Compact Scanning Research Articles

Mineralogy of ores of the Vosneenskoe gold deposit (Southern Ural)

The mineralogical features of the ores of the Voznesenskoye gold deposit located in the zone of the Main Ural Fault at the northern end of the Magnitogorsk megazone of the Southern Urals have been studied. The chemical composition of minerals was determined using a Tescan Vega Compact scanning electron microscope with an Oxford Instruments Xplorer 15 energy dispersive analyzer. Two stages of ore formation have been identified and characterized. On the early of them, arsenic pyrite (0.38–0.84% As), which is the main mineral of ores, was first formed, and later sulfurous arsenopyrite (S/As = 1.12–1.19), molybdenite enriched in Fe (7.25–8.07%), and chalcopyrite. Using an arsenopyrite geothermometer, it was found that the formation of sulfides at an early stage occurred approximately in the temperature range of 318–380°C. At a late stage, an association was formed that united pyrite containing Sb (0.28–0.31%), Zn-Fe-tetrahedrite (Cu9.1–9.4 (Fe1.2–1.3 Zn1.1–1.4)2.4–2.6 (As0.2–0.4 Sb3.7–4.1)4.2–4.3 S12.9–13.2) and native high-grade gold (952–997‰) with impurities Ag and Cu. Minerals of this association, which have an insignificant distribution, are found in crushing zones developed in arsenic pyrite. In terms of chemical composition, the studied tetrahedrite is close to the fahlores of the subepithermal mineralization of the Mikheevka porphyry Cu deposit. Based on the results of the studies performed, a preliminary conclusion was made that the Voznesenskoye deposit belongs to the subepithermal type of gold mineralization.

Enamel Analysis by 3D Scanning after Three Orthodontic Clean-Up Procedures: An In-Vitro Test of a New Piezoelectric Tool.

(1) Background: To assess the clinical safety and efficacy of a new piezoelectric instrument for orthodontic clean-up; (2) Methods: An in-vitro comparative study on 75 teeth extracted for orthodontic reasons compared the tested method (Treatment 1) with two other procedures: One step finisher and polisher (Inverted cone One gloss Shofu Dental, Kyoto, Japan) (Treatment 2) and twelve-fluted tungsten carbide bur (123-603-00, Dentaurum, Pforzheim, Germany) and Sof-Lex discs Pop-On XT Kit (3M ESPE) (Treatment 3), with n:25 samples in each group. Clinical safety (enamel volume loss) and effectiveness (residual adhesive volume) were assessed using the structured light 3D scanner Atos Compact Scan (GOM GmbH) together with the support of Atos Professional software. The surfaces were scanned three times to assess: (i) the volume of the residual adhesive (RAV) after bracket removal; (ii) the volume of the relative residual adhesive (dAV) after the clean-up procedure; (iii) volume of the enamel loss (EVL); (3) Results: The mean RAV (mm3) was 0.239 ± 0.337; 0.069 ± 0.124, 0.120 ± 0.193 and the mean EVL (mm3) was 0.1870 ± 0.177, 0.187 ± 0.299 and 0.290 ± 0.205, for treatment 1, 2 and 3, respectively. The distribution was asymmetrical between groups in both cases; (4) Conclusions: The tested instrument proved to be effective and safe for post-orthodontic clean-up. With the increasing use of invisible aligners, the possibility of using an ergonomic and fast instrument is of benefit to both patient and practitioner.

Retrieval of terahertz ice cloud properties from airborne measurements based on the irregularly shaped Voronoi ice scattering models

