Optical diffractometry with directionally variable incident light wave

1991 ◽  
Author(s):  
Marek Daszkiewicz
Keyword(s):  
Light Wave ◽  
Incident Light ◽  
Incident Light Wave

scholarly journals Detection of nanoparticles suspended in a light scattering medium

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yan Ye ◽  
David Y. H. Pui
Keyword(s):  
Light Scattering ◽  
Visible Light ◽  
Light Wave ◽  
Incident Light ◽  
Scattering Medium ◽  
Light Interference ◽  
Potential Applications ◽  
Power Frequency ◽  
Suspended Nanoparticles ◽  
Incident Light Wave

AbstractIntentionally intensifying the light scattering of medium molecules can allow the detection of suspended nanoparticles under conditions not suitable for conventional optical microscopies or laser particle counters. Here, we demonstrate how the collective light scattering of medium molecules and nanoparticles is imaged in response to the power, frequency, and oscillating direction of the incident light wave electric field, and how this response can be used to distinguish between nanoparticles and microparticles, such as viruses or bacteria. Under conditions that the medium light scattering is intensified, suspended nanoparticles appear as magnified shiny moving dots superimposed on the quasi-steady background of medium light scattering. Utilizing the visual enlargement resulted from the enhanced light scattering and possible light interference, we can detect directly suspended nanoparticles that are much smaller than visible light wavelengths even in unopened water bottles or other large containers. This suggests new approaches for detecting nanoparticles with many potential applications.

Fourier Analysis of Digital STEM Images in the Study of Transparency in Human Cornea And Sclera

1988 ◽  
Vol 46 ◽  
pp. 178-179
Author(s):  
S . Vaezy
Keyword(s):  
Fourier Transform ◽  
Fourier Analysis ◽  
Visible Light ◽  
Light Wave ◽  
Incident Light ◽  
Human Cornea ◽  
Quantitative Measurements ◽  
Spatial Fluctuations ◽  
The Fourier Transform ◽  
Incident Light Wave

The structure of transparent human cornea is similar to that of the opaque human sclera, and they both consist of collagen fibers embedded in a mucopolysaccharide matrix.[1] This similarity in structure and composition, in contrast to a large difference in turbidity, presents an important question regarding the basis of transparency in the cornea.In general, a transparent structure permits most of the incident light to be transmitted, whereas an opaque structure scatters it. Scattering of an incident light wave occurs when the spatial fluctuations in the index of the refraction of the medium have dimensions close to the wavelength of visible light.[2] To analyze spatial fluctuations in cornea and sclera we have developed techniques based on Fourier analysis of digital STEM images.Fourier analysis allows direct quantitative measurements of the fluctuations in any signal. The signal is resolved into its constituent sinusoids or Fourier components. Amplitude, and frequency of each component are quantitatively obtained using the Fourier Transform (FT).

scholarly journals 2D Octagon-Structure Carbon and Its Polarization Resolved Raman Spectra

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2252
Author(s):  
Chunshan He ◽  
Weiliang Wang
Keyword(s):  
Raman Spectra ◽  
Density Functional ◽  
Light Wave ◽  
Incident Light ◽  
Vibrational Properties ◽  
Polarization Angle ◽  
Two Dimensional ◽  
Functional Theory ◽  
New Phase ◽  
Incident Light Wave

We predict a new phase of two-dimensional carbon with density functional theory (DFT). It was found to be semimetal with two Dirac points. The vibrational properties and the polarization resolved Raman spectra of the carbon monolayer are predicted. There are five Raman active modes: 574 cm−1 (Eg), 1112 cm−1 (B1g), 1186 cm−1 (B2g), 1605 cm−1 (B2g) and 1734 cm−1 (A1g). We consider the incident light wave vector to be perpendicular and parallel to the plane of the carbon monolayer. By calculating Raman tensor of each Raman active mode, we obtained polarization angle dependent Raman intensities. Our results will help materials scientists to identify the existence and orientation of octagon-structure carbon monolayer when they are growing it.

On the Derivation of the Integral Equation for the Propagation of Light in Dielectric Crystals

1971 ◽  
Vol 49 (10) ◽  
pp. 1384-1395 ◽  
Author(s):  
J. Vlieger
Keyword(s):  
Integral Equation ◽  
Light Wave ◽  
Dipole Moments ◽  
Incident Light ◽  
Phenomenological Theory ◽  
Dipole Interaction ◽  
Dielectric Tensor ◽  
Simple Lattice ◽  
Propagation Of Light ◽  
Set Up

A new derivation is given of the integral equation for the macroscopic polarization set up in a dielectric crystal by an incident light wave. The molecules are assumed to lie on the points of a perfect, simple lattice and to interact only via the retarded dipole–dipole interaction. The derivation is based on a direct averaging of the microscopic equations for the dipole moments induced by the incident wave and the dipole fields. The averaging is a space averaging with a weight function with a width Δ satisfying [Formula: see text], where a is the lattice constant and λ the wavelength of the incident field. The derivation is an application of Nijboer and De Wette's method for the evaluation of lattice sums.In contrast to the more indirect derivation given earlier by Hoek, (i) the present derivation is not based on an expansion in powers of the molecular polarizability, α, so that, e.g., there is no limitation to frequencies outside the resonance regions, and (ii) the integral equation is shown to be valid everywhere in the crystal except in a macroscopically negligible boundary layer of thickness Δ rather than λ. The latter improvement is crucial in the presence of superradiance.The integral equation is shown to be equivalent to the usual wave equation derived from Maxwell's phenomenological theory supplemented by the appropriate constitutive equations. An explicit expression is derived for the frequency dependent dielectric tensor in terms of rapidly convergent lattice sums.

