- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Nonequilibrium Magnetic Oscillation with Cylindrical Vector Beams
摘要： Magnetic oscillation is a generic property of electronic conductors under magnetic fields and widely appreciated as a useful probe of their electronic band structure, i.e. the Fermi surface geometry. However, the usage of the strong static magnetic field makes the measurement insensitive to the magnetic order of the target material. That is, the magnetic order is anyhow turned into a forced ferromagnetic one. Here we theoretically propose an experimental method of measuring the magnetic oscillation in a magnetic-order-resolved way by using the azimuthal cylindrical vector (CV) beam, an example of topological lightwaves. The azimuthal CV beam is unique in that, when focused tightly, it develops a pure longitudinal magnetic field. We argue that this characteristic focusing property and the discrepancy in the relaxation timescale between conduction electrons and localized magnetic moments allow us to develop the nonequilibrium analogue of the magnetic oscillation measurement. Our optical method would be also applicable to metals under the ultra-high pressure of diamond anvil cells.
关键词： Topological lightwaves,Magnetic oscillation,Cylindrical vector beams,Nonequilibrium measurement,Fermi surface geometry
更新于2025-09-23 15:21:21
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Design of a 3D printed compact interferometric system and required phone application for small angular measurements
摘要： A 3D printed smartphone based interferometric system is proposed, and its usability has been demonstrated by measuring small angular rotations. All necessary fringe processing and data analysis have been performed within the phone itself using custom designed application developed in an android platform. The main objective of the proposed work is to demonstrate the usability of modern smartphone and 3D printing technology for optical interferometric applications. The smartphone camera has been used to record the interference fringes which has been formed due to the change in the optical path difference (OPD) between light rays re?ected from the top and bottom surface of a microscopic glass slide. The angular variation of the slide causes a detectable change in the OPD between the interfering beams which subsequently would cause a variation in the fringe pattern. By evaluating necessary interferometric parameters, small angular rotation can be computed within the smartphone application. With the designed smartphone based interferometric system, angular rotation as small as 0.02? can be measured accurately and reliably having a dynamic range of ?3.68? to 3.68?. Due to the involvement of the smartphone as a platform for recording as well as onboard fringe processing, the designed interferometric system can be visualized as a truly ?eld portable tool for different optical metrological applications.
关键词： smartphone,optical metrology,interferometry,angular measurement,3D printing
更新于2025-09-23 15:21:21
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Characterization and application of cerium bromide spectrometers for analysis of γ-ray emitting radionuclides in food matrices
摘要： Cerium bromide (CeBr3) scintillators are useful room temperature gamma-ray detectors that provide the robustness of a scintillator with improved resolution over traditional sodium iodide (NaI) detectors. This makes them attractive for field deployment or emergency response operations especially when combined with the power of Monte-Carlo based efficiency determinations. This work documents the characterization of CeBr3 detectors and the efficiency determination of a portable CeBr3 detector based gamma-ray detection system for food measurements.
关键词： Gamma-ray measurement,Cerium bromide,Efficiency calculation,Food safety
更新于2025-09-23 15:21:21
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Differentiation of the Laser Pulse in a Waveguide with a Bragg Grating
摘要： A novel one-port probe technique, which combines the measurements of a rectangular waveguide and coaxial probe to nondestructively yield the permittivity and permeability of a PEC-backed material, is presented. A brief description of the derivation of the theoretical probe reflection coefficients, necessary for permittivity and permeability extraction via numerical inversion, is provided. Experimental characterization results of a PEC-backed magnetic material are presented to validate the proposed approach. Error analysis is also undertaken to quantify the new technique’s sensitivity to common experimental errors.
关键词： moment methods,microwave measurements,waveguides,Integral equations,permeability measurement,uncertainty,permittivity measurement,measurement uncertainty
更新于2025-09-23 15:21:01
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[IEEE 2020 Moscow Workshop on Electronic and Networking Technologies (MWENT) - Moscow, Russia (2020.3.11-2020.3.13)] 2020 Moscow Workshop on Electronic and Networking Technologies (MWENT) - Laser Optical Fiber Systems Prospects Use Evaluation
摘要： The paper considers the various fiber-optic devices, systems and its components improvement issues. The fiber-optic information-measuring systems structure questions on the fiber-optic devices basis are considered. The various fiber-optic devices, systems and its components dignity and benefits are shown. It is shown that fiber-optic laser measuring systems can be successfully used to measure pressure, temperature, linear and angular micro-displacements, vibration parameters, mechanical tensions, etc.
关键词： fiber optical device,information and measurement system,measurement,optical fiber,laser
更新于2025-09-23 15:21:01
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Experimental optical phase measurement approaching the exact Heisenberg limit
摘要： The use of quantum resources can provide measurement precision beyond the shot-noise limit (SNL). The task of ab initio optical phase measurement—the estimation of a completely unknown phase—has been experimentally demonstrated with precision beyond the SNL, and even scaling like the ultimate bound, the Heisenberg limit (HL), but with an overhead factor. However, existing approaches have not been able—even in principle—to achieve the best possible precision, saturating the HL exactly. Here we demonstrate a scheme to achieve true HL phase measurement, using a combination of three techniques: entanglement, multiple samplings of the phase shift, and adaptive measurement. Our experimental demonstration of the scheme uses two photonic qubits, one double passed, so that, for a successful coincidence detection, the number of photon-passes is N = 3. We achieve a precision that is within 4% of the HL. This scheme can be extended to higher N and other physical systems.