Abstract. Currently, terahertz remote sensing technology is one of the best ways to detect the microphysical properties of ice clouds. Influenced by the representativeness of the ice crystal scattering (ICS) model, the existing terahertz ice cloud remote sensing inversion algorithms still have significant uncertainties. In this study, based on the Voronoi ICS model, we developed a terahertz remote sensing inversion algorithm of the ice water path (IWP) and median mass diameter (Dme) of ice clouds. This study utilized the single-scattering properties (extinction efficiency, single-scattering albedo, and asymmetry factor) of the Voronoi, sphere, and hexagonal column ICS models in the terahertz region. Combined with 14 408 groups of particle size distributions obtained from aircraft-based measurements, we developed the Voronoi, sphere, and column ICS schemes based on the Voronoi, sphere, and column ICS models. The three schemes were applied to the radiative transfer model to carry out the sensitivity analysis of the top-of-cloud (TOC) terahertz brightness temperature differences between cloudy and clear skies (BTDs) on the IWP and Dme. The sensitivity results showed that the TOC BTDs between 640 and 874 GHz are functions of the IWP, and the TOC BTDs of 380, 640, and 874 GHz are functions of the Dme. The Voronoi ICS scheme possesses stronger sensitivity to the Dme than the sphere and column ICS schemes. Based on the sensitivity results, we built a multi-channel look-up table for BTDs. The IWP and Dme were searched from the look-up table using an optimal estimation algorithm. We used 2000 BTD test data randomly generated by the RSTAR model to assess the algorithm's accuracy. Test results showed that the correlation coefficients of the retrieved IWP and Dme reached 0.99 and 0.98, respectively. As an application, we used the inversion algorithm to retrieve the ice cloud IWP and Dme based on the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) airborne terahertz radiation measurements. Validation against the retrievals of the Bayesian algorithm reveals that the Voronoi ICS model performs better than the sphere and hexagonal column ICS models, with enhancement of the mean absolute errors of 5.0 % and 12.8 % for IWP and Dme, respectively. In summary, the results of this study confirmed the practicality and effectiveness of the Voronoi ICS model in the terahertz remote sensing inversion of ice cloud microphysical properties.

Accuracy of four recent intraoral scanners with respect to two different ceramic surfaces

ObjectivesTo investigate the complete arch accuracy of intraoral scanners (IOS) on two different ceramic surfaces. MethodsTwo maxillary master cast samples were prepared. The bases of both the master casts were made from zirconium oxide. The difference between the two casts was that the teeth of the [ZR] cast were produced from zirconium oxide and that of the [LD] cast were made of lithium disilicate glass-ceramic. Unlike the zirconia teeth of the [ZR] cast, the lithium disilicate teeth of the [LD] cast were glazed. The two master casts were digitized using a high-resolution scanner (Atos Compact Scan 5 M, GOM GmbH, Braunschweig, Germany) to obtain digital reference casts. Subsequently, each master cast was scanned 15 times using four IOSs. The IOSs were the Cerec Omnicam [OM], Primescan [PR], Trios 4 [TR4], and VivaScan [VS]. On surface comparison, the absolute mean deviation values were obtained for trueness and precision. For multiple comparisons, statistically significant differences were analyzed using one-way ANOVA and the Kruskal-Wallis H test. The p-value was adjusted to control for the increased risk of type I error (p < 0.0083). To compare the two means, the t-test and Mann-Whitney U test were used (p < 0.05). ResultsTrueness values for [ZR] ranged from 24.6 (±6.3) µm for [PR] and 77.1 (±8.3) µm for [OM]. Trueness values for [LD] were between 28.3 (±6.3) µm for [PR] and 72.8 (±15.6) µm for [OM]. Precision values for [ZR] ranged from 17.6 (±3.7) µm for [PR] to 37.3 (±9.9) µm for [OM]. Precision values for [LD] ranged from 17.5 (±3.6) µm for [PR] to 41.8 (±8.7) µm for [OM]. Statistically significant differences were found among all the IOSs (p < 0.0083). The trueness values of the four IOSs did not differ significantly (p < 0.05) with respect to either the [ZR] or [LD] cast. The precision values of [OM] and [VS] differed significantly with respect to the scanned surface. ConclusionsComplete arch scans achieved with the four IOSs showed significantly different trueness and precision results. [VS] and [OM] were more sensitive in terms of the scanned material. Clinical significanceThe latest IOSs showed the required accuracy for complete arch digital impressions in-vitro investigations. These findings should be implemented under conditions relevant to complete arch deviations, such as the construction of occlusal splints, analysis of occlusal relationships, and long-span restorations. Clinicians should be aware that the clinically acceptable threshold varies depending on the purpose of the IOS.

