- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Improvement of photogrammetric accuracy by modeling and correcting the thermal effect on camera calibration
摘要： This paper presents a new method for improving the geometric accuracy of photogrammetric reconstruction by modeling and correcting the thermal effect on camera image sensor. The objective is to verify that when the temperature of image sensor varies during the acquisition, image deformation induced by the temperature change is quantifiable, modelisable and correctable. A temperature sensor integrated in the camera enables the measurement of image sensor temperature at exposure. It is therefore natural and appropriate to take this effect into account and to finally model and correct it after a calibration step. Nowadays, in cartography applications performed with UAV, the frame rate of acquisitions is continuously increasing. A high frame rate over a long acquisition time can result in an important temperature increase of the image sensor and thus introduces image deformations. The correction of the above-mentioned effect can improve the measurement accuracy. We present three methods to calibrate the thermal effect and experiments on two datasets are carried out to verify the improvement in terms of the photogrammetric accuracy.
关键词： Metrology,Photogrammetry,CMOS,Thermal deformation
更新于2025-09-23 15:22:29
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Modular-value-based metrology with spin coherent pointers
摘要： We discuss an optimal modular-value-based measurement with a spin coherent pointer: A quantum system is exposed to a field whose strength is to be estimated through its modular value. We evaluate the quantum Fisher information as a figure of merit. We found that the modular-value-based measurement can reach the same ultimate precision limit of the estimation as those of measurements without postselections. The quantum Fisher information can be increased when the dimension of the pointer state increases. We also consider the pointer under a phase-flip error. Our study should motivate researchers to apply the modular-value-based measurements for quantum metrology.
关键词： Quantum Fisher information,Modular values,Weak values,Quantum metrology
更新于2025-09-23 15:21:21
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Characterization and on-line adjustment of the sagittal-bent Laue crystal profile
摘要： The sagittal-bent Laue monochromator can provide an ideal way to focus high-energy X-ray beams. However, the anticlastic curvature induced by sagittal bending has a great influence on the crystal performance. Thus, characterizing the bent-crystal shape is very important for predicting the performance of the bent-crystal monochromator. In this paper the crystal profile is measured by off-line optical metrology and on-line X-ray experiments. The off-line results showed that the bent-crystal surface could be well fitted to a saddle surface apart from a redundant cubic term which was related to the different couples applied on the crystal. On-line characterization of the meridional and the sagittal radius of the bent crystal includes double-crystal topography and ray-tracing measurement. In addition, the double-crystal topography experiment could be used as a quick diagnostic method for the bending condition adjustment. The sagittal radius of the bent crystal was characterized through a ray-tracing experiment by using a particularly designed tungsten mask. Moreover, rocking curves under different bending conditions were measured as well. The results were highly consistent with analytical results derived from the elastic theory. Furthermore, radii along different vertical positions under various bending conditions were measured and showed a quadratic relationship between the vertical positions and the meridional radii.
关键词： ray-tracing measurement,double-crystal topography,sagittal-bent Laue crystal,optical metrology,anticlastic curvature
更新于2025-09-23 15:21:21
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Improving signal strength in serial crystallography with <i>DIALS</i> geometry refinement
摘要： The DIALS diffraction-modeling software package has been applied to serial crystallography data. Diffraction modeling is an exercise in determining the experimental parameters, such as incident beam wavelength, crystal unit cell and orientation, and detector geometry, that are most consistent with the observed positions of Bragg spots. These parameters can be re?ned by nonlinear least-squares ?tting. In previous work, it has been challenging to re?ne both the positions of the sensors (metrology) on multipanel imaging detectors such as the CSPAD and the orientations of all of the crystals studied. Since the optimal models for metrology and crystal orientation are interdependent, alternate cycles of panel re?nement and crystal re?nement have been required. To simplify the process, a sparse linear algebra technique for solving the normal equations was implemented, allowing the detector panels to be re?ned simultaneously against the diffraction from thousands of crystals with excellent computational performance. Separately, it is shown how to re?ne the metrology of a second CSPAD detector, positioned at a distance of 2.5 m from the crystal, used for recording low-angle re?ections. With the ability to jointly re?ne the detector position against the ensemble of all crystals used for structure determination, it is shown that ensemble re?nement greatly reduces the apparent nonisomorphism that is often observed in the unit-cell distributions from still-shot serial crystallography. In addition, it is shown that batching the images by timestamp and re-re?ning the detector position can realistically model small, time-dependent variations in detector position relative to the sample, and thereby improve the integrated structure-factor intensity signal and heavy-atom anomalous peak heights.
