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Underwater imaging is a crucial and challenging problem. The backscattering caused by particles in turbid water can severely degrade the image. In this paper, A novel image dehazing method is devised, which combines optics with image processing technology. This method can directly remove part of the backscattering through polarization technology, and then quickly solve the dehazing image through our algorithm. Experimental results show that our method is valid and robust for targets of diverse materials, grayscale images and color images in diverse scattering environments. Furthermore, our method takes only 2 percent of the time of the fast dark channel prior (DCP) method when processing 1 K resolution images, which meets the requirements of real-time.

We proposed and fabricated toroidal dipole (TD) metasurfaces(MSs) with a metamolecule of two coplanar U-shaped split ring resonators(USRRs) fabricated on polyimide substrate, and TD metamaterials (MMs) were the stacks of two TD MSs layers, whose frequencies, electromagnetic (EM) distributions and Q factor can be efficiently affected by the EM coupling effect in TD MSs/MMs. It was found that the resonances frequencies of TD MMs were shifted to lower frequencies due to the increase of inductance by the stacks of metallic layer. Meanwhile, the high-frequency TD resonance in TD MMs would be tailored by the periodicity. Considering the relation between TD resonances and the scattering power of TD (Ty), the Q factor depended highly on the value of Ty in the same metamolecule structure. The optimization in excitation of TD provide opportunity to further increase the Q-factor of metamaterial and pave a way for potential applications in terahertz sensor and other functional devices.

The classification of the type of trapped particles is a crucial task for an efficient integration of optical-tweezers in intelligent microfluidic devices. In the recent years, the use of the temporal scattering signal of the trapped particle paved for the use of versatile optical fiber solutions for performing such tasks, a feature previously unavailable as most methods required conventional optical tweezer setups. This work presents a comprehensive comparison of performances achieved with two distinct implementations – i)optical fiber and ii)conventional optical tweezers – for the classification of the material of particles through the analysis of the scattering signal with machine learning algorithms. The results suggest that while micron-sized particles can be accurately classified using the forward scattering information in conventional optical tweezers, when equipped with a quadrant photodetector, the optical fiber tweezers solutions can easily surpass its performance using the back-scattered information if the laser is modulated. Together with the advantages of being simpler, less expensive and more versatile, the results presented suggest that optical fiber solutions can become a valuable tool for miniaturization and integration of intelligent microfluidic devices working towards nanoscopic scales.

A state-of-the-art encapsulation technique for evaluating a photovoltaic device in laboratory is needed for replicating real-time devices. In this context, earlier we proposed the pouch lamination as a cost-effective and reproducible lab-scale encapsulation technique. In this work, we apply this technique in evaluating the optical and electrical performances of a mc-Si device with a front spectral shifting layer before and after encpasulation. Our coating contains the red-emitting nitride phosphor CaAlSiN3:Eu2+ (CASN:Eu2+) in (poly)-methyl methacrylate (PMMA). On coating, a drastic reduction in the device's reflectance was observed below 450 nm. Correspondingly, the external and internal quantum efficiencies of the devices are also improved relative to the bare. When irradiated by an AM1.5G source, the electrical parameters remain of the device remain unaffectd after the coating. However, on encapsulating the coated device, impedance losses drastically reduce its conversion efficiency. This paper thus reveals the need for including an encapsulant while demonstrating device modifications through optical coatings.

Optical phonon scattering mobility has been calculated using numerical methods, and a general program was developed in Matlab to calculate mobility due to scattering on optical phonons. Calculations were done for InAs material that was irradiated by fast neutrons.

Planar temperature images using laser Rayleigh scattering have been obtained to determine the spatial distribution of temperature in a constant volume combustion chamber. Burning velocities were also measured from measured pressures and calculated flame surface area from Rayleigh scattering images. A high power KrF excimer laser was used as a light source and a high gain ICCD camera was used to obtain temperature images. Methane/air premixed combustion at different equivalence ratios and initial pressures were tested. Since the thermodynamics are well known, a constant volume chamber can be used as a reference device for diagnostics in high temperatures and pressures combustion. With the Rayleigh scattering technique, temperature and burning velocity can be measured simultaneously using a single-shot laser light. An additional laser Rayleigh experiment is described which yields scattering cross sections at the wavelength of 248 nm. The experimental results show an excellent agreement with previous data.

Thermoelectric materials are capable of directly converting heat into electricity by the Seebeck effect, which are applicable to a wide range of industrial applications. For semiconductor thermoelectrics, one of the most effective ways to enhance their performance is to use nanostructures to significantly reduce their lattice thermal conductivity, which is governed by lattice vibrations referred to as phonons, without dramatically sacrificing their electrical properties. Hence, the transport of phonons in nanostructured thermoelectrics is of crucial importance. This chapter stresses the basic concepts and fundamental principles of the transport of phonons in nanostructured materials. Starting with the concepts of phonons and phonon Boltzmann transport equation, we can derive the phonon gas model for thermal conductivity. Various scattering mechanisms of phonons that affect the thermal conductivity in nanostructured materials, well-established theoretical and experimental methods used for the investigation of phonon transport, and examples in terms of manipulating phonons with nanostructures in the field of thermoelectrics are described.

