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Topic: Fraunhofer diffraction

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	Diffraction - Wikipedia, the free encyclopedia
		Diffraction also occurs when any group of waves of a finite size is propagating; for example, a narrow beam of light waves from a laser must, because of diffraction of the beam, eventually diverge into a wider beam at a sufficient distance from the laser.
		Diffraction is one particular type of wave interference, caused by the partial obstruction or lateral restriction of a wave.
		The most common demonstration of Bragg diffraction is the spectrum of colors seen reflected from a compact disc: the closely-spaced tracks on the surface of the disc form a diffraction grating, and the individual wavelengths of white light are diffracted at different angles from it, in accordance with Bragg's law.
	en.wikipedia.org /wiki/Diffraction (1581 words)

	Diffraction -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-19)
		Diffraction is one particular type of wave (The act of hindering or obstructing or impeding) interference, caused by the partial obstruction or lateral restriction of a wave.
		Diffraction is not the same as (The change in direction of a propagating wave (light or sound) when passing from one medium to another) refraction, although both are phenomena in which a wave does not propagate in a single direction.
		It is the diffraction of "particles," such as electrons, which stood as one of the powerful arguments in favor of (The branch of quantum physics that accounts for matter at the atomic level; an extension of statistical mechanics based on quantum theory (especially the Pauli exclusion principle)) quantum mechanics.
	www.absoluteastronomy.com /encyclopedia/d/di/diffraction.htm (1620 words)

	Diffraction - Open Encyclopedia (Site not responding. Last check: 2007-10-19)
		Diffraction occurs with electromagnetic waves, such as light and radio waves, and also in sound waves and water waves.
		The diffraction angles are invariant under scaling; that is, they depend only on the ratio of the wavelength to a dimension, d, of the diffracting object.
		In addition to diffraction of classical waves, it is also possible, due to wave-particle duality, to observe diffraction of particles such as neutrons or electrons.
	open-encyclopedia.com /Diffraction (1099 words)

	Fraunhofer diffraction - Wikipedia, the free encyclopedia
		Fraunhofer diffraction is diffraction of light through an aperture for small values of the Fresnel number, F<<1.
		In far-field diffraction, if the observation screen is moved relative to the aperture, the diffraction pattern produced changes uniformly in size.
		This is not the case in near-field diffraction, where the diffraction pattern changes both in size and shape.
	en.wikipedia.org /wiki/Fraunhofer_diffraction (142 words)

	Joseph Von Fraunhofer
		Fraunhofer attempted to bridge the gap between artisans and experimental natural philosophers, but his attempts were thwarted by his own secrecy.
		Fraunhofer, now an orphan, left his hometown in 1799 to move in with Philipp Anton Weichselberger, court mirror maker and decorative glass cutter, to be his apprentice [4].
		Fraunhofer investigated the properties of diffraction in the “far field” using a diffraction grating (instead of a prism, which adds complications due to varying index of refraction with wavelength).
	www.u.arizona.edu /~kennelly/finaldraft.htm (1224 words)

	Encyclopedia: Diffraction
		Electron diffraction is a technique used to examine solids by firing a beam of electrons at a sample and observing their deflection.
		Fresnel diffraction is the diffraction pattern obtained a small number of wavelengths away from the diffracting object.
		This effect limits the minimum size d of spot of light formed at the focus of a lens, known as the diffraction limit: A lens is a device for either concentrating or diverging light, usually formed from a piece of shaped glass.
	www.nationmaster.com /encyclopedia/Diffraction (2616 words)

	Near and far field - Wikipedia, the free encyclopedia
		In the study of diffraction and antenna design, the near field is that part of the radiated field that is within one quarter of a wavelength of the diffracting edge or the antenna.
		In the study of diffraction and antenna design, the near field is that part of the radiated field that is within a small number of wavelengths of the diffracting edge or antenna.
		The diffraction pattern in the near field typically differs significantly from that observed at infinity and varies with distance from the source.
	www.wikipedia.org /wiki/Far-field_region (296 words)

	Fraunhofer Diffraction (Site not responding. Last check: 2007-10-19)
		The diffraction pattern at the right is taken with a helium-neon laser and a narrow single slit.
		These single slit diffraction patterns were photographed with a helium-neon laser as the light source and a micrometer-controlled single slit.
		The sketches of the slit widths at right were scaled to the difference between the first minima of the diffraction patterns.
	hyperphysics.phy-astr.gsu.edu /hbase/phyopt/fraungeo.html (98 words)

	Fraunhofer Diffraction
		Diffraction arises from the superposition of waves originating from different points on a wave front restricted by an aperture.
		At a slit spacing of w the diffraction pattern is that of a slit of width nw.
		Fraunhofer patterns have a symmetry that is independent of the symmetry of the array of points from which Huygens' wavelets originate.
	www.kw.igs.net /~jackord/df/d1.html (739 words)

