3D Topography Research Articles

Laser Surface Texturing in Single-Point Incremental Sheet Forming

Abstract Single-point incremental sheet forming (SPIF) offers high flexibility, cost-effectiveness, mass customization, ease of setup, and scalability. However, the process can result in poor surface characteristics, making it important to control them, especially for applications requiring enhanced wettability. To overcome this challenge, the present study introduces a novel technique that uses laser surface texturing (LST) to create micropatterns on the SPIF forming tool and replicate on the planar surface of workpiece. After SPIF process on the opposite side of the workpiece, the replicated micropatterns are maintained without significant effect to the laser textures and keep the surface's wettability. The 3D surface topography of the imprinted micropatterns was characterized. Additionally, a sessile drop test was performed to assess the wettability of the surface both before and after the deformation process. The results showed that a functionalized micropatterned surface can be achieved using the proposed technique without affecting the geometric accuracy. No cracks were observed on the workpiece surface, but during the SPIF process, deformation stretched the imprinted microvalleys, leading to a slight decrease in hydrophobicity compared to the original LST surface.

Review of 3D topography stitching and registration algorithms: procedure, error evaluation and mathematical modelling

Review of 3D topography stitching and registration algorithms: procedure, error evaluation and mathematical modelling

Impact of topography on extraordinary magnetoresistive devices

Abstract The extraordinary magnetoresistance (EMR) effect is a form of geometric magnetoresistance that occurs when the current redistribution inside a hybrid metal-semiconductor device changes when subjected to an external out-of-plane magnetic field. While the influence of material and geometrical properties on sensor performance has been extensively studied, the topography of EMR devices has not yet received much attention. Typically, flat, 2D topographies are assumed when optimizing EMR devices, which does not reflect the significant topography present in actual devices. This study fills this gap by numerically investigating concentric circular EMR devices with different topographies using a 3D finite element model. We show that EMR devices with metal top contacts, which are more straightforward to fabricate, behave similarly to conventional EMR devices where the metal shunt of the same thickness is embedded into the devices. For InSb/Au devices, both types of devices produce a magnetoresistance of 4.9×105 % at 1 T. Our results also reveal that the magnetoresistance increases with the thickness for a large range of metal thicknesses. In addition, we also explore sidewall dimensions and show that it is desirable to have a thicker shunt with thinner sidewalls, compared to the opposite case.

Distorting crack-front geometry for enhanced toughness by manipulating bioinspired heterogeneity

Control of crack propagation is crucial to make tougher heterogeneous materials. As a crack interacts with material heterogeneities, its front distorts and adopts complex tortuous configurations. While the behavior of smooth cracks with straight fronts in homogeneous materials is well understood, the toughening by rough cracks with tortuous fronts in heterogeneous materials remains unsolved. Here we highlight a distorted crack-front geometric toughening mechanism by manipulating bioinspired anisotropic heterogeneities of microstructural orientations and component properties. We reveal theoretically and demonstrate experimentally that the local mixed-mode I + II + III fracture triggered by local anisotropic heterogeneities lead to a helical crack front in a representative heterogeneous system with bioinspired twisted plywood structures under remote mode I loading. An anomalous nonlinear law of both the enhanced fracture resistance and the helical crack-front length versus the microstructural orientation is revealed, in contrast to the linear toughening law ignoring the hidden 3D topography within crack fronts. An optimization design protocol towards toughness amplification is developed by parametrically manipulating anisotropic heterogeneities to helically distort crack front. Our findings not only provide physical insights into the origin of biological heterogeneities modulated tortuous crack fronts but also offer a benchmark solution for enhancing toughness by parametrically engineering spatial heterogeneities.

