Dr. Gero A. Nootz Profile

Dr. Gero A. Nootz

NRC Research Associate at Univ of Southern Mississippi

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Author

Publications (15)

Proceedings Article | 7 June 2017 Presentation

Beam wander due to optical turbulence in water (Conference Presentation)

Gero Nootz, Silvia Matt, Andrey Kanaev, Ewa Jarosz, Weilin Hou

Proceedings Volume 10186, 1018605 (2017) https://doi.org/10.1117/12.2264922

KEYWORDS: Optical communications, Environmental sensing, Free space, Optical turbulence, Laser beam propagation, Optical simulations, Ocean optics, Free space optics, Refraction, Water

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Proceedings Article | 22 May 2017 Presentation + Paper

The impact of optical turbulence on particle image velocimetry

Silvia Matt, Gero Nootz, Samuel Hellman, Weilin Hou

Proceedings Volume 10186, 101860J (2017) https://doi.org/10.1117/12.2264751

KEYWORDS: Liquids, CMOS cameras, Optical turbulence, Turbulence, Particles, Particle image velocimetry, Velocity measurements, CCD cameras, Refraction, Stars

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Proceedings Article | 17 May 2016 Paper

Measurements of optical underwater turbulence under controlled conditions

A. Kanaev, S. Gladysz, R. Almeida de Sá Barros, S. Matt, G. Nootz, D. Josset, W. Hou

Proceedings Volume 9827, 982705 (2016) https://doi.org/10.1117/12.2230256

KEYWORDS: Atmospheric propagation, Geometrical optics, Ocean optics, Atmospheric propagation, Wavefront sensors, Wave propagation, Beam propagation method, Phase modulation, Turbulence, Modulation transfer functions, Light emitting diodes

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Proceedings Article | 23 May 2014 Paper

Experimental studies of the compressive line sensing underwater serial imaging system

Bing Ouyang, Weilin Hou, Fraser Dalgleish, Frank Caimi, Gero Nootz, Anni Vuorenkoski

Proceedings Volume 9111, 91110M (2014) https://doi.org/10.1117/12.2050691

KEYWORDS: Digital micromirror devices, Imaging systems, Image compression, Sensing systems, Computer programming, Prototyping, Scattering, Image quality, Spatial light modulators, Image restoration

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Proceedings Article | 23 May 2014 Paper

3D imaging using compressive line sensing serial imaging system

Bing Ouyang, Frank Caimi, Fraser Dalgleish, Gero Nootz, Anni Vuorenkoski

Proceedings Volume 9109, 91090V (2014) https://doi.org/10.1117/12.2050667

KEYWORDS: Imaging systems, Digital micromirror devices, Stereoscopy, Scattering, Sensing systems, LIDAR, Image compression, Computer programming, Pulsed laser operation, Compressed sensing

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SPIE Journal Paper | 22 April 2014

Compressive line sensing underwater imaging system

Bing Ouyang, Fraser Dalgleish, Frank Caimi, Thomas Giddings, Walter Britton, Anni Vuorenkoski, Gero Nootz

OE, Vol. 53, Issue 05, 051409, (April 2014) https://doi.org/10.1117/12.10.1117/1.OE.53.5.051409

KEYWORDS: Imaging systems, Sensing systems, Underwater imaging, Image compression, Receivers, Image quality, Spatial light modulators, Signal attenuation, Compressed sensing, Scattering

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Proceedings Article | 3 June 2013 Paper

In situ laser sensing of mixed layer turbulence

Fraser Dalgleish, Weilin Hou, Anni Vuorenkoski, Gero Nootz, Bing Ouyang

Proceedings Volume 8724, 87240D (2013) https://doi.org/10.1117/12.2019193

KEYWORDS: LIDAR, Turbulence, Backscatter, Water, Sensors, Optical turbulence, Temperature metrology, Profiling, High speed cameras, Laser scattering

