3D Imaging Applications Research Articles

Anatomical variations in 3D imaging: a case report of a dorsal metacarpal artery anomaly

This report presents a novel anatomical variant of the second dorsal metacarpal artery (SDMA). In this unique case, the SDMA abnormally penetrates the second dorsal interosseous muscle (SDIM), dividing into two major branches. A deep dorsal branch of the SDMA (dbSDMA) is located within the SDIM and extends to the distal end of the metacarpal. The other branch forms a perforating branch called the P-SDMA, which anastomoses with the palmar metacarpal artery branch (PMAb) and the deep palmar arch branch (DPAcb) in the deep palmar area. The discovery of this SDMA variant is significant for procedures involving complex hand surgeries such as DMA flaps. Understanding this anatomical variation is crucial for accurate surgical planning and can help avoid potential complications during surgery. To elucidate these unique variations, we employ three-dimensional (3D) imaging techniques, demonstrating the potential of these technologies to advance the visualization of anatomical structures and enhance medical education. 3D imaging also facilitates augmented reality applications and 3D printing. Our findings underscore the possible applications of 3D imaging in medical practice and education, potentially transforming anatomy education and surgical planning.

Robotic-based terahertz spectroscopy imaging for non-destructive monitoring of water loss-induced damage in timber materials under low temperature stress

Timber materials are widely used in various industries, from construction to furniture manufacturing. One of the critical factors affecting the structural integrity and longevity of timber is water loss-induced damage, which often occurs under low-temperature stress conditions. Monitoring and assessing this damage traditionally involve invasive and time-consuming methods. This study explores the application of robotic-based terahertz spectroscopy 3D imaging as a non-destructive and efficient system for assessing the impact of water loss on timber materials under low-temperature stress. The detection and localization of damage in a various species of timber-based structures were experimentally investigated by performing pulsed terahertz time-domain spectroscopy and using a six- DOF (degree-of-freedom) robotic arm. The thickness and damage length were monitored by designing the reflection geometry of the terahertz scanner. Additionally, the terahertz source was controlled with a six-DOF robot arm for path planning. The corresponding measured dielectric property reference value for the damage identification was computed using a captured terahertz wave at 12% of moisture content. The reflected signals were analyzed to determine the thickness, defectiveness, and locations of the defects through signal processing in the time and frequency domains. Finally, the validity of the structural health monitoring approach for 3D detection and visualization of water loss-induced defects in timber structures using terahertz waves, was discussed.

Application of 3D Imaging for Analyzing the Chip Groove Shapes of Cutting Inserts

An effective chip formation process is significant for an efficient metal-cutting process. Long continuous chips can lead to scratches on the machined surface, increasing the risk to operator safety and stability of the machining process. The use of chip grooves on cutting inserts allows for control of the chip formation and breaking process during machining. The shape of the rake surface and the design of the chip groove also affect the efficiency of the machining process. The article presents the use of 3D imaging to analyze changes in the selected chip groove shapes depending on the cutting depth ap = 0.10, 0.25, and 0.50 mm and the angular location of the cutting insert relative to the machined surface of the workpiece (i.e., major cutting-edge angle K = 60° and K = 90°). The analysis methodology was based on the use of 3D image registration and surface shape modeling. In the analysis based on the 3D imaging presented, the novelty was the adaptation of methods typically used to map and model the terrain surface, which have not been used previously in cutting processes. The evaluation of the shape of the chip groove surface was carried out using, e.g., watershed maps and 3D surface maps. The obtained results indicated a significant influence of the cutting depth and major cutting-edge angle on the surface shape, profile, and length of the chip former; chip groove volume; and the theoretical contact area of the formed chip with the cutting insert. It was observed that for small depths of cut, i.e., ap < 0.25 mm, the chip-curling process may be difficult due to the flattened shape of the rake surface. In addition, the influence of the convexity of the rake surface of the cutting insert on the chip formation process was demonstrated. The results of the experimental research that verified the conclusions are presented. The developed results may be useful in the process of selecting the parameters and conditions of the metal finishing through use of tools with a shaped rake surface.