Natural and anthropogenic factors controlling organic carbon storage in riverine wetlands along South Korea’s four rivers

This study explores carbon sequestration in South Korea’s riverine wetlands, focusing on the four major rivers: Han, Yeongsan, Geum, and Nakdong. Field data from the Yeongsan River wetland, including 3D topography surveys, grainsize analyses, and loss-on-ignition measurements, were used to assess carbon stocks and their environmental drivers. The Yeongsan River was selected as a representative site due to its geomorphological, hydrological, and climatic similarities with the other three major rivers, which influence sediment transport and carbon dynamics. Carbon stocks of 3.31 megagrams (Mg) per hectare, observed in the Dam-Yang Stream Wetland, suggest that the four major rivers collectively have the potential to store approximately 23.42 million metric tons of carbon annually, accounting for 3.9% of South Korea’s carbon budget. Geomorphological features at different elevations significantly influence soil carbon storage, with finer sediments contributing to higher carbon retention in low-energy environments. Seasonal variations in stream geomorphology, driven by floods and tropical cyclones, are dominant factors regulating sediment transport and organic matter deposition. Our findings suggest that controlled discharge events could enhance sediment and organic material retention, boosting carbon sequestration across riverine wetlands. This study highlights the critical role of geomorphological and hydrological processes in enhancing wetland carbon storage and mitigating carbon emissions.

An Insight into Chip and Surface Texture Shaping Under Finish Turning of Powder Steels Infiltrated with Tin Bronze.

The manufacturing of work parts made of powder (sintered) steels is currently widespread in industry, as it provides minimal processing allowances and high dimensional accuracy, as well as the required properties and unconventional chemical composition. At the same time, their low tensile or bending strength must be considered a serious disadvantage. In order to minimize these disadvantages, a number of strengthening technologies are used, among which is the infiltration of porous base materials with metal alloys. In this study, the details of finish turning of sintered iron-graphite-based steel infiltrated with tin bronze with molybdenum disulfide addition are considered. Changes in the shape of chips and their geometric features, as well as the 3D parameters and topography features of the surface machined, are presented after finish turning with AH8015 carbide inserts. The cutting speed (vc) and feed rate (f) were used as variable parameters. It was found that when turning the powder steels under study, the chips took the shape of small fragments or element chips, including segmented chips. For quenching steel, the formation of irregular lamellae was observed and for the initial state, a serrated chip was registered. For the initial state, a reduction in Kb values was observed in the range of the vc of 50-100 m/min and f of 0.05-0.075 mm/rev, and for quenching in the range of 225-250 m/min and 0.05-0.075 mm/rev. Compared to the initial state, for quenching, depending on the cutting parameters, a 14% reduction in the chip spreading ratio Kb or an increase from 2 to 32% was registered. For the initial state and quenching, a decrease in the Sp and Sv parameters was achieved in the range of the vc of 200-250 m/min and f of 0.05-0.075 mm/rev, and there was an increase in the range of 50-150 m/min and 0.125-0.15 mm/rev. Compared to the initial state, an increase in the Sz parameter from 10 to 35% was observed for quenching. On the surfaces machined with vc = 50 m/min and f = 0.05 mm/rev, waves and single significant peaks were observed. On the other hand, vc = 250 m/min and f = 0.15 mm/rev provided classical feed tracks in the form of valleys and irregular ridges on the surfaces machined. The test results can be useful in the design and manufacturing of industrial parts made of powder steels.

Optimizing the Electrical Microenvironment Provided by 3D Micropillar Topography on a Piezoelectric BaTiO3 Substrate to Enhance Osseointegration.

The electrical properties of bone implant scaffolds are a pivotal factor in regulating cellular behavior and promoting osteogenesis. The previous study shows that built-in electric fields established between electropositive nanofilms and electronegative bone defect walls are beneficial for promoting bone defect healing. Considering that the physiological electrical microenvironment is spatially distributed in 3D, it is imperative to establish a 3D spatial charged microenvironment on bone scaffolds to optimize the efficacy of osseointegration. Nevertheless, this still poses a formidable challenge. Here, a bone repair strategy that utilizes micro-scale 3D topography is developed on a piezoelectric BaTiO3 (BTO) substrate to provide 3D spatial electrical stimulation. The BTO micropillar arrays, especially with a height of 50 µm and positive-charge distribution (50 µm positive), promote the spreading, cytoskeletal reorganization, focal adhesion maturation, and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). They enhanced the clustering of mechanosensing integrin α5 in BMSCs. The biomimetic 3D spatial electrical microenvironment accelerated bone repair and osseointegration in a rat femoral diaphysis defect repair model. The study thus reveals that implants with a 3D spatial electrical microenvironment can significantly enhance osseointegration, thereby providing a new strategy to optimize the performance of electroactive biomaterials for tissue regenerative therapies.

