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<div><font face="Arial" size="+1" color="#000000">Seminar on<br>
<b>Modern Optics and Spectroscopy<br>
<br>
Yoel Fink</b>, MIT<br>
<br>
<i><b>Can invisible objects see? On the imaging properties of
transparent photodetecting fiber webs<br>
<br>
</b></i>December 13, 2005</font></div>
<div><font face="Arial" size="+1" color="#000000">12:00 - 1:00
p.m.</font></div>
<div><font face="Arial" size="+1" color="#000000">Grier Room
34-401</font></div>
<div><font face="Arial" size="+1" color="#000000"><br>
</font><font face="Times" size="+1"
color="#000000">Abstract:</font><br>
<font face="Times" size="+1" color="#000000"></font></div>
<div><font face="Times" size="+1" color="#000000"><b>Measurements of
optical fields are typically performed using sequential arrangements
of optical components such as lenses, filters, beam splitters in
conjunction with planar arrays of point detectors placed on a common
axis; both the human eye and the photographic camera are examples of
such systems. While the specifics may vary from system to system, all
are constrained in terms of size, weight, durability and field of view
around the optical axis. In my talk, a new,<i> geometric,</i> approach
to optical field measurements which enables access to optical
information on unprecedented length and volume scales will be
described. Enabling this approach are tough polymeric photodetecting
fibers drawn from a fiber perform to produce hundreds of meters of
light sensitive fibers. These are subsequently woven into
light-weight, low-optical-density, two- and three-dimensional fiber
constructs. These constructs can measure the basic attributes of
electromagnetic fields on large areas. The precise geometric construct
is tailored to address specific measurement requirements and, in
particular, does not necessitate an optical axis. A three-dimensional
spherical geometry is used to demonstrate an omnidirectional light
detection system capable of discerning the direction of illumination
over 4_ steradians. The acquisition of the amplitude of an optical
field is demonstrated through the reconstruction of an arbitrary
intensity distribution using a tomographic algorithm. Finally, the
ability of these geometric fiber constructs to measure the phase of an
optical field will be demonstrated. Hence, the problem of optical
field measurement is transformed from one involving the choice and
placement of lenses and detector arrays to that of designing
geometrical constructions of polymeric, light-sensitive fibers. I will
also survey recent developments in th</b></font><font face="Times"
size="+2" color="#000000"><b>e field of multimaterial fibers for
transmission and device applications.</b></font></div>
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