Commercial Scanning Research Articles

A perspective on Varian edge live view calibration

Modern radiotherapy relies heavily on precise, real-time monitoring of both the patient and the linear accelerator (linac) components. However, current commercial surface scanning systems often overlook the monitoring of linac components, such as the gantry, collimator, and couch, focusing solely on the patient. This study aims to address this issue by developing a comprehensive understanding of the Varian TrueBeam Edge system using a live view calibration method. This method ensures accurate alignment between the machine's 3D model and live camera images, improving the precision and reliability of radiotherapy treatments.

Correlative Microscopy Analysis for Battery Materials

Lithium batteries (LB) are in high demand for a diverse range of applications, such as automotive industry, consumer electronics, wearable and medical devices, grid storage, etc. Each application demands a specific set of performance advantages, such as high capacity and/or energy density, long cycle life, superior electrochemical stability. Therefore, there is no one-size-fits-all for a LB chemistry and its form factor. Battery performance advantages rely on optimization of the battery components, including active materials, electrolyte, separator, binder system, and current collectors. For meaningful device optimization, electrochemical battery testing needs to be combined with a deep understanding of the material and device microstructure. Physical and chemical characterization on the material- and electrode-level is needed to establish root-cause relationships with battery performance. Properties of the interfaces between layers of the battery components often define the device characteristics. Critical information is usually buried beneath the surface of a material specimen or encapsulated in a closed-form device. Microstructural defect identification in the battery needs to be followed by a targeted defect study. Different battery form factors and chemistries make it hard to streamline root-cause analysis.Recently, a commercial focused-ion beam scanning electron microscope was developed with an integrated fs-laser mill attached to the load lock of the microscope, opening the door to new and more powerful analysis approaches in energy materials research. Applications include rapid access to deeply buried structures for high resolution imaging and analytics, large area cross-section preparation, and massive material ablation for sample preparation of structures; e.g. FIB-SEM tomography, TEM, APT, or X-ray nanoCT. Additionally, each of these methods may be correlatively guided by prior imaging, with techniques like 3D X-ray microscopy (XRM), to enable targeted analysis and preparation. The non-destructive nature of 3D XRM makes it an ideal tool for microstructural defect identification in LB. Laser mill allows researchers to combine non-destructive X-ray defect identification with electron microscopy methods for targeted defect characterization. This approach can be used for various battery types and form factors.By combining the laser mill with 3D X-ray microscopy, this platform enables comprehensive analysis of energy materials at the nanoscale. We illustrate these concepts with application examples, and use cases demonstrating the utility of the approach.

Segmented fluorescence correlation spectroscopy (FCS) on a commercial laser scanning microscope

Performing accurate Fluorescence Correlation Spectroscopy (FCS) measurements in cells can be challenging due to cellular motion or other intracellular processes. In this respect, it has recently been shown that analysis of FCS data in short temporal segments (segmented FCS) can be very useful to increase the accuracy of FCS measurements inside cells. Here, we demonstrate that segmented FCS can be performed on a commercial laser scanning microscope (LSM), even in the absence of the dedicated FCS module. We show how data can be acquired on a Leica SP8 confocal microscope and then exported and processed with a custom software in MATLAB. The software performs segmentation of the data to extract an average ACF and measure the diffusion coefficient in specific subcellular regions. First of all, we measure the diffusion of fluorophores of different size in solution, to show that good-quality ACFs can be obtained in a commercial LSM. Next, we validate the method by measuring the diffusion coefficient of GFP in the nucleus of HeLa cells, exploiting variations of the intensity to distinguish between nucleoplasm and nucleolus. As expected, the measured diffusion coefficient of GFP is slower in the nucleolus relative to nucleoplasm. Finally, we apply the method to HeLa cells expressing a PARP1 chromobody to measure the diffusion coefficient of PARP1 in different subcellular regions. We find that PARP1 diffusion is slower in the nucleolus compared to the nucleoplasm.

