Simultaneous optical trapping and imaging in axial plane

Introduction: Patients with idiopathic pulmonary fibrosis (IPF) are at increased risk of pulmonary hypertension (PH). Right heart catheterization (RHC) is the gold standard for diagnosing PH, however, it is invasive. Noninvasive means such as echocardiography have external factors limiting its accuracy. Pulmonary artery (PA) diameter and PA to aorta (PA/Ao) ratio from a CT chest can be used as a noninvasive way to screen for PH. Here, we performed a retrospective study to see if PA diameter and PA/Ao ratio can be effective at predicting PH by RHC. Methods: A retrospective study of 31 IPF patients with group 3 PH undergoing lung transplant evaluation was performed. These results were compared to 27 IPF patients without PH. Each patient required a CT chest, transthoracic echocardiogram, and RHC to be included. Patients in the PH group were all >18 years old with mPAP >20 and pulmonary capillary wedge pressure <15. All CT chests were read by a single radiologist. Cross sectional imaging in axial plane was set to the level of the main PA bifurcation. Main PA diameter was measured in the transverse axis midway between its root and the bifurcation in the axial plane. The diameter of the ascending aorta in the axial plane was measured at the same level in anteroposterior axis. The PA diameter, PA/Ao ratio were compared to the mPAP from RHC. Those with greater than 6 months between CT chest and RHC were excluded. Receiver operator curve (ROC) and logistic regression (LR) analyses were performed to assess the efficacy of PA diameter, PA/Ao ratio and RVSP compared to RHC parameters. ROC was used to determine the cutoff value for PA diameter and PA/Ao ratio and calculate sensitivity and specificities. Results: A PA diameter >3.05 cm, PA/Ao ratio >0.805, and RVSP >33.5 mmHg as determined by ROC analysis were all found to be significant predictors of PH by RHC. LR analysis of those having both PA diameter >3.05 cm and PA/Ao ratio >0.805 demonstrated that having both also predicts PH by RHC with p<0.001, sensitivity of 81.25% and specificity of 76.92%. All ROC and LR analyses with associated AUC, sensitivities, and specificities are reported in Figure 1. Conclusion: A PA diameter >3.05 cm and a PA/Ao ratio >0.805 are statistically significant predictors of PH by RHC. RVSP was effective at predicting PH but in this cohort CT parameters were more effective than RVSP given the higher AUC.

Background:Recurrent monoarthritis (RM) causes serious disability in many rheumatic diseases. Local interventions, namely intra-articular synovial fluid aspiration (IAA) and intra-articular corticosteroid injection (IAS) are frequently used to control single-joint involvement....

Airy beams showing curved paths have found extensive applications in fields such as optical trapping, biomedical analysis, and material processing. Despite their utility, dynamic control of Airy beams poses a significant challenge. This work investigates the experimental realization of dynamic steering of Airy beams by utilizing computer-generated holograms with phase-amplitude encoding on a phase-only spatial light modulator (SLM). We successfully generated and controlled Airy beams by imposing dynamic phase masks that manipulated both the phase and amplitude of the field, which sets our approach apart from conventional methods with only phase manipulation. By directly encoding in situ such a hologram and transferring it to an SLM, we are able to control the initial position and rotational orientation of Airy beams without relying on mechanical movement or traditional optical setups involving lenses and apertures. Generating Airy beams in any initial position and rotational direction is anticipated to significantly impact applications such as optical trapping, optical communication, and biomedical imaging by providing a flexible platform for dynamic Airy beam manipulation.

