“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
Interference and diffraction of light are arguments for wave
charactiristics of light.
We know that there are two types of wave processes: transverse &
longitutional waves →to what are light waves belong ?
Study of polarization of light makes clear that
This conclusion is in according to the concept that light waves are
electromagnetic waves with a definte band of frequencies. Recall that
electromagnetic waves are transervse waves in which e-vectors &
m-vectors oscillate in such follwing directions...
Ads for one Macintosh computer bragged that it could do an arithmetic
calculation in less time than it took for the light to get from the
screen to your eye. We find this impressive because of the contrast
between the speed of light and the speeds at which we interact with
physical objects in our environment. Perhaps it shouldn’t surprise
us, then, that Newton succeeded so well in explaining the motion of
objects, but was far less successful with the study of light.
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
Lithography, the fundamental fabrication process of semiconductor devices, is playing
a critical role in micro- and nano-fabrications and the revolution in high density integrated
circuits. Traditional optical lithography (photolithography) including contact and project
photolithography has contributed significantly to the semiconductor device advancements.
POLARIZATION DEVICES A. Polarizers B. Wave Retarders C. Polarization Rotators
Augustin Jean Fresnel (1788-1827) advanced a theory of light in which waves exhibit transverse vibrations. The equations describing the partial reflection and refraction of light are named after him. Fresnel also made important contributions to the theory of light diffraction.
Conventional optical instruments make use of light that is transmitted between different locations in the form of beams that are collimated, relayed, focused, or scanned by mirrors, lenses, and prisms. Optical beams diffract and broaden, but they can be refocused by the use of lenses and mirrors. Although such beams are easily obstructed or scattered by various objects, this form of free-space transmission of light is the
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.
Dermoscopy, also called dermatoscopy, epiluminescence microscopy or skin surface
microscopy, was developed in the 1990s in order to augment the early diagnosis of
melanoma. First technologies allowed the observer to examine pigmented skin lesions
covered by a drop of oil and a glass slide through a stereo microscope. Then dermoscopy
developed into a hand-held lighted magnifier to analyze skin lesions by observing newly
defined and descriptively named subsurface structures: eg, dots, streaks, veils, and
We measured cocrystals of the membrane protein Photosystem I
with its soluble electron acceptor ferredoxin for the first time at the
ALS (Berkeley, CA). Previous data collected at our home source
and at other synchrotron sources showed crystals with very high
mosaicity (2–5%) and a diffraction limit to 7–8 Aresolution. This
first beamtime at ALS was very successful and may represent a
breakthrough for the determination of the crystal structure. 110
crystals, grown under modified crystallization conditions, were
scanned and for the first time, crystals diffraction to 3.5 A were
Holography is the synthesis of interference and diffraction. In recording a hologram, two waves interfere to form an interference pattern on the recording medium. When reconstructing the hologram, the reconstructing wave is diffracted by the hologram. When looking at the reconstruction of a 3-D object, it is like looking at the real object. It is therefore said that: ‘A photograph tells more than a thousand words and a hologram tells more than a thousand photographs’.
Titanium oxide ST01, ST31, TiO2 catalysts modified by V5+, N2+ and supported on MCM41 and SiO2 have been used for photooxidation of p-xylene in gas phase. Physicochemical properties of catalysts were determined by the methods of BET Adsorption, Xray Diffraction (XRD), UV-Vis spectroscopy, and atom adsorption spectroscopy (AAS) methods. The photocatalytic activity of catalysts were determined after thermal treatment as well as UV lighting. The common observation is that the higher temperature of treatment the lower conversion of p-xylene obtained.
Three-dimensional (3D) laser micro-fabrication has become a fast growing field of
science and technology. The very first investigations of the laser modifications
and structuring of materials immediately followed the invention of the laser in
1960. Starting from the observed photomodifications of laser rod materials and
ripple formation on the irradiated surfaces as unwanted consequences of a high
laser fluence, the potential of material structuring was tapped.