A combined approach of SFM-MVS photogrammetry and reflectance transformation imaging to enhance 3D reconstructions

One of the problems that arises when applying 3D Structure from Motion and Multi-View-Stereo photogrammetry to certain heritage objects characterized by minimal surface features and monochrome textures is that the obtained 3D models have low quality and accuracy. Within such scenarios, the smallest lengths that can be measured on it with high accuracy is usually one or more orders of magnitude worse than the maximum resolution of the input photographs. Additionally, when contrasted with outputs from scanning systems, these reconstructions tend to exhibit relatively lower quality. This article presents a simple approach wherein the incorporation of normal maps acquired through Reflectance Transformation Imaging technique improves the quality and accuracy of 3D photogrammetric reconstructions (mesh + texture). This enhancement also surpasses the capabilities of some commercial structured light scanning systems and reaches values that are in the order of magnitude of the maximum resolution of the photographs used.

Tungsten Nanoparticles Generated in an Atmospheric Pressure Plasma Jet

AbstractThe atmospheric pressure plasma source HelixJet has been used to generate tungsten nanocrystals with narrow size distributions, well defined size control and with a considerably good particle yield. Tungsten particles are produced as the result of an evaporation process of a tungsten wire inserted on the middle axis of the jet after the wire is heated by interaction with the plasma. Temperature measurements using a thermocouple and by optical emission spectroscopy showed that, while the overall temperature of the wire is very high, it is not in the range of the melting temperature of tungsten; however, it can reach values needed for sublimation. Additionally, the wire is heated selectively while the temperature of the jet components reaches only a few hundred degrees Celsius. The particles cluster into agglomerates and their formation has been analyzed in relation to the reliability of a commercial scanning mobility particle sizer spectrometer. The dependence of the particle morphology and crystal structure on the plasma parameters such as power and gas flow was studied via transmission electron microscopy and the average size of the tungsten nanocrystals could be tuned between 12 and 25 nm.

A novel mirror-assisted method for full-field vibration measurement of a hollow cylinder using a three-dimensional continuously scanning laser Doppler vibrometer system

A novel general-purpose three-dimensional (3D) continuously scanning laser Doppler vibrometer (CSLDV) system was recently developed by the authors to measure 3D vibration of a structure with a curved surface. As a non-contact system, it can avoid the mass-loading problem in 3D vibration measurement using triaxial accelerometers. In previous studies, the 3D CSLDV system was used to measure 3D full-field vibration of a turbine blade with a curved surface and identify its operating deflection shapes (ODSs) and mode shapes. The 3D CSLDV system had the same level of accuracy as that with a commercial 3D scanning laser Doppler vibrometer system, but can measure many more points in much less time than the latter. However, the 3D CSLDV system can be limited by its field of view, which is a common problem for optical-based measurement devices. Moving the 3D CSLDV system to different positions to measure different parts of a test structure is not practical during 3D CSLDV measurement, since the system has to be re-calibrated once it has been moved, which can be time-consuming and introduce measurement errors. This work proposes a novel mirror-assisted testing methodology for 3D CSLDV measurement that aims to measure vibration of difficult-to-access areas of a structure without moving the 3D CSLDV system during the test, and stitch ODSs of its different parts together to obtain its panoramic 3D ODSs. The proposed methodology includes a novel scan trajectory design method that uses virtual areas of the structure behind the mirror to conduct continuous and synchronous scanning of three laser spots, and a novel velocity transformation method that uses virtual positions of three laser heads behind the mirror to stitch ODSs of different parts of the structure together. To demonstrate the proposed methodology, 3D CSLDV measurement is conducted on an aluminum hollow cylinder specimen, which has difficult-to-access areas such as its side and back surfaces, with the assistance of the mirror to obtain its panoramic 3D ODSs corresponding to its first two modes. Comparison between identified ODSs of the hollow cylinder specimen from the experiment and mode shapes from its finite element model is made and modal assurance criterion values are larger than 0.98.

Stability of the Formation of an Image Using a Terajet with Respect to the Beam Shift

The shift of an image of a dielectric sphere asymmetrically irradiated by a terahertz Gaussian beam in terahertz imaging systems has been demonstrated experimentally. Numerical calculations using the operator scattering theory have shown the bending of the localization region of the electromagnetic field near the shadow surface of the dielectric sphere when it is shifted with respect to the waist center of the Gaussian beam, leading to the formation of the so-called “photonic hook” with the properties depending on the polarization and frequency of the incident radiation. The possibility of reaching a spatial resolution of 0.38λ in the studied range has been shown experimentally. The obtained results can be used to increase the resolution of commercial scanning terahertz systems.