Study on the application of 3D imaging based on the γ-photon silk thread method for visualisation and detection of flow fields

As a flow display technique, the silk thread method can clearly show the state of the flow field. However, displaying the state of the flow field in industrial closed metal cavities is impossible, and results of the traditional silk thread method fail to present depth information. To address these limitations, we propose a display method based on γ-photon silk thread 3D imaging. Firstly, a flow field visualization experimental platform applicable for industrial closed metal cavity was designed. Then, aiming at the shortcomings of insufficient γ-photon scanning data and limited imaging quality in flow field visualization, an adaptive sinogram interpolation-iterative filtering reconstruction algorithm was proposed to expand the data via the adaptive interpolation processing of the sinogram in image reconstruction. Beltrami filtering was also embedded in the iterative algorithm to effectively reduce noise and artifacts in the imaging image. Finally, the internal flow field inspection of the NACA0018 airfoil and the industrial confinement turbine were used as examples to visualise the wing upper surface flow and turbine blade passage secondary flow, respectively, and the results were consistent with those of the numerical simulation analysis. As the angle of attack of the wing increased, laminar flow separation occurred, and the silk thread structure state changed to the point where the aircraft stalled. After the imaging map analysis, the stall angle ranged between (15°,19°), which is consistent with the simulation results. In the turbine blade passage secondary flow detection, the imaging map formed a horseshoe vortex with airflow separation at the central saddle point and silk threads clearly presenting the structural state of the flow field along different directions.

Optical path optimization of chromatic line confocal displacement sensor for high resolution and wide range.

This study introduces the optical path-optimized dual-grating chromatic line confocal imaging (DG-LCI) technique for high-resolution and wide-range surface topography measurements. Chromatic line confocal imaging (LCI) finds extensive applications in high-speed 3D imaging of surface morphology, roughness analysis in industrial production, and quality inspection. A key advantage of LCI is its ability to achieve a large depth of focus, enabling the imaging system to measure a wide range in the Z direction. However, the challenge lies in the trade-off between the measurement range and resolution. Increasing the measurement range reduces the resolution, making it unsuitable for precise measurements required in industrial processing. Conversely, enhancing the resolution limits the measurement range, thereby sacrificing the advantage of LCI systems' broad measurement capabilities. Addressing this limitation, we propose a dual optical path dual-grating structure using a simplified and ingenious optical path optimization design. This design overcomes the challenge of sacrificing the millimeter-level measurement range while simultaneously improving the resolution. Rigorous simulations and experiments validate the effectiveness and validity of our proposed method.

Digital Holography and 3D Imaging 2023: introduction to the joint feature issue in Applied Optics and Journal of the Optical Society of America A.

The Optica Topical Meeting on Digital Holography and 3D Imaging (DH) was held 14-17 August 2023 in Boston, Massachusetts. The meeting was organized co-jointly with the Optica Imaging Congress. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. Since 2017, AO and the Journal of the Optical Society of America A (JOSA A) have presented a feature issue in each journal. This feature issues includes 17 papers in AO and 9 in JOSA A. Together they cover a large range of topics, reflecting the rapidly expanding techniques and applications of digital holography and 3D imaging. The upcoming DH Conference (DH 2024) will be held from 3 to 6 June in Paestum, Italy.

Digital Holography and 3D Imaging: introduction to the joint feature issue in Applied Optics and Journal of the Optical Society of America A.

The Optica Topical Meeting on Digital Holography and 3D Imaging (DH) was held 14-17 August 2023 in Boston, Massachusetts. The meeting was organized co-jointly with the Optica Imaging Congress. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. Since 2017, AO and the Journal of the Optical Society of America A (JOSA A) have presented a feature issue in each journal. This feature issues includes 17 papers in AO and 9 in JOSA A. Together they cover a large range of topics, reflecting the rapidly expanding techniques and applications of digital holography and 3D imaging. The upcoming DH Conference (DH 2024) will be held from 3 to 6 June in Paestum, Italy.

Generalized Lorenz-Mie theory and simulation software for structured light scattering by particles

Structured light refers to an optical field with modulated phase and amplitude, characterized by distinct spatial patterns. It has applications in optical manipulation, 3D imaging, remote sensing, and communications. The Generalized Lorenz-Mie Theory (GLMT) extends foundational Mie theory to accommodate complex structured lights, enabling precise characterization of structured light-particle interactions. GLMT has emerged as a central theoretical framework for analyzing interactions between spherical particles and arbitrary structured light. This paper introduces ABSphere, simulation software utilizing GLMT to model structured light-spherical particle interactions. It then comprehensively reviews representative structured lights, including Laguerre–Gaussian, Bessel, and Airy beams, elucidating their interactions with spherical particles. Understanding structured light scattering behavior is crucial for elucidating underlying interaction mechanisms with spherical particles. The paper also emphasizes the significance of modeling structured light scattering by particles and discusses future directions for ABSphere software. Through continuous theoretical refinements and advancements, deeper understanding of structured light-particle interaction mechanisms can be achieved, enabling innovations in optical applications and technologies.