Phonons are fundamental carriers of thermal energy in crystalline solids. Microscopic heat transfer analysis rely on properties and dynamics of phonons. Phonon wave packet method is a molecular dynamics simulation to visualize the phonon dynamics and scattering to calculate the energy transmission coefficient and to study phonon conversion. In this chapter, the machinery and the practice of phonon wave packet method are discussed with applications on carbon nanostructures.

Summary Optical metasurface as a booming research field has put forward profound progress in optics and photonics. Compared with metallic-based components, which suffer from significant thermal loss and low efficiency, high-index all-dielectric nanostructures can readily combine electric and magnetic Mie resonances together, leading to efficient manipulation of optical properties such as amplitude, phase, polarization, chirality, and anisotropy. These advances have enabled tremendous developments in practical photonic devices that can confine and guide light at the nanoscale. Here we review the recent development of local electromagnetic resonances such as Mie-type scattering, bound states in the continuum, Fano resonances, and anapole resonances in dielectric metasurfaces and summarize the fundamental principles of dielectric resonances. We discuss the recent research frontiers in dielectric metasurfaces including wavefront-shaping, metalenses, multifunctional and computational approaches. We review the strategies and methods to realize the dynamic tuning of dielectric metasurfaces. Finally, we conclude with an outlook on the challenges and prospects of dielectric metasurfaces., Graphical Abstract, Optics; Electromagnetic Waves; Metamaterials

Scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS) has become a standard technique to map localized surface plasmon resonances with a nanometer spatial and a sufficient energy resolution over the last 15 years. However, no experimental work discussing the influence of experimental conditions during the measurement has been published up to now. We present an experimental study of the influence of the primary beam energy and the collection semi-angle on the plasmon resonances measurement by STEM-EELS. To explore the influence of these two experimental parameters we study a series of gold rods and gold bow-tie and diabolo antennas. We discuss the impact on experimental characteristics which are important for successful detection of the plasmon peak in EELS, namely: the intensity of plasmonic signal, the signal to background ratio, and the signal to zero-loss peak ratio. We found that the primary beam energy should be high enough to suppress the scattering in the sample and at the same time should be low enough to avoid the appearance of relativistic effects. Consequently, the best results are obtained using a medium primary beam energy, in our case 120 keV, and an arbitrary collection semi-angle, as it is not a critical parameter at this primary beam energy. Our instructive overview will help microscopists in the field of plasmonics to arrange their experiments.

The photon spectrum from electrons scattering on multiple laser pulses exhibits interference effects not present for scattering on a single pulse. We investigate the conditions required for the experimental observation of these interference effects in electron-laser collisions, in particular analysing the roles of the detector resolution and the transverse divergence of the pump electron beam., Comment: 8 pages, 5 figures

6 pags., 8 figs., 3 tabs., CALIFA is the high efficiency and energy resolution calorimeter for the RB experiment at FAIR, intended for detecting high energy light charged particles and gamma rays in scattering experiments, and is being commissioned during the Phase-0 experiments at FAIR, between 2018 and 2020. It surrounds the reaction target in a segmented configuration with 2432 detection units made of long CsI(Tl) finger-shaped scintillator crystals. CALIFA has a 10 year intended operational lifetime as the RB calorimeter, necessitating measures to be taken to ensure enduring performance. In this paper we present a systematic study of two groups of 6 different detection units of the CALIFA detector after more than four years of operation. The energy resolution and light output yield are evaluated under different conditions. Tests cover the aging of the first detector units assembled and investigates recovery procedures for degraded detection units. A possible reason for the observed degradation is given, pointing to the crystal-APD coupling., This work has been financially supported by the European Union Horizon 2020 research and innovation programme under grants agree-ments No 262010 (ENSAR) and No 654002 (ENSAR2), the Spanish MICCIN grants FPA47831-C2-1P and FPA2015-69640-C2-1-P, by the Plan Galego de Investigación, Innovación e Crecemento (I2C) of Xunta de Galicia, Spain under projects POS-B/2016/015, GRC2013-011 andED431C 2017/54 and by the German BMBF (No. 05P19RDFN1), TUDarmstadt - GSI cooperation contract, HIC for FAIR.

