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[IEEE 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Hangzhou (2018.8.13-2018.8.17)] 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Optimization of Phase Noise in Digital Holographic Microscopy
摘要： A phase noise optimizing method was proposed in this paper to improve the imaging quality of digital microscopic holography (DHM). In this method, bidimensional empirical mode decomposition (BEMD) was utilized to decompose the digital hologram. According to the principle of decomposition, the characteristics of first order intrinsic mode function (IMF1) are close to the gray value of ideal interference fringes. Therefore, after using BEMD method the digital hologram was optimized with enhanced interference fringes, from which phase image with reduced noise can be retrieved. The validity of the proposed method on noise reduction was verified by experimental results on a nano-step.
关键词： digital holography,phase,bidimensional empirical mode decomposition,noise
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Amplified and Spontaneous Stokes Noise Features in a Singlemode Silica Fiber
摘要： the division technique of the total optical noise in (FRA) onto stimulated and spontaneous parts is presented in this work. The maximum power of the amplified spontaneous noise in silica single-mode fiber is experimentally studied as function of the pump power variation in the idle mode of counter-pumped FRA. It is shown that the real FRA noise figure may be considerably less than 3 dB at a pump power of several hundreds of mW.
关键词： Amplified spontaneous emission,Raman gain coefficient,Noise figure,Fiber Raman amplifier,Quantum limit
更新于2025-09-23 15:22:29
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A Quantum Field Approach for Advancing Optical Coherence Tomography Part I: First Order Correlations, Single Photon Interference, and Quantum Noise
摘要： Optical coherence tomography has become an important imaging technology in cardiology and ophthalmology, with other applications under investigations. Major advances in optical coherence tomography (OCT) imaging are likely to occur through a quantum field approach to the technology. In this paper, which is the first part in a series on the topic, the quantum basis of OCT first order correlations is expressed in terms of full field quantization. Specifically first order correlations are treated as the linear sum of single photon interferences along indistinguishable paths. Photons and the electromagnetic (EM) field are described in terms of quantum harmonic oscillators. While the author feels the study of quantum second order correlations will lead to greater paradigm shifts in the field, addressed in part II, advances from the study of quantum first order correlations are given. In particular, ranging errors are discussed (with remedies) from vacuum fluctuations through the detector port, photon counting errors, and position probability amplitude uncertainty. In addition, the principles of quantum field theory and first order correlations are needed for studying second order correlations in part II.
关键词： Plaque,Quantum mechanics,Interferometry,Ophthalmology,Noise,Vacuum,Cardiology,Arthritis,Optical coherence tomography
更新于2025-09-23 15:22:29
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Applications of Cell-Ratio Constant False-Alarm Rate Method in Coherent Doppler Wind Lidar
摘要： A cell-ratio constant false-alarm rate (CR-CFAR) method for detecting the Doppler frequency shift is proposed to improve the accuracy of velocity measured by coherent Doppler wind lidar (CWL) in low signal-to-noise ratio (SNR) environments. The method analyzes the spectrum to solve issues of weak signal submergence in noise encountered in the widely used periodogram method. This characteristic is that the signal region slope is larger than the noise region slope in the frequency spectrum. We combined the ratio and CFAR to propose the CR-CFAR method. The peak area is discriminated from the spectrum using this method. By removing background noise, the peak signal is obtained along with the Doppler shift. To verify the CR-CFAR method, a campaign experiment using both CWL and a commercial Doppler lidar was performed in Hami, China (42°32' N, 94°03' E) during 1–7 June 2016. The results showed that the proposed method significantly improved the reliability of CWL data under low SNR conditions. The height—at which both horizontal wind speed correlativity and horizontal wind direction correlativity exceeded 0.99—increased by 65 m. The relative deviation of the horizontal wind speed at 120 m decreased from 40.37% to 11.04%. We used the CR-CFAR method to analyze continuous data. A greater number of wind field characteristics were obtained during observation compared to those obtained using the common wind field inversion method.
关键词： coherent Doppler wind lidar,cell-ratio constant false alarm rate (CR-CFAR),signal-to-noise ratio (SNR)
更新于2025-09-23 15:22:29
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An FPGA-Oriented Algorithm for Real-Time Filtering of Poisson Noise in Video Streams, with Application to X-Ray Fluoroscopy
摘要： In this paper we propose a new algorithm for real-time ?ltering of video sequences corrupted by Poisson noise. The algorithm provides effective denoising (in some cases overcoming the ?ltering performances of state-of-the-art techniques), is ideally suited for hardware implementation, and can be implemented on a small ?eld-programmable gate array using limited hardware resources. The paper describes the proposed algorithm, using X-ray ?uoroscopy as a case study. We use IIR ?lters for time ?ltering, which largely simpli?es hardware cost with respect to previous FIR ?lter-based implementations. A conditional reset is implemented in the IIR ?lter, to minimize motion blur, with the help of an adaptive thresholding approach. Spatial ?ltering performs a conditional mean to further reduce noise and to remove isolated noisy pixels. IIR ?lter hardware implementation is optimized by using a novel technique, based on Steiglitz–McBride iterative method, to calculate ?xed-point ?lter coef?cients with minimal number of nonzero elements. Implementation results using the smallest StratixIV FPGA show that the system uses only, at most, the 22% of the resources of the device, while performing real-time ?ltering of 1024 × 1024@49fps video stream. For comparison, a previous FIR ?lter-based implementation, on the same FPGA, in the same conditions and constraints (1024 × 1024@49fps), requires the 80% of the logic resources of the FPGA.