	Web of OPTICS
		Diffraction may be envisioned as arising from the interaction of em waves with some sort of physical obstructions.
		A practical realization of Fraunhofer condition is achieved by locating a point source at the first principal focus of a lens and observing the diffraction at the second focal plane of another lens.
		Fraunhofer or far-field diffraction is a special case of Fresnel or near-field diffraction.
	ap.polyu.edu.hk /apakslau/Optics%20Web/chapter09/html/part01.html (130 words)

	Anomalous behaviors of the Fraunhofer diffraction patterns for a class of partially coherent light
		In this paper, we investigate the Fraunhofer diffraction of a class of partially coherent light diffracted by a circular aperture.
		It is shown that by the illumination of partially coherent light of the special spatial correlation function, the anomalous behaviors of the diffraction patterns are found.
		However, as the coherence decreases, the diffraction pattern becomes an annulus, and the radius of the annulus increases with the decrease of the coherence.
	www.opticsexpress.org /abstract.cfm?URI=OPEX-11-4-339 (389 words)

	THE RIFE MICROSCOPE BY GARY WADE
		From theory and experimentation it has been found that Fraunhofer diffraction phenomenon is usually by far the dominant limiting factor in determining the resolution ability of a lens system to form an image.
		However, due to Fraunhofer diffraction phenomenon as the diameters of o and o' go to zero, the diameters of the images I and I' converge to a finite non zero size.
		For simplicity the Fraunhofer diffraction pattern shown is that of a single lens, however the actual pattern would be a composite of the separate Fraunhofer diffraction patterns from the three lenses in the system.
	www.rifeenergymedicine.com /AppAH.html (3097 words)

	Journal of Research of the National Institute of Standards and Technology: Fraunhofer diffraction effects on total ...
		An algorithm for computing diffraction effects on total power in the case of Fraunhofer diffraction by a circular lens or aperture is derived.
		The result for Fraunhofer diffraction of monochromatic radiation is well known, and this work reports the result for radiation from a Planckian source.
		Fraunhofer diffraction by a circular lens or aperture is a ubiquitous phenomenon in optics in general and radiometry in particular.
	www.findarticles.com /p/articles/mi_m0IKZ/is_5_106/ai_83448413 (1044 words)

	[No title]
		Diffraction is the tendency of a wave emitted from a finite source or passing through a finite aperture to spread out as it propagates.
		Diffraction results from the interference of an infinite number of waves emitted by a continuous distribution of source points.
		Diffraction of light through a rectangular aperture is a rather straightforward extension of 1-dimensional diffraction from a slit, as shown in the diagram below.
	electron9.phys.utk.edu /optics421/modules/m5/Diffraction.htm (1561 words)

	Programmable detector configuration for Fraunhofer diffraction particle sizing instruments - Patent 5007737
		Fraunhofer diffraction may be defined as the field transmitted through an aperture in an absorbing screen.
		Fraunhofer diffraction is observed in practice by rendering the light from a source parallel with a lens, and focusing it on a screen with another lens placed behind the aperture, an arrangement which effectively removes the source and screen to infinity.
		The diffracted light is directed by a focusing element which consists of the collecting lens 20 through the mask 22 which lies in the Fraunhofer plane of lens 20.
	www.freepatentsonline.com /5007737.html (6930 words)

	Melles Griot Optics Guide - Diffraction (Site not responding. Last check: 2007-10-19)
		Fresnel diffraction is primarily concerned with what happens to light in the immediate neighborhood of a diffracting object or aperture.
		A lens or lens system of finite positive focal length with plane-wave input maps the far-field diffraction pattern of its aperture onto the focal plane; therefore, it is Fraunhofer diffraction that determines the limiting performance of optical systems.
		Fraunhofer diffraction at a circular aperture dictates the fundamental limits of performance for circular lenses.
	www.mellesgriot.com /products/optics/fo_3_1.htm (947 words)

	Fresnel and Fraunhofer Diffraction (Site not responding. Last check: 2007-10-19)
		Diffraction is a phenomena arising from the wave nature of light.
		Fraunhofer diffraction: Light can occur as plane waves, which we can imagine as the waves that come rolling in over the ocean.
		Fresnel diffraction: Light can also occur as spherical waves, which is analogous to the circular waves expanding from where we just dropped a pebble in water.
	dauger.com /fresnel/FresnelFraunhoferDesc.html (667 words)

	optics
		Fraunhofer diffraction occurs when the light rays reaching a point are parallel.
		As previously stated, the Fraunhofer diffraction pattern of a uniformly illuminated mask is the Fourier transform of the mask.
		You can understand why Fraunhofer diffraction and the imaging of the pattern with a lens is an exciting area of study if you consider that this process performs a two-dimensional Fourier transform in the time that it takes for the light to travel from the image to the lens and then to the focal plane.
	physics.mtsu.edu /~sps/research/optics/optics.html (1277 words)