Summary Small-angle X-ray scattering (SAXS) method is widely used in investigating protein structures in solution, but high-quality 3D model reconstructions are challenging. We present a new algorithm based on a deep learning method for model reconstruction from SAXS data. An auto-encoder for protein 3D models was trained to compress 3D shape information into vectors of a 200-dimensional latent space, and the vectors are optimized using genetic algorithms to build 3D models that are consistent with the scattering data. The program has been tested with experimental SAXS data, demonstrating the capacity and robustness of accurate model reconstruction. Furthermore, the model size information can be optimized using this algorithm, enhancing the automation in model reconstruction directly from SAXS data. The program was implemented using Python with the TensorFlow framework, with source code and webserver available from http://liulab.csrc.ac.cn/decodeSAXS., Graphical Abstract, Highlights • A convolutional neural network auto-encoder framework for 3D models is developed • The auto-encoder compresses protein shape information to 200 parameters • Accurate 3D models (both shape and radius) can be reconstructed from 1D SAXS data, Computational Molecular Modeling; Algorithms; Computer Science Applications

Photonic structures allow reducing the thickness of photovoltaic (PV) devices while improving their photocurrent, thereby enabling high-efficient, low-cost, and mechanically flexible solar cells. Wave-optical front structures have shown to be promising for integration in various thin-film PV technologies, as those based on silicon or perovskite semiconductors, due to a combination of: (1) Broadband absorption amplification—wavelength-sized structures provide geometrical index-matching for the impinging light, strongly reducing reflection while boosting the photons' path length within the absorber via scattering. (2) Improved electrical performance—their incorporation in the transparent contact can enable higher electrode volume, thereby improving the cells' voltage and fill factor. Such a location can also prevent increasing the cells' roughness, therefore not contributing to recombination. (3) Enhanced stability—particularly in perovskite cells, the front photonic structures block most of the harmful UV radiation that degrades such devices. Colloidal lithography methods have revealed to be highly cost-effective for the nanopatterning of such structures, allowing compatibility with industrial scalability and low-cost requirements.

Publisher Summary This chapter focuses on spontaneous light scattering and acoustooptics. Spontaneous light scattering means light scattering under conditions such that the optical properties of the material system are unmodified by the presence of the incident light beam. Several physical processes can lead to light scattering. One of the processes is Raman scattering that results from the interaction of light with the vibrational modes of the molecules constituting the scattering medium. Raman scattering can equivalently be described as the scattering of light from optical phonons. Brillouin scattering is the scattering of light from sound waves, that is, from propagating pressure (and hence density) waves. Brillouin scattering can also be considered to be from acoustic phonons. In RayLeigh scattering or Rayleigh-center scattering, light is scattered because of nonpropagating density fluctuations. Formally, it can be described as scattering from entropy fluctuations. It is known as quasielastic scattering because it induces no frequency shift. The scattering of light from sound waves can also be applied to the situation, in which the sound wave is applied to the interaction region externally by means of a transducer. Such acoustooptic devices are useful as intensity or frequency modulators for laser beams or as beam deflectors. Acoustooptic devices are commonly classified as falling into one of two regimes; namely, Bragg scattering and Raman-Nath scattering.

The area of non-resonant dielectric metamaterials comprises phenomena which occur at long wavelengths, where Mie resonances and Bragg diffraction in ordered structures do not play a role. In this spectral range effective-medium theories can be applied quite well and are therefore revisited in the first part of the chapter. Isotropic as well as anisotropic effective media are discussed and the dispersion relation for light predicted by the effective-medium theories is compared to exact photonic bandstructures in ordered metamaterials, demonstrating overall very good correspondence in the long wavelength range. After a short look at more advanced modern homogenization methods experimental techniques are discussed to determine the effective parameters. In particular measurements based on interference effects are suggested to determine group velocity, effective indices and birefringence with greater confidence. The power to control the effective refractive index and anisotropy on a local level by arranging and shaping the scattering elements in a designed way is employed to create a large variety of graded effective-index structures. These can be used to realize designs originating from transformation optics. Recent examples of graded index landscapes for metasurfaces, 2D in-plane light guiding, subwavelength structured waveguides and antireflection coatings are presented. Most of the discussed designs are based on silicon as a high index material facilitating a large range of effective refractive indices and exploiting existing nanofabrication methods. While most of the artificially created metamaterials exhibit a strict periodic order, in the last section disordered systems are discussed and possibilities of hyperuniform arrangements of scattering elements outlined.

There are many situations when it is desirable to estimate not only a diameter of the nanoparticles but also their composition and the composition of the interface between nanoparticles and surrounding matrix. Ion beam analysis methods, such as medium energy ion scattering spectroscopy and low energy ion scattering, offer distinctive advantages. This chapter will provide a background discussion of ion beam analysis (IBA) methods and give their advantages and limitations for nanoparticle characterization. To illustrate the applications of IBA methods to the characterization of ensembles of nanoparticles, several examples will be presented with the methodologies involved.

This chapter reviews the fundamental physics and associated limitations of semiconductor lasers operating across the mid-infrared (MIR) range of 2–20 μm. Using a combination of temperature and hydrostatic pressure dependence techniques, we have shown how short-wavelength 1.9–3.7-μm type I quantum well interband devices are dominated by Auger recombination, the nature and type of which depends upon the wavelength. In the intermediate wavelength range (3–7 μm), interband type II “W” lasers offer significant performance improvements despite the reduced wavefunction overlap. Quantum cascade lasers dominate at the longest MIR wavelengths with performance limited by intervalley scattering and leakage processes.

