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Topic: Coherent light

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	light. The Columbia Encyclopedia, Sixth Edition. 2001-05
		The term “light” is often extended to adjacent wavelength ranges that the eye cannot detect—to infrared radiation, which has a frequency less than that of visible light, and to ultraviolet radiation and fl light, which have a frequency greater than that of visible light.
		Light that is all of the same wavelength and phase (all the waves are in step with one another) is called “coherent”; one of the most important modern applications of light has been the development of a source of coherent light—the laser.
		The scientific study of the behavior of light is called optics and covers reflection of light by a mirror or other object, refraction by a lens or prism, diffraction of light as it passes by the edge of an opaque object, and interference patterns resulting from diffraction.
	www.bartleby.com /65/li/light.html (1379 words)

	Definition: Coherent Light (Site not responding. Last check: 2007-10-08)
		Coherent light are light waves that are "in phase" with one another.
		For example, two waves are coherent if the crests of one wave are aligned with the crests of the other and the troughs of one wave are aligned with the troughs of the other.
		Light from light bulbs or the sun, however, are incoherent light.
	library.thinkquest.org /27356/d_coherentlight.htm (57 words)

	Olympus FluoView Resource Center: Non-Coherent Light Sources for Confocal Microscopy
		As illustrated in Figure 3, light emerges from the sides of the light emitting diode semiconductor chip and is reflected forward by a cup that is joined into the end of one electrode (the cathode) while the top face of the chip is connected with a gold bonding wire to a second electrode (anode).
		Light emitting diode output may be modulated at high frequencies (10 megahertz, MHz) and their output brightness may be regulated by limiting the available current, features that eliminate the need for mechanical shutters and neutral density filters in microscopy applications.
		The phase of the light is scrambled due to the varying path lengths of light waves passing through the fiber, although the high radiance and monochromaticity are preserved.
	www.olympusfluoview.com /theory/noncoherentsources.html (4165 words)

	Quantum properties of light
		The stimulated emission of light is the crucial quantum process necessary for the operation of a laser.
		Coherence is one of the unique properties of laser light.
		This coherence is described in terms of temporal coherence and spatial coherence, both of which are important in producing the interference which is used to produce holograms.
	hyperphysics.phy-astr.gsu.edu /hbase/optmod/qualig.html (838 words)

	Detection of biofield – ambient light interactions
		Vitiello proposes that endogenous coherent bioelectomagnetic field causes molecules to behave as 'sensitive' particles that exhibit a sort of intelligence and the connectedness with the whole organism [ 9 ].
		Regarding the emission of coherent oscillations, which could serve as a basis for their detection, Fröhlich maintains that because of the usual resonant transfer of energy characterizing coherent oscillations and being almost without loss, the emission should normally be very small, achieving higher values only at defects on inner surfaces.
		We denote this influences as changes of coherence because influences cause large, continuous regions and disconnected areas of higher density of oscillations to appear, which cannot be caused by chance or noise as it appears.
	www.bion.si /DVB03/detection_biofield_ambient_light_ijs03.htm (2810 words)

	New Developments in Color Therapy: Acupuncture Meridians Facilitate the Body's Absorption of Light
		Colored light has a particular ability to balance the autonomic nervous system, which is crucial in most chronic and functional disorders as it regulates all of the automatic processes of the human body: breathing, the beating of the heart, the functioning of the digestive tract, the stress response.
		Light from the hypothalamus is then sent to the pineal gland, the body's light meter and only gland in the body not controlled by higher neurological centers.
		So the light emitted from a full spectrum fluorescent bulb would be different in nature from the full spectrum light emitted by one of the noble plasma gases, as it is in the case of the Photon Stimulator, and certainly different from that emitted by an incandescent bulb.
	www.explorepub.com /articles/light_therapy.html (4777 words)

	Natural Light From Organisms: What, If Anything, Can It Tell Us?
		The more coherent the interaction is between the emitter and the receiver, the less energy is needed for resonance, and hence for communication to occur.
		For example, the intensity of the biological light emitted may be greatly enhanced for a small increase in concentration of a toxic agent, contrary to standard chemiluminescence theory that predicts a linear relationship between them.
		Furthermore, this relationship between light intensity and cell density dependence, always the opposite for normal and malignant cell populations, shows that the results cannot be explained in terms of properties of single cells, but in terms of whole tissues, again suggesting a novel communication mechanism within the organism.
	www.bibliotecapleyades.net /ciencia/ciencia_light01.htm (3743 words)