	Fraunhofer diffraction (from light) -- Encyclopædia Britannica (Site not responding. Last check: 2007-10-19)
		When the source and pattern screen are sufficiently far from the slit, the phase differences corresponding to different parts dS of the slit opening vary linearly with x and y coordinates in the plane of the aperture (Figure 15).
		Diffraction takes place with sound; with electromagnetic radiation, such as light, X-rays, and gamma rays; and with very small moving particles such as atoms, neutrons, and electrons, which show wavelike properties.
		One consequence of diffraction is that sharp shadows are not produced.
	www.britannica.com /eb/article-69293?tocId=69293 (885 words)

	Laboratory Seven (Site not responding. Last check: 2007-10-19)
		The objective of this laboratory is to investigate diffraction in the Fresnel and Fraunhofer regimes both experimentally and computationally.
		Although diffraction is normally presented pedagogically in the context of a freely propagating beam encountering an aperture in a planar screen, the conceptual basis for diffraction theory underlies Fourier optics and more generally any rigorous analysis of light wave propagation through a lens or genral optical system.
		Suppose that the wedge forms a circular aperture with a 5mm diameter and the optical axis in the image space is perpendicular to the output facet of the wedge and passes through the aperture center.
	www.ece.utexas.edu /~milner/courses/Optics_Lab/Lab_7_Description.htm (437 words)

	Encyclopedia: Fraunhofer diffraction
		Diffraction is the apparent bending and spreading of waves when they meet an obstruction.
		Fraunhofer, or far-field, diffraction occurs when this is not the case and the curvature of the incident wavefronts is taken into account.
		In the physics of wave propagation (especially electromagnetic waves), a plane wave (also spelled planewave) is a constant-frequency wave whose wavefronts (surfaces of constant amplitude and phase) are infinite parallel planes normal to the propagation direction.
	www.nationmaster.com /encyclopedia/Fraunhofer-diffraction (325 words)

	Diffraction - Fraunhofer ILT
		This phenomenon is known as diffraction and is due to the wave-like properties of light.
		Diffraction is more prominent for smaller Fresnel numbers.
		The Fresnel number for optical resonators usually ranges between 1 and 10, for high power solid state lasers up to 100, the structure of laser radiation fields is therefore strongly affected by diffraction.
	www.ilt.fhg.de /eng/beugung.html (206 words)

	Phasor analysis of Fraunhofer scattering (Site not responding. Last check: 2007-10-19)
		Fraunhofer scattering from a single slit can be analyzed by looking at wavefronts originating from different segments of the aperture.
		The objective of the applet is to allow to observe the Fraunhofer diffraction pattern for different slit width / wavelength ratios without a mathematical derivation.
		This is the result of the fact that a light source will produce not a sharp spot in the image plane, but a Fraunhofer diffraction pattern.
	www.physics.yorku.ca /undergrad_programme/highsch/Fraunh.html (382 words)

	EOP541L - Laboratory 3
		Examine the diffraction pattern in the neighborhood of the test lens focus by moving the microscope lens along the optical axis.
		To observe the diffraction pattern from a lens, first expand the laser beam using a telescope consisting of a spatial filter assembly and collimating lens.
		Observe the Fraunhofer diffraction pattern in the focal plane of the lens.
	www.engr.udayton.edu /ElOptics/courses/eop541l/lab3.html (708 words)

	Diffraction
		This is known as diffraction, and it was first shown in the 1600s to be a general characteristic of wave phenomenon which occurs whenever a portion of a wavefront is obstructed in some way.
		Fraunhofer diffraction through a circular aperture can be found in a manner similar to that used for the rectangular aperture.
		In Fraunhofer diffraction, the diffracting system was relatively small and the point of observation was very distant.
	physics.tamuk.edu /~suson/html/4323/diffract.html (2004 words)

	The Thomas Group - PTCL, Oxford
		This behaviour is common to all diffraction; the position of the stripes or spots depends on the arrangement of the slits or objects, but the intensity contour is determined by the structure of each individual slit or object.
		Note that the diffraction spots are always broader along the direction of fewer apertures (all part of the inverse relation between scattering pattern and separation).
		This behaviour is common to all diffraction; the position of the stripes or spots depends on the arrangement of the objects, but the intensity contour is determined by the structure of each individual object.
	physchem.ox.ac.uk /~rkt/techniques/smallanglescattering.html (1256 words)

	FRAUNHOFER DIFFRACTION
		The first multiplier of the equation in the square brackets describes the Fraunhofer diffraction on one slit and the second multiplier describes the interference from two point sources.
		This figure shows the dependence of the light intensity on the angle in the case of diffraction on one slit (red curve) and for two slits diffraction (blue curve).
		The frequency of the interferometric fringes is increasing proportionally to the distance d between the slits, while the width of the diffraction pattern is the same and depends only on b.
	www.infoline.ru /g23/5495/Physics/English/stri_txt.htm (461 words)

	Dauger Research, Inc., Fresnel Diffraction Explorer Page
		Diffraction is an important physical effect inherent in all wave phenomena.
		Fresnel diffraction is the same, except that the waves are spherical, effectively originating from a point source.
		It is a simple exercise to show that Fraunhofer diffraction by an aperture is mathematically equivalent to the Fourier transform of the aperture shape.
	daugerresearch.com /fresnel/index.shtml (1293 words)

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