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Honolulu, HI, United States

Cone tracking is a well-known method to optimize the pointing of a beam, and has been reported previously in the case of direct-mode free-space optical communication links, using a beacon or a dedicated wavelength to carry the feedback. In a retro link, because the beam is reflected back to the transmitter, feedback data are locally available. We present here the results of an evaluation (both simulation and experiments) of the cone-tracking technique applied to a retro link and how the implementation can be optimized for this specific case. We show that, using only a small number of samples (as few as 16 with 625-Hz modulation frequency), we can retrieve the pointing error. We finally demonstrate cone tracking (a closed loop maintaining the beam center on the retroreflector) with modulation amplitude as low as 1 of the beam divergence. © 2010 Society of Photo-Optical Instrumentation Engineers. Source


Murphy J.L.,U.S. Navy | Ferraro M.S.,U.S. Navy | Rabinovich W.S.,U.S. Navy | Goetz P.G.,U.S. Navy | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Tele-operated robots used for Explosive Ordnance Disposal (EOD) are ordinarily controlled using a radio frequency (RF) link. Use of RF links on the battlefield presents several challenges including spectrum allocation and jamming effects (both by the enemy and friendly forces). Several solutions have been attempted including electrical or fiber optic umbilicals and spread spectrum radios with varying degrees of success. Modulating Retro-reflector Free Space Optical (MRR-FSO) communications links avoid these effects entirely but are limited to line of sight operation. We have developed a system consisting of an MRR-FSO link with a tracking optical terminal, a conventional RF link and a deployable pod to provide a relay node bridging the FSO link to the operator and the RF link to the robot. The MRRFSO link provides the capability to operate the robot in the presence of jamming while the RF link allows short range non line of sight operation. The operator uses the MRR-FSO link to drive the robot to a position downrange outside the influence of the jammer or other interference. Once the robot is positioned downrange near the area of operation the pod is deployed. This allows the robot to maneuver freely including venturing beyond line of sight using the short range RF link to maintain communications between the vehicle and pod while the FSO link maintains connectivity between the pod and the operator. © 2014 SPIE. Source


Dayton D.,Applied Technology Associates | Nolasco R.,Applied Technology Associates | Myers M.,Air Force Research Lab | Sena J.-P.,Air Force Research Lab | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Recent advances in InGaAs camera technology has stimulated interest in the short wave infra-red (SWIR) band in the spectral region 0.84 - 1.7 μm. Located between the visible and thermal infra-red, the SWIR band shows interesting properties of both. Images tends to have the look of the visible and are less affected by scattering from aerosol haze, however the solar irradiance is dropping rapidly with wavelength in the SWIR. Spectral signatures, particularly of paints and dyes, may be different in the SWIR band compared to the visible. For these reasons we have chosen to investigate hyper-spectral measurements in this band using the NovaSol μHSI SWIR hyper-spectral imager system. © 2012 SPIE. Source


Dayton D.,Applied Technology Associates | Nolasco R.,Applied Technology Associates | Myers M.,Air Force Research Lab | Gonglewski J.,Air Force Research Lab | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Recent advances in InGaAs camera technology has stimulated interest in the short wave infra-red (SWIR) band in the spectral region 0.9 - 1.7 μm. Located between the visible and thermal infra-red, the SWIR band shows interesting properties of both. Images tends to have the look of the visible and are less affected by scattering from aerosol haze, however the solar irradiance is dropping rapidly with wavelength in the SWIR. Spectral signatures, particularly of paints and dyes, may be different in the SWIR band compared to the visible. For these reasons we have chosen to investigate hyper-spectral measurements in this band using the NovaSol ìHSI SWIR hyper-spectral imager system. © 2011 SPIE. Source


Rabinovich W.S.,U.S. Navy | Moore C.I.,U.S. Navy | Burris H.R.,U.S. Navy | Murphy J.L.,U.S. Navy | And 16 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Free space optical (FSO) communication has enjoyed a renewal of interest in the past decade driven by increasing data rate requirements and decreasing amounts of radio frequency spectrum. These needs exist in both the commercial and military sectors. However military communications requirements differ in other ways. At the U.S. Naval Research Laboratory (NRL) we have been conducting research on FSO communications for over ten years with an emphasis on tactical applications. NRL's FSO research has covered propagation studies in the maritime domain, new component development, and systems demonstrations. In addition NRL has developed both conventional, direct, laser communications systems and retro-reflecting systems. In this paper we review some of this work and discuss possible future applications of FSO communications. © 2010 Copyright SPIE - The International Society for Optical Engineering. Source

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