Two methods for passive cooling are introduced in this chapter, namely radiative cooling and cool paint. These are notably different from the more commonly known methods of heat absorption and rejection. Radiative cooling makes use of the natural black-body radiation of everyday objects, combined with the atmospheric transmission window at mid infra-red wavelengths. Cool paint incorporates particles with sizes comparable to the wavelength of visible and near infra-red light, thus is effective at scattering solar irradiation. This chapter introduces the basic physics behind these phenomena, reviews recent development and use cases of these passive cooling technologies, and discusses their potential impact on reducing building heat envelope gain and air-conditioning usage.

This chapter aims to present a new approach in optical fiber sensors using side coupling of light into the core modes of plastic optical fiber (POF) coated with zinc oxide (ZnO) nanorods. The approach employs ZnO nanorods grown on POF to enhance coupling inside the fiber by scattering light. Structuring the growth of ZnO to specific regions allows scattering from different segments along the fiber to enhance the total coupled power. According to this capability approach, various sensing applications can be performed based on needs to develop a low-cost, high sensitivity and uncomplicated sensor system.

Random lasers are photonic sources of coherent emission, which differ from conventional lasers because their optical feedback mechanism is provided by a scattering medium rather than by a conventional set of mirrors. In general, nanoparticles and a gain medium form a nanocomposite with laser properties when appropriately pumped. In this chapter, we review the development and some applications of nanocomposite-based organic random lasers and fiber random lasers. Considering the fascinating growth of the field over the last 25 years, this chapter will give an overall insight into the state-of-the-art literature for random lasers and fiber random lasers, with examples for nanocomposites mainly exploiting dyes and nanoscatterers, including both dielectric and metallic.

We describe the scattering properties of planar metasurfaces composed of arrays of dielectric resonators supporting both electric and magnetic Mie resonances. We focus on the study of metasurfaces with such functionalities as perfect reflection, perfect transmission, and perfect absorption of light at the normal or oblique incidence. Each effect is presented in its simplest form for the cases of electric and magnetic dipole resonances. Generalizations to higher orders and higher numbers of multipoles are discussed as well.

Outlines image formation theory and computer-aided interpretation in transmission electron microscopes (TEMs). (i) Near-axis electron ray optics; the transition to electron wave optics; spherical aberration, defocus and astigmatism. (ii) Beam-specimen interactions for weak (thin) specimens; multiple scattering; Bloch wave propagation in crystals; inelastic scattering; negative staining of biological specimens. (iii) Linear imaging: complex Fourier space filters modelling imaging of weakly scattering objects; phase and amplitude object components transferred by separate filters (contrast transfer functions or CTFs), and superposed in the image; coherence envelopes averaging CTF over a range of incident beam directions and focus levels; tilted-beam imaging; the charge density approximation. (iv) Nonlinear imaging, also with imperfect coherence; scanning transmission microscopy (STEM) and the reciprocal relationship with TEM. (v) Image analysis and object reconstruction: simple inverse filtering leaving gaps in the transform; using differently focused images to fill the gaps in single image transforms, and to separate the phase and amplitude components; 3D reconstruction; averaging images to recover signals buried in noise; using differently recorded images to eliminate inelastic contributions; ptychography; holography. (vi) Resolution, contrast, noise and radiation damage: the limitations imposed by electron shot noise (counting statistics); the inter-relation of resolution and contrast.

Summary: A high-energy-level blue phosphor FIr-p-OC8 has been developed for solution-processed white organic light-emitting diodes (WOLEDs) with comparable fluorescent tube efficiency. Benefiting from the electron-donating nature of the introduced alkoxy, FIr-p-OC8 shows not only efficient blue light but also elevated highest occupied molecular orbital/lowest unoccupied molecular orbital levels to well match the dendritic host H2. Consequently, the hole scattering between FIr-p-OC8 and H2 can be prevented to favor the direct exciton formation on the blue phosphor, leading to reduced driving voltage and thus improved power efficiency. By exploiting this approach, a maximum power efficiency of 68.5 lm W−1 is achieved for FIr-p-OC8-based white devices, slightly declining to 47.0 lm W−1 at a practical luminance of 1,000 cd m−2. This efficiency can be further raised to 96.3 lm W−1 @ 1,000 cd m−2 when a half-sphere is applied to increase light out-coupling. We believe that our results can compete with commercial fluorescent tubes, representing an important progress in solution-processed WOLEDs. : Organometallic Chemistry; Inorganic Materials; Optoelectronics Subject Areas: Organometallic Chemistry, Inorganic Materials, Optoelectronics

Stimulated Raman scattering (SRS) excited by incoherent light is studied via particle-in-cell simulations. It is shown that a large bandwidth of incoherent light can reduce the growth of SRS and electron heating considerably in the linear stage. However, different components of the incoherent light can be coupled by the Langmuir waves, so that stimulated Raman backward scattering can develop. When the bandwidth of incoherent light is larger than the Langmuir wave frequency, forward SRS can be seeded between different components of the incoherent light. The incoherent light can only increase the time duration for nonlinear saturation but cannot diminish the saturation level obviously. Keywords: Stimulated Raman scattering, Instability suppression, Incoherent light, Inertial confinement fusion, PACS Codes: 52.25.Os, 52.35.-g, 52.38.Bv

