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Topic: Evanescent waves

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In the News (Thu 20 Jun 19)

  03.22.2007 - Goal of nanoscale optical imaging gets boost with new hyperlens
Evanescent waves contain far greater detail and resolution of an object, but they decay too quickly for conventional lenses to capture them.
In 2005, Zhang led a research team that developed a superlens capable of capturing evanescent waves and imaging an object at a half-pitch resolution of 60 nanometers.
This exponential loss of the evanescent waves required the image plane to sit close to the lens.
www.berkeley.edu /news/media/releases/2007/03/22_hyperlens.shtml   (1042 words)

 Canadian Instrumentation and Research, Ltd.
This demonstrates that there is an evanescent energy field outside the cube material allowing interaction of the two surfaces across the small air gap.
If the evanescent tails of each waveguide have considerable overlap, it can be shown that there are two possible solutions for mode propagation in the two waveguide structure.
The polished evanescent wave coupler is based on bringing the cores of two fibers close together by removing part of the cladding and optically contacting the polished faces.
www.cirl.com /evanescent.php   (785 words)

  Introduction to Evanescent Waves
A light beam reflects at an interface at an angle that exceeds the critical angle.
, the "effective thickness" of this evanescent wave corresponds to the equivalent thickness required to obtain the same spectral contrast of a transmission experiment.
The "effective thickness" leads to a Beer-Lambert-like law for evanescent wave spectroscopy.
www.nist.gov /crds/ev_wave1.htm   (100 words)

  Olympus Microscopy Resource Center: Specialized Microscopy Techniques - TIRFM - Evanescent Field Polarization Profiles
Evanescent wave intensity at the interface surface (I(o)) is a function of both the incident angle and the polarization components of the light beam.
The electric and magnetic field components of the evanescent waves are indicated by arrows or dots (perpendicular to the plane of the browser window) in the tutorial.
The evanescent electric field vector for the s-polarized incident light is perpendicular (or normal) to the plane of incidence.
www.olympusmicro.com /primer/java/tirf/evaintensity   (874 words)

 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal
"Evanescent" means "tends to vanish", which is appropriate because the intensity of evanescent waves decays exponentially with the distance from the interface at which they are formed.
Mathematically, evanescent waves are characterized by a wave vector where one or more of the vector's components has an imaginary value.
This type of evanescent wave is created when an electromagnetic wave, incident upon the interface between two dielectric media of different refractive indices, experiences total internal reflection.
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=evanescent_wave   (426 words)

 | International School of Photonics | Research | Fibre Optic Sensors | Evanescent Waves |
Evanescent waves are formed when sinusoidal waves are (internally) reflected off an interface at an angle greater than the critical angle so that total internal reflection occurs.
The energy flow of this evanescent wave is parallel to the surface of the core and in the same direction as the main flow of energy within the core.
In an evanescent wave fibre optic sensor, the cladding of the optical fibre is removed and it is placed in direct contact with the sample.
www.photonics.cusat.edu /Research_Fiber%20Sensors_EW.html   (312 words)

 The educational encyclopedia, physics: waves
Evanescent waves evanescent means "tending to vanish", which is appropriate because the intensity of evanescent waves decays exponentially (rather than sinusoidally) with distance from the interface at which they are formed.
Mechanical waves a wave pulse is a disturbance that moves through a medium, a periodic wave is a periodic disturbance that moves through a medium.
Ripple tank wave phenomena plane waves off of a parabolic reflector, law of reflection, circular reflections off of a straight barrier, two-point source interference, diffraction, refraction (refraction is the bending of a wavefront resulting from a change in medium)
www.educypedia.be /education/physicswaves.htm   (571 words)

 Evanescent wave - Wikipedia, the free encyclopedia
An evanescent wave is a wave that decays exponentially with distance.
"Evanescent" means "tending to vanish", which is appropriate because the intensity of evanescent waves decays exponentially with the distance from the interface at which they are formed.
Mathematically, evanescent waves are characterized by a wave vector where one or more of the vector's components has an imaginary value.
en.wikipedia.org /wiki/Evanescent_waves   (369 words)