The Optical Response of Trapezoidal Comb-Like Nanostructures

2013 ◽  
Vol 284-287 ◽  
pp. 2816-2820
Author(s):  
Yun Dong Zhang ◽  
Jin Li ◽  
Han Yang Li ◽  
Ping Yuan
Keyword(s):  
Power Spectrum ◽  
Light Transmission ◽  
Light Wave ◽  
Incident Light ◽  
Resonance Effect ◽  
Optical Filter ◽  
Polarized Light ◽  
Metal Nanostructures ◽  
Wave Oscillation ◽  
Oscillation Modes

Metal nanostructures can be used to control light transmission on the nanometer scale. In this paper, we propose a ladder-type comb-like metal nano-grating structure, based on optical filtering properties of the comb-like nanostructures and surface plasmon resonance effect of the metal nano-structures. The comb part of the structure is the silver nano-grating with the width of 20nm and a depth difference of 5nm between the adjacent gratings. We use the 532nm CW laser as the incident light source to study the reflective properties of the P polarized light and calculate the reflected power spectrum of the structure in three different parameters, which are the silver nano-grating, the silver-air nano-grating (silver grating are separated by air) and silver-SiO2 nano-grating. The experimental results show that the light wave oscillation modes are closely related to the comb-like structure parameters (including the depth and width) on the power spectrum. Meanwhile, we also draw conclusions that different intervention media does not change the position of the light wave oscillation modes, but only a significant effect on the reflection intensity of the different modes. Furthermore, we also noted that the depth of silver nano-gratings can affect the position of the resonance peak. As the waveguide depth of the silver nano-gratings increasing, the spacing of different modes’ oscillation peak is becoming larger. Based on the finding, we can modulate the light wave oscillation modes in a very wide spectral range. The results of this paper will promote the development of the optical filter, light wave mode selection and random laser excitation.

scholarly journals On the complex anisotropic molecule in relation to the dispersion and scattering of light

1923 ◽  
Vol 104 (726) ◽  
pp. 333-357 ◽  
Keyword(s):  
Large Scale ◽  
Light Wave ◽  
Incident Light ◽  
Point Of View ◽  
Experimental Point ◽  
Molecular Scattering ◽  
The Earth ◽  
Good Account ◽  
Symmetrical Molecule ◽  
Temperature And Pressure

It has now been known for several years that the molecules of a gas consisting of positive and negative charges set into forced vibrations by the electric field of an incident light-wave are responsible, not only for the refractive properties of the medium, but also for lateral scattering and extinction as exemplified on a large scale by the blue of the sky and the colour of the setting sun. In fact, until comparatively recently, observations on the extinction of solar radiation of various wave-lengths by the earth’s atmosphere have provided the only dataf by means of which the theory of molecular scattering and extinction could be tested, this by satisfactory evaluations of the number of molecules per cubic centimetre of air under standard conditions of temperature and pressure, making use for the purpose of Rayleigh’s well-known extinction formula based on the idea of the symmetrical molecule , i.e. , one in which the dispersion electrons move in the direction of the electric vector in the lightwavewave. As far as observations were then available, theory gave a tolerably good account of measurements of sky-intensity, both as regards quality and polarization. The difficulty in this case is to take into account the illumination of the atmosphere by itself, a problem capable of reasonably simple solution in terms of integral equations only if the curvature of the earth is disregarded. From the experimental point of view, satisfactory observations are made difficult by the omnipresent and ever-varying dust content of the atmosphere at ordinary levels, to say nothing of the “ haziness ” and extinction due to the presence of water-vapour.

scholarly journals Optical dispersion : an analysis of its actual dependence upon physical conditions

1911 ◽  
Vol 84 (573) ◽  
pp. 492-523 ◽  
Keyword(s):  
Natural Frequencies ◽  
Light Wave ◽  
Incident Light ◽  
Additional Term ◽  
Free Vibrations ◽  
Individual Molecule ◽  
Physical Conditions ◽  
Light Passing ◽  
Two Factors ◽  
The Right

The influence of a transparent medium upon light passing through it may be ascribed to two factors ; one is the existence, in each individual molecule or particle, of vibrating parts with certain natural frequencies, and the other is the physical condition of the aggregation of molecules composing the medium. Suppose that a typical vibrating part is an electrified particle of charge e and mass m ,whose free vibrations are given by equations of the type m d 2 x / dt 2 + fx = 0. Let X be the corresponding component of electric force in the incident light wave. The impressed force, to be supplied on the right-hand side of (1) for the actual motion, is not simply e X, but has an additional term to express the effect of the surrounding molecules ; the simplest concep­tion of this effect indicates a term directly proportional to the average polarisation P of the surrounding molecules at each instant. Hence, instead of (1), we have an equation m d 2 x / dt 2 + fx = e (X + σP x ).

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