Motion-induced phase shift for dynamic structured light measurement.

Structured light 3D shape measurement is extensively utilized in semiconductor inspection, smart manufacturing, and biomedical imaging due to its rapid measurement speed, high precision, and versatile applicability to different objects. However, the traditional implementations of this method often require that the object remains static while recording the phase-shifting structured light images, which limits the adaptability of dynamic measurement. Here, we propose a dynamic 3D shape measurement using structured light based on a motion-induced phase shift (MIPS). As the object moves, the surface features distort the fringe pattern, resulting in a phase-shifting effect. By employing the MIPS method, we can determine the phase even in the situations where the knowledge of phase-shifting conditions is not accurate. This enables the acquisition of the 3D topography of the object surface with a high level of precision. Experimental results demonstrate that the MIPS method can accurately measure the 3D shape of objects moving as fast as 100 mm/s, with a relative discrepancy of less than 0.23%.

Proposal of a Biobased and Biodegradable Polymer as a Hot Embossing Substrate for Holographic Security Marks Fabrication

ABSTRACTThe alarming increase in counterfeiting has determined a more intensive application of authentication solutions such as holographic security marks. Polycarbonate or polymethyl methacrylate currently used in the hot embossing process to produce security marks are discarded as non‐biodegradable waste after utilization. For the first time, poly(lactic acid) (PLA) was studied here as a hot‐embossing substrate to imprint a micro‐relief containing diffractive gratings, as a stage in the fabrication of holographic security marks. Four PLA grades, which differ by crystallinity and mechanical properties, were used to define the suitability of PLA for hot embossing. The 3D topography of embossed micro‐relief in PLA plates was investigated by quantitative phase imaging, scanning electron microscopy, and atomic force microscopy (AFM). The analyses showed that a high crystallinity and a low d‐lactide content of PLA render the hot‐embossing process more difficult and decrease the quality of the imprinted micro‐relief. The average height of the micro‐relief and the difference in height values, which were determined by AFM, allowed the ranking of the PLA grades according to the quality of the diffracted image. The possibility of recycling the embossed PLA substrate several times before composting was also demonstrated in this work. The variation of the mechanical properties, thermal stability, melting, and crystallization behaviors after each recycling cycle has shown that PLA can be reprocessed six times without significant damage to the properties. This study demonstrated that PLA can replace petroleum‐based polymers in the fabrication of holographic security marks and its suitability for a plethora of optoelectronics applications.

Adaptive Threshold Algorithm for Outlier Elimination in 3D Topography Data of Metal Additive Manufactured Surfaces Obtained from Focus Variation Microscopy

The topography of surfaces produced by metal additive manufacturing is a challenge for optical measurement systems such as focus variation microscopes. These irregularities can lead to artifacts, such as incorrectly measured protrusions or spikes, hampering reliable topographic characterization. In order to eliminate this problem, we introduce a new algorithm based on dual convolving a vertical Sobel operator with cross sections of an image stack parallel to the scanning direction of the so-called depth scan. This has proven beneficial in order to distinguish the focus region from out-of-focus areas where outliers are frequently detected. This paper introduces a method for deriving self-adaptive thresholds from the convolution result and compares the effects of different operators in creating self-adaptive thresholds. Additionally, a simulation model of focus variation microscopy is introduced to validate both the measuring system and the proposed algorithm, thereby enhancing the overall performance of focus variation microscopy. Finally, comparisons of measurement results on rough metal additive manufacturing workpieces with and without self-adaptive thresholds are discussed to demonstrate the algorithm’s effectiveness.The utilization of self-adaptive thresholds demonstrably reduces the uncertainty range in roughness parameter calculations. For example, in the case of an additive manufactured metal sample due to outlier elimination, the Sz roughness value reduces from 543 µm to 413 µm.

