- 标题
- 摘要
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- 实验方案
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Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process
摘要： Recently developed concentric laser metal wire deposition (LMWD) heads allow metal addition processes which are independent of the deposition direction, thus enabling complex paths to be generated. The sensitivity of the process to height deviations has experimentally been observed to be greater with this type of head than with powder ones, therefore requiring more precise and local process control algorithms to be implemented. This work developed a methodology for measuring the part, layer by layer, using a 3D scanner based on structured laser light. Height corrections were applied to the mean and intra-layer height deviations by recalculating the deposition trajectories of the next layer to be deposited. Local height deviations were adjusted by varying the scanning speed, thus increasing the feed rate in the lower areas and decreasing it in the higher ones. Defects generated in the purpose, with height differences within the layer, were successfully corrected. A flat layer was re-established through the application of the control strategy. The internal integrity of the parts due to the scanning speed variation was analyzed, resulting in fully dense parts. The structured light measurement and height correction systems are found to be an affordable and time-efficient solution that can be integrated into an LMWD environment, thereby improving the process robustness.
关键词： cladding,coaxial wire feed,metal wire,additive manufacturing,monitoring,laser deposition,structured light scanning,height control
更新于2025-11-28 14:24:20
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Stereo-Matching Network for Structured Light
摘要： Recently, deep learning has been widely applied in binocular stereo matching for depth acquisition, which has led to an immense increase of accuracy. However, little attention has been paid to the structured light ?eld. In this letter, a network for structured light is proposed to extract effective matching features for depth acquisition. The proposed network promotes the Siamese network by considering receptive ?elds of different scales and assigning proper weights to the corresponding features, which is achieved by combining pyramid-pooling structure with the squeeze-and-excitation network into the Siamese network for feature extraction and weight calculations, respectively. For network training and testing, a structured-light dataset with amended ground truths is generated by projecting a random pattern into the existing binocular stereo dataset. Experiments demonstrate that the proposed network is capable of real-time depth acquisition, and it provides superior depth maps using structured light.
关键词： SLNet,stereo matching,Structured light,siamese network
更新于2025-09-23 15:23:52
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Structured-Light Based 3D Reconstruction System for Cultural Relic Packaging
摘要： The non-contact three-dimensional measurement and reconstruction techniques have played a significant role in the packaging and transportation of precious cultural relics. This paper develops a structured light based three-dimensional measurement system, with a low-cost for cultural relics packaging. The structured light based system performs rapid measurements and generates 3D point cloud data, which is then denoised, registered and merged to achieve accurate 3D reconstruction for cultural relics. The multi-frequency heterodyne method and the method in this paper are compared. It is shown that the relative accuracy of the proposed low-cost system can reach a level of 1/1000. The high efficiency of the system is demonstrated through experimental results.
关键词： 3D reconstruction,cultural relics packaging,structured light
更新于2025-09-23 15:23:52
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Real-Time Geometric Parameter Measurement of High-Speed Railway Fastener Based on Point Cloud from Structured Light Sensors
摘要： With the increase in the number of service years for high-speed railways, the foundation of the rail track suffers from settlement, which causes rail track irregularity. To adjust the position of the track and meet track regularity demands, several components of the fastening system will be replaced by different sized components. It is important to measure the exact geometric parameters for the components of a fastening system before adjusting the track. Currently, the measurement process is conducted manually, which is laborious and error-prone. In this paper, a real-time geometric parameter measurement system for high-speed railway fastener based on 2-D laser profilers is presented. Dense and precise 3-D point clouds of high-speed railway fasteners are obtained from the system. A fastener extraction method is presented to extract fastener point cloud and a region-growing algorithm is used to locate key components of the fastener. Then, the geometric parameter of the fastener is worked out. An experiment was conducted on a high-speed railway near Wuhan, China to verify the accuracy and repeatability of the system. The maximum root-mean-square-error between the manual measurement and the system measurement is 0.3 mm, which demonstrates adequate accuracy. This system can replace manual measurements and greatly improve the efficiency of geometric parameter measurements for fasteners.
关键词： fastener geometric parameter measurement,region grow,high-speed railway,dense point cloud,structured light sensor
更新于2025-09-23 15:21:21
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Temperature Compensation Method for Digital Cameras in 2D and 3D Measurement Applications
摘要： This paper presents the results of several studies concerning the effect of temperature on digital cameras. Experiments were performed using three different camera models. The presented results conclusively demonstrate that the typical camera design does not adequately take into account the effect of temperature variation on the device’s performance. In this regard, a modified camera design is proposed that exhibits a highly predictable behavior under varying ambient temperature and facilitates thermal compensation. A novel temperature compensation method is also proposed. This compensation model can be applied in almost every existing camera application, as it is compatible with every camera calibration model. A two-dimensional (2D) and three-dimensional (3D) application of the proposed compensation model is also described. The results of the application of the proposed compensation approach are presented herein.
关键词： temperature effect,3D imaging,structured light,camera calibration
更新于2025-09-23 15:21:21
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Measuring singularities of cylindrically structured light beams using a radial grating
摘要： Optical singularities, including phase and polarization singularities that are prevalent in vortex beams, cylindrical vector beams, and cylindrical vector vortex beams, were widely investigated in the past few decades because of their physical and application interest. Here, we propose a method for measuring the singularities within these cylindrically structured light beams by using a radial grating (RG), which is fabricated by etching patterns on the chrome plated soda-lime glass and exhibits a broadband performance. We demonstrate the versatility and compatibility of the measuring method by obtaining the topological charge and polarization order that characterize the phase and polarization singularity, respectively. The reliability of the RG was also inspected by analyzing the grating period and the illumination location of the input field on it.
