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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Operation verification of tunable plasmonic color filter composed by metal-insulator-metal subwavelength grating and MEMS actuator
摘要： Signal processing in light-microscopy and cell imaging is concerned with reconstructing latent ground truth from imperfect images. This typically requires assuming prior knowledge about the latent ground truth. While this assumption regularizes the problem to an extent where it can be solved, it also biases the result toward the expected. It thus often remains unclear what prior to use for a given practical problem. We argue here that the gradient distribution of natural-scene images may provide a versatile and well-founded prior for light-microscopy images that does not impose assumptions about the geometry of the ground-truth signal, but only about its gradient spectrum. We provide motivation for this choice from different points of view, and we illustrate the resulting regularizer for use on light-microscopy images. We provide a simple parametric model for the resulting prior, leading to ef?ciently solvable variational problems. We demonstrate the use of these models and solvers in a variety of common image-processing tasks, including contrast enhancement, noise-level estimation, denoising, blind deconvolution, and dehazing. We conclude by discussing the limitations and possible interpretations of the prior.
关键词： parametric prior,gradient distribution,noise-level estimation,dehazing,naturalization,denoising,Deconvolution,variational method
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) - Improvement of Ohmic Behavior of Back Contact in ZnSnP <sub/>2</sub> Solar Cells by Inserting Cu <sub/>3</sub> P
摘要： We propose a sampling scheme that can perfectly re- construct a collection of spikes on the sphere from samples of their lowpass-?ltered observations. Central to our algorithm is a gen- eralization of the annihilating ?lter method, a tool widely used in array signal processing and ?nite-rate-of-innovation (FRI) sam- pling. The proposed algorithm can reconstruct spatial samples. For large, this sampling require- ment improves over previously known FRI sampling schemes on the sphere by a factor of four. We showcase the versatility of the proposed algorithm by applying it to three problems: 1) sampling diffusion processes induced by localized sources on the sphere, 2) shot noise removal, and 3) sound source localization (SSL) by a spherical microphone array. In particular, we show how SSL can be reformulated as a spherical sparse sampling problem.
关键词： sparse sampling,spherical harmonics,sphere,Annihilation ?lter,?nite rate of innovavtion,diffusion sampling,shot noise removal,sound source localization
更新于2025-09-23 15:21:01
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Explosion induced rogue waves and chaotic multi-pulsing in a passively mode-locked all-normal dispersion fiber laser
摘要： In this work, an experimental study of non-stationary pulse dynamics consisting of explosion events and chaotic multi-pulsing from an all-normal dispersion Yb-fiber laser operating in noise-like pulse (NLP) state have been reported. During explosion in NLP state, which resembled soliton explosion, dispersive Fourier transform measurements revealed large, intermittent amplitude fluctuations in the real-time spectrum indicative of rogue waves. The fluctuations either appeared randomly at the lasing wavelength within the Yb-gain spectra or at the frequency downshifted Raman Stokes wavelength. It was also observed that such fluctuation at the Raman wavelength could even exceed the amplitude of the spectral components at the main lasing wavelength. With suitable adjustments, the laser operation could be switched to chaotic multi-pulsing state where the acquisition of a large number of consecutive roundtrips revealed inter-pulse motion with unique trajectories occurring over millisecond time scales.
关键词： optical rogue waves,multi-pulsing,non-stationary pulse dynamics,noise-like pulse,fiber lasers,mode-locked fiber lasers,non-linear dynamics
更新于2025-09-23 15:21:01
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Mobile Robot Path Planning Using a Laser Range Finder for Environments with Transparent Obstacles
摘要： Environment maps must ?rst be generated to drive mobile robots automatically. Path planning is performed based on the information given in an environment map. Various types of sensors, such as ultrasonic and laser sensors, are used by mobile robots to acquire data on its surrounding environment. Among these, the laser sensor, which has the property of being able to go straight and high accuracy, is used most often. However, the beams from laser sensors are refracted and re?ected when it meets a transparent obstacle, thus generating noise. Therefore, in this paper, a state-of-the-art algorithm was proposed to detect transparent obstacles by analyzing the pattern of the re?ected noise generated when a laser meets a transparent obstacle. The experiment was carried out using the environment map generated by the aforementioned method and gave results demonstrating that the robot could avoid transparent obstacles while it was moving towards the destination.
