[MOS] MOS 12/13/05

[Zina Queen]

Seminar on
Modern Optics and Spectroscopy

Yoel Fink, MIT

Can invisible objects see?  On the imaging properties of transparent 
photodetecting fiber webs

December 13, 2005
12:00 - 1:00 p.m.
Grier Room 34-401

Abstract:

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, geometric, 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 the field of multimaterial fibers for transmission 
and device applications.
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