Analysis of speckle reduction based on theory of optical eigenfunction
The principle of optical eigenfunction is used in the analysis of speckle reduction in laser projection display. When the moving diffuser is used in the speckle reduction approach, the speckle contrast is decided by both the degree of freedom (DOF) of the projector and the area of resolving cell of the eyes on the screen. It can gain high DOF of the projector by increasing the space-bandwidth product, i.e., adopting a projection lens with a high numerical aperture or a large viewing field. The b
Speckle reduction of synthetic aperture imaging ladar based on wavelength characteristics2021-02-05
We propose a speckle-reduction method based on wavelength characteristics of speckle effect in synthetic aperture imaging ladar (SAIL). The return signal, which is the back scattering field with speckle effect from the rough surface of target, can be integrated over N chirp periods and heterodyne detected with a local-oscillator signal. After performing image processing respectively, the final image can be regarded as the incoherent superposition of the N sub-images. Numerical simulations indica
SAR影像数据处理过程中需要用到的滤波算法，matlab的一些滤波算法封装函数源代码，无其他依赖。 文件中包含滤波算法： Mean filter. -Frost filter. -Modified frost filter(added thresholds). -Lee filter(Using Masks, ENL ect). 如果想要知道怎么操作，欢迎访问我的博客，有一篇记录。
Improving temporal resolution and speed sensitivity of laser speckle contrast analysis imaging based on noise reduction with an anisotropic diffusion filter2021-02-08
Improving temporal resolution and speed sensitivity of laser speckle contrast analysis imaging based on noise reduction with an anisotropic diffusion filter
Speckle Reduction in Optical Coherence Tomography via Super-Resolution Reconstruction2021-02-08
Speckle Reduction in Optical Coherence Tomography via Super-Resolution Reconstruction
Handbook of 3D machine vision : optical metrology and imaging 完整 高清扫描 pdf2017-11-20
With the ongoing release of 3D movies and the emergence of 3D TVs, 3D imaging technologies have penetrated our daily lives. Yet choosing from the numerous 3D vision methods available can be frustrating for scientists and engineers, especially without a comprehensive resource to consult. Filling this gap, Handbook of 3D Machine Vision: Optical Metrology and Imaging gives an extensive, in-depth look at the most popular 3D imaging techniques. It focuses on noninvasive, noncontact optical methods (optical metrology and imaging). The handbook begins with the well-studied method of stereo vision and explains how random speckle patterns or space-time varying patterns substantially improve the results of stereo vision. It then discusses stereo particle image velocimetry as a major experimental means in fluid dynamics, the robust and easy-to-implement structured-light technique for computer science applications, digital holography for performing micro- to nanoscale measurements, and grating, interferometry, and fringe projection techniques for precisely measuring dynamically deformable natural objects. The book goes on to describe techniques that do not require triangulation to recover a 3D shape, including time-of-flight techniques and uniaxial 3D shape measurement, as well as 3D measurement techniques that are not restricted to surface capture, such as 3D ultrasound, optical coherence tomography, and 3D endoscopy. The book also explores how novel 3D imaging techniques are being applied in the promising field of biometrics―which may prove essential to security and public safety. Written by key players in the field and inventors of important imaging technologies, this authoritative, state-of-the-art handbook helps you understand the core of 3D imaging technology and choose the proper 3D imaging technique for your needs. For each technique, the book provides its mathematical foundations, summarizes its successful applications, and discusses its limitations.
Influence of the sparsity of random speckle illumination on ghost imaging in a noise environment2021-02-23
The influence of the sparsity of random speckle illumination on traditional ghost imaging (GI) and GI via sparsity constraint (GISC) in a noise environment is investigated. The experiments demonstrate that both GI and GISC obtain their best imaging quality when the sparsity of random speckle illumination is 0.5, which is also explained by some parameters such as detection of the signal to noise ratio and mutual coherence of the measurement matrix.
Fringe Pattern Analysis for Optical Metrology2018-09-06
The main objective of this book is to present the basic theoretical principles behind modern fringe-pattern analysis as applied to optical metrology. In addition to this, for the experimentalist, we present in a ready-to-use form the most common algorithms for recovering the modulating phase from single or multiple fringe patterns. This book deals with phase demodulation of fringe patterns typically encountered in optical metrology techniques such as optical interferometry, shadow moire, fringe projection, photoelasticity, moir´e interferometry, moir´e deflectometry, holographic interferometry, shearing interferometry, digital holography, speckle interferometry, and corneal topography.