关键词： Poisson noise,X-ray video?uoroscopy processing,Field-programmable gate array (FPGA),IIR ?ltering,IIR ?lter design,Real-time video ?ltering
更新于2025-09-23 15:22:29
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Time–frequency-based non-harmonic analysis to reduce line-noise impact for LIGO observation system
摘要： Gravitational waves (GWs) are the subjects of a new type of space observation that is expected to reveal new information on the early universe, neutron stars, and black holes. To reduce the impact of the widely used notch filter on GW observations, we propose the use of non-harmonic analysis (NHA) for the high-accuracy visualization of GWs. A simulated signal is used to compare the results obtained using short-time Fourier transform, Hilbert spectrum analysis, Hilbert–Huang transformation, and NHA. We demonstrate that NHA exhibits superior performance. In addition, we verify the analytical precision of NHA using actual data measured by the Laser Interferometer Gravitational-Wave Observatory (LIGO). We found that the high time–frequency resolution of NHA and the small influence that the analysis window has on this technique facilitate effective quantitative analysis, even for LIGO signals containing mixing noise. In addition, we achieve GW visualization up to the noise limit without using a notch filter.
关键词： Noise reduction,Non-harmonic analysis,Gravitational wave
更新于2025-09-23 15:22:29
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A Tri- State Filter for the Removal of Salt and Pepper Noise in Mammogram Images
摘要： A new algorithm which uses tree based decision and tri-state non linear values to eliminate high density outlier noise in mammogram images is proposed. The proposed algorithm uses the number of non noisy pixels in the current processing vicinity as values in the decision tree. Tri-state values such as unsymmetrical truncated median or modified Winsorized mean or midpoint replaces the corrupted pixel based on the decision tree in the current processing kernel. The algorithm exhibits good PSNR, IEF, low MSE and High structural preservation property even after removing high density noise. The performance of the proposed algorithm was also found good visually. The Key aspect of the work is the combination of tree based decision and tri-state non linear values which preserves the information content of images that are required for further processing.
关键词： Detail preserving algorithm,Mammogram images,Non linear filter,Outlier noise
更新于2025-09-23 15:22:29
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Caracterización y simulación de ruido en las imágenes de PET reconstruidas con OSEM: desarrollo de un método para la generación de imágenes sintéticas
摘要： Introduction: The goals of the study are to characterize imaging properties in 2D PET images reconstructed with the iterative algorithm ordered-subset expectation maximization (OSEM) and to propose a new method for the generation of synthetic images. Material and methods: The noise is analyzed in terms of its magnitude, spatial correlation, and spectral distribution through standard deviation, autocorrelation function, and noise power spectrum (NPS), respectively. Their variations with position and activity level are also analyzed. This noise analysis is based on phantom images acquired from 18F uniform distributions. Experimental recovery coefficients of hot spheres in different backgrounds are employed to study the spatial resolution of the system through point spread function (PSF). The NPS and PSF functions provide the baseline for the proposed simulation method: convolution with PSF as kernel and noise addition from NPS. Results: The noise spectral analysis shows that the main contribution is of random nature. It is also proven that attenuation correction does not alter noise texture but it modifies its magnitude. Finally, synthetic images of 2 phantoms, one of them an anatomical brain, are quantitatively compared with experimental images showing a good agreement in terms of pixel values and pixel correlations. Thus, the contrast to noise ratio for the biggest sphere in the NEMA IEC phantom is 10.7 for the synthetic image and 8.8 for the experimental image. Conclusions: The properties of the analyzed OSEM-PET images can be described by NPS and PSF functions. Synthetic images, even anatomical ones, are successfully generated by the proposed method based on the NPS and PSF.
关键词： PET,Autocorrelation function,OSEM,Iterative reconstruction,Noise power spectrum,Point spread function
更新于2025-09-23 15:22:29
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Noise-optimized ultrastable low-noise current amplifier
摘要： We have developed a noise-optimized ultrastable low-noise current amplifier (ULCA) aimed at reducing the uncertainty at low currents. It involves a thin-film resistor network with 6.75 GΩ at the high-ohmic path which reduces the noise level to 1.6 fA/√Hz. Noise investigations as well as short-term and long-term stability studies were carried out. The stability of the input current gain was measured using a cryogenic current comparator at ±6.1 nA. Methods for investigating the measurement accuracy at low input currents of about 100 pA at a level of below one part in 10^7 are introduced and experimentally verified. The performance of the noise-optimized ULCA is compared with that of the standard variant introduced in 2014. It is shown that the reduced noise floor is achieved without impairing the stability of the transresistance.
关键词： low-current measurement,cryogenic current comparator,current amplifier,stability,noise optimization
更新于2025-09-23 15:22:29
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Loop Parameters Designing Method for Optical Phase-Locked Loop System
摘要： A comprehensive loop parameters designing method and an auxiliary pulling module for an optical phase-locked system were discussed. The experiment successfully demonstrated a pull-in frequency range as wide as 2.4GHz and a frequency accuracy of 2MHz.
关键词： optical phase-locked,auxiliary pulling module,noise performance,acquisition,loop parameters,tracking
更新于2025-09-23 15:22:29