N-slit laser interferometer developed
Scientists have developed an N-slit laser
interferometer that is suitable for secure terrestrial free-space optical communications
over propagation distances and clear-air turbulence detection.
The device was created by physicists from Interferometric Optics
and the US Army Space and Missile Defense Command. The findings were reported in
the Feb. 3, 2011, issue of
Journal of Optics (doi: 10.1088/2040-8978/13/3/035710).
Previously, N-slit interferometers were used for industrial metrology
applications, including microdensitometry, microscopy and optical modulation measurement
of thin-film gratings generated from a variety of manufacturing processes. Advantages
of this type of interferometer include a simple architecture and the use of low-
to medium-power single-transverse-mode narrow-linewidth lasers.
The scientists proved experimentally that the device is a viable
interferometric tool over long free-space propagation paths under fair atmospheric
conditions. In the lab, they demonstrated that very subtle attempts to intercept
the interferometric characters, using microscopic natural fibers, could be detected
by observing the diffraction patterns superimposed over the interferometric signal.
The US Army High Energy Laser Laboratory project was funded through
a subcontract to BAE Systems.
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