Comparison of Antera 3D® and TcPO2 for Evaluation of Blood Flow in Skin.

There is a need for quick skin blood flow tests that can be performed in the wound healing field. Antera 3D® is a compact scanner using multispectral imaging. It can perform quick assessment of skin conditions. The purpose of the present study was to investigate the ability of the Antera 3D® to assess skin blood flow in comparison with transcutaneous partial pressure of oxygen (TcPO2) measurements. This study was conducted on 13 patients with a history of lower extremity ulcers. Measurements of hemoglobin average level (hereafter, Hb score) measured by Antera 3D® and TcPO2 measured by a transcutaneous blood gas monitor were obtained at the same sites on the dorsal foot and lower leg. Differences in Hb score and TcPO2 were analyzed by t-test for each measurement site and for the presence of peripheral arterial disease (PAD). The correlation between TcPO2 and Hb score was analyzed by Pearson's correlation coefficient. Twenty-four limbs were tested. Hb score was higher (P < 0.001) and TcPO2 was lower (P = 0.056) in the dorsal foot compared to the lower leg. In the dorsal foot, Hb score was higher (P = 0.023) and TcPO2 was lower (P = 0.046) in patients with PAD compared to those without PAD. A significant negative correlation (r = -0.68; 95% confidence interval -0.85 to -0.38, P < 0.001) between TcPO2 and Hb score was observed in the dorsal foot. The negative correlation between TcPO2 and Hb score may reflect compensatory peripheral vasodilation due to occlusion or stenosis of central arteries. This study showed that Hb score measured by Antera 3D® may be related to skin blood flow.

WHU-Helmet: A Helmet-Based Multisensor SLAM Dataset for the Evaluation of Real-Time 3-D Mapping in Large-Scale GNSS-Denied Environments

Real-time 3D mapping of large-scale Global Navigation Satellite System (GNSS)-denied environments plays an important role in forest inventory management, disaster emergency response, and underground facility maintenance. Compact helmet laser scanning (HLS) systems keep the same direction as the user’s line of sight and have the advantage of “what you see is what you get”, providing a promising and efficient solution for 3D geospatial information acquisition. However, the violent motion of the helmet, the limited field of view of the laser scanner, and the repeated symmetrical geometric structures in GNSS-denied environments pose enormous challenges for the existing simultaneous localization and mapping (SLAM) algorithms. To promote the development of HLS and explore its application in large-scale GNSS-denied environments, the first large-scale HLS dataset covering multiple difficult GNSS-denied areas (e.g., forests, mountains, underground spaces) was built in this study. Besides using an additional very high accuracy fiber-optic inertial measurement unit (IMU), a novel post-processing multi-source fusion method—progressive trajectory correction (PTC)—is proposed to generate a reliable ground-truth trajectory for the benchmark, which overcomes the problems of scan matching degradation and non-rigid distortion. The accuracies of the ground truth are controlled and checked by manually surveyed feature points along the trajectory. Finally, the existing state-of-the-art SLAM methods were evaluated on the WHU-Helmet dataset, summarizing the future HLS SLAM research trends. The full dataset is available for download at: https: //github.com/kafeiyin00/WHU-HelmetDataset.

A Novel Ice Cloud Retrieval Algorithm for Submillimeter Wave Radiometers: Simulations and Application to an Airborne Experiment

A retrieval methodology based on the Bayesian neural network (BNN) is presented that inverts the ice water path (IWP), mean mass-weighted diameter (D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">me</sub> ), and cloud height of ice clouds from sub-millimeter radiometer observations. The training dataset was created using collecting cloud profiles from the DARDAR (raDAR/liDAR) database and running simulations by the Atmospheric Radiative Transfer Simulator (ARTS) model. Since the effective radius (r <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> ) is the size descriptor of ice particles in the DARDAR database, a look-up table of ice water content (IWC), D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">me</sub> , and r <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> was constructed to convert r <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> profiles into D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">me</sub> profiles. In addition, random noises corresponding to the measurement uncertainties of the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) during the TC4 experiment were added to the simulated brightness temperatures before training the BNN. The proposed retrieval method was first applied to the simulated testing database, and then to the observations of CoSSIR. Moreover, the retrieved IWP and D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">me</sub> were compared to the retrievals of the Bayesian Monte Carlo Integration (BMCI) method. The retrieved cloud height was assessed by cloud height extracted from the reflectivity data of the Cloud Radar System (CPS) flow on the same aircraft with CoSSIR. The comparison showed that the correlation coefficients of the retrieved IWP and D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">me</sub> from the two methods are above 0.8, and the retrieved cloud height also showed good agreement with that extracted from the CPS.