Integrated Circular Dichroism and Circularly Polarized Luminescence Measurements.

Circularly polarized luminescent (CPL) systems have a plethora of potential applications owing to their interesting excited-state properties. However, the progress in developing new chiral luminescence systems is significantly hindered by the lack of available instrumentation for the broader chemistry and materials science community to perform routine, reproducible measurements of chiral spectroscopies. In this work, we present data from an easy-to-use custom-built instrument based on a Jasco circular dichroism (CD) spectropolarimeter coupled with a CPL emission monochromator (CD/CPL hybrid system). The hybrid system measures CPL, fluorescence, CD, and absorbance on the same part of the sample without the need to move between the CD and CPL measurements. The instrument uses a xenon arc lamp as the light source, enabling a wide range of excitation wavelengths to support flexible development of new molecules and materials. Data obtained and presented for camphor, ruthenium metal complexes, the peptide gramicidin, and a DNA-ligand (4',6-diamidino-2-phenylindole, DAPI) system in this work highlight the ease of use and reproducibility of the results. The g-factors for CD and CPL obtained for the different compounds are shown to be the same for isolated transitions and some examples of how to use variations of g-factors with wavelength are demonstrated. The reliable and excellent benchmark results obtained from a custom-built commercial wavelength scanning CPL/CD hybrid instrument open up new avenues for the broader chemical and materials science community to intensify research on chiral luminescent systems.

Heating samples to 2000 °C and above for scanning tunneling microscopy studies in ultrahigh vacuum

A simple device for heating single-crystal samples to temperatures ≥2000 °C in ultrahigh vacuum that is compatible with the standard sample plates used in a common commercial scanning tunneling microscope (STM) is described. Heating high melting point samples to higher temperatures than is possible with many existing STM sample holders is necessary to obtain clean, well-ordered surfaces. Results are demonstrated for the (0001) surface of ZrB2, which has a melting point of 3050 °C.

MRI T2 mapping assessment of T2 relaxation time in desmoid tumors as a quantitative imaging biomarker of tumor response: preliminary results.

Because size-based imaging criteria poorly capture biologic response in desmoid-type fibromatosis (DF), changes in MRI T2 signal intensity are frequently used as a response surrogate, but remain qualitative. We hypothesized that absolute quantification of DF T2 relaxation time derived from parametric T2 maps would be a feasible and effective imaging biomarker of disease activity. This IRB-approved retrospective study included 11 patients with DF, managed by observation or systemic therapy, assessed by 3T MRI. Tumor maximum diameter, volume, and T2-weighted signal intensity were derived from manual tumor segmentations. Tumor:muscle T2 signal ratios were recorded. Two readers measured tumor T2 relaxation times using a commercial T2 scanning sequence, manual ROI delineation and commercial calculation software enabling estimation of reader reliability. Objective response rates based on RECIST1.1 and best responses were compared between size-based and signal-based parameters. Median patient age was 52.6 years; 8 subjects were female (73%). Nine patients with longitudinal assessments were followed for an average of 314 days. Median baseline tumor diameter was 7.2 cm (range 4.4 - 18.2 cm). Median baseline T2 was 65.1 ms (range 40.4 - 94.8 ms, n=11); median at last follow-up was 44.3 ms (-32% from baseline; range 29.3 - 94.7 ms, n=9). T2 relaxation times correlated with tumor:muscle T2 signal ratios, Spearman p=0.78 (p<0.001). T2 mapping showed high inter-reader reliability, ICC=0.84. The best response as a percentage change in T2 values was statistically significant (mean -17.9%, p=0.05, paired t-test) while change in diameter was not (mean -8.9%, p=0.12). Analysis of T2 relaxation time maps of DF may offer a feasible quantitative biomarker for assessing the extent of response to treatment. This approach may have high inter-reader reliability.