Graphical abstract, A method for determining the critical values of the flow speed and the flow constriction degree characteristic of the alignment of cylindrical nano-objects in a flowing suspension is proposed. Previously, the alignment process of cylindrical nano-objects in suspensions was investigated by using birefringence of the polarized light and the small-angle X-ray scattering. While both methods are suitable for measuring the alignment degree of cylindrical nano-objects in suspensions diluted down to low concentrations, they are restricted for the application to undiluted concentrated suspensions because of non-transparency and multiple scattering of X-rays. In addition, the use of the second method requires an expensive synchrotron equipment. We present a simple and faster method based on the direct ultrasound attenuation measurements of longitudinal viscosity of a suspension containing cylindrical nano-objects, which decreases monotonically, approaching its asymptotic value with increase in the flow speed and the flow constriction degree. The principle and advantages of the proposed method are as follows: • The cylindrical nano-objects align along an accelerated flow at overcritical values of the flow speed and the constriction degree. • The critical values correspond to the state of a suspension possessing viscosity close to the asymptotic value. • The method is applicable to undiluted concentrated suspensions, including opaque ones.

The scale measurement has a great significance in studying electromagnetic scattering properties. But there still exist great difficulties in constructing an accurate scale model including nonmetallic materials such as magnetic absorbing coatings. Based on the reflective loss of a coating irradiated obliquely by plane microwave, a method is proposed to solve the problem of designing the scale coating. The commercial simulation software FEKO is used to investigate the use of the method. According to simulating monostatic RCS of coating plate models, coating sphere models and coating spherecone models, results reveal that the monostatic RCS of the designed scale model have a great agreement with that of the theoretical scale model in the whole incidence angle range. Furthermore, the coating SLICY models, which include many electromagnetic scattering mechanisms, are constructed to verify the proposed method. The simulated result of the designed scale SLICY model is very close to that of the theoretical scale SLICY model. All the simulated results indicate that the method proposed in this paper is valid. Keywords: A magnetic absorbing coating, Scale measurement, Reflective loss, Monostatic RCS

XaNSoNS is an open source software with GPU support, which simulates X-ray and neutron 1D (or 2D) diffraction patterns and pair-distribution functions (PDF) for amorphous or crystalline nanoparticles (up to ∼107 atoms) of heterogeneous structural content. Among the multiple parameters of the structure the user may specify atomic displacements, site occupancies, molecular displacements and molecular rotations. The software uses general equations nonspecific to crystalline structures to calculate the scattering intensity. It supports four major standards of parallel computing: MPI, OpenMP, Nvidia CUDA and OpenCL, enabling it to run on various architectures, from CPU-based HPCs to consumer-level GPUs. Keywords: X-ray and neutron diffraction, Simulation, GPU

Many recent metasurfaces, consisting of one or two-dimensional artificial structures with subwavelength unit cells, have been designed to manipulate optical waves by achieving the 2π continuous phase gradients. In this paper, a method to transfer and control multi-beam reflections from a normal incident wave using a gradient-index metasurface is presented. By tuning properly the phase difference over the gradient-index metasurface, multi-beam anomalous reflections can be achieved, where the beam wavefronts are fully controlled by the refractive index distribution. The theoretical and simulated results show that some excellent multi-beam anomalous reflections are demonstrated by field distribution and radiation pattern of scattering field. Our method may help to offer a new design methodology for multi-beam steering in many interesting optics and microwave applications.

Optics studies the behavior of light, or the properties of transmission and deflection of other forms of radiation. It forms the basis of optical transducers used in a variety of applications from imaging and spectroscopy to light-based manipulation and manufacturing in life sciences, chemistry, physics, and engineering. Optical transducers typically offer high sensitivity, combined spatial and spectral measurements, and detection with no direct contact to the objects under investigation. There are many types of optical transducers. In optical waveguides, there are several high-contrast modes available for light transmission, sensing, and imaging. Disadvantages include the need for the optical transducers to be transparent at the wavelength used for sensing, the use of labels, interferences, and issues arising from fluorophore decay in fluorescence imaging. In this chapter, we describe molecular sensors based on optical transduction. Lights interact with molecules in various ways, which are observed as transmission, scattering, fluorescence, and other forms of optical readout. We explain principles of optics used for molecular sensing and describe the instrumentation for optical measurements. The chapter starts with the introduction of the basic electromagnetic theory, followed by discussions on waveguides and sensors based on waveguide structures, and surface plasmon resonance-based (SPR) sensors. Lastly, theories and practices of optical spectroscopy techniques are described. Methods discussed include absorption and fluorescence microscopy and spectroscopy, static and dynamic light scattering, Doppler velocimetry, Raman spectroscopy, and near-field optical microscopy.