关键词： sparse algebra,refinement,DIALS,metrology,XFEL
更新于2025-09-23 15:21:21
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An Optoelectronic Pulse Drive for Quantum Voltage Synthesizer
摘要： An optoelectronic pulse drive system based on commercially available telecoms optoelectronic components and a field-programmable gate array has been developed. In order to allow the use of ac-coupled optoelectronic components, a method of adding and subtracting complementary pulses was developed. The system was used to drive a Josephson junction array to synthesize quantum-accurate voltage waveforms. These waveforms will be used in voltage waveform metrology applications. Results from the synthesis of sinusoidal unipolar voltage waveforms from 3 to 300 kHz are presented. The margin of operation was measured and shown to require an optical pulse height stability better than 0.15 mW. The use of delta–sigma code with repeated sections, suitable for a quantum voltage digitizer was also examined. A test code corresponding to a delta–sigma feedback loop rate of 250 MHz was used to synthesize a 3.125 kHz sinusoidal waveform.
关键词： Josephson arbitrary waveform synthesizer,optoelectronics,metrology,Josephson arrays,measurement,voltage measurement
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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Interferometric Evanescent Wave Excitation of a Nanoantenna for Ultrasensitive Displacement and Phase Metrology
摘要： We propose a method for ultrasensitive displacement and phase measurements based on a nanoantenna illuminated with interfering evanescent waves. We show that with a proper nanoantenna design, tiny displacements and relative phase variations can be converted into changes of the scattering direction in the Fourier space. These sensitive changes stem from the strong position dependence of the orientation of the purely imaginary Poynting vector produced in the interference pattern of evanescent waves. Using strongly confined evanescent standing waves, high sensitivity is demonstrated on the nanoantenna’s zero-scattering direction, which varies linearly with displacement over a wide range. With weakly confined evanescent wave interference, even higher sensitivity to tiny displacement or phase changes can be reached near a particular location. The high sensitivity of the proposed method can form the basis for many metrology applications. Furthermore, this concept demonstrates the importance of the imaginary part of the Poynting vector, a property that is related to reactive power and is often ignored in photonics.
关键词： nanoantenna,Poynting vector,evanescent waves,displacement metrology,phase metrology
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Simulation of Optical and Electrical Losses of PV Modules in Moderate and Desert Conditions
摘要： Measurements of the PV modules are based on standard test conditions. However, PV modules have significant difference in performance based on the locations, environmental conditions and mounting situation. One of the environmental factors which influence the performance of the PV module is the spectrum of incident light on the PV module. In this paper, we compare the optical reflection losses, thermal losses as well as electricity production of modules under moderate (AM1.5) and desert-like spectrums (AM1.0). The results show quantitatively that thermalization has the highest loss portion with an average of 29.5% of the total incoming power density for both spectrums. The highest relative change is for absorption of light in polymer encapsulant especially between 280-400 nm with 24.3% and total resistive losses (in cell and interconnection) with 21.3% extra losses from desert to moderate conditions. Finally, we show that similar modules in desert climate produce 5% extra power gain while it suffers from 7.2% extra heat and 5% extra reflections.
关键词： Photovoltaic cells,Si PV Modelling,Metrology and Characterization,PV,Crystalline Silicon PV
更新于2025-09-23 15:21:01
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Quantum cascade laser based hybrid dual comb spectrometer
摘要： Four-wave-mixing-based quantum cascade laser frequency combs (QCL-FC) are a powerful photonic tool, driving a recent revolution in major molecular fingerprint regions, i.e. mid- and far-infrared domains. Their compact and frequency-agile design, together with their high optical power and spectral purity, promise to deliver an all-in-one source for the most challenging spectroscopic applications. Here, we demonstrate a metrological-grade hybrid dual comb spectrometer, combining the advantages of a THz QCL-FC with the accuracy and absolute frequency referencing provided by a free-standing, optically-rectified THz frequency comb. A proof-of-principle application to methanol molecular transitions is presented. The multi-heterodyne molecular spectra retrieved provide state-of-the-art results in line-center determination, achieving the same precision as currently available molecular databases. The devised setup provides a solid platform for a new generation of THz spectrometers, paving the way to more refined and sophisticated systems exploiting full phase control of QCL-FCs, or Doppler-free spectroscopic schemes.
关键词： frequency comb,spectroscopy,Quantum cascade laser,metrology,terahertz
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