Ultrasonic Scattered Field Distribution of One and Two Cylindrical Solids with Phased Array Technique

The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.

Prediction of Fresh Pork Quality using Hyperspectral Scattering Imaging(HSI) Technique

In this study, fresh pork tenderness, drip-loss, pH value and color parameters （ CIE, a ＊ , b ＊ and L ＊ values） were simultaneously predicted using hyperspectral scattering imaging （HSI） technique. The hyperspectral scattering images of dO fresh pork samples were collected at the wavelength of 400 -I 100 nm, and the scattering profiles were fitted via Lorontzian distribution （ LD ） function to give three parameters a （ asymptotic value ）, b （peak value ） and c （ full width at b/2）. Stepwise discrimination was performed to determine the optimal wavelengths combinations. The LD parameters combinations （a, b and c） of optimal wavelengths were used to establish multi-linear regression （MLR） models to predict the pork attributes. The models were able to predict pork with high correlation coefficients of 0.92 for drip-loss, 0.94, 0.92 and 0.98 respectively for color parameters （ a ＊ , b＊ and L ＊ ）, and for tenderness and pH value the models gave the correlation coefficients of 0.69 and 0.76, respectively. These results showed that the hyperspectral scattering technique was capable of predicting quality parameters of perk. The study provides an efficient means for rapid and nondestructive determination of pork quality simultaneously.

Resonance Light Scattering Imaging Determination of Heparin

A laser-induced resonance light scattering （RLS） imaging method to determine heparin is described based on the high light scattering emission power of the aggregation species of heparin with α, β, γ, δ-tetra（4-trimethylaminoniumphenyl）prophyrin （TAPP） in solution, By imaging the light scattering signals of the aggregation species, we proposed the method to determine the heparin with a detection range of 0.02 - 0.6μg/mL and the detection limit （30） of 1.3 ng/mL.

Numerical simulation of scattering wave imaging in a goaf

Goafs are threats to safe mining.Their imaging effects or those of other complex geological bodies are often poor in conventional reflected wave images.Hence,accurate detection of goafs has become an important problem,to be solved with a sense of urgency.Based on scattering theory,we used an equivalent offset method to extract Common Scattering Point gathers,in order to analyze different scattering wave characteristics between Common Scattering Point and Common Mid Point gathers and to compare stack and migration imaging effects.Our research results show that the scattering wave imaging method is more efficient than the conventional imaging method and is therefore a more effective imaging method for detecting goafs and other complex geological bodies.It has important implications for safe mining procedures and infrastructures.

Wide-Field Vibrational Phase Contrast Imaging Based on Coherent Anti-Stokes Raman Scattering Holography

We propose and implement a wide-field vibrational phase contrast detection to obtain imaging of imaginary components of third-order nonlinear susceptibility in a coherent anti-Stokes Raman scattering （CARS） microscope with full suppression of the non-resonant background. This technique is based on the unique ability of recovering the phase of the generated CARS signal based on holographic recording. By capturing the phase distributions of the generated CARS field from the sample and from the environment under resonant illumination, we demonstrate the retrieval of imaginary components in the CARS microscope and achieve background free coherent Raman imaging.

Scattered light imaging beyond the memory effect using the dynamic properties of thick turbid media

Scattered light imaging through complex turbid media has significant applications in biomedical and optical research.For the past decade,various approaches have been proposed for rapidly reconstructing fullcolor,depth-extended images by introducing point spread functions(PSFs).However,because most of these methods consider memory effects(MEs),the PSFs have angular shift invariance over certain ranges of angles.This assumption is valid for only thin turbid media and hinders broader applications of these technologies in thick media.Furthermore,the time-variant characteristics of scattering media determine that the PSF acquisition and image reconstruction times must be less than the speckle decorrelation time,which is usually difficult to achieve.We demonstrate that image reconstruction methods can be applied to timevariant thick turbid media.Using the time-variant characteristics,the PSFs in dynamic turbid media within certain time intervals are recorded,and ergodic scattering regimes are achieved and combined as ensemble point spread functions(ePSFs).The ePSF traverses shift-invariant regions in the turbid media and retrieves objects beyond the ME.Furthermore,our theory and experimental results verify that our approach is applicable to thick turbid media with thickness of 1 cm at visible incident wavelengths.