Composite lens-based compact and lightweight handheld scanner for terahertz time-domain system

The non-destructive behavior of terahertz (THz) radiation is used in a wide variety of applications in industry and research and has inspired researchers to explore different configurations of THz-based measurement systems to bring such systems from the laboratory to the field. In this work, an optical system is presented for terahertz reflectivity measurement based on refractive optical elements. The optical arrangement is housed in a handheld THz scanner head unit that is realized using additive manufacturing. The THz scanner head is modular, compact, lightweight, and easy to handle, making it field deployable and suitable for outdoor measurements. Further, the applicability of this THz scanner head is demonstrated in applications such as hydration sensing, surface roughness characterization, and interface detection in multilayered structures, which play key roles in industrial environment for non-contact quality control and assessment of consumer products.

Development of a GAGG(Ce)-based compact 3D scanning setup for assessment of active volume in [formula omitted]-ray detectors

A Ce-doped GAGG (Gadolinium Aluminum Gallium Garnet: Gd3Al2Ga3O12) scintillator crystal has been coupled with a multianode position sensitive photomultiplier tube (PSPMT). The system is made compact by employing an external resistive network that reduces the 64 readouts of the PSPMT to only four signals. The resulting GAGG(Ce)-PSPMT setup has been put to use for quick scanning of γ-ray detectors by reconstructing the image of the latter with coincident photons between the pair of detectors. In the present work, such scans are demonstrated for an old single-crystal coaxial reverse-electrode HPGe detector as well as an old clover HPGe detector. For the single-crystal HPGe, the growth of the effective depleted region under increasing reverse-bias voltages has been visualized from the image reconstruction. The active volume is seen to grow from the surface towards the axial cavity. For the clover HPGe detector, dysfunctional portions in the crystals could be identified. The experimental results are found to agree well with simulation carried out using the GEANT4 toolkit. Scanning a detector using this method is faster compared to the scanning process by a point source.

Validating a Novel Device to Improve Skin Color Matching for Face Transplants.

A prospective study of 100 individuals was conducted. All participants were photographed and scanned with the Nix Color Sensor. Sixty pairwise comparisons were randomly generated. Skin color analysis was performed using photographs and the Nix Color Sensor. Delta E2000 values were compared to mean evaluator ratings using a Spearman correlation analysis. One hundred patients were included. A Spearman's correlation demonstrated a strong inverse correlation between Delta E2000 values and the mean evaluator ratings. The higher the mean evaluator rating for likeness, the lower the delta. A correlation coefficient of -0.850 demonstrates a statistically significant relationship (P < 0.01). When the Delta E2000 rises above 5 there is a significant drop in the mean evaluator ratings. As mean evaluator ratings of 5 and above would be considered adequate for face transplant amongst most plastic surgeons, an E2000 value of 5 or lower should be targeted when matching donors with recipients for face transplant. The Nix Color Sensor positively correlates to the plastic surgeon's perception of skin color and can serve as an adjunct in donor selection for facial VCAs.

Tip-scan high-speed atomic force microscopy with a uniaxial substrate stretching device for studying dynamics of biomolecules under mechanical stress.

High-speed atomic force microscopy (HS-AFM) is a powerful tool for studying the dynamics of biomolecules in vitro because of its high temporal and spatial resolution. However, multi-functionalization, such as combination with complementary measurement methods, environment control, and large-scale mechanical manipulation of samples, is still a complex endeavor due to the inherent design and the compact sample scanning stage. Emerging tip-scan HS-AFM overcame this design hindrance and opened a door for additional functionalities. In this study, we designed a motor-driven stretching device to manipulate elastic substrates for HS-AFM imaging of biomolecules under controllable mechanical stimulation. To demonstrate the applicability of the substrate stretching device, we observed a microtubule buckling by straining the substrate and actin filaments linked by α-actinin on a curved surface. In addition, a BAR domain protein BIN1 that senses substrate curvature was observed while dynamically controlling the surface curvature. Our results clearly prove that large-scale mechanical manipulation can be coupled with nanometer-scale imaging to observe biophysical effects otherwise obscured.

