“Diffraction” of light can be understood as any deviation of light rays
from their geometrical propagation line (that is straight in a homogeneuos material)
An example (shown in the picture):The edge of shadow is never
perfectly sharp. Some light
appears in the geometrical
shadow, and there are dark
and light fringers in the area of
In 2009 the world celebrated 50 years of lasers, bringing to the attention of the
public how deeply lasers and laser related technologies have revolutionized both
science and everyday life. Next year will be the fiftieth anniversary of the semiconductor
laser. Used as a compact light source with high modulation rates, it
transformed telecommunications in combination with glass fibers. Today laser
diodes are omnipresent in data storage and communication. Still, most of these
applications are based on infrared or red laser diodes.
The book collects original and innovative research studies of the experienced and actively working scientists in the field of wave propagation which produced new methods in this area of research and obtained new and important results. Every chapter of this book is the result of the authors achieved in the particular field of research. The themes of the studies vary from investigation on modern applications such as metamaterials, photonic crystals and nanofocusing of light to the traditional engineering applications of electrodynamics such as antennas, waveguides and radar investigations....
Change of public opinion about Mohammed Astonishing triumph of Mohammedanism Old religious systems
of Arabia Polytheism succeeds the doctrines of the Magians The necessity of reform Early life of Mohammed
Cadijeh Mohammed's meditations and dreams His belief in a personal God He preaches his new doctrines The
opposition and ridicule of his countrymen The perseverance of Mohammed amid obstacles His flight to
Medina The Koran and its doctrines Change in Mohammed's mode of propagating his doctrines Polygamy
and a sensual paradise Warlike means to convert Arabia Mohammed accommodates his do...
Brillouin scattering was discovered in 1922 by Louis Brillouin . It is one of
a number of characteristic scattering phenomena that occur when light interacts
with solid, liquid or gaseous media and corresponds to the scattering of
light from thermally-induced acoustical waves (propagating pressure/density
waves) present in media at all temperatures. At normal light levels the
amount of scattering is small. The characteristics of the scattering can offer
interesting information about the properties of the medium (temperature,
pressure) and form the basis for remote fibre sensor devices.
There are strong interdependencies between
banks and governments, through both balance
sheet and contingent claim exposures. These
interdependencies mutually reinforce the
macroeconomic propagation of banking or
sovereign market tensions. Second, given the
fragmentation of some market segments and the
setback to European banking sector integration,
persistent cross-country heterogeneity needs to
be considered. Third, a proper assessment of
ﬁ nancing conditions hinges on the distinction
between demand and supply-side factors in
I first want to thank my collaborator, Collins Hemingway, for his help
in synthesizing and developing the material in this book and for his
overall management of this project. The tunnel propagation hypothesis, as part of the set of mechanisms operating during
defibrillation, is expected to shed light on possible strategies for lowering DFT as well as for
developing new defibrillation devices.
BRIEF HISTORY OF RF AND MICROWAVE WIRELESS SYSTEMS
The wireless era was started by two European scientists, James Clerk Maxwell and Heinrich Rudolf Hertz. In 1864, Maxwell presented Maxwell's equations by unifying the works of Lorentz, Faraday, Ampere, and Gauss. He predicted the propagation of electromagnetic waves in free space at the speed of light. He postulated that light was an electromagnetic phenomenon of a particular wavelength and predicted that radiation would occur at other wavelengths as well.
The wireless era was started by two European scientists, James Clerk Maxwell and Heinrich Rudolf Hertz. In 1864, Maxwell presented Maxwell's equations by unifying the works of Lorentz, Faraday, Ampere, and Gauss. He predicted the propagation of electromagnetic waves in free space at the speed of light. He postulated that light was an electromagnetic phenomenon of a particular wavelength and predicted that radiation would occur at other wavelengths as well. His theory was not well accepted until 20 years later, after Hertz validated the electromagnetic wave (wireless) propagation.
Before entering into the different techniques of optical metrology some basic terms and deﬁnitions have to be established. Optical metrology is about light and therefore we must develop a mathematical description of waves and wave propagation, introducing important terms like wavelength, phase, phase fronts, rays, etc. The treatment is kept as simple as possible, without going into complicated electromagnetic theory.