In situ nanobubble sizing by visualization particle tracking and image-based dynamic light scattering

A novel method combining visualization particle tracking with image-based dynamic light scattering was developed to achieve the in situ and real-time size measurement of nanobubbles(NBs).First,the in situ size distribution of NBs was visualized by dark-field microscopy.Then,real-time size during the preparation was measured using image-based dynamic light scattering,and the longitudinal size distribution of NBs in the sample cell was obtained in a steady state.Results show that this strategy can provide a detailed and accurate size of bubbles in the whole sample compared with the commercial ZetaSizer Nano equipment.Therefore,the developed method is a real-time and simple technology with excellent accuracy,providing new insights into the accurate measurement of the size distribution of NBs or nanoparticles in solution.

Image Analysis in Microbiology: A Review

This review is focused on using computer image analysis as a means of objective and quantitative characterizing optical images of the macroscopic (e.g. microbial colonies) and the microscopic (e.g. single cell) objects in the microbiological research. This is the way of making many visual inspection assays more objective and less time and labor consuming. Also, it can provide new visually inaccessible information on relation between some optical parameters and various biological features of the microbial cul-tures. Of special interest is application of image analysis in fluorescence microscopy as it opens new ways of using fluorescence based methodology for single microbial cell studies. Examples of using image analysis in the studies of both the macroscopic and the microscopic microbiological objects obtained by various imaging techniques are presented and discussed.

Dynamic imaging through scattering medium under white-light illumination [Invited]

Imaging objects hidden behind turbid media is of great scientific importance and practical value, which has been drawing a lot of attention recently. However, most of the scattering imaging methods rely on a narrow linewidth of light, limiting their application. A mixture of the scattering light from various spectra blurs the detected speckle pattern, bringing difficulty in phase retrieval. Image reconstruction becomes much worse for dynamic objects due to short exposure times. We here investigate non-invasively recovering images of dynamic objects under white-light irradiation with the multi-frame OTF retrieval engine (MORE). By exploiting redundant information from multiple measurements, MORE recovers the phases of the optical-transfer-function (OTF) instead of recovering a single image of an object. Furthermore, we introduce the number of non-zero pixels (NNP) into MORE, which brings improvement on recovered images. An experimental proof is performed for dynamic objects at a frame rate of 20 Hz under white-light irradiation of more than 300 nm bandwidth.

Analysis and Performance of the Thomson Scattering Diagnostics on HT-7 Tokamak Based on I-EMCCD

A visible light imaging Thomson scattering （VIS-TVTS） diagnostic system has been developed for the measurement of plasma electron temperature on the HT-7 tokamak. The system contains a Nd：YAG laser （A = 532 nm, repetition rate 10 Hz, total pulse duration ≈ 10 ns, pulse energy 〉 1.0 J）, a grating spectrometer, an image intensifier （I.I.） lens coupled with an electron multiplying CCD （EMCCD） and a data acquisition and analysis system. In this paper, the measurement capability of the system is analyzed. In addition to the performance of the system, the capability of measuring plasma electron temperature has been proved. The profile of electron temperature is presented with a spatial resolution of about 0.96 cm （seven points） near the center of the plasma.

Optical scattering imaging with sub-nanometer precision based on position-ultra-sensitive giant Lamb shift

The Lamb shift of a quantum emitter in close proximity to a plasmonic nanostructure can be three or more orders of magnitude larger than that in the free space and is ultra-sensitive to the emitter position and polarization.We demonstrate that this large Lamb shift can be sensitively observed from the scattering or absorption spectrum dip shift of the coupled system when the plasmonic nanoparticle or tip scans the emitter.Using these observations,we propose a scanning optical scattering imaging method based on the plasmonic-enhanced Lamb shift with achieves sub-nanometer resolution.Our method is based on the scattering or absorption spectrum of the plasmon-emitter coupling system,which is free of the fluorescence quenching problem and easier to implement in a plasmon-emitter coupling system.In addition,our scheme works even if the quantum emitter is slightly below the dielectric surface,which can bring about broader applications,such as detecting atoms and molecules or quantum dots above or under a surface.