Atomic force microscopy reveals morphological and mechanical properties of schistosoma mansoni tegument

Schistosoma mansoni, an intravascular parasitic worm and the causative agent of schistosomiasis, relies on its tegument (outer layer) for survival and host interaction. This study explored the morphology and mechanical properties of S. mansoni tegument using Atomic Force Microscopy (AFM). Notably, we employed the PeakForce Quantitative Nanomechanical Mapping (PF-QNM) mode in air, enabling simultaneous acquisition of 3D topography and mechanical property contrasts (adhesion, elastic modulus). Additionally, nanoindentation (AFM contact mode) was performed on female worm tegument for elastic modulus measurement. Both techniques revealed an elastic modulus range of fractions or units of GPa for the tegument. Interestingly, mechanical property maps, particularly adhesion contrast, displayed a recurring pattern of light and dark bands. We also measured the depth of annular furrows on the female tegument, finding an average of 128 ± 10 nm. These findings establish AFM, particularly PF-QNM, as a valuable tool to characterize S. mansoni tegument properties, offering insights for future investigations into parasite biology and its response to immunological or pharmacological challenges.

Optical Extinction-Based 3D Nano-Imaging of WS2 on Gold.

Broadband nanoextinction images recorded in tip-enhanced optical spectroscopy geometry track the 3D topography of a single layer of WS2 on Au substrate. The described nano-optical method is complementary to conventional atomic force microscopy and offers additional information about the buried material-metal interface that is not accessible using conventional topographic imaging. Beyond 3D optical imaging, we observe large variations in the junction plasmon resonance on the nanoscale. The latter is important to understand and account for in tip-enhanced Raman and photoluminescence studies that target low-dimensional materials specifically. Our observations and (coherent) optical scattering-based method are also relevant to emerging efforts aimed at exploring strong coupling and Fano interferences in hybrid plasmonic-low dimensional quantum material systems.

Automated comparison and evaluation of striated cutting plier toolmarks on metal wires

Toolmarks examination validity and subjectivity have come under scrutiny. This research focuses on the case of cutting plier marks. This paper presents an automatic comparison method and assesses its performance. It is designed to assign a weight to the forensic evidence (i.e, a comparison between toolmarks) with a likelihood ratio (LR). 3D topographies are acquired and treated to be compared using a set of correlation metrics. A machine learning algorithm combines comparison metrics and enables LR computation. Pliers of various brands and models were used to study the variability both within and between tools. We explained why the specific zone (area along the blade) has to be chosen to build the within-source variability and how the between-source variability can be built in different scenarios. Misleading evidence rates between 0 % and 4 % have been measured and it demonstrates the accuracy of the method when applied on the pliers used.

Experimental study on tribological behavior of a binderless cemented carbide at high contact stress

Knowledge of frictional evolution and associated damage mechanism during sliding wear conditions using binderless WC-based cemented carbide is lacking. In this study, the frictional evolution and corresponding transformation of microstructure, and wear mechanisms of Al2O3/WC-based cemented carbide due to the effect of different contact pressure, especially high pressure have been explored using a reciprocating ball-on-flat sliding wear tester, which was experimentally simulated following the ASTM G133–02 standard. The dynamic curves in friction coefficient with the sliding time were described. The microscopic 3D topography of contact surface was obtained by the MFP-3D atomic force microscope. The material removal and the wear rate were discussed. Worn surface morphologies at different moments, cross-sectional images of wear tracks at different loads, and wear debris were taken by field emission scanning electron microscope. The results suggested that the pressure plays a decisive role in frictional evolution and wear characteristics. Two models of frictional evolution were declared. A novel “surge” phenomena in friction coefficient was found and explained at high contact pressure. Wear transition from mild wear to severe wear was confirmed. More than one wear mechanism was observed, including micro-cutting (polishing), generation and propagation of cracks, cracking-induced spalling, plastic deformation, and the formation of tribolayer.