Applying edge artificial intelligence to closed-loop real time control and monitoring of laser based battery pack welding

The manufacturing of battery packs plays an essential role in e-mobility. In this context, laser welding of batteries has taken a considerable momentum in recent years as it can quickly adapt to different form factors and battery arrangements which is crucial for short runs and on-demand manufacturing. In this paper, we present an assisted battery pack welding system applying a novel sensor fusion strategy. The presented work introduces a multi-camera solution combining a camera in the visual range and an infrared camera in a compact scanner head that applies graphics processing unit acceleration for image processing and real-time field programmable gate array processing for process control. In order to acquire accurate temperature measurements, the infrared camera has been characterized and calibrated for the temperature ranges of the welding process. In addition, we propose a method for image space coordinate transformation based on affine transformations used to transform the coordinates of the detected battery joints into different image spaces to adapt to the welding process in real time. A single shot multibox detector Mobilenet-v2 neural network has been retrained with custom images to detect and classify a set of battery pack types allowing the extraction of the battery cell joint coordinates using image processing, which enables the application of real-time corrections to the laser aiming system and a closed-loop laser power control. Finally, we present some battery welding results using different welding strategies on the described system.

PHYSICAL AND CHEMICAL CONDITIONS FOR THE FORMATION OF THE ORLOVKA OROGENIC GOLD DEPOSIT IN THE SOUTHERN URALS (ACCORDING TO THE DATA OF A CHLORITE&#x0D; GEOTHERMOMETER AND REE DISTRIBUTION IN CALCITE)

The chemical composition of chlorite from ore-bearing albite-biotite-quartz-chlorite-epidote-actinolite schists and the REE content in calcite of sulfide-carbonate-quartz veinlet ores of the Orlovsky orogenic gold deposit located in the zone of the Main Ural Fault in the Southern Urals have been studied. The chemical composition of chlorite was determined on a Tescan Vega Compact scanning electron microscope with an Oxford Instruments Xplorer 15 energy-dispersive analyzer. The REE content in calcite was studied using inductively coupled plasma mass spectrometry (ICP-MS) on a PerkinElmer ELAN 9000 instrument. It has been established that chlorite, represented by a variety with a transitional chemical composition from clinochlore to pycnochlorite (5.78–6.0 Si f.u.; 0.27–0.28 Fetot/(Fetot + Mg)) was formed at a temperature of 295.6–266.2°C. The REE distribution spectra in calcite, normalized to C1 chondrite, are characterized by the accumulation of light lanthanides ((La/Yb)N=1.28–7.18), the value of the ratio (La/Lu)N=1.1–6.58, indicating the predominance of rare earth sorption processes in the fluid, small negative anomalies of cerium (Ce/Ce*=0.71–0.92) and positive anomalies of europium (Eu/Eu*=1.05–2.38). Negative Ce anomalies in calcite may be due to the interaction of the fluid with limestones, as well as the presence of meteoric water in its composition in a small amount. Positive Eu anomalies indicate low-temperature conditions for calcite crystallization (&lt;250°С). A model of deposit formation is proposed, which provides for the generation of mineral-forming fluid at the progressive stage of greenschist dynamometamorphism of host rocks and the formation of calcite and gold-bearing mineralization at the regressive stage. Data on REE geochemistry confirm the hydrothermal-metamorphogenic genesis of the gold-bearing sulfide-carbonate-quartz mineralization of the Orlovsky deposit. Keywords: Southern Urals, orogenic gold deposit, chlorite geothermometer, REE distribution, europium anomaly.