关键词： re?ection noise,path planning,mobile robot,transparent obstacle recognition,laser range ?nder
更新于2025-09-23 15:21:01
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Effect of critical current spread on the noise performance of SQUID magnetometers: An experimental study
摘要： We investigate the noise performance dependence on the critical current spread of a fully integrated magnetometer based on superconducting quantum interference device (SQUID). In particular, we analyze the behavior of spectral density of magnetic field noise carrying out an experimental study on 200 magnetometers. The magnetic sensors consist of a superconducting flux transformer connected to a SQUID in a washer shape and include both a feedback coil for flux locked loop operation and an additional positive feedback circuit to increase the intrinsic voltage responsivity. A damping resistor in parallel to the SQUID inductance has been used in order to prevent both the degradation due to the non-optimal βL value and the washer resonances. Such sensors are often employed in magnetoencephalography or more in general in ultra-high sensitivity applications requiring the magnetic noise spectral density as low as 2 fT/√Hz in the white region. We will show that a SQUID critical current varying from 8 to 40 μA does not cause an evident degradation of the magnetometer sensibility. In addition, the magnetic field noise vs critical current indicates an optimal value of SQUID critical current of 20 μA. It corresponds to an inductance parameter βL of about 2 highlighting the effectiveness of the damping resistor in parallel to the SQUID inductance.
关键词： SQUIDs,Superconducting Magnetometers,Magnetic field noise
更新于2025-09-23 15:21:01
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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) - Narrow Linewidth Fiber Brillouin Ring Laser for Sensing Applications
摘要： A novel tunable, stable and low-noise Brillouin ring laser layout composed of a doubly-resonant short-cavity Brillouin ring laser (DR-SC) paired with an active wavelength stabilization setup is presented in this work. Measurements of temporal signal stability, relative intensity noise, spectral linewidth and tunability range yielded a marked improvement over the long-cavity version that we have previously reported, making the new layout a promising alternative for applications in fiber sensing and other fields that require highly coherent and stable tunable sources.
关键词： relative intensity noise,fiber sensing,Brillouin ring laser,tunable sources,spectral linewidth
更新于2025-09-23 15:21:01
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Temperature and Emissivity Inversion Accuracy of Spectral Parameter Changes and Noise of Hyperspectral Thermal Infrared Imaging Spectrometers
摘要： The emergence of hyperspectral thermal infrared imaging spectrometers makes it possible to retrieve both the land surface temperature (LST) and the land surface emissivity (LSE) simultaneously. However, few articles focus on the problem of how the instrument?s spectral parameters and instrument noise level affect the LST and LSE inversion errors. In terms of instrument development, this article simulated three groups of hyperspectral thermal infrared data with three common spectral parameters and each group of data includes tens of millions of simulated radiances of 1525 emissivity curves with 17 center wavelength shift ratios, 6 full width at half maximum (FWHM) change ratios and 6 noise equivalent differential temperatures (NEDTs) under 15 atmospheric conditions with 6 object temperatures, inverted them by two temperature and emissivity separation methods (ISSTES and ARTEMISS), and analyzed quantitatively the effects of the spectral parameters change and noise of an instrument on the LST and LSE inversion errors. The results show that: (1) center wavelength shifts and noise affect the inversion errors strongly, while FWHM changes affect them weakly; (2) the LST and LSE inversion errors increase with the center wavelength shift ratio in a quadratic function and increase with FWHM change ratio slowly and linearly for both the inversion methods, however they increase with NEDT in an S‐curve for ISSTES while they increase with NEDT slightly and linearly for ARTEMISS. During the design and development of a hyperspectral thermal infrared instrument, it is highly recommended to keep the potential center wavelength shift within 1 band and keep NEDT within 0.1K (corresponding LST error < 1K and LSE error < 0.015) for normal applications and within 0.03K (corresponding LST error < 0.5K and LSE error < 0.01) for better application effect and level.