Biological tissue has a complex structure and exhibits rich spectroscopic behavior. Light of longer wavelength is less scattered by typical tissue, yet it is unexpectedly scattered more into the forward directions (the anisotropy of light scattering increases) within the visible and near-infrared (NIR) spectral range as revealed by some thorough measurements. We present a plum pudding random medium (PPRM) model for biological tissue to account, for the first time, for the observed spectroscopy of tissue light scattering and its anisotropy. PPRM succinctly describes tissue as a superposition of distinctive scattering structures (plum) embedded inside a fractal continuous medium of background refractive index fluctuation (pudding). PPRM faithfully reproduces the power law wavelength dependence of tissue light scattering and attributes the “anomalous” trend in the anisotropy to the plum. As light scattering is the key factor hampering the depth and resolution of optical biomedical imaging, PPRM provides much needed quantitative model of light scattering by biological tissue to gauge the merits of biomedical imaging with light of varying wavelengths. Optical breast and brain imaging are used as two examples to compare the performance of imaging in NIR and shortwave infrared (SWIR) spectral windows.

Dielectric metamaterials create a low-loss platform for a variety of applications in photonics involving a complex manipulation of the amplitude, polarization, and phase of light. However, for many applications it is important to understand how an artificial periodic system operating as a photonic crystal with the properties dominated by the Bragg scattering can transform into a metamaterial described by effective parameters. This chapter provides a comprehensive overview of the transitions between photonic crystals and metamaterials. As an example, we consider the structures composed of dielectric rods arranged in a periodic lattice. The metamaterial regime is defined by a polariton-like feature in the photonic bandgap diagram below all Bragg stop-bands created by the periodicity. This definition makes it possible to introduce the concept of a photonic phase diagram for the metamaterial and photonic crystal regimes as a function of the geometric parameters and dielectric rod permittivity. Transition between the photonic crystal and metamaterial “phases” is accompanied by a dramatic modification of the electromagnetic field patterns in the wave scattering. In addition, we describe the existence of epsilon-near-zero regime, stability of the metamaterial bandgap spectra in the presence of disorder, experimental studies of dielectric metamaterials for the microwave frequencies, and also discuss practical realizations of silicon-based metamaterials operating in the visible frequency range.

Charged-particle spectra at midrapidity are measured in Pb-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair $\sqrt{s_{\rm NN}}$ = 5.02 TeV and presented in centrality classes ranging from most central (0-5%) to most peripheral (95-100%) collisions. Possible medium effects are quantified using the nuclear modification factor ($R_{\rm AA}$) by comparing the measured spectra with those from proton-proton collisions, scaled by the number of independent nucleon-nucleon collisions obtained from a Glauber model. At large transverse momenta ($8, Comment: 24 pages, 7 captioned figures, 2 tables, authors from page 18, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/4437

The optical constants of many metals commonly used in solar cells, e.g. as contacts, rear side planar reflectors, or more complex nanopatterned light-trapping structures, can vary depending on deposition method, thickness and other factors, and as such are not documented consistently in the literature. In the case of nanometallic light-trapping structures specifically designed to improve absorption in a solar cell, the choice of optical constants used in simulations significantly affects the predicted enhancement, as well as the structure's optimal dimensions. The trade-off between coupling into guided modes in the photovoltaic material and the number of photons absorbed parasitically in the metal leads to small differences in the optical constants giving significantly different results for the quantum efficiency and photogenerated current. This work documents several optical constant sources for silver, aluminium, gold and titanium, and the effect this has on plasmon quality factors. The effect of choosing different optical constant sources on modelling outcomes is quantified by considering the optimization of a test structure comprising a grid of metal nanodisks on the front surface of a thinned-down GaAs cell. Finally, we define a new spectrally-integrated figure of merit for comparing the expected performance of metals in light-trapping structures based on their optical constants, which we name the spectral absorption enhancement factor (SAEF).

This paper examines the electromagnetic energies developed in the scales of the Lepidoptera Danaus plexippus. The Green tensor method was used to calculate and simulate the energies at specific wavelengths. Scattering of electromagnetic waves within the scales was simulated at different wavelengths (λ) with the corresponding maximum energy occurred at λ = 0.45 μm. The study shows that the design of wing's cross-ribs maximizes the eigenmode of electromagnetic energy. This shows promising applications in bio-sensors of Solar light and likewise in waveguide for photonic transmission.

In this chapter we address how to identify the online presence of companies as the basic strategy for conducting a cybermetric analysis. Presence is determined by a web domain node, which is the core around which content is generated. From this web presence the web size is calculated: The number of hosted files or indexed URLs in the domain node. Then we look at the scattering of presence and size, both internally (or vertically) within the web domain nodes (through subdirectories or web subdomains) and externally (or horizontally) from alternative or satellite web domains. Finally, we explore two case studies focusing on internal and external scattering, respectively. The first is an analysis of 10 global companies that are leaders in their respective sectors. For each company, internal scattering is calculated from the first-level subdomains and subdirectories. The results show a wide variability in both the chosen approach (subdirectory or subdomain) and in the distribution of content, no specific patterns having been found. The second case study is a comprehensive analysis of the external scattering of Microsoft, both through its alternative web domains and its web satellites (in this case limited to Twitter). With regard to alternative web domains, the results show not only high external scattering but also considerable interaction between the various alternative domains, an aspect that may adversely affect the measurement of impact. As for the web satellites, there is clearly a need to rethink the concept of web presence in social networks, to go from simply counting files to considering blocks of information.