	Olympus Microscopy Resource Center: Physics of Light and Color - Thomas Young's Double Slit Experiment: Interactive ...
		Light waves exiting the first slit are then made incident on a pair of slits positioned close together on a second barrier.
		A screen is placed in the region behind the slits to capture overlapped light rays that have passed through the twin slits, and a pattern of bright red and dark interference bands becomes visible on the screen.
		Although Young achieved this coherence through the diffraction of sunlight from the first slit, any source of coherent light (such as a laser) can be substituted for light passing through the single slit.
	www.olympusmicro.com /primer/java/doubleslitwavefronts (1079 words)

	Coherent, Monochromatic and Collimated (Site not responding. Last check: 2007-10-08)
		The classical view of light is that it is an electromagnetic wave, with the properties of frequency, wavelength and speed.
		The quest for such light stayed mainly in the dark, because generating light with such properties was found to be quite impossible.
		Given a blinding dose of light the atoms in ruby did the dancing trick and produced a brief burst of coherent light.
	cactus.eas.asu.edu /partha/Columns/2002/05-06-laser.htm (1495 words)

	THz Science & Technology Network » Archive » Shock Produced Coherent THz Light
		Coherent light has a very narrow bandwidth and consists of photons that are all in phase with one another.
		The frequency of the emitted light is determined by the speed of the shock wave and the periodic lattice structure of the crystal, and not by the coherence of the source that generates the shock wave.
		Making coherent light in lasers is a feat of coordination: all the photons are released together thanks to a positive feedback process through which one photon stimulates the release of another.
	www.thznetwork.org /wordpress/index.php/archives/166 (1851 words)

	::: i Light :::
		Coming up next is a type of light which brings about another kind of characterisation of the various properties of light.
		Coherence in close relation to polarization and to monochromaticity which actually refers to the ability of a beam of light to interfere with itself.
		Light from a mercury arc lamp will produce fringes over a range of one or two centimeters.
	library.thinkquest.org /C001377/coherent.htm (168 words)

	glossary of terms
		Light which is of the same frequency and is vibrating in phase.
		The light from a laser beam that illuminated the object and is reflected to the holographic film.
		Light that contains most of the wavelengths in the visible spectrum, such as light from the sun or from a spotlight.
	web.mit.edu /museum/lightforest/glossary.html (464 words)

	CMS—Researchers Find New Way to Produce Coherent Light (Site not responding. Last check: 2007-10-08)
		Coherent light is very narrow bandwidth radiation; it is useful for interferometry (the measurement of two or more waves coming together at the same time and place, such as optical and shock waves) and is usually associated with lasers.
		The invention of the laser in 1958 as a source of coherent light enabled a wide range of applications including medical technologies and energy production because of the coherence of the light they generate.
		However, producing coherent light from a source other than a laser can serve as a diagnostic for understanding shock waves, specifically providing information about shock speed and the degree of crystallinity, Reed said.
	www-cms.llnl.gov /s-t/light.html (578 words)

	The Electromagnetic and Visible Spectra
		And similarly, two coherent waves traveling along two different paths to the same point will interfere destructively if there is a difference in distance traveled that is equivalent to a half number of wavelengths.
		Coherent light sources are sources of light which produce waves which have a constant phase difference between them over a significant duration of time.
		To be coherent, two waves must have the same frequency and their must not be any disruption of their cycle over the course of time.
	www.glenbrook.k12.il.us /gbssci/phys/class/light/u12l3e.html (1838 words)

	AFH LIBRARY - Assessing Food Quality by Its Afterglow (Site not responding. Last check: 2007-10-08)
		In contrast, coherent light vibrates in phase in one direction and usually at a single frequency, as in a monochromatic laser.
		Moreover, he thinks that both the spontaneously emitted biophotons as well as the after-glow stimulated by external light are coherent, and come from a coherent "light-field" in the cells and organisms.
		Because light vibrates much faster than the coherent motion of the molecules, living organisms look as if they are made of statically aligned liquid crystals, thereby generating the same kind of ‘interference colours’ that are produced by rock crystals.
	www.alkalizeforhealth.net /Lcoherentbiophotons.htm (2955 words)

	A 'salty' source of coherent light
		Coherent light is produced by a beam of photons that all have the same frequency and are all at the same phase.
		As I mentioned above, there are many applications for such a source of coherent light, but according to Reed, one of the first to come could be a new diagnostic tool to determine the properties of shock waves.
		We predict that coherent electromagnetic radiation in the 1-100 THz frequency range can be generated in crystalline materials when subject to a shock wave or solitonlike propagating excitation.
	www.primidi.com /2006/01/15.html (635 words)

	Physics News Graphics: Stopping Light
		However, a control beam (also laser light) is adjusted to create a condition of "electromagnetically induced transparency" (EIT) in the cell, and the signal beam is not absorbed.
		At the same time atomic spins are being flipped: the signal and the spins form a coupled excitation called a "polariton." (c) After the signal is entirely in the cell, one begins to reduce the intensity of the control beam.
		The light pulse departs at the normal speed of light, while the atomic vapor is left as it was before the signal pulse arrived.
	www.aip.org /mgr/png/2001/107.htm (203 words)