Poor Man's Line Scan – a simple tool for the acquisition of high-resolution, undistorted drill core photos

Abstract. The analysis and presentation of drill cores, an essential part of geoscientific research, requires the acquisition of high-quality core photos. Typically, core photos are either taken by hand, which often results in poor and inconsistent image quality and perspective distortions, or with large, heavy, and thus inflexible as well as expensive line scan setups. We present a simple, portable “Poor Man's Line Scan” setup that turns a customary smartphone into a semi-automatic core scanner utilising its panoramic photo function while guided on a rail in order to record undistorted core photographs at high resolution. The resulting images, although affected by some minor artefacts, are clearly superior in quality and resolution to single photos taken by hand and are comparable to images taken with commercial line scan cameras. The low cost (∼ EUR 100) and high flexibility, including the potential for modifications, of our tool make it an interesting alternative to the classical line scan setup.

Performance benchmarking of an ultra-low vibration laboratory to host a commercial millikelvin scanning tunnelling microscope

Ultra-low temperature scanning tunnelling microscopy and spectroscopy (STM/STS) achieved by dilution refrigeration can provide unrivalled insight into the local electronic structure of quantum materials and atomic-scale quantum systems. Effective isolation from mechanical vibration and acoustic noise is critical in order to achieve ultimate spatial and energy resolution. Here, we report on the design and performance of an ultra-low vibration (ULV) laboratory hosting a customized but otherwise commercially available 40 mK STM. The design of the vibration isolation consists of a T-shaped concrete mass block (∼55t), suspended by actively controlled pneumatic springs, and placed on a foundation separated from the surrounding building in a ‘room-within-a-room’ design. Vibration levels achieved are meeting the VC-M vibration standard at >3 Hz, reached only in a limited number of laboratories worldwide. Measurement of the STM’s junction noise confirms effective vibration isolation on par with custom built STMs in ULV laboratories. In this tailored low-vibration environment, the STM achieves an energy resolution of 43 μeV (144 mK), promising for the investigation and control of quantum matter at atomic length scales.

Artificially controlled nanoscale chemical reduction in VO2 through electron beam illumination

Chemical reduction in oxides plays a crucial role in engineering the material properties through structural transformation and electron filling. Controlling the reduction at nanoscale forms a promising pathway to harvest functionalities, which however is of great challenge for conventional methods (e.g., thermal treatment and chemical reaction). Here, we demonstrate a convenient pathway to achieve nanoscale chemical reduction for vanadium dioxide through the electron-beam illumination. The electron beam induces both surface oxygen desorption through radiolytic process and positively charged background through secondary electrons, which contribute cooperatively to facilitate the vacancy migration from the surface toward the sample bulk. Consequently, the VO2 transforms into a reduced V2O3 phase, which is associated with a distinct insulator to metal transition at room temperature. Furthermore, this process shows an interesting facet-dependence with the pronounced transformation observed for the c-facet VO2 as compared with the a-facet, which is attributed to the intrinsically different oxygen vacancy formation energy between these facets. Remarkably, we readily achieve a lateral resolution of tens nanometer for the controlled structural transformation with a commercial scanning electron microscope. This work provides a feasible strategy to manipulate the nanoscale chemical reduction in complex oxides for exploiting functionalities.

Ultrawide-bandwidth high-resolution all-optical intravascular ultrasound using miniaturized photoacoustic transducer.

Conventional intravascular ultrasound (IVUS) uses piezoelectric transducers to electrically generate and receive ultrasound. However, it remains a challenge to achieve large bandwidth for high resolution without compromising imaging depth. We report an all-optical IVUS (AO-IVUS) imaging system using picosecond laser pulse-pumped carbon composite for ultrasound excitation and π-phase-shifted fiber Bragg gratings for ultrasound detection. Using this all-optical technique, we achieved ultrawide-bandwidth (147%) and high-resolution (18.6 micrometers) IVUS imaging, which is unattainable by conventional technique. Imaging performance has been characterized in phantoms, presenting 18.6-micrometer axial resolution, 124-micrometer lateral resolution, and 7-millimeter imaging depth. Rotational pullback imaging scans are performed in rabbit iliac artery, porcine coronary artery, and rabbit arteries with drug-eluting metal stents, in parallel with commercial intravenous ultrasound scans as reference. Results demonstrated the advantages of high-resolution AO-IVUS in delineating details in vascular structures, showing great potential in clinical applications.