关键词： inversion error,hyperspectral thermal infrared,FWHM change,instrument noise,center wavelength shift,temperature and emissivity separation
更新于2025-09-23 15:21:01
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Detailed modeling of the video signal and optimal readout of charge-coupled devices
摘要： This article provides a practical design methodology to calculate an optimal filter for noise reduction in the readout of charge-coupled devices (CCDs) taking into account the charge transfer and feedthroughs due to capacitive coupling in the CCD. A detailed analysis of the dynamics of the video signal and charge transfer is presented, including the circuital modeling of the output stage of the CCD and the dynamics of the electronics in the video chain before the analog-to-digital (AD) converter. This model is used to compute an optimal filter that minimizes the variance of the pixel noise and uses the samples of the charge transfer, before the charge is fully settled. This is necessary to enhance the performance of previous results that also use optimal filters but do not use the transition samples, while also reducing the pixel readout time, resulting in faster readouts. As a proof of concept for the optimal filter, we present novel experimental results using a Skipper CCD, which has a floating sense node that allows to measure the charge packet an arbitrary number of times. However, this technique can be applied to any CCD that has a readout system that digitally samples the video signal.
关键词： CCD,optimal filter,minimum noise variance,readout,charge transfer
更新于2025-09-23 15:21:01
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Noise-robust transparent visualization of large-scale point clouds acquired by laser scanning
摘要： We propose a high-quality transparent visualization method suitable for large-scale laser-scanned point clouds. We call the method “stochastic point-based rendering (SPBR),” which is based on a novel stochastic algorithm. SPBR enables us to clearly observe the deep interior of laser-scanned 3D objects with the correct feeling of depth. The high quality of SPBR originates from the effect of “stochastic noise transparentization,” which is an effect to make the measurement noise transparent and invisible in the created images. We mathematically prove that this effect also makes the created transparent images coincide with the results of the conventional methods based on the alpha blending, which is time-consuming and impractical for large-scale laser-scanned point clouds. We also demonstrate the effectiveness of SPBR by applying it to modern buildings, cultural heritage objects, forests, and a factory. For all of the cases, the method works quite well, realizing clear and correct 3D see-through imaging of the laser-scanned objects.
关键词： High quality 3D see-through imaging,Laser-scanned point cloud,Large-scale data,Stochastic noise transparentization,Visualization
更新于2025-09-23 15:21:01
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Harmonic detection method based on adaptive noise cancellation and its application in photovoltaic - active power filter system
摘要： The adaptive harmonic detection method based on the adaptive noise cancellation principle has the advantages of strong adaptability and good robustness. However, when the step size of the algorithm is selected, there is a conflict between the convergence speed and the steady-state accuracy. To solve this problem, this paper proposes an improved variable step size adaptive harmonic detection method. The algorithm uses the sliding integrator to find the feedback that can truly reflect the tracking situation, and substitutes it into the step size iteration formula based on L2 norm to achieve the step size adjustment. In order to further verify the superiority and practicability of the improved algorithm, the algorithm is applied to the photovoltaic-active power filter (PV-APF) system, and simulation verification is performed in MATLAB. The simulation results show that under the same simulation conditions, the convergence speed of the improved algorithm is half a cycle faster than that of the traditional method, and the steady-state error is smaller. In the application of PV-APF system, under normal light, the dual functions of grid-connected photovoltaic system and harmonic compensation are realized. The total harmonic distortion (THD) of the system is 2.09%, which effectively improves the power quality of photovoltaic system.
关键词： Photovoltaic grid-connected,Adaptive noise cancellation,Harmonic detection,Active power filter,Photovoltaic-active power filter system
更新于2025-09-23 15:21:01