Speckle Evolution of Diffusive and Localized Waves Azriel Z. Genack, Queens College of CUNY, DMR 0538350

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Speckle Evolution of Diffusive and Localized
Waves Azriel Z. Genack, Queens College of CUNY,
DMR 0538350

• The addition of randomly scattered waves gives
  rise to a speckled intensity pattern for any type
  of wave, including light, sound and electrons.
  The evolution of such patterns as the incident
  frequency is scanned is observed for microwave
  radiation. Though random, the patterns observed
  have an intricate structure. A network of phase
  singularities appears about points of vanishing
  intensity. We show that the motion of these
  points of darkness provides a diagnostic of the
  nature of wave transport within the scattering
  object.
• For waves strongly localized within the sample,
  the speckle pattern develops in fits and starts
  as opposed to the smooth development for
  spatially extended waves. This work provides
  measures of speckle evolution which can be
  exploited to monitor motion of hidden objects and
  the development of structural defects.

Patterns of intensity and phase produced by
microwave radiation transmitted through a
strongly scattering sample filling a metal tube.
The resulting speckle pattern of intensity (left)
and phase (right) are magnified in the lower
panel. The motion of points of undetermined
phase, seen as the center of a pinwheel, give a
clear diagnostic of the nature of waves inside
the sample.
Physical Review Letters 99, 063902 (2007).
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Speckle Evolution of Diffusive and Localized
Waves Azriel Z. Genack, Queens College of CUNY,
DMR 0538350
Societal Impact Speckle techniques being
developed via microwave and optical measurements
may find applications to surveying geological
formations and ice caps, as well as inspecting
aerospace components. Transmitted optical speckle
patterns may also find application to locating
tumors. Measurements of speckle though glass
stacks may point the way to probing naturally
occurring layered media such as the earths crust.
Education and outreach Three high school
students who participated in research on wave
propagation in the summer of 2006 plan to
continue in physics or engineering. Elizabeth
Shechner was a semi-finalist in the Intel Science
program and will go on to Harvard, Gennady
Rozenberg will go on to the Columbia School of
Engineering, and Yitzchak Locerman, published his
first scinetific paper as a Freshman at Queens
College. Two graduate students, Jing Wang and
Jongchul Park are about to defend their Ph.D.
proposal this September. One postdoctoral fellow,
Sheng Zhang has made a transition from quantum
computimg to experimetnal physics.