Optimisation of Imaging Confocal Microscopy for Topography Measurements of Metal Additive Surfaces

Additive manufactured surfaces, especially metal powder bed fusion surfaces, present unique challenges for measurement because of their complex topographies. To address these measurement challenges, optimisation of the measurement process is required. Using a statistical approach, sensitivity analyses were performed on measurement settings found on a commercial programmable array scanning confocal microscope. The instrument measurement process parameters were compared by their effects on three quality indicators: the areal surface texture parameter Sa, measurement noise, and number of non-measured points. An analysis was performed using a full factorial design of experiments for both the top and side surfaces of test surfaces made from Inconel 718 and Ti-6Al-4V using powder bed fusion. The results indicated that measurements of metal additive surfaces are robust to changes in the measurement control parameters for Sa, with variations within 5% of the mean parameter value for the same objective, surface, and measured area. The number of non-measured points and the measurement noise were more varied and were affected by the choice of measurement control parameters, but such changes could be predicted by the statistical models. The contribution offered by this work is an increased understanding of imaging confocal microscopy measurement of metal additive surfaces, along with the establishment of good practice guidance for measurements.

The pinhole effect on proton exchange membrane fuel cell (PEMFC) current density distribution and temperature distribution

The proton exchange membrane (PEM) is a critical portion of a proton exchange membrane fuel cell (PEMFC). However, it is strongly influenced by pinhole defects owing to degradation during its operation or manufacture. Such defects may accelerate chemical polymer decomposition, eventually causing fuel cell failure and other safety issues. Thus, it is necessary to detect and characterize pinhole degradation while determining the effect of pinhole on electrochemical behavior and fuel cell performance. Herein, pinholes of different sizes (10 and 100 µm) were fabricated on a 50-cm2 catalyst-coated membrane (CCM) and characterized using commercial current scan shunt (CSS) S++ Simulation Services (Hephas Energy) to investigate the effects of pinhole size on current density and temperature distributions of the PEMFC. Our analyses show that hydrogen crossover from the anode to the cathode through a pinhole can cause hydrogen diffusion and a hydrogen oxidation reaction (HOR) on the cathode electrode surface under certain conditions. Consequently, local reverse currents and hot spots are detected around the pinhole position under open-circuit voltage (OCV) and the corresponding current and temperature distribution trends are uniform. Conversely, the reverse current immediately disappeared from the current distribution map because water exists under operation conditions, resulting in membrane swelling and pinhole sealing. Thus, hydrogen crossover decreased and local reverse currents reappeared as a result of anode overpressure during fuel cell operation. The local reverse current becomes weaker when using the same-sized pinhole under the same anode overpressure because the overall current density increases. Furthermore, owing to the presence of water, the capillary force for the 100-µm pinhole was higher than that for the 10-µm pinhole, indicating that more anode overpressure is required to generate a local reverse current. Thus, the position and size of the pinhole can be effectively detected using in situ characterization.

Identification of modal parameters of a model turbine blade with a curved surface under random excitation with a three-dimensional continuously scanning laser Doppler vibrometer system

Modal parameters of a model turbine blade with a curved surface excited by white noise are identified by a novel general-purpose 3D continuously scanning laser Doppler vibrometer (CSLDV) system via an extended demodulation method (EDM). The proposed general-purpose system is calibrated to synchronously and continuously move three laser spots on the curved surface of the blade along the same scan trajectory and capture its 3D vibrations. The EDM is used to estimate its damped natural frequencies (DNFs) and 3D full-field undamped mode shapes. Identified modal parameters are compared with those from a commercial 3D scanning laser Doppler vibrometer (SLDV) system. Differences between their first six DNFs are less than 1.5%; their first six mode shapes are highly correlated as their modal assurance criterion values all exceed 95%. However, the 3D CSLDV system has much higher efficiency in obtaining 3D mode shapes of the blade than the 3D SLDV system.