Efficient waveguide-type four-color (red–green–blue–infrared) laser beam combiner for compact laser beam scanning image projectors

Efficient waveguide-type four-color (red–green–blue–infrared) laser beam combiner for compact laser beam scanning image projectors

High-resolution and high-sensitivity PET for quantitative molecular imaging of the monoaminergic nuclei: A GATE simulation study.

Quantitative in vivo molecular imaging of fine brain structures requires high-spatial resolution and high-sensitivity. Positron emission tomography (PET) is an attractive candidate to introduce molecular imaging into standard clinical care due to its highly targeted and versatile imaging capabilities based on the radiotracer being used. However, PET suffers from relatively poor spatial resolution compared to other clinical imaging modalities, which limits its ability to accurately quantify radiotracer uptake in brain regions and nuclei smaller than 3 mm in diameter. Here we introduce a new practical and cost-effective high-resolution and high-sensitivity brain-dedicated PET scanner, using our depth-encoding Prism-PET detector modules arranged in a conformal decagon geometry, to substantially reduce the partial volume effect and enable accurate radiotracer uptake quantification in small subcortical nuclei. Two Prism-PET brain scanner setups were proposed based on our 4-to-1 and 9-to-1 coupling of scintillators to readout pixels using mm3 and mm3 crystal columns, respectively. Monte Carlo simulations of our Prism-PET scanners, Siemens Biograph Vision, and United Imaging EXPLORER were performed using Geant4 application for tomographic emission (GATE). National Electrical Manufacturers Association (NEMA) standard was followed for the evaluation of spatial resolution, sensitivity, and count-rate performance. An ultra-micro hot spot phantom was simulated for assessing image quality. A modified Zubal brain phantom was utilized for radiotracer imaging simulations of 5-HT1A receptors, which are abundant in the raphe nuclei (RN), and norepinephrine transporters, which are highly concentrated in the bilateral locus coeruleus (LC). The Prism-PET brain scanner with 1.5 mm crystals is superior to that with 1 mm crystals as the former offers better depth-of-interaction (DOI) resolution, which is key to realizing compact and conformal PET scanner geometries. We achieved uniform 1.3 mm full-width-at-half-maximum (FWHM) spatial resolutions across the entire transaxial field-of-view (FOV), a NEMA sensitivity of 52.1 kcps/MBq, and a peak noise equivalent count rate (NECR) of 957.8 kcps at 25.2 kBq/mL using 450-650 keV energy window. Hot spot phantom results demonstrate that our scanner can resolve regions as small as 1.35 mm in diameter at both center and 10 cm away from the center of the transaixal FOV. Both 5-HT1A receptor and norepinephrine transporter brain simulations prove that our Prism-PET scanner enables accurate quantification of radiotracer uptake in small brain regions, with a 1.8-fold and 2.6-fold improvement in the dorsal RN as well as a 3.2-fold and 4.4-fold improvement in the bilateral LC compared to the Biograph Vision and EXPLORER, respectively. Based on our simulation results, the proposed high-resolution and high-sensitivity Prism-PET brain scanner is a promising cost-effective candidate to achieve quantitative molecular neuroimaging of small but important brain regions with PET clinicallyviable.

Demonstration of real-time structured-light depth sensing based on a solid-state VCSEL beam scanner.

We demonstrated a real-time scanning structured-light depth sensing system based on a solid-state vertical cavity surface-emitting laser (VCSEL) beam scanner integrated with an electro-thermally tunable VCSEL. Through a swept voltage added to the tunable VCSEL, a field of view of 6°×12° could be scanned with a scanning speed of 100 kHz by the beam scanner. Adopting the beam scanner, the real-time depth image with a lateral resolution of 10,000 (20×500) was obtained by measuring a step target placed at 35cm. The frame rate could be >10Hz even if sunlight shot noise is artificially added to the experimental data. By using a higher-speed camera, a potential lateral resolution could be reached at 50,000 (100×500) with a frame rate of > 20Hz. By using flat optics, a compact scanning module offering line pattern with FoV of >40°×20° was also demonstrated. It could help to realize high-resolution and high-accuracy structured-light sensing with a compact module.