关键词： topological charge,optical singularities,cylindrically structured light beams,radial grating,polarization order
更新于2025-09-23 15:21:21
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Inverse projected-fringe technique for measurement of dimensions and surface profile of axisymmetric objects
摘要： An inverse projected-fringe technique based on simulating the system of a projector-part-camera is proposed for an on-machine inspection of axisymmetric parts. Parts considered for this study are relatively large, have high specular surfaces and have sharp slopes. A computer simulation-based method and the CAD model of the part was used to produce the inverse fringes as well as to find an appropriate trace passing through the symmetrical axis of the part that offers the best signal to noise ratio. This technique measures the deviation from a master-part and provides an accuracy of better than 10 microns for the part with a radial dimension of about 10 cm. It is shown that the proposed technique improves the signal to noise ratio and the repeatability of the system compared to the standard fringe projection technique, in particular for the areas with a steep slope.
关键词： Fringe projection,Structured light,Inverse fringe projection,Optical metrology,Quality control
更新于2025-09-23 15:21:01
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photoinduced Liquid Crystal Domain Engineering for Optical Field Control
摘要： Liquid crystals (LCs) have attracted considerable attention due to their pronounced high optical anisotropy/transparency over a wide electromagnetic spectrum, high sensibility to various external field stimuli (such as electric/magnetic field, light irradiation, and heat) and strong capability for matter and electromagnetic field interactions. Thanks to their large birefringence and reconfigurable director (i.e. local optical axis) orientation, LCs have become one of the most attractive candidates for making optical devices requiring versatile functionalities. Particularly, liquid crystal display (LCD) holds a dominant position in the flat panel display market nowadays. Essentially, they are composed of a huge number of separate light intensity modulators in the visible range. In addition to amplitude, LCs can freely manipulate other spatial degrees of light, such as polarization and phase. Through specifical designing of the director distribution of LC domains, one could arbitrarily manipulate the optical field. Optical field control is a key requirement for optics and photonics. Structured light, also known as shaped light or tailored light, is a light beam that has customized intensity, polarization, and phase. Recently, specific beams including vortex beams, vector beams (VBs), and Airy beams have been studied intensively due to their fantastic properties and diverse applications in optical trapping, laser processing, high‐resolution imaging, etc. Generally, these beams can be directly generated from Gaussian beams by spatially manipulating the amplitude or phase of light. Such manipulations could be accomplished by lens or plates with specific curvature radius, photoresist masks, or metasurfaces with delicately designed structures. However, their optical characteristics are static once the respective device is fabricated, which severely restricts corresponding applications. Thanks to the electro‐optical tunability of LCs, structured LC domains make these devices dynamic and more efficient.
关键词： vector beams,Airy beams,photoalignment,vortex beams,optical field control,structured light,Liquid crystals
更新于2025-09-23 15:21:01
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Gallium nitride micro-light-emitting diode structured light sources for multi-modal optical wireless communications systems
摘要： Gallium nitride-based light-emitting diodes (LEDs) have revolutionized the lighting industry with their efficient generation of blue and green light. While broad-area (square millimetre) devices have become the dominant LED lighting technology, fabricating LEDs into micro-scale pixels (micro-LEDs) yields further advantages for optical wireless communications (OWC), and for the development of smart-lighting applications such as tracking and imaging. The smaller active areas of micro-LEDs result in high current density operation, providing high modulation bandwidths and increased optical power density. Fabricating micro-LEDs in array formats allows device layouts to be tailored for target applications and provides additional degrees of freedom for OWC systems. Temporal and spatial control is crucial to use the full potential of these micro-scale sources, and is achieved by bonding to pitch-matched complementary metal-oxide-semiconductor control electronics. These compact, integrated chips operate as digital-to-light converters, providing optical signals from digital inputs. Applying the devices as projection systems allows structured light patterns to be used for tracking and self-location, while simultaneously providing space-division multiple access communication links. The high-speed nature of micro-LED array devices, combined with spatial and temporal control, allows many modes of operation for OWC providing complex functionality with chip-scale devices.
关键词： Gallium nitride,structured light,light-emitting diodes,optical wireless communications
更新于2025-09-23 15:19:57
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A flexible 3D point reconstruction with homologous laser point array and monocular vision
摘要： A 3D recovery approach is achieved by the monocular vision sensor and the homologous laser point array with the arbitrary relative pose to the 2D reference. In the modeling process, firstly, the 3D texture board is moved to different positions in the view field of the vision sensor. Therefore, the laser rays intersect with the cubic board and generate laser points on it. Then, the Plücker matrices of the laser rays are determined by the laser points. The algebraic solution of the joint point of laser rays, the optic center of the projector, is contributed by the singular value decomposition. Thirdly, the laser rays are refined by the algebraic solution of the joint point and represented in the 2D-reference coordinate frame. Finally, the reconstruction is achieved by the calibrated laser rays of the projector. The reconstruction method is experimentally conducted to verify the performance and precision in various measurement conditions. The reconstruction error averages are 0.942 mm, 1.055 mm, 1.374 mm, 2.063 mm, under the 700 mm–1000 mm measuring distances between the vision sensor and the optic center. As there is no strict requirement for the relative installation position and orientation between the laser-ray projector and the 2D reference, the approach prompts the flexibility for the on-site active-vision measurement.
关键词： Structured light,Optical inspection,Laser rays,Reconstruction
更新于2025-09-23 15:19:57