USA as Represented by Secretary of the Navy

David T Wayne

Burton Hamilton Neuner, Iii

Michael Garrett Lovern

Colin Norris Reinhardt

Galen D Cauble

Paul David Swanson

Alexandru Hening

Peter M Poirier

John Stephen deGrassie

A system and method are provided for receiving light that has traveled from an optical source through an atmosphere along a distance. The system includes: a receiver lens system having an aperture and being arranged to receive the light from the optical source; a beam splitter; an imaging lens; an image processing component; a photodetector system; and a refractive index structure parameter component. The photodetector system outputs data associated with averaged scintillation data of the aperture. The image processing component generates a normalized covariance curve based on a first portion of the received light. The refractive index structure parameter component generates a refractive index structure parameter, C, of the atmosphere along the distance based on the data associated with averaged scintillation data of the aperture and the normalized covariance curve.

Characterizing atmospheric turbulence using the covariance and temporal intensity fluctuations of an optical source

An optical interrogator for illuminating an object comprising a laser, a splitter, an optical polarizing element, and an optical recombiner. The laser is configured to generate a laser pulse, which the splitter splits into first, second, third, fourth, fifth, and sixth laser segments such that each of the laser segments are separated by a time delay on the order of nanoseconds between each laser segment. The optical polarizing element is positioned so as to respectively polarize the first, second, third, fourth, fifth, and sixth laser segments with a 0&#xb0; linear polarization, a 45&#xb0; linear polarization, a 90&#xb0; linear polarization, a 135&#xb0; linear polarization, a right-handed, circular polarization (RHCP), and a left-handed, circular polarization (LHCP). The optical recombiner combines the polarized laser segments into a train of co-aligned pulses for illuminating the object.

Optical interrogator for measuring polarization properties

A retroreflective optical system for creating a passive optical tag in an absence of electrical power, involving: a retroreflector having a surface and a retroreflective element disposed in relation to the surface, the retroreflective element configured to: passively impart a unique signature in relation to incoming light by using at least one of spectral filtration and color filtration, whereby a plasmonic response is effectible; and reflect outgoing light having the unique signature; and an optical device having an input aperture, the optical device disposed at a distance from the retroreflector and configured to transmit the incoming light and the outgoing light.

Retroreflective optical system and methods

A system and method involve using a first laser to generate a laser-induced plasma filament within an optically-transparent medium, using a second laser to generate a communication signal, and using a signal combiner positioned within the path of both the first laser and the second laser to direct the communication signal through the laser-induced plasma filament to a receiver located within the optically-transparent medium.

Laser-induced plasma filaments for communication

Methods for characterizing atmospheric turbulence along an optical path from a laser transmitter to a laser receiver can include the steps of counting the number of laser speckles at the receiver imaging plane, and then finding Fried's parameter rusing the counting result to characterize the turbulence along the path. Before counting speckles, images at the receiver image plane can be preprocessed by capturing the images. The captured images at the image plane can then be blurred and a threshold can be chosen so that only certain pixels in the image are further processed. The thresholding can be via Otsu's methods or via variants of a Gaussian fit. Kostelec's method can then be used to count speckles in the portions of the image that have made it through the thresholding step. Other counting methods could be used. Fried's can then be found using the speckle count.

Measuring optical turbulence using cell counting algorithms

A system comprises a tracking electromagnetic beam generator, a retro-reflecting device, a signal generator, a communication electromagnetic beam generator and a receiver. The tracking electromagnetic beam generator transmits a tracking electromagnetic beam. The retro-reflecting device reflects the tracking electromagnetic beam toward the tracking electromagnetic beam generator. The signal generator generates a communication signal. The communication electromagnetic beam generator transmits a communication electromagnetic beam, based on the communication signal, to the retro-reflecting device. The receiver receives a portion of the communication electromagnetic beam as reflected from the retro-reflecting device.

System and method for line-of-sight optical broadcasting using beam divergence and an orbiting or airborne corner cube reflector

A system and method involve detecting a modulated optical signal from an atmospheric propagation channel, wherein the modulated optical signal comprises an optical signal from an optical source modulated with a periodic signal at a modulation frequency greater than the bandwidth of the turbulence within the atmospheric propagation channel, and converting the detected modulated optical signal into a digitized electrical signal. The method also includes determining the root mean square signal power of an AC component of the digitized electrical signal at the modulation frequency. The method further includes determining the power spectral density of the digitized electrical signal, determining the magnitude of the peak component at the modulation frequency, and determining the effective optical depth of the atmospheric propagation channel using the magnitude of the peak component at the modulation frequency.

Atmospheric transmissometer using a modulated optical source

A method for characterizing an atmospheric propagation channel comprising: generating a database of atmospheric modulation transfer functions (MTFs) over a range of known values for at least one image-quality-related parameter; capturing at least one image of an object with an image capture device, wherein the image capture device is separated from the object by the atmospheric channel; deconvolving the captured image with every atmospheric MTF in the database to create a plurality of deconvolved, captured images; scoring each deconvolved, captured image according to an image quality metric (IQM); using an optimization-decision algorithm to find the best IQM score; and characterizing the atmospheric propagation channel as possessing the type and value of the image-quality-related parameters that are associated with the corresponding MTFs used to deconvolve the image having the best IQM score.

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San Diego, CA, United States of America

David T Wayne