Generally the term photonic crystal refers to two dimensional (2-D) and three
dimensional (3-D) structures. Using 2-D and 3-D photonic crystals it is possible to
control the propagation of light at arbitrary angles of incidence and not only the light
normally incident as is the case for conventional optical films. Further, using photonic
crystals, it is possible to achieve optical functionality not possible using conventional
optical materials. This book provides a complete overview about photonic crystals
including properties, applications, approaches and methods for the study....
THE AMPLITUDE MODULATED RADIO RECEIVER
The electromagnetic disturbance created by the transmitter is propagated by the transmitter antenna and travels at the speed of light as described in Chapter 2. It is evident that, if the electromagnetic wave encounters a conductor, a current will be induced in the conductor. How much current is induced will depend on the strength of the electromagnetic ﬁeld, the size and shape of the conductor and its orientation to the direction of propagation of the wave....
• Imagine an atom with excess energy. Without external action,
the atom would, after a period of time, spontaneously emit light,
whose properties (e.g. its direction) are random — only the
energy is fixed.
• This situation changes when the
atom is shone with a light wave of
the corresponding energy. There
is then a higher probability that
the atom will also simply copy the
remaining properties of the incident
wave: It then emits light that is
in step with the original and
propagates in the same direction....
PROPAGATION OF LIGHT IN FREE SPACE A. Correspondence Between the Spatial Harmonic and the Plane Wave B. Transfer Function of Free Space C. Impulse-Response Function of Free Space OPTICAL FOURIER TRANSFORM A. Fourier Transform in the Far Field B. Fourier Transform Using a Lens DIFFRACTION OF LIGHT A. Fraunhofer Diffraction *B. Fresnel Diffraction IMAGE FORMATION A. Ray-Optics Description of Image Formation B. Spatial Filtering C. Single-Lens Imaging System HOLOGRAPHY
When light passes an edge, it will deviate from rectilinear propagation. This phenomenon (which is a natural consequence of the wave nature of light) is known as diffraction and plays an important role in optics. The term diffraction has been conveniently deﬁned by Sommerfeld as ‘any deviation from rectilinear paths which cannot be interpreted as reﬂection or refraction’. A rigorous theory of diffraction is quite complicated. Here we develop expressions for the diffracted ﬁeld based on Huygens’ principle of secondary spherical wavelets.
Photoelasticity and Polarized Light
Up to now we have treated the light ﬁeld as a scalar quantity. The electromagnetic ﬁeld, however, is a vector quantity which is perpendicular to the direction of propagation and with a deﬁned orientation in space. This property is known as the polarization of light. In our treatments of interferometry and holography it is silently understood that the interfering waves have the same polarization. In practice, however, this condition is fulﬁlled to a greater or lesser degree....
Sounding, Sampling and Simulation
In the earlier chapters we discussed the characteristics of mobile radio channels in some detail. It emerged that there are certain parameters which provide an adequate description of the channel and it remains now to describe measuring equipment (channel sounders) that can be used to obtain experimental data from which these parameters can be derived.
The basic physics of sound propagation are simple, but the interaction of
sound pressure waves with complex shapes and multi-layer constructions with
openings, as you find in buildings, is more challenging. Controlling noise, both
from the internal and external environment and from the internal mechanical
and electrical services in buildings, is essential to create environments that
promote aural communication and comfortable working conditions.
Optical fibers, an important and promising material, have been the subject of intensive
research and development due to their many scientific and practical applications. They
are designed to guide light along its length by confining as much light as possible in
its core. The interaction between the propagating light with the fiber material is the
foundation of the development of various applications such as optical amplifiers, fiber
lasers, sensors etc.
Different terms are employed in the literature to specify this method on investigations: dualbeam
coherent interferometry or laser Doppler interferometry, optical coherence
tomography (OCT) or optical coherence reflectometry. OCT is analogous to ultrasonic
imaging, which measures the intensity of reflected infrared light rather than reflected sound
waves from the sample. Time gating is employed so that the time for the light to be reflected
back (or echo delay time) is used to assess the intensity of back-reflection as a function of