ELI trifocal microscope: a precise system to prepare target cryo-lamellae for in situ cryo-ET study

Cryo-electron tomography (cryo-ET) has become a powerful approach to study the high-resolution structure of cellular macromolecular machines in situ. However, the current correlative cryo-fluorescence and electron microscopy lacks sufficient accuracy and efficiency to precisely prepare cryo-lamellae of target locations for subsequent cryo-ET. Here we describe a precise cryogenic fabrication system, ELI-TriScope, which sets electron (E), light (L) and ion (I) beams at the same focal point to achieve accurate and efficient preparation of a target cryo-lamella. ELI-TriScope uses a commercial dual-beam scanning electron microscope modified to incorporate a cryo-holder-based transfer system and embed an optical imaging system just underneath the vitrified specimen. Cryo-focused ion beam milling can be accurately navigated by monitoring the real-time fluorescence signal of the target molecule. Using ELI-TriScope, we prepared a batch of cryo-lamellae of HeLa cells targeting the centrosome with a success rate of ~91% and discovered new in situ structural features of the human centrosome by cryo-ET.

Artificial confocal microscopy for deep label-free imaging.

Widefield microscopy of optically thick specimens typically features reduced contrast due to "spatial crosstalk", in which the signal at each point in the field of view is the result of a superposition from neighbouring points that are simultaneously illuminated. In 1955, Marvin Minsky proposed confocal microscopy as a solution to this problem. Today, laser scanning confocal fluorescence microscopy is broadly used due to its high depth resolution and sensitivity, but comes at the price of photobleaching, chemical, and photo-toxicity. Here, we present artificial confocal microscopy (ACM) to achieve confocal-level depth sectioning, sensitivity, and chemical specificity, on unlabeled specimens, nondestructively. We equipped a commercial laser scanning confocal instrument with a quantitative phase imaging module, which provides optical path-length maps of the specimen in the same field of view as the fluorescence channel. Using pairs of phase and fluorescence images, we trained a convolution neural network to translate the former into the latter. The training to infer a new tag is very practical as the input and ground truth data are intrinsically registered, and the data acquisition is automated. The ACM images present significantly stronger depth sectioning than the input (phase) images, enabling us to recover confocal-like tomographic volumes of microspheres, hippocampal neurons in culture, and 3D liver cancer spheroids. By training on nucleus-specific tags, ACM allows for segmenting individual nuclei within dense spheroids for both cell counting and volume measurements. In summary, ACM can provide quantitative, dynamic data, nondestructively from thick samples, while chemical specificity is recovered computationally.

A novel general-purpose three-dimensional continuously scanning laser Doppler vibrometer system for full-field vibration measurement of a structure with a curved surface

Three-dimensional (3D) full-field vibration measurement is significant to structures, especially those with curved surfaces. A triaxial accelerometer and a commercial non-contact 3D scanning laser Doppler vibrometer (SLDV) system are usually used in 3D vibration measurement of a structure. However, the triaxial accelerometer can lead to the mass-loading problem for a light-weight structure, and the 3D SLDV system can take a long time to complete scanning of a structure with a large surface in a step-wise scanning mode. This study proposes a novel general-purpose 3D continuously scanning laser Doppler vibrometer (CSLDV) system to measure 3D full-field vibration of a structure with a curved surface in a non-contact and fast way. The proposed 3D CSLDV system consists of three CSLDVs, a profile scanner, and an external controller, and is experimentally validated by measuring 3D full-field vibration of a turbine blade with a curved surface under sinusoidal excitation and identifying its operating deflection shapes (ODSs). A 3D zig-zag scan path is proposed for scanning the curved surface of the blade based on results from the profile scanner, and scan angles of mirrors in CSLDVs are adjusted based on relations among their laser beams to focus three laser spots at one location, and direct them to continuously and synchronously scan the proposed 3D scan path. A signal processing method that is referred to as the demodulation method is used to identify 3D ODSs of the blade. The first six ODSs from 3D CSLDV measurement have good agreement with those from a commercial 3D SLDV system with modal assurance criterion values larger than 95%. In the experiment, it took the 3D SLDV system about 900 s to scan 85 measurement points, and the 3D CSLDV system 115.5 s to scan 132,000 points, indicating that the 3D CSLDV system proposed in this study is much more efficient than the 3D SLDV system for measuring 3D full-field vibration of a structure with a curved surface.