Tunnel Lining Crack Detection Method Based on Polarization 3D Imaging

Non-contact and non-destructive polarization 3D imaging uses a passive, single-frame array image to calculate 3D information, making it possible to obtain high-precision 3D information about tunnel cracks, and offering outstanding technical advantages. Based on the introduction of the principle of crack detection with polarization 3D imaging, a tunnel lining crack detection plan was developed and a detection equipment was designed. The method and process of polarization 3D imaging for lining crack detection are described in detail. A model of the impact of the tunnel environment on 3D detection and a method for obtaining absolute information have been established to obtain high-precision 3D information about cracks. In a real tunnel environment, tests were conducted to detect wide cracks, narrow cracks, and artificial cracks. The crack detection accuracy with respect to the crack width was 0.2–0.3 mm, and with respect to crack length was 0.2–0.3 mm. At the same time, crack depth information could be obtained. The present research results can provide technical support for the application of polarization 3D imaging in tunnel crack detection.

Deep Learning Enhanced Volumetric Photoacoustic Imaging of Vasculature in Human.

The development of high-performance imaging processing algorithms is a core area of photoacoustic tomography. While various deep learning based image processing techniques have been developed in the area, their applications in 3D imaging are still limited due to challenges in computational cost and memory allocation. To address those limitations, this work implements a 3D fully-dense (3DFD) U-net to linear array based photoacoustic tomography and utilizes volumetric simulation and mixed precision training to increase efficiency and training size. Through numerical simulation, phantom imaging, and in vivo experiments, this work demonstrates that the trained network restores the true object size, reduces the noise level and artifacts, improves the contrast at deep regions, and reveals vessels subject to limited view distortion. With these enhancements, 3DFD U-net successfully produces clear 3D vascular images of the palm, arms, breasts, and feet of human subjects. These enhanced vascular images offer improved capabilities for biometric identification, foot ulcer evaluation, and breast cancer imaging. These results indicate that the new algorithm will have a significant impact on preclinical and clinical photoacoustic tomography.

Broadband Mechanically Tunable Metasurface Reflectivity Modulator in the Visible Spectrum.

Reflectivity modulation is a critical feature for applications in telecommunications, 3D imaging and printing, advanced laser machining, or portable displays. Tunable metasurfaces have recently emerged as a promising implementation for miniaturized and high-performance tunable optical components. Commonly, metasurface response tuning is achieved by electro-optical effects. In this work, we demonstrate reflectivity modulation based on a nanostructured, mechanically tunable, metasurface, consisting of an amorphous silicon nanopillar array and a suspended amorphous silicon membrane with integrated electrostatic actuators. With a membrane displacement of only 150 nm, we demonstrate reflectivity modulation by Mie resonance enhanced absorption in the pillar array, leading to a reflectivity contrast ratio of 1:3 over the spectral range from 400-530 nm. With fast, low-power electrostatic actuation and a broadband response in the visible spectrum, this mechanically tunable metasurface reflectivity modulator could enable high frame rate dynamic reflective displays.

A New Breakpoint to Classify 3D Voxels in MRI: A Space Transform Strategy with 3t2FTS-v2 and Its Application for ResNet50-Based Categorization of Brain Tumors.

Three-dimensional (3D) image analyses are frequently applied to perform classification tasks. Herein, 3D-based machine learning systems are generally used/generated by examining two designs: a 3D-based deep learning model or a 3D-based task-specific framework. However, except for a new approach named 3t2FTS, a promising feature transform operating from 3D to two-dimensional (2D) space has not been efficiently investigated for classification applications in 3D magnetic resonance imaging (3D MRI). In other words, a state-of-the-art feature transform strategy is not available that achieves high accuracy and provides the adaptation of 2D-based deep learning models for 3D MRI-based classification. With this aim, this paper presents a new version of the 3t2FTS approach (3t2FTS-v2) to apply a transfer learning model for tumor categorization of 3D MRI data. For performance evaluation, the BraTS 2017/2018 dataset is handled that involves high-grade glioma (HGG) and low-grade glioma (LGG) samples in four different sequences/phases. 3t2FTS-v2 is proposed to effectively transform the features from 3D to 2D space by using two textural features: first-order statistics (FOS) and gray level run length matrix (GLRLM). In 3t2FTS-v2, normalization analyses are assessed to be different from 3t2FTS to accurately transform the space information apart from the usage of GLRLM features. The ResNet50 architecture is preferred to fulfill the HGG/LGG classification due to its remarkable performance in tumor grading. As a result, for the classification of 3D data, the proposed model achieves a 99.64% accuracy by guiding the literature about the importance of 3t2FTS-v2 that can be utilized not only for tumor grading but also for whole brain tissue-based disease classification.