关键词： Heisenberg limit,adaptive measurement,entanglement,quantum metrology,optical phase measurement
更新于2025-09-23 15:21:01
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Determining complementary properties using weak-measurement: uncertainty, predictability, and disturbance
摘要： It is often said that measuring a system’s position must disturb the complementary property, momentum, by some minimum amount due to the Heisenberg uncertainty principle. Using a “weak-measurement”, this disturbance can be reduced. One might expect this comes at the cost of also reducing the measurement’s precision. However, it was recently demonstrated that a sequence consisting of a weak position measurement followed by a regular momentum measurement can probe a quantum system at a single point, with zero width, in position-momentum space. Here, we study this “joint weak-measurement” and reconcile its compatibility with the uncertainty principle. While a single trial probes the system with a resolution that can saturate Heisenberg’s limit, we show that averaging over many trials can be used to surpass this limit. The weak-measurement does not trade-away precision, but rather another type of uncertainty called “predictability” which quantifies the certainty of retrodicting the measurement’s outcome.
关键词： weak-measurement,Heisenberg uncertainty principle,phase space,predictability,quantum measurement
更新于2025-09-23 15:21:01
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[ACM Press the 5th international Workshop - Berlin, Germany (2018.09.20-2018.09.21)] Proceedings of the 5th international Workshop on Sensor-based Activity Recognition and Interaction - iWOAR '18 - Respiration Rate Estimation with Depth Cameras
摘要： Depth cameras have been known to be capable of picking up the small changes in distance from users’ torsos, to estimate respiration rate. Several studies have shown that under certain conditions, the respiration rate from a non-mobile user facing the camera can be accurately estimated from parts of the depth data. It is however to date not clear, what factors might hinder the application of this technology in any setting, what areas of the torso need to be observed, and how readings are affected for persons at larger distances from the RGB-D camera. In this paper, we present a benchmark dataset that consists of the point cloud data from a depth camera, which monitors 7 volunteers at variable distances, for variable methods to pin-point the person’s torso, and at variable breathing rates. Our findings show that the respiration signal’s signal-to-noise ratio becomes debilitating as the distance to the person approaches 4 metres, and that bigger windows over the person’s chest work particularly well. The sampling rate of the depth camera was also found to impact the signal’s quality significantly.
关键词： ToF sensing,Kinect v2,respiratory rate,respiration measurement,non-contact measurement
更新于2025-09-23 15:21:01
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Removing Random Phase Contributions of Sweeping Local Oscillator From Modulated RF Measurements
摘要： This paper proposes a measurement strategy to remove the random phase contributions of the sweeping local oscillator (LO) from modulated radio frequency phase measurements based on downconversion. To obtain a stable phase spectrum for each run of tone-by-tone sweeping measurement, the LO used for downconversion is coupled out to an extra path and modulated to be a wideband multisine signal. By monitoring the phase change of multisine signal at a specific and fixed frequency point, random LO phase offsets during the frequency sweep can be measured and compensated. In this paper, two experimental test benches with the same core measurement strategy but different architectures are established for method validation. According to the experimental results using test bench one, the phase stability is ±(0.2°–0.4°) at 1.8 GHz for fundamental mixing-based downconversion and ±(0.6°–1°) for harmonic mixing at 6 GHz. Based on test bench two, relative phase deviations of ±(0.8°–1.2°) at 22 GHz for fundamental mixing and ±(2°–3°) at 66 GHz for harmonic mixing are reachable.
关键词： modulated measurement,Local oscillator (LO),phase measurement,mixer,vector network analyzer (VNA)
更新于2025-09-23 15:21:01
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Correlations between thermal history and keyhole porosity in laser powder bed fusion
摘要： Additive manufacturing has the potential to revolutionize the production of metallic components as it yields near net shape parts with complex geometries and minimizes waste. At the present day, additively manufactured components face qualification and certification challenges due to the difficulty in controlling defects. This has driven a significant research effort aimed at better understanding and improving processing controls – yielding a plethora of in-situ measurements aimed at correlating defects with material quality metrics of interest. In this work, we develop machine-learning methods to learn correlations between thermal history and subsurface porosity for a variety of print conditions in laser powder bed fusion. Un-normalized surface temperatures (in the form of black-body radiances) are obtained using high-speed infrared imaging and porosity formation is observed in the sample cross-section through synchrotron x-ray imaging. To demonstrate the predictive power of these features, we present four statistical machine-learning models that correlate temperature histories to subsurface porosity formation in laser fused Ti-6Al-4V powder.
关键词： in-situ measurement,keyhole porosity,machine learning,laser powder bed fusion,x-ray imaging
更新于2025-09-23 15:21:01