Method and portable bench for tests of the laser optical calibration system components for the Baikal-GVD underwater neutrino Cherenkov telescope

The Large-scale deep underwater Cherenkov neutrino telescopes like Baikal-GVD, ANTARES or KM3NeT, require calibration and testing methods of their optical modules. These methods usually include laser-based systems which allow us to check the telescope responses to the light and for real-time monitoring of the optical parameters of water such as absorption and scattering lengths, which show seasonal changes in natural reservoirs of water. We will present a testing method of a laser calibration system and a set of dedicated tools developed for Baikal-GVD, which includes a specially designed and built, compact, portable, and reconfigurable scanning station. This station is adapted to perform fast quality tests of the underwater laser sets just before their deployment in the telescope structure, even on ice, without a darkroom. The testing procedure includes the energy stability test of the laser device, 3D scan of the light emission from the diffuser and attenuation test of the optical elements of the laser calibration system. The test bench consists primarily of an automatic mechanical scanner with a movable Si detector, beam splitter with a reference Si detector and, optionally, Q-switched diode-pumped solid-state laser used for laboratory scans of the diffusers. The presented test bench enables a 3D scan of the light emission from diffusers, which are designed to obtain the isotropic distribution of photons around the point of emission. The results of the measurement can be easily shown on a 3D plot immediately after the test and may be also implemented to a dedicated program simulating photons propagation in water, which allows us to check the quality of the diffuser in the scale of the Baikal-GVD telescope geometry.

LiDAR-based Simultaneous Localization and Mapping in an underground mine in Złoty Stok, Poland

The mining sector is one of the most promising areas for implementing advanced autonomous robots. The benefits of increased safety, robot actions’ repeatability, and reducing human presence in hazardous locations are especially important in underground mines. One of the core functionalities of such a device is the robot’s ability to localize and navigate itself in the working environment. To achieve this, simultaneous localization and mapping (SLAM) techniques are used. In selected cases, they also allow the acquisition of dense spatial data in the form of 3D point clouds, which can be utilized for various 3D modeling and spatial analysis purposes. In this work, a mobile robot, equipped only with a compact laser scanner, is used to acquire spatial data in the adit of a closed mine in Zloty Stok, Poland. This data is further processed with selected SLAM algorithms to create a homogeneous 3D point cloud. Results are visualized and compared to a model obtained with a survey-grade laser scanner. Accuracy evaluation shows that employing SLAM algorithms to process data collected by a mobile robot can produce a reasonably accurate 3D geometrical model of an underground tunnel, even without incorporating any additional sensors.

Average SAR prediction, validation, and evaluation for a compact MR scanner head-sized RF coil

A recently developed compact 3 T (C3T) MRI scanner with high performance gradients [1, 2] has a dedicated radiofrequency (RF) transmit coil that exposes only the head, neck and a small portion of the upper body region during head-first scanning. Due to the unique coil geometry and patient positioning, the established SAR model used for a conventional whole-body scanner cannot be directly translated to the C3T. Here a specific absorption rate (SAR) estimation and validation framework was developed and used to implement a dedicated and accurate SAR prediction model for the C3T. Two different SAR prediction models for the C3T were defined and evaluated: one based on an anatomically derived exposed mass, and one using a fixed anatomical position located caudally to the RF coil to determine the exposed mass. After coil modeling and virtual human body simulation, the designed SAR prediction model was implemented on the C3T and verified with calorimetry and in vivo scan power monitoring. The fixed-demarcation exposed mass model was selected as appropriate exposed mass region to accurately estimate the SAR deposition in the patient on the C3T.

A Compact Full-Space Scanning Leaky-Wave Antenna With Stable Peak Gain

A full-space scanning leaky-wave antenna featuring small aperture size and relatively stable gain is proposed in this communication. We propose three key conditions for full-space scanning capability, including single-harmonic radiation, field cancellation suppression at endfire, and open stopband suppression at broadside. Results from a prototype based on paired stubs and crossover offset parallel striplines are provided to verify the proposed principle. Experimental results show that the main beam is able to continuously scan from backfire to endfire with stable gain around 9.1 dBi within the frequency range of 4.5–10.2 GHz. The antenna aperture is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.85\lambda _{0}\times 0.1\lambda _{0}$ </tex-math></inline-formula> only.