Accurate 3D reconstruction of single-frame speckle-encoded textureless surfaces based on densely connected stereo matching network.

Speckle projection profilometry (SPP) determines the global correspondence between stereo images by speckle pattern(s) projection in three-dimensional (3D) vision. However, it is extremely challenging for traditional algorithms to achieve a satisfactory 3D reconstruction accuracy generally via single-frame speckle pattern, which heavily constraints the application in dynamic 3D imaging. Recently some deep learning (DL) based methods have made process in this issue but there exist deficiencies in feature extraction, leading to a limited improvement in accuracy. In this paper, we propose a stereo matching network called Densely Connected Stereo Matching (DCSM) Network that requires only single-frame speckle pattern as input, adopts densely connected feature extraction and incorporates attention weight volume construction. The densely connected multi-scale feature extraction module we constructed in DCSM Network has a positive effect on the combination of global and local information and inhibition of information loss. We also establish a real measurement system and its digital twin through Blender to obtain rich speckle data under SPP framework. Meanwhile, we introduce Fringe Projection Profilometry (FPP) to obtain phase information to assist in generating high-precision disparity as Ground Truth (GT). Experiments with different types of models and models with various perspectives are implemented to prove the effectiveness and generalization of the proposed network compared with classic and the latest DL-based algorithms. Finally, the 0.5-Pixel-Error of our method in the disparity maps is as low as 4.81%, and the accuracy is verified to be improved by up to 33.4%. As for the cloud point, our method has a reduction of 18%∼30% compared with other network-based methods.

An improved differential evolution algorithm based on basis vector type and its application in fringe projection 3D imaging

According to the different generation methods, the types of candidate position (basis vector) in the meta-heuristic algorithm can be divided into stochastic, deterministic, and probabilistic. The stochastic type is beneficial to the preservation of population diversity, deterministic model can accelerate convergence, and probabilistic style emphasizes the balance between population diversity and convergence speed. In order to make full use of various characteristics, an improved differential evolution algorithm based on basis vector type (DEBVT) is proposed. On the one hand, in the process of mutation, individuals in the population choose the appropriate basis vector form for evolution in light of their features and needs. On the other hand, the control parameters are adaptively adjusted for the purpose of balancing exploration and exploitation. Based on twenty-nine benchmark functions, DEBVT is compared with several meta-heuristics and differential evolution variants with different types of basis vectors. All experimental results demonstrate that compared with other competitive algorithms, the optimization performance of the proposed DEBVT is remarkable. In addition, an improved UNET network (IUnet) is proposed for absolute phase extraction in fringe projection 3D imaging technology, and the activation function configuration of the network is optimized by DEBVT to construct the IUnet-DEBVT network, which further reduces the error of absolute phase and verifies of the effectiveness of DEBVT.

Topological spin defects of light

Topological defects are found in a variety of systems, and their existence is robust under perturbations due to their topological nature. Here we introduce a type of topological defect found in electromagnetic waves: topological spin defects. Such a defect is associated with a point where the electromagnetic spin density is zero, and generically has a nontrivial topological spin texture surrounding the defect point. Due to such spin texture, a topological spin defect possesses a quantized topological charge. We provide examples of isolated defect points, periodic or quasi-periodic defect lattices in electromagnetic fields. Such topological spin defect points may find applications in 3D imaging and nanoparticle manipulation.

The Application of 3D Imaging as an Appropriate Method of Wildlife Craniometry: Evaluation of Accuracy and Measurement Efficiency.

The suitability of CT and 3D scanners for craniometric proposes was tested using digital calipers when determining linear measurements, and a measuring cylinder was used for the accuracy of 3D printing of deer antlers obtained by the CT and 3D scanners. The resolution of digitized objects from a 3D scanner ranged from 0.008 mm to 0.122 mm. For mandibular dimensions, a positive deviation (p < 0.01) from the primary control measurement was recorded. The average antler volume measured with the cylinder was 60.47 cm3 at the first measurement, in the case of the CT scanner 61.62 cm3 and for the 3D scanner 64.76 cm3—both technologies exhibit a positive deviation from the primary measurement. Precise sensing and measurements can be used to evaluate the quality and evolution of wildlife populations, create digital museum collections, or to examine in detail certain traits such as antler and horn development or dentition.