Microsurgical Anatomy of the Common Tendinous Ring and Its Surgical Implications

BACKGROUND AND OBJECTIVES: The common tendinous ring (CTR), also known as the common annular tendon or annulus of Zinn, is a critical anatomic structure located at the convergence of the orbital apex, superior orbital fissure (SOF), optic canal, and the anterior aspect of the lateral sellar compartment. It plays a vital role in both neurosurgical and neuro-ophthalmological interventions. The aim of this study was to delineate the complex 3-dimensional (3D) topography of the CTR and explore its implications for surgical procedures. METHODS: Ten formalin-fixed skull base specimens from adult Chinese cadavers were meticulously dissected to investigate the morphology of the CTR, focusing particularly on its relationship with the 4 extraocular rectus tendons, the optic strut, the SOF, and the optic canal. Additional skull base specimens were subjected to 3D surface scanning, computed tomography, and histopathological examinations to deepen our understanding of the CTR's structural complexities. RESULTS: The CTR establishes a spatial, 3D tendinous assembly, encompassing 4 rectus tendons, 2 tendinous connections, and a singular common tendinous root. These components interlink to form a distinctive dual-ring configuration, featuring the optic foramen and the oculomotor foramen. The posterior part of the superior rectus tendon demarcates the common boundary between these 2 foramina. The oculomotor foramen itself serves as the central sector of the SOF. Precise incisions of the medial and lateral tendinous connections and fusions are essential for safely opening the CTR. CONCLUSION: The structural composition, interconnections, and dual-ring configuration of the CTR are crucial for precise and safe surgery of orbital apex and adjacent regions.

Multi-line laser scanning reconstruction with binocularly speckle matching and trained deep neural networks

A multi-line laser scanning system for 3D topography measurement is proposed. This method not only has the advantages of high precision of laser scanning technology, but also has high reconstruction efficiency. In this paper, speckle reconstruction technique, multi-line laser technique and Biocular reconstruction technique are used to construct a 3D reconstruction system, and test equipment is built, and the problems existing in the system establishment process are actually studied. In order to solve the problem of mismatching in binocular multi-line laser matching, a method to sort out the correspondence of multiple laser lines in binocular images based on speckle matching results is proposed. In order to optimize the multi-line laser matching effect, a speckle matching network based on deep learning is proposed, which integrates the grayscale images of the left and right cameras as supplementary information, and takes the speckle image and grayscale image as the input of the network model to obtain more accurate and edge-complete matching results. Finally, the matching results of the multi-line laser and the camera calibration parameters were used to reconstruct the object point cloud. Experimental results show that the proposed speckle matching method can make binocular multiline laser point cloud reconstruction more robust and stable than the traditional method, and through the accuracy analysis of the system, it is proved that the average measurement accuracy of the proposed method can reach 0.05 mm.

A full-morphology measurement method and system for tubing internal thread based on rotating-mirrored structured light vision

The major methods of tubing internal thread (TIT) measurement are low efficiency, poor accuracy and incomplete measurement. Therefore, a new full-morphology measurement method and system based on rotating-mirrored structured light vision (RMSLV) is proposed in this paper. Firstly, a measurement model of RMSLV is proposed, which establishes the mathematical relationship between two-dimensional (2D) pixel and three-dimensional (3D) topography data. Subsequently, a step-by-step calibration method for this model is put forward to accurately solve model parameters, so that the high-precision restoration from 2D images to intricate 3D full-morphology of TIT is realized. Finally, the measurement system is built, and the verification experiments are conducted. The results indicate that the system’s measurement accuracy of taper, pitch and tooth height is 6.61 times, 5.60 times and 4.48 times higher than traditional equipment, and the efficiency is exponentially improved. This study provides an effective means for highly precise and fast measurement of the TIT.