BackgroundT2* mapping provides objective data on chondromalacia. However, its reliability in evaluating both patellar and trochlear cartilages has not yet been established.PurposeTo evaluate the repeatability and reproducibility of T2* mapping of patellar and trochlear cartilage in patients with patellofemoral maltracking, and to compare the reliability of axial and sagittal imaging planes for early detection of chondromalacia.Material and MethodsThis retrospective study included 106 knees from patients aged 18-40 years presenting with anterior knee pain and MRI evidence of patellofemoral malalignment between January 2023 and August 2025. T2* mapping was performed on a 3 T MRI scanner using standardized protocols. Patellar and trochlear cartilage were manually divided into 12 compartments in axial and sagittal planes. Regions of interest were placed manually, and T2* relaxation times were measured independently by a musculoskeletal radiologist and an orthopedic surgeon. Intra- and inter-observer reliability were assessed using intraclass correlation coefficients (ICCs).ResultsMost compartments demonstrated good-to-excellent intra- and inter-observer agreement (ICC ≥0.75), particularly in the upper and mid patellar cartilage zones. Axial-plane measurements consistently showed higher ICC values than sagittal-plane measurements. The lowest reliability was observed in lower cartilage zones and in sagittal-plane measurements. All results were statistically significant (P <0.001).ConclusionT2* mapping of the patellofemoral joint provides reliable measurements, with superior performance in the axial plane and in mid-upper zones. Routine use of axial-plane T2* mapping may facilitate early detection of chondromalacia in young adults with anterior knee pain, potentially improving clinical decision-making and preventing irreversible cartilage damage.

Detection of Forces and Displacements along the Axial Direction in an Optical Trap

Optical trapping offers robust nanoscale control of matter but, to date, has been dominated by the interaction between a material’s electric polarizability, αe, and the electric part of light, therefore defined by electric-field intensity-gradient forces. Magnetic light-matter interactions, despite their potential to reshape optical trapping research, have remained experimentally unrealized. This paper addresses this long-standing deficiency by realizing optical magnetic field-associated trapping of high-index (i.e., Si) nanoparticles. Experiments, validated by our theoretical framework and Maxwell stress tensor calculations, reveal the essential role of a material’s magnetic polarizability, αm, and electric-magnetic scattering forces arising from the photonic Hall effect. This magnetic contribution allows exploration of stable trapping, distinct from purely electric-field control. Our findings open avenues for nanoparticle manipulation beyond conventional paradigms, enable previously unexamined optical matter formation driven by magnetic interactions, and suggest unexplored N-body effects and symmetry-breaking dynamics in optical matter systems.

In this paper, we consider a 2D polychromatic transparency serving as an object in front of a dispersive thick lens. The RGB based constituent colors are treated in terms of a center wavelength with a spectral spread, thereby enabling the phasor interpretation and tracking along axial image planes. It turns out that any individual color of the input transparency has a unique focal length or image position in the (meridional) observation plane after propagation through the lens. Under dispersion, image characteristics such as foci, axial location, magnification, and amplitude are controlled by narrow sidebands around a monochromatic carrier. The analytical results (derived numerically) are compared with standard non-dispersive imaging. Particular attention is given to the nature of transverse paraxial images in fixed axial planes, whereby defocusing effects due to dispersion are demonstrated in the manner of spherical aberration. Such selective axial focusing of individual wavelengths may find applications in improving the conversion efficiency of solar cells and photodetectors exposed to white light illumination.

Quantum state preparation of mesoscopic objects is a powerful playground for the elucidation of many physical principles. The field of cavity optomechanics aims to create these states through laser cooling and by minimizing state decoherence. Here we demonstrate simultaneous optical trapping and rotation of a birefringent microparticle in vacuum using a circularly polarized trapping laser beam—a microgyroscope. We show stable rotation rates up to 5 MHz. Coupling between the rotational and translational degrees of freedom of the trapped microgyroscope leads to the observation of positional stabilization in effect cooling the particle to 40 K. We attribute this cooling to the interaction between the gyroscopic directional stabilization and the optical trapping field.

Tailored time-dependent variations of the transverse profile together with longitudinal phase shifts of laser beams are studied. It is shown theoretically that a standing wave setup and real-time beam forming techniques (e.g. by computer-addressed holograms) should make it possible to implement smooth transport across and along the beams employed in optical trapping schemes. Novel modes for the efficient collection, transport, and concentration of trapped particles should thus become realizable in optical trapping setups.

We demonstrate the use of microfabricated supporting structures for maneuvering and supporting polystyrene microspheres for use as magnifying lenses in imaging applications. The supporting structure isolates the trapping light from the magnifier, hence avoiding direct radiation to the sample being observed which could be damaging, especially for biological specimens. Using an optical trapping setup, we demonstrate the actuation of a microsphere not held by optical traps, and show the possibility of imaging through such microspheres.

