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Nagel J.A.,University of Arizona | Temyanko V.,University of Arizona | Dobler J.,ITT Geospatial Systems | Dianov E.M.,Fiber Optics Research Center | And 4 more authors.
IEEE Photonics Technology Letters | Year: 2011

A high-power narrow-linewidth continuous-wave (CW) Raman fiber amplifier at 1.27 μm is demonstrated for remote sensing measurements of atmospheric oxygen O2. The amplifier uses phosphosilicate fiber in both a standard single-mode design and with the core size varying in the longitudinal direction for stimulated Brillouin scattering (SBS) suppression. The highest reported power level at this wavelength to date, a total peak power of 3 W, has been achieved for online (2.4 W) and offline (580 mW) spectroscopic measurements, in agreement with theoretical predictions. Additionally, it is shown that when 60-kHz sinusoidal amplitude modulation is applied to the amplifier seed signal, the modulated wave form is preserved at the amplifier output with 1.8 W total average power being obtained. © 2006 IEEE. Source

Whitman T.,ITT Geospatial Systems
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The James Webb Space Telescope (JWST) requires cryogenic testing of a critical stray light path, named as the Rogue Path. Although blockage of this path is verified during fabrication and assembly of JWST, simple small light sources added to the test configuration provide an opportunity to check for successful blockage at the system level in the cryogenic environment. Although the test occurs in the largest environmental chamber at the NASA Johnson Space Center, the size of the chamber challenges this test by placing the origin of the Rogue Path within the collimated beam of the telescope. The design of the test overcomes this challenge with sufficient signal to noise ratio and without interference with the optical test of the system. © 2010 SPIE. Source

Brunton S.L.,Princeton University | Rowley C.W.,Princeton University | Kulkarni S.R.,Princeton University | Clarkson C.,ITT Geospatial Systems
IEEE Transactions on Power Electronics | Year: 2010

This study develops a maximum power point tracking algorithm that optimizes solar array performance and adapts to rapidly varying irradiance conditions. In particular, a novel extremum seeking (ES) controller that utilizes the natural inverter ripple is designed and tested on a simulated solar array with a grid-tied inverter. The new algorithm is benchmarked against the perturb and observe (PO) method using high-variance irradiance data gathered on a rooftop array experiment in Princeton, NJ. The ES controller achieves efficiencies exceeding 99% with transient rise-time to the maximum power point of less than 0.1 s. It is shown that voltage control is more stable than current control and allows for accurate tracking of faster irradiance transients. The limitations of current control are demonstrated in an example. Finally, the effect of capacitor size on the performance of ripple-based ES control is investigated. © 2010 IEEE. Source

Ramsey P.G.,ITT Geospatial Systems | Swanson K.S.,ITT Geospatial Systems
Cryogenics | Year: 2012

The Advanced Baseline Imager (ABI) is a prime payload for the GOES-R (Geostationary Operational Environmental Spacecraft) series of meteorological satellites. Focal plane temperature control is provided by a two-stage cryocooler based on the NGAS HEC (Northrop Grumman Aerospace Systems High Efficiency Cryocooler) design. To demonstrate the long-term operation of this cooler, a dedicated life test is being performed. The life test cooler is close to the flight design, differing only in minor details of the cold head structure. The test concept simulates continuous operation the cooler at flight like conditions. Long term testing started on 12 June 2009, and has continued to this date. Test performance and anomalies are discussed. © 2012 Elsevier Ltd. All rights reserved. Source

Hart B.T.,ITT Geospatial Systems
Optical Engineering | Year: 2011

A choice of methods exists for determining the variability of an averaged wavefront measurement. Pixel-by-pixel standard deviation (SD) maps provide a spatial description of the variability as well as a scalar magnitude. An efficient algorithm for computing SD maps as measurements occur is given. Results for simulated and experimental wave-front maps are shown. Plots of the average SD as a measurement progresses can be used to characterize a test system and determine the minimum number of measurements required for acceptable results. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). Source

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