Total internal reflection fluorescence microscopy (TIRFM) selectively excites sample fluorescence in a thin zone within a fraction of a wavelength of the supporting coverslip. As such, it greatly reduces out-of-focus background fluorescence and is used commonly for single molecule and for subcellular organelle imaging. This article qualitatively focuses on TIR-related issues of lateral and axial resolution, polarization, multiphoton variations, refractive index measurement, scattering, and combinations of TIRFM with other optical techniques.

The scattering of electromagnetic waves from films with randomly rough surfaces and/or volume disorder is discussed in this chapter. One or both of the surfaces of the film are rough. The surface roughness considered is either one-dimensional or two-dimensional, while the volume disorder is three-dimensional. Advances in computational approaches to the solution of these scattering problems, with an emphasis on multiple-scattering phenomena are described, and results obtained by these approaches are presented. Examples of applications of the results of calculations of scattering from rough surfaces of, and volume disorder in, films are presented with a focus on remote sensing.

The most critical property of an imaging system is the degree of accuracy with which objects under surveillance can be imaged or reproduced by that system. This property is usually termed resolution, and is affected by both fundamental physical limits as well as environmental effects and manufacturing imperfections. This contribution presents the theoretical principles to quantify the imaging resolution limits of canonical passive and active imaging systems. The intrinsic resolution limit of basic imaging systems is computed based on the Rayleigh criterion and bandlimitation considerations in Fourier domain. The concept of superresolution is introduced, and the role of evanescent waves in enabling superresolution is discussed. The nonlinear nature of multiple scattering imaging is explained, and the possibility of achieving superresolution thanks to multiple scattering is discussed.

In this chapter we discuss possible sources and cameras for small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) experiments. One should differentiate between laboratory sources (only available for SAXS) and large-scale installations like synchrotrons and storage rings for SAXS, and reactors or spallation sources for SANS. Details of the instruments, which are often called cameras, are important to understand the limitations in flux, resolution, and sample thickness. Instrumental broadening effects influence the data evaluation process. Pinhole cameras are absolutely necessary for oriented samples, while slit cameras offer a higher primary beam power. Low background is important, and is available for pinhole systems when using scatterless slits, while the block collimation system has a low background under slit conditions. Gobel mirrors help to focus the X-ray beam into the sample position. Detectors must have a high efficiency, a wide dynamic range, and a small channel or pixel size. Pinhole cameras need a two-dimensional detector, while one-dimensional detectors can be used in slit cameras without disadvantage.

Since 2011, a three-dimensional (3D) scanning irradiation system has been utilized for treatments at the National Institute of Radiological Sciences-Heavy Ion Medical Accelerator in Chiba (NIRS-HIMAC). In 2012, a hybrid depth scanning method was introduced for the depth direction, in which 11 discrete beam energies are used in conjunction with the range shifter. To suppress beam spread due to multiple scattering and nuclear reactions, we then developed a full energy scanning method. Accelerator tuning and beam commissioning tests prior to a treatment with this method are time-consuming, however. We therefore devised a new approach to obtain the pencil beam dataset, including consideration of the contribution of large-angle scattered (LAS) particles, which reduces the time spent on beam data preparation. The accuracy of 3D dose delivery using this new approach was verified by measuring the dose distributions for different target volumes. Results confirmed that the measured dose distributions agreed well with calculated doses. Following this evaluation, treatments using the full energy scanning method were commenced in September 2015.

This chapter is an extension of the previous chapter where the physics of the propagation of the wave is explained. Starting with the electrical polarization created within the material as a result of the incident electric field, this chapter derives the relation between different related parameters. It states the definition of a perfect dielectric. Further, it also considers a practical dielectric with finite conductivity and sets the conditions for which it behaves as a conductor or as a dielectric. The dispersive nature of the electric parameters of the material medium is also described to finally demonstrate their relation to the causes of the propagation impairments. At the end, the Rayleigh and Mie scattering and diffraction is discussed.

Nanocomposites in general have gained importance in current products, leading to improved performance of these complex compound materials. The structure of the solid particles is not limited in terms of shape in advance, but their specific function is tightly connected to their shape. Scattering experiments are often employed to supervise production routes and the final performance, but not all possibilities of scattering experiments are exploited due to several reasons: engineers need to enter the unknown stage of scattering experiments, and the scattering experts need to simplify their experience to simple, usable recipes that are applicable and reliable. This process is still ongoing, and the authors hope to contribute to this highly interesting journey.

Publisher Summary The chapter presents a demonstration that it is possible to prepare a real disperse system in which only one of the six mechanisms dominates the acoustic and electroacoustic properties of the colloid. This chapter is organized such that each discussion corresponds to a different mechanism of ultrasound interaction. In each of these discussions, the chapter presents experimental tests that verify the corresponding theory. The chapter presents the test of the viscous loss theory by selecting two examples of stable colloids by performing a dilution experiment and testing whether (1) the measured attenuation conforms to the theory, (2) the calculated size using this theory is correct, and, importantly, (3) the calculated size remains constant with dilution. The chapter presents the use of two different techniques to produce the equilibrium dispersion medium needed for dilution: centrifugation and dialysis. The chapter also discusses thermal losses, structural losses, scattering losses, electroacoustic phenomena, and so on.