	Physics news Update 761
		Physicists at MIT and Livermore National Lab have discovered a new source of coherent radiation distinct from traditional lasers and free-electron lasers; they propose to build a device in which coherent photons are produced by sending shock waves through a crystal.
		The result would be coherent light resembling the radiation issuing from a laser; but the mechanism of light production would not be stimulated emission, as it is in a laser, but rather the concerted motion of row after row of atoms in the target crystal.
		Although sources of coherent light in this part of the electromagnetic spectrum have developed in recent years, it is still a difficult task.
	www.aip.org /pnu/2006/split/761-4.html (220 words)

	Lasers and coherence; "coherent light," WHAT IS COHERENCE?
		Light is transverse waves, so we should imagine that photons look like little wiggling snakes.
		Whenever all the "snakes" pack together side by side with their wiggles aligned, that's "coherence." The atoms in a laser are all emitting their light in locked phase, and the end result is supposedly special kind of in-phase light where the little sine-waves stack together like egg cartons.
		Imagine a lightwave to be spherical, like layers of an onion, but where the onion is expanding at the speed of light, and where the tiny light source is adding more layers in the middle.
	amasci.com /miscon/coherenc.html (663 words)

	Researchers find new source of coherent light
		This figure shows the emission of coherent light at 22 THz from a molecular dynamics simulation of shocked NaCl (table salt).
		The right panel shows the generated radiation as a function of location within the shocked crystal indicating the 22 THz coherent signal is generated at the shock front (between the white dotted lines).
		However, a group of researchers from Lawrence Livermore National Laboratory and the Massachusetts Institute of Technology have found a new source of coherent optical radiation that is distinct from lasers and free-electron lasers.
	www.physorg.com /news9884.html (877 words)

	A Cone of Coherent Light
		But if the light is intense enough to accelerate the electron close to the speed of light with each cycle--the relativistic regime--"you get all kinds of interesting phenomena," says Donald Umstadter of the University of Michigan in Ann Arbor.
		When these electrons are accelerated close to the speed of light, the laser's magnetic field becomes just as influential as its electric field, so the electrons travel in figure-eight patterns while emitting harmonics in specific angular patterns.
		The theory predicts that higher harmonic light produced this way should be even more intense than the lower harmonics, unlike conventional harmonic generation, where the lowest harmonics are the strongest.
	focus.aps.org /story/v5/st25 (555 words)

	Linac Coherent Light Source
		Using the Linac Coherent Light Source (LCLS)-an x-ray machine with unprecedented brilliance being considered for construction at the Stanford Linear Accelerator Center-researchers will be able to measure, for the first time, melting, recrystallization, and light-induced structural change on time scales down to a quadrillionth of a second.
		Third-generation light sources rely on storage rings where electrons traveling at nearly the speed of light are forced into a circular path by magnets.
		Both the spontaneous and coherent x radiation pass through an ultrahigh-vacuum system to the experimental areas, which may ultimately be as much as a kilometer away.
	www.llnl.gov /str/Toor.html (1362 words)

	Quantum Antenna Hypothesis
		In this manner one avoids the basic problem of the quantum cavity models (by Uncertainty Principle the typical wave length of the coherent light should be determined by the transverse size of the microtubule and should be in UV region).
		The em current associated with ME:s generates a coherent state of photons and microtubule acts as a quantum antenna: inverse wave lengths are integer multiples of the microtubule length so that the longest microtubules generate infrared light.
		Vision could correspond quite generally to coherent light in the sense that conscious visual experience is associated with the coherent light sent and received by the neuronal microtubules.
	www.helsinki.fi /~matpitka/tubula.html (1229 words)

	Coherent Inc. : Company
		Founded in 1966, Coherent, Inc. is a world leader in providing superior laser reliability and performance.
		Until the development of the laser, all light was basically incoherent.
		Coherent light, by contrast, can be directed, focused and used to illuminate new possibilities well beyond the realm of its everyday, incoherent counterpart.
	www.coherent.com /company (191 words)

	laser: Coherent Light and Its Emission in Lasers
		The coherent light produced by a laser differs from ordinary light in that it is made up of waves all of the same wavelength and all in phase (i.e., in step with each other); ordinary light contains many different wavelengths and phase relations.
		This produces a sudden burst of coherent radiation as all the atoms discharge in a rapid chain reaction.
		Often the laser is constructed so that the emitted light is reflected between opposite ends of a resonant cavity; an intense, highly focused light beam passes out through one end, which is only partially reflecting.
	www.infoplease.com /ce6/sci/A0859189.html (544 words)

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