 Fiber-Optic Probe Uses Evanescent Waves To Sense Biofilm
The effect is primarily a result of (1) a change in the index of refraction to which the evanescent wave is subject and (2) increased scattering of light.
The evanescent wave is shallow enough that the instrument exhibits a significant response to as little as a monolayer of bacteria.
The design of the instrument was guided by a mathematical model that assisted in the optimization of the instrument performance and the prediction of the response of the instrument to specified changes in the index of refraction of the medium surrounding the sensory element.
www.nasatech.com /Briefs/Oct02/MSC22880.html   (447 words)

 [No title]
Also known as the evanescent wave (meaning “passing away quickly”), this intriguing behavior between electrons in relation to electromagnetic waves was extremely difficult to quantify [2].
When light is sent through at an angle greater than the critical angle, the boundary wave existing in the layers is detected by the dye molecules, which emit yellow fluorescence with an intensity proportional to the square of the amplitude of the localized electric field [2].
From the intensity apparent in the dye molecules, a verification of the exponential decay of the evanescent wave was found with a large amount of precision [5].
www.u.arizona.edu /~gshih/draft2.doc   (1158 words)

 A reexamination of evanescent acoustic-gravity waves: Special properties and aeronomical significance
It is shown that this behavior is equivalent to assuming incorrectly that wave energy is the same function of vertical wave number for internal and evanescent waves.
For waves near the Lamb-wave solution, the dominant dynamical control of the vertically integrated airglow response is the horizontal divergence.
Wave properties are well behaved near the characteristic curve and solutions are linked at the common intersection of the Lamb and BV curves implying that waves should be able to transfer energy from one regime to the other in response to background variations.
www.agu.org /pubs/crossref/2003/2002JD002421.shtml   (383 words)

 Acoustic-Gravity Waves   (Site not responding. Last check: )
Waves are propagating in the acoustic and gravity dominated regimes.
Figure 2.1 shows the dispersion relation for waves propagating in the vertical direction (i.e., along the z axis).
Between the acoustic and gravity dominated regimes, waves are evanescent.
hesperia.gsfc.nasa.gov /~jma/thesis/online/node28.html   (128 words)

 Technology Review: From the Lab: Nanotechnology
Instead, it uses evanescent waves, which are produced when light hits a lens at such an angle that it bounces off instead of passing through.
Evanescent waves emerge on the other side of the lens and add optical information to normal "propagating" light waves, but they decay very quickly over short distances.
Next Step: The superlens didn't spread out the evanescent waves enough that the human eye could see the image directly; it had to be observed with an atomic force microscope.
www.technologyreview.com /NanoTech/14676   (469 words)

 Evanescent wave optical manipulation   (Site not responding. Last check: )
Cartoon of the evanescent waves located in a gap between an interface and a micro-object.
Near-field forces propel microparticles in the direction of the propagating evanescent waves due to radiation pressure exerted by the light to these microparticles.
Due to the nature of the evanescent waves, the manipulated particles are organized near an interface, which may be of importance for Surface-Enhanced Raman Spectroscopy (SERS), studies of signalling during cell growth, and many other applications where proximity to a physical substrate is critical.
www.st-andrews.ac.uk /~atomtrap/Research/Beams/Near_Field/evanescent.htm   (1244 words)

 04.21.2005 - New superlens opens door to nanoscale optical imaging and high-density optoelectronic devices
Breaking this diffraction limit and capturing evanescent waves are critical to the creation of a 100-percent perfect representation of an object, considered the Holy Grail in optics.
These theories are based on the fact that when electromagnetic waves of light reach the surface of a negative refraction lens, they excite a collective movement of surface waves, such as electron oscillations, also known as surface plasmons.
That results in an enhancement of the evanescent waves and is different from the way light typically behaves when it reaches a conventional lens.
www.berkeley.edu /news/media/releases/2005/04/21_superlens.shtml   (1307 words)

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