Optical vortices: A methodology for generating single-focus phase singularity with binary square spiral zone plates

<p indent="0mm">Since 1992, the British researcher Allen demonstrated theoretically and experimentally that vortex beams have orbital angular momentum, many novel optical physical phenomena have been discovered through the study of optical vortices, and they have a wide application prospect in optical manipulation, optical communication, photonic chip and other fields. By combining the advantages of square spiral zone plate and Gabor zone plate, a novel binary single focused square spiral zone plate is designed to realize the optical vortex with square symmetry and alleviate the influence of the higher order foci in the propagation direction. The theoretical results are consistent with the experimental results. This finding has potential in the applications of multi-particle manipulation and 3D imaging.

Sub-10 nm radial resolution achieved by cascading a graded structure outside a spherical hyperlens.

Due to the excellent ability to break the diffraction limit in the subwavelength range, metamaterial-based hyperlens has received extensive attention. Unfortunately, radial resolution of most current hyperlens is not high enough, which is a huge obstacle to the application in 3D super-resolution imaging. In this paper, we propose a theoretical solution to this issue by cascading a graded structure outside the conventional Ag-TiO2 spherical hyperlens. The product of the thickness and the refractive index (RI) of the dielectric layer in the graded structure is fixed to 19.8 while RI increases linearly from 1.38 to 3.54 along the radial direction. By reducing the asymptote slope of the dispersion curve, the coupling of the wave vectors to the hyperlens is enhanced and thus radial resolution is significantly improved to 5 nm while ensuring that the focus is still detectable in the far-field. This design paves the way to high-performance hyperlens for 3D imaging and biosensing in the future.

Rapid variable flip angle positive susceptibility contrast imaging for clinical metal seeds

Positive susceptibility contrast imaging (PSCI) based on susceptibility mapping exhibits excellent efficacy for visualizing magnetic resonance (MR)-compatible metallic devices because of their high magnetic susceptibility compared to that of human tissues. However, the long-acquisition time required by the two-dimensional fast spin echo (2D FSE)-based PSCI approach, impedes its practical applications in 3D imaging. In this study, a three-dimensional (3D) susceptibility-based variable flip angle (vFA) FSE sequence was proposed to accelerate data acquisition in the clinical radiotherapy applications of ex vivo and in vivo rapid 3D PSCI for the imaging of metal seeds. Here, the proposed scheme applied a 3D modulated vFA technique for refocused imaging with an extended echo-train sequence for sampling data. The scheme integrated the projection-onto-dipole fields (PDF) to remove the background field and accelerate PSCI by using a compressive sensing framework with a variable-densitysampling mask. The experiments involved some gelatin phantoms, porcine tissues and patients with scapular tumors and brachytherapy seeds. All of the experimental results showed that the proposed scheme could accelerate data acquisition of 3D PSCI at the reduction factors of 2 ∼ 5 while accurately localizing the actual positions of the brachytherapy seeds in the ex vivo and in vivo applications. The results were compared with those of the existing methods, including susceptibility gradient mapping using the original resolution (SUMO) and gradient echo acquisition for superparamagnetic particle (GRASP).

Application of 3D imaging and selfies in forensic dental identification

With increased access to smartphones, the selfie has gained immense popularity in the past decade. Selfie images could be a significant source of ante-mortem (AM) image data in cases where dental records are unavailable or considered insufficient. The application of 3D imaging and selfies has not been explored to its full potential in human dental identification. The present study aimed to evaluate the feasibility of using selfies as AM data and comparing with 3D post-mortem (PM) scans as an alternative to multiple 2D PM photographs in forensic dental identification. The study sample consisted of 18 selfies (12 matching and 6 non-matching) and 15 3D dental scans obtained from the study participants. The study sample was assessed by 6 experienced forensic odontologists (Raters) in two phases; Phase I-Visual comparison of 2D selfies to 3D scans and Phase II-2D selfies superimposed upon 3D scans. Each rater looked at 15 cases, and a total of 1620 comparisons were made by 6 raters (72 for the 12 matching cases and 1548 were for non-matching) and the opinions for each of the comparisons were analyzed. The results of the study show that use of the 3D superimposition method increased the certainty of the conclusions reached by the raters for the cases with correct matches. Furthermore, 94.2% of the 1548 non-matching comparisons were correctly excluded, compared with 77% for the 2D visual comparison method. The study demonstrated the applicability of this 3D method as a valuable tool in assisting the forensic odontologist with dental identification using selfies.