Multi-frame speckle reduction in OCT using supercontinuum pumped by noise-like pulses2021-02-22
In most coherent imaging modality, speckle noise is a major cause that blurs the boundary of tissues and degrades the image contrast. By utilizing the unique properties of supercontinuum (SC) generated by noise-like pulses (NLPs) and a simple multi-frame averaging technique, we achieved significant speckle reduction in spectral domain optical coherence tomography (SD-OCT). We quantitatively compared the speckle of our proposed method with those of conventional swept source OCT (SS-OCT) and SD-OC
Speckle reduction of SAR images using ICA basis enhancement and separation2021-03-05
An approach for synthetic aperture radar (SAR) image de-noising based on independent component analysis (ICA) basis images is proposed. Firstly, the basis images and the code matrix of the original image are obtained using ICA algorithm. Then, pointwise Holder exponent of each basis is computed as a cost criterion for basis enhancement, and then the enhanced basis images are classified into two sets according to a separation rule which separates the clean basis from the original basis. After the
Optical Metrology 3rd ed2015-04-14
This edition of Optical metrology contains a new chapter about computerized optical processes, including digital holography and digital speckle photography. Chapter 2, on Gaussian optics, and Chapter 5, on light sources and detectors, are greatly expanded to include descriptions of standard imaging systems, light-emitting diodes and solid-state detectors. Separate new sections on optical coherence tomography, speckle correlation, the Fast Fourier Transform, temporal phase unwrapping and fibre Bragg sensors are included. Finally, a new appendix about Fourier series is given. Solutions to the end-of-chapter problems can be found http://www.wiley.co.uk/opticalmetrology
Effect of speckle pattern on laser Doppler velocimeters2021-02-11
The effect of speckle pattern on laser Doppler velocimeters is studied theoretically and experimentally. We have found that dynamic speckle patterns can cause error in velocity measurement. Increasing sampling time and using proper signal processing circuits can eliminate this bad effect caused by speckle pattern. The accuracy of velocity measurement is better than 2.1% in a wide velocity range (4.66-468.86 mm/s) when speckle effects are taken into account.
Speckle analysis in laser scanning display system2021-02-10
The theory of speckle formation in laser scanning display system is established based on the averaging effect of eye response as laser beam scanning through an eye resolution spot. It is analyzed that speckle reduction can be obtained by averaging states of speckle during scanning. The theoretical results show that a smaller correlation length of screen surface and the narrowing of laser beam in scanning direction can reduce speckle contrast for this system.
Speckle reduction in line scan laser display system by static diffuser with 2D binary code2021-02-09
A set of two-dimensional (2D) binary codes are created by the calculation of the speckle contrast in line scan laser display system. According to the 2D binary code, phase plates are fabricated by etched glass or photoresist with different thicknesses corresponding to the code. It is introduced on the intermediate image plane to reduce speckle in laser based line scan display system. The experimental results show that the phase plate with the 2D binary code of order 5 can successfully reduce spe
Speckle noise reduction in medical ultrasound image using monogenic wavelet and Laplace mixture distribution2021-02-08
Medical ultrasound images are corrupted with speckle noise inherently, which can cause negative effects on image-based interpretation and diagnostic procedure. Speckle reduction is an important step prior to the processing and analysis of the medical ultrasound images. In this study, a new speckle noise reduction algorithm in medical ultrasound images is proposed by employing monogenic wavelet transform (MWT) and Bayesian framework. The monogenic coefficients are modeled as the sum of noise-free
Displacement measurement method based on laser self-mixing interference in the presence of speckle2021-01-26
In order to achieve the accurate measurement of displacement, this Letter presents a self-mixing interference displacement measurement method suitable for the speckle effect. Because of the speckle effect, the amplitude of the self-mixing interference signal fluctuates greatly, which will affect the measurement accuracy of displacement. The ensemble empirical mode decomposition is used to process the interference signal, which can filter out high-frequency noise and low-frequency noise at the sa
Speckle noise reduction in digital holography by use of multiple polarization holograms2021-02-09
A novel speckle reduction technique for digital holography is proposed. Multiple off-axis holograms are recorded using a circularly polarized illumination beam and a rotating linearly polarized reference beam. The speckle noise in the reconstructed images is suppressed by averaging these fields. We demonstrate the effectiveness of this technique experimentally and conduct additional statistical evaluation.
Homomorphic partial differential equation filtering method for electronic speckle pattern interferometry fringes based on fringe density2021-02-10
Noise reduction is one of the most exciting problems in electronic speckle pattern interferometry. We present a homomorphic partial differential equation filtering method for interferometry fringe patterns. The diffusion speed of the equation is determined based on the fringe density. We test the new method on the computer-simulated fringe pattern and experimentally obtain the fringe pattern, and evaluate its filtering performance. The qualitative and quantitative analysis shows that this techni
Principles of Synthetic Aperture Radar Imaging: A System Simulation Approach2016-07-02
Principles of Synthetic Aperture Radar Imaging: A System Simulation Approach demonstrates the use of image simulation for SAR. It covers the various applications of SAR (including feature extraction, target classification, and change detection), provides a complete understanding of SAR principles, and illustrates the complete chain of a SAR operation. The book places special emphasis on a ground-based SAR, but also explains space and air-borne systems. It contains chapters on signal speckle, radar-signal models, sensor-trajectory models, SAR-image focusing, platform-motion compensation, and microwave-scattering from random media. While discussing SAR image focusing and motion compensation, it presents processing algorithms and applications that feature extraction, target classification, and change detection. It also provides samples of simulation on various scenarios, and includes simulation flowcharts and results that are detailed throughout the book.
Exploiting the point spread function for optical imaging through a scattering medium based on deconvolution method2021-01-26
Visual perception of humans penetrating turbid medium is hampered by scattering. Various techniques have been prompted recently to recover optical imaging through turbid materials. Among them, speckle correlation based on deconvolution is one of the most attractive methods taking advantage of high imaging quality, robustness, ease-of-use, and ease-of-integration. By exploiting the point spread function (PSF) of the scattering system, large Field-of-View, extended Depth-of-Field, noninvasiveness