Polarized imaging dynamic light scattering for simultaneous measurement of nanoparticle size and morphology

The performance of nanoparticles is often affected by particle size and morphology.Currently,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of nanoparticles.However,there are issues such as difficult sample preparation,long processing times,and challenges in quantitative characterization.Therefore,it is of great significance to develop a fast,accu-rate,and statistical method to measure the size and morphology of nanoparticles.In this study,a new method,called polarized imaging dynamic light scattering(PIDLS),is proposed.The nanoparticles are irradiated with a vertical linearly polarized laser beam,and a polarization camera collected the dynamic light scattering images of particles at four different polarization directions(0°,45°,90°,and 135°)at a scattering angle of 90°.The average particle size and distribution are obtained using the imaging dy-namic light scattering method at 0°polarization direction,and the morphology of the particles is ob-tained based on the depolarization patterns of the scattered light.The optical sphericityΦis defined based on the degree of linear polarization(DoLP).It is also implemented for the quantitative evaluation of the sphericity of the nanoparticles,including spherical,octahedral,nanoplate,nanorod,and linear ones.Together with the Poincarésphere parameterψ,the morphology of the nanoparticles can be roughly identified.In addition,PIDLS enables the measurement of particle size and morphology distributions simultaneously for evaluating the uniformity of particles.The effectiveness of PIDLS is verified by the measurement of five kinds of industrial titanium dioxide as well.

Deep learning-based scattering removal of light field imaging

Light field imaging has shown significance in research fields for its high-temporal-resolution 3D imaging ability.However,in scenes of light field imaging through scattering,such as biological imaging in vivo and imaging in fog,the quality of 3D reconstruction will be severely reduced due to the scattering of the light field information.In this paper,we propose a deep learning-based method of scattering removal of light field imaging.In this method,a neural network,trained by simulation samples that are generated by light field imaging forward models with and without scattering,is utilized to remove the effect of scattering on light fields captured experimentally.With the deblurred light field and the scattering-free forward model,3D reconstruction with high resolution and high contrast can be realized.We demonstrate the proposed method by using it to realize high-quality 3D reconstruction through a single scattering layer experimentally.

Learning-based lensless imaging through optically thick scattering media

The problem of imaging through thick scattering media is encountered in many disciplines of science,ranging from mesoscopic physics to astronomy.Photons become diffusive after propagating through a scattering medium with an optical thickness of over 10 times the scattering mean free path.As a result,no image but only noise-like patterns can be directly formed.We propose a hybrid neural network for computational imaging through such thick scattering media,demonstrating the reconstruction of image information from various targets hidden behind a white polystyrene slab of 3 mm in thickness or 13.4 times the scattering mean free path.We also demonstrate that the target image can be retrieved with acceptable quality from a very small fraction of its scattered pattern,suggesting that the speckle pattern produced in this way is highly redundant.This leads to a profound question of how the information of the target being encoded into the speckle is to be addressed in future studies.

Sensitive semi-quantitative detection of respiratory syncytial virus by dark-field light scattering imaging of the infected host cells

A novel sensitive semi-quantitative virus detection technique was developed using the respiratory syncytial virus(RSV) as an example, through dark-field light scattering imaging of the surface state of the virusinvaded host cells. In this method, anti-RSV-antibody modified gold nanoparticles(Au NPs) could bind with the invading virus on the cell membrane of the infected host cells through the specific antibody-antigen binding. Then,the host cells could be imaged by the localized surface plasmon resonance light scattering properties of Au NPs under a dark-field light scattering microscopy, which could be further used to semi-quantify the invading virus.

Round-trip imaging through scattering media based on optical transmission matrix

Traditional one-way imaging methods become invalid when a target object is completely hidden behind scattering media. In this case, it has been much more challenging, since the light wave is distorted twice.To solve this problem, we propose an imaging method, so-called round-trip imaging, based on the optical transmission matrix of the scattering medium. We show that the object can be recovered directly from the distorted output wave, where no scanning is required during the imaging process. We predict that this method might improve the imaging speed and have potential application for real-time imaging.