Photorefractive and computational holography in the experimental generation of Airy beams

The ability to optically trap and manipulate artificial microswimmers, such as active Janus particles (JPs), provides a breakthrough in active matter research and applications. However, it presents significant challenges because of the asymmetry in the optical properties of JPs and remains incomprehensible. Illustrating the interplay between optical and thermophoretic forces, we demonstrate dynamically stable optical trapping of Pt-silica JPs, where the force-balanced position evolves spontaneously within a localized volume around the focal point and in a vertically shifted annular confinement at low and high laser powers, respectively. Intriguingly, the orientational and orbital dynamics of JP remain strongly coupled in the delocalized confinement. Furthermore, we demonstrate simultaneous optical trapping of multiple JPs. This first report on thermophoresis of Pt-silica JPs and localized-to-delocalized crossover in the position distributions of an optically trapped active JP, verifying theoretical predictions, advances our understanding of confined active matter and their experimental realizations.

Optical trapping with non-diffracting Airy beams array using a holographic optical tweezers

To determine the three-dimensional orientation of the lateral ankle ligaments with MRI. Twenty healthy volunteers without previous injury to the ankle were included in the study. With the right ankle in the normal anatomic position stabilized in a splint, coronal T2-weighted spin-echo sequences (TSE) were obtained. The three-dimensional orientation was determined by placing paths through the ligaments and by measuring the angles between corresponding tangents and the three main imaging planes. Using the calculated angles, full-length visualization of the lateral ligaments of the ankle was achieved. The angles deviating from the axial imaging plane were 18.0 degrees for the anterior talofibular ligament, 52.3 degrees for the calcaneofibular ligament and 28.2 degrees for the posterior talofibular ligament. MRI enables the exact determination of the three-dimensional orientation of the lateral ankle ligaments. Orienting the imaging planes according to the calculated angular deviation allows the full-length visualization of the ligaments and is the basis for optimal imaging of the lateral ankle ligaments.

It has been hypothesized that the MR relaxation time T2* of bone marrow present in the intertrabecular spaces may be related to the density of the trabecular network and may be a predictor of trabecular bone properties. To derive a relationship between the marrow relaxation time T2* and biomechanical properties of trabecular bone, we studied two sets of trabecular bone specimens from human tibiae. The first set consisted of 12 specimens that were defatted and immersed in saline; the second set consisted of 18 specimens with marrow in the trabecular spaces. The MR studies were conducted on a 1.5 T imaging system. In the first set of specimens, a GE sequence (TR = 70 ms; TE = 5, 10, 15, 20, 25 ms) was used to obtain images in the axial plane. In the second set, a water suppression pulse was used prior to an asymmetric SE sequence (TR = 300 ms; TE = 4, 8, 12, 16, 20, 24 ms) to obtain images in the axial, coronal, and sagittal planes. The T2* of the intertrabecular saline of the marrow fat was calculated assuming a monoexponential decay. In both sets, the elastic moduli were measured in three orthogonal directions (superoinferior, anteroposterior, and mediolateral). The ash density was determined after the completion of the experiments. Our results indicate a moderate significant negative correlation between T2* and ash density or elastic modulus (E) in both sets of specimens. The correlation coefficients were slightly improved between the transverse relaxation rate 1/T2* and bone density or E. We found a good correlation between T2* and the reciprocal ash density (r = 0.88) and between T2* and the reciprocal elastic modulus 1/E (r = 0.87 to r = 0.95) in the first set, while in the second set the correlation remained moderate. With use of a multiple linear regression model (1/E = a x T2* + b x 1/T2* + n), the reciprocal elastic moduli 1/E were predicted to > 90% by T2* and 1/T2* in the first set of specimens. This finding was not replicated with the second set of specimens. In the second set of specimens, we found poor to moderate correlation coefficients between the T2* times in the three orthogonal planes (r = 0.45 to r = 0.71). Trabecular bone properties such as density and strength may potentially be assessed with quantitative MR techniques. However, especially for in vitro studies, specimen preparation, acquisition parameters, and specimen geometry may have a significant impact on the obtained results.