arm moves the detection system along the pre-planned scanning path and stops in the area to be tested; S2: The plane to be measured is measured using the plane measurement module of the detection system based on the principle of triangulation. The robotic arm is then adjusted according to the measurement results so that the object light emitted by the dual-wavelength digital holographic detection module of the detection system is perpendicular to the plane to be measured. S3: The dual-wavelength digital holographic detection module emits an object light at wavelength λ1, acquires a hologram of the plane under test at wavelength λ1, and selects the hologram with the best effect. S4: The dual-wavelength digital holographic detection module emits an object light with wavelength λ2 to acquire a hologram of the plane under test with wavelength λ2 under the same conditions as wavelength λ1. S5: Process the two holograms from steps S3 and S4 and obtain the phase difference; S6: Utilizing λ 1、 The synthesized wavelength of λ2 and the phase distribution obtained in S5 are used to reconstruct the continuous height information and contour of the surface of the plane under test; S7: Based on the reconstructed data of the plane to be tested obtained from S6, calculate the roughness parameters according to the definition of surface roughness, and output the detection results.

2. The robotic dual-wavelength digital holographic in-situ surface roughness detection method in complex scenarios according to claim 1, characterized in that, In S3, based on Fourier transform, the real-time spectrum corresponding to the hologram is obtained, and the hologram with the best effect is selected based on the quality of the spectrum.

3. A robotic dual-wavelength digital holographic in-situ surface roughness detection system for complex scenarios, used to implement the robotic dual-wavelength digital holographic in-situ surface roughness detection method for complex scenarios as described in any one of claims 1-2, characterized in that, The detection system includes a dual-wavelength digital holographic detection module and a planar measurement module; The dual-wavelength digital holographic detection module includes an optical path unit and a fixing unit. The optical path unit is used to emit object light of various wavelengths and receive reflected light from the plane to be measured. The fixing unit is used to fix the optical path unit. The plane measurement module is used to measure the perpendicular relationship between the object light and the plane to be measured, and to adjust the robotic arm according to the detection results.

4. The robotic dual-wavelength digital holographic in-situ surface roughness detection system in complex scenarios according to claim 3, characterized in that, The dual-wavelength digital holographic detection module includes three parallel optical path components. The first optical path component includes a laser source (101), a laser collimating lens (102), a zoom beam expander (104), and a first right-angle optical reflector arranged coaxially in sequence. The second optical path component includes a first beam splitter (108a), a plano-convex lens (109), a second beam splitter (108b), and a CCD camera (111) arranged coaxially in sequence. The third optical path component includes a second right-angle optical reflector, a neutral density filter (110), and a third right-angle optical reflector arranged coaxially in sequence. The optical path of the dual-wavelength digital holographic detection module is as follows: the laser generated by the laser source (101) passes through the collimating lens (102) and the zoom beam expander (104), and is reflected by the first right-angle optical reflector to the first beam splitter (108a) and then split into two beams. One beam vertically illuminates the plane to be measured. The reflected light from the plane to be measured passes through the first beam splitter (108a), the plano-convex lens (109), and the second beam splitter (108b) in sequence and is acquired by the CCD camera (111). The other beam is continuously reflected by the second right-angle optical reflector and the third right-angle optical reflector, and is acquired by the CCD camera (111) after passing through the second beam splitter (108b).

5. The robotic dual-wavelength digital holographic in-situ surface roughness detection system in complex scenarios according to claim 4, characterized in that, The first right-angle optical reflector, the second right-angle optical reflector and the third right-angle optical reflector have the same structure, each including a right-angle optical adjustment frame (106) and a dielectric film plane mirror, wherein the dielectric film plane mirror is fixed on the inclined surface of the right-angle optical adjustment frame (106).

6. The robotic dual-wavelength digital holographic in-situ surface roughness detection system in complex scenarios according to claim 4, characterized in that, The first right-angle optical reflector has a first adjustable aperture (105a) on the side facing the zoom beam expander (104) for adjusting the size of the output laser spot and filtering the laser edge; the plano-convex lens (109) is mounted on the coaxial base frame (103), and the coaxial base frame (103) has a second adjustable aperture (105b) on the side facing the second beam splitter (108b) for adjusting the light intensity and NA value of the object light.

7. The robotic dual-wavelength digital holographic in-situ surface roughness detection system in complex scenarios according to claim 3, characterized in that, The fixing unit includes a base plate (201) and a fixing base (202); the base plate (201) has multiple parallel sliding grooves (201a); the fixing base (202) is snapped onto the base plate (201) and fixed onto the base plate (201) by screws; and each component of the optical path unit is installed on the corresponding fixing base (202).

8. The robotic dual-wavelength digital holographic in-situ surface roughness detection system in complex scenarios according to claim 7, characterized in that, The lower end of the fixed base (202) is provided with a groove (202b), and a slider (202d) that cooperates with the sliding groove (201a) is provided in the groove (202b). The slider (202d) can be slidably engaged in the sliding groove (201a). The fixed base (202) is provided with a fixing waist hole (202a) for installing screws. The fixed base (202) is provided with an optical element mounting hole (203c).

9. The robotic dual-wavelength digital holographic in-situ surface roughness detection system in complex scenarios according to claim 7, characterized in that, The fixing unit also includes a beam splitter holder (203). One side of the beam splitter holder (203) is provided with a beam splitter placement groove (203a). Both ends of the beam splitter placement groove (203a) are respectively covered with fixing tabs (203b). The beam splitter is inserted into the beam splitter placement groove (203a) from one end. The bottom end of the beam splitter holder (203) is provided with a mounting hole (203c) and is installed on the fixing base (202) through the mounting hole (203c).

10. The robotic dual-wavelength digital holographic in-situ surface roughness detection system in complex scenarios according to claim 3, characterized in that, The planar measurement module includes a system housing (301), which covers the dual-wavelength digital holographic detection module. The front end of the system housing (301) is provided with three rectangular holes and one light-transmitting hole. Laser displacement sensors (303) are installed in the rectangular holes respectively. The light-transmitting hole corresponds to the laser emission position of the dual-wavelength digital holographic detection module.

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