Acoustical diffraction tomographic imaging under non-weak scattering

Under the assumption of weak scattering , the acoustical diffraction tomographic imaging of an object can be reconstructed by using the Born (or Rytov) approximation method . When the weak scattering assumption within the medium is not satisfied the multiple ultrasound scattering must be taken into account . In this case , the reconstruction results under the first-order Born approximation will be seriously distorted . In this paper we introduce an ' intermediate object function' into the wave equation and take iterative modification in space domain and spatial frequancy domain based on Born approximation . In this way , the distorted image will be improved step by step . In order to examine the method as mentioned above , we have just tried to make computerized simulations . The initial result shows that the quality of the image reconstructed from the object under non-weak scattering may be improved significantly .

Background-free three-dimensional selective imaging of anisotropic plasmonic nanoparticles

There is an increasing demand for advanced optical imaging techniques that can detect and resolve nanosize objects at a spatial resolution below the optical diffraction limit, especially in three-dimensional （3D） cellular environments. In this study, using a polarization-activated localization scheme based on the orientation-dependent properties of anisotropic plasmonic metal nanoparticles （MNPs）, ＂photoswitchable＂ imaging of single gold nanorods （AuNRs） was accomplished not only in two dimensions but also in three dimensions. Moreover, the Rayleigh scattering background arising from the congested subcellular structures was efficiently suppressed. Thus, we obtained the 3D distributions of both the position and the orientation of the AuNRs inside the cells and investigated their intemalization kinetics. To our knowledge, this is the first demonstration of the confocal-like 3D imaging of non-fluorescence nanoparticles with a high resolution and almost zero background. This technique is easy to implement and should greatly facilitate MNP studies and applications in biomedicine and biology.

Resonance Light Scattering Imaging Detection of Single Suprahelical Species of DNA Induced by Porphine-5,10,15,20-tetrakis（ρ-phenyltri met hylaminiu m）

A resonance light scattering （RLS） imaging method was proposed based on imaging and measuring the RLS features of single suprahelical species of DNA, and its appfication to DNA assay was also investigated. In acidic medium, porphine-5,10,15,20-tetrakis（p-phenyltlimethylaminium） （PTPTMA）, could stack along the molecular surface of DNA with the mode of long-range assembly to induce the formation of suprahelical species of DNA, resulting in strong RLS signals in the range of 450-510 nm. Under the excitation of 488 nm fight beam of argon ion laser source, single suprahelical species could be observed with the aid of a common microscope due to the strong scattered fight emitted by the suprahelical species. By capturing the RLS images of the single suprahelical species with a cooled charge coupled device （CCD） camera, and analyzing the RLS data, herein an RLS imaging method of DNA was proposed based on the linear relationship between the counts of suprahelical species in the detection focus plane and the concentration of DNA in nanograms. When 1.8 μmol/L PTPTMA was employed, both calf thymus DNA （ct DNA） and fish sperm DNA （fs DNA） in the range of 25-1100 ng/mL could be detected with the limits of detection lower than 25 ng/mL （3a）. Four synthetic samples were detected satisfactorily with relative standard deviations less than 5.1%.

Efficient reference-less transmission matrix retrieval for a multimode fiber using fast Fourier transform

Imaging through multimode fiber(MMF)provides high-resolution imaging through a fiber with cross section down to tens of micrometers.It requires interferometry to measure the full transmission matrix(TM),leading to the drawbacks of complicated experimental setup and phase instability.Reference-less TM retrieval is a promising robust solution that avoids interferometry,since it recovers the TM from intensity-only measurements.However,the long computational time and failure of 3D focusing still limit its application in MMF imaging.We propose an efficient reference-less TM retrieval method by developing a nonlinear optimization algorithm based on fast Fourier transform(FFT).Furthermore,we develop an algorithm to correct the phase offset error of retrieved TM using defocused intensity images and hence achieve 3D focusing.The proposed method is validated by both simulations and experiments.The FFT-based TM retrieval algorithm achieves orders of magnitude of speedup in computational time and recovers 2286×8192 TM of a 0.22 NA and 50μm diameter MMF with 112.9 s by a computer of 32 CPU cores.With the advantages of efficiency and correction of phase offset,our method paves the way for the application of reference-less TM retrieval in not only MMF imaging but also broader applications requiring TM calibration.