This chapter deals with small-angle light scattering (SALS) and small-angle X-ray scattering (SAXS) techniques. The importance of X-ray scattering over the X-ray diffraction techniques is discussed. It is well known that the diffraction of light from an object is due to the wave nature of light, whereas scattering is considered a phenomenon of the dual (both particle and wave) nature of light. Scattering is a wave interaction but diffraction is a wave propagation phenomenon. Developments in nanoscience and nanotechnology necessitate various techniques to characterize various nanomaterials. This chapter reviews the progress in characterizing nanomaterials with SALS and SAXS along with the fundamental working principles.

Publisher Summary Any acoustic theory for particulates should yield a relationship between some measured macroscopic acoustic properties, such as sound speed, attenuation, acoustic impedance, angular dependence of the scattered sound, and so on; and some microscopic characteristics of the heterogeneous system, such as its composition, structure, electric surface properties, particle size distribution (PSD), and so on. The theory should be valid for concentrated suspensions and therefore must take into account particle-particle interactions. The theory should reflect the multiple mechanisms of ultrasound interaction with colloids—namely, viscous, thermal, scattering, intrinsic, structural, and electrokinetic. The heuristic description of these mechanisms is discussed in the chapter. The Epstein, Carhart, Allegra, and Hawley (ECAH) theory is constructed in two stages. The first stage is called the “single-particle theory,” because it attempts to account for all of the ultrasound disturbances surrounding just a single particle. This stage relates the microscopic properties of both the fluid and particle to the system properties at the single-particle level. The second stage, which is referred to as the “macroscopic theory,” then relates this single-particle level to the macroscopic level at which experimental raw data are obtained.

Transmission Raman spectroscopy is a mode of Raman spectroscopy that is especially beneficial to probe the bulk content of diffusely scattering samples. It decreases the issue of sub-sampling, which has been an obstacle for quantitative analysis of solid bulk samples for Raman systems with focused optics, and has mainly found applications not only in the pharmaceutical, agricultural, and polymer fields but also in the medical area. This chapter gives an overview of the principle, advantages, limitations, and applications of transmission Raman spectroscopy.

The understanding of the physical principles of light guidance and its interactions with surrounding matter is the main requirement for a detailed study of polymer-optical fibres (POFs). This chapter briefly summarises the physical fundamentals of light and the application of physical laws in optical fibres. Beginning with Maxwell equations and a definition of electromagnetic (EM) waves, interactions in solid matter in the form of polarisation and magnetisation will be discussed. The EM wave equations in vacuum and solid-state media are motivated as fundamental physical law of light's propagation. Scattering phenomena like Mie and Rayleigh scattering occurring in optical fibres are discussed afterward, and their influence onto the fibres' performances is deduced. As it is essential for data transport and signal transmission in optical fibres, boundary phenomena in the form of Snell's law and total reflexions are described by using mathematical and geometrical approaches. Finally, an overview of anisotropic effects like birefringence and the dispersion of light in real media is given in order to finalise the understanding of physical processes in POFs. A summary of the importance of physical effects in optical fibres is made which enables a qualitative understanding of the parameters which determine the efficiency of optical fibres and the currently existing bottlenecks and challenges towards high-performance polymer-optical fibres.

This chapter contains basic concepts and applications of wide-angle X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) to studies of nanostructured materials. The first part includes an introduction to the technique of X-ray powder diffraction (XPD), which is commonly applied to phase identification of powdered materials, characterization of unit cells, determinations of lattice parameters and, in some cases, also coordinates of atoms inside the unit cells. The main aspect described here is the analysis of the shape of X-ray diffraction peak profiles, which allows one to determine additional and also valuable structural information of nanomaterials, such as average crystallite sizes and crystallite microstrains. Detailed deductions of the equations used for different applications of X-ray diffraction and basic concepts of crystallography (such as those related to symmetries, Bravais and reciprocal lattices, etc.) are not described. The second part presents the basic equations related to the SAXS method and their applications to several biological systems (proteins in solution). Classical SAXS is an experimental procedure that is employed in transmission mode and is also applied to the study of many nanostructured inorganic materials. The third part includes two variants of the classical SAXS procedure, namely grazing incidence small-angle X-ray scattering (GISAXS) and anomalous small-angle X-ray scattering (ASAXS). The basic concepts of the GISAXS method and several applications to studies of nanostructured materials deposited on flat substrates and buried nanostructures are presented. The basic concepts of the ASAXS method are described, together with its applications to complex materials that cannot be properly studied using the classical SAXS technique, such as, for example, materials modeled by three phases with different electron densities. Most of the experiments described in this chapter were performed by the authors using X-ray beam lines of the National Synchrotron Light Laboratory (LNLS), Campinas, Brazil.