A novel 3D reconstruction method of blast furnace burden surface based on virtual camera array

Accurate three-dimensional (3D) blast furnace burden surface topography is crucial for optimizing material distribution and furnace operation. However, harsh conditions within the furnace pose challenges to this 3D reconstruction, such as difficulties in matching feature points and sparse 3D point clouds. To overcome these challenges, we propose a 3D reconstruction method for the blast furnace burden surface using virtual camera array. Firstly, an ORB feature extraction and matching method based on bidirectional optical flow tracking is proposed to solve the impact of illumination changes and noise. Then, the virtual camera array is constructed to generate a sparse 3D point cloud from an image sequence. Finally, dense surface reconstruction of the burden surface is achieved based on the improved PMVS and the Poisson surface reconstruction method. Experimental results demonstrate that the proposed method can extract accurate feature points and reconstruct the accurate 3D topography of the burden surface.

Combining three-dimensionality and CaP glass-PLA composites: Towards an efficient vascularization in bone tissue healing

Bone regeneration often fails due to implants/grafts lacking vascular supply, causing necrotic tissue and poor integration. Microsurgical techniques are used to overcome this issue, allowing the graft to anastomose. These techniques have limitations, including severe patient morbidity and current research focuses on stimulating angiogenesis in situ using growth factors, presenting limitations, such as a lack of control and increased costs. Non-biological stimuli are necessary to promote angiogenesis for successful bone constructs. Recent studies have reported that bioactive glass dissolution products, such as calcium-releasing nanoparticles, stimulate hMSCs to promote angiogenesis and new vasculature. Moreover, the effect of 3D microporosity has also been reported to be important for vascularisation in vivo. Therefore, we used room-temperature extrusion 3D printing with polylactic acid (PLA) and calcium phosphate (CaP) based glass scaffolds, focusing on geometry and solvent displacement for scaffold recovery. Combining both methods enabled reproducible control of 3D structure, porosity, and surface topography. Scaffolds maintained calcium ion release at physiological levels and supported human mesenchymal stem cell proliferation. Scaffolds stimulated the secretion of vascular endothelial growth factor (VEGF) after 3 days of culture. Subcutaneous implantation in vivo indicated good scaffold integration and blood vessel infiltration as early as one week after. PLA-CaP scaffolds showed increased vessel maturation 4 weeks after implantation without vascular regression. Results show PLA/CaP-based glass scaffolds, made via controlled 3D printing, support angiogenesis and vessel maturation, promising improved vascularization for bone regeneration.

Simultaneous 2D Projection and 3D Topographic Imaging of Gas-Dependent Dynamics of Catalytic Nanoparticles.

Catalyst deactivation through pathways such as sintering of nanoparticles and degradation of the support is a critical factor when designing high-performance catalysts. Here, structural changes of supported nanoparticle catalysts are investigated in controlled gas environments (O2, H2O, and H2) at different temperatures by imaging simultaneously the nanoparticle structures in 2D projection and the 3D surface-sensitive topography. Platinum nanoparticles on carbon support as a model system are imaged in an environmental transmission electron microscope (ETEM), with concurrent acquisition of high-angle annular dark field scanning TEM (HAADF-STEM) and secondary electron (SE) images. Particle migration and coalescence occurs and shows gas-dependent kinetics, with nanoparticles moving across and through the support during and after coalescence. The temperature required for motion is lower in O2 than in H2O and H2, explained through the nature of the gas/nanoparticle interactions. In O2 and H2, the carbon support degrades by trench formation along migration pathways, and the particles move continuously, indicating a chemical reaction between gas and support. In H2O gas, motion is more discontinuous and oriented particle attachment occurs, as expected from theoretical predictions. These results suggest that multimodal imaging in ETEM that combines HAADF-STEM and SE data provides comprehensive information regarding catalyst dynamics and degradation mechanisms.