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This paper will discuss and compare some recent oceanic test results from the Bahamas Optical Turbulence Exercise (BOTEX) cruise, where vertical profiling was conducted with both time-resolved laser backscatter measurements being acquired via a subsurface light detection and ranging (lidar) profiling instrument, and laser beam forward deflection measurements were acquired from a matrix of continuous wave (cw) laser beams (i.e. structured lighting) being imaged in the forward direction with a high speed camera over a one-way path, with both transmitter and camera firmly fixed on a rigid frame. From the latter, it was observed that when within a natural turbulent layer, the laser beams were being deflected from their still water location at the image plane, which was 8.8 meters distance from the laser dot matrix transmitter. As well as suggesting that the turbulent structures being encountered were predominately larger than the beam diameter, the magnitude of the deflection has been confirmed to correlate with the temperature dissipation rate. The profiling lidar measurements which were conducted in similar conditions, also used a narrow collimated laser beam in order to resolve small-scale spatial structure, but with the added attribute that sub-nanosecond short pulse temporal profile could potentially resolve small-scale vertical structure. In the clear waters of the Tongue of the Ocean in the Bahamas, it was hypothesized that the backscatter anomalies due to the effect of refractive index discontinuities (i.e. mixed layer turbulence) would be observable. The processed lidar data presented herein indicates that higher backscatter levels were observed in the regions of the water column which corresponded to higher turbulent mixing which occurs at the first and second themoclines. At the same test stations that the laser beam matrix and lidar measurements were conducted, turbulence measurements were made with two non-optical instruments, the Vertical Microstructure Profiler (VMP) and a 3D acoustical Doppler velocimeter with fast conductivity and temperature probes. The turbulence kinetic energy dissipation rate and the temperature dissipation rates were calculated from both these setups in order to characterize the physical environments and corroborate with the laser measurements. To further investigate the utility of elastic lidar in detecting small-scale turbulent structures, controlled laboratory experiments were also conducted, with the objective of concurrently acquiring both the laser beam spatial characteristics in the forward direction and the laser backscatter temporal profile from each transmitted sub-nanosecond pulse. An artificial refractive index discontinuity was generated in clear test tank conditions by placing a clean ice-filled carboy above the laser beam propagation path. The results from both field and laboratory experiments confirm our hypothesis that turbulent layers are detectable by lidar sensors, and motivates that more research and lidar instrumentation development is needed to better quantify turbulence, especially for mitigating associated performance degrading effects for the U.S. Navy’s next generation electro-optic (EO) systems, including active laser imaging and laser communications.

SPIE Journal Paper | 1 March 2013

Compressive sensing underwater laser serial imaging system

Bing Ouyang, Fraser Dalgleish, Frank Caimi, Thomas Giddings, Joseph Shirron, Anni Vuorenkoski, Walter Britton, Benjamin Metzger, Brian Ramos, Gero Nootz

JEI, Vol. 22, Issue 02, 021010, (March 2013) https://doi.org/10.1117/12.10.1117/1.JEI.22.2.021010

KEYWORDS: Imaging systems, Compressed sensing, Receivers, Binary data, Matrices, Electro optical modeling, Monte Carlo methods, Image processing, Modulation, Digital micromirror devices

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Proceedings Article | 12 June 2012 Paper

Bahamas Optical Turbulence Exercise (BOTEX): preliminary results

Weilin Hou, Ewa Jorosz, Fraser Dalgleish, Gero Nootz, Sarah Woods, Alan Weidemann, Wesley Goode, Anni Vuorenkoski, B. Metzger, B. Ramos

Proceedings Volume 8372, 837206 (2012) https://doi.org/10.1117/12.920740

KEYWORDS: Turbulence, Optical turbulence, Ocean optics, Sensors, Scattering, Imaging systems, Particles, Water, Image transmission, High speed cameras

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The Bahamas Optical Turbulence Exercise (BOTEX) was conducted in the coastal waters of Florida and the Bahamas from June 30 to July 12 2011, onboard the R/V FG Walton Smith. The primary objective of the BOTEX was to obtain field measurements of optical turbulence structures, in order to investigate the impacts of the naturally occurring turbulence on underwater imaging and optical beam propagation. In order to successfully image through optical turbulence structures in the water and examine their impacts on optical transmission, a high speed camera and targets (both active and passive) were mounted on a rigid frame to form the Image Measurement Assembly for Subsurface Turbulence (IMAST). To investigate the impacts on active imaging systems such as the laser line scan (LLS), the Telescoping Rigid Underwater Sensor Structure (TRUSS) was designed and implemented by Harbor Branch Oceanographic Institute. The experiments were designed to determine the resolution limits of LLS systems as a function of turbulence induced beam wander at the target. The impact of natural turbulence structures on lidar backscatter waveforms was also examined, by means of a telescopic receiver and a short pulse transmitter, co-located, on a vertical profiling frame. To include a wide range of water types in terms of optical and physical conditions, data was collected from four different locations. . Impacts from optical turbulence were observed under both strong and weak physical structures. Turbulence measurements were made by two instruments, the Vertical Microstructure Profiler (VMP) and a 3D acoustical Doppler velocimeter with fast conductivity and temperature probes, in close proximity in the field. Subsequently these were mounted on the IMAST during moored deployments. The turbulence kinetic energy dissipation rate and the temperature dissipation rates were calculated from both setups in order to characterize the physical environments and their impacts. Beam deflection by multiple point patterns are examined, using high speed camera recordings (300 to 1200 fps), in association with measured turbulence structures. Initial results confirmed our hypothesis that turbulence impacted optical transmissions. They also showed that more research will be needed to better quantify and mitigate such effects, especially for the U.S. Navy's next generation EO systems, including active imaging, lidar and optical communications.

Proceedings Article | 21 September 2011 Paper

High-resolution imaging through horizontal path turbulence

William Rhodes, Diego Pava, Fraser Dalgleish, Gero Nootz, Sinjara Rishi Silva

Proceedings Volume 8122, 812202 (2011) https://doi.org/10.1117/12.895405

KEYWORDS: Turbulence, Signal detection, Fringe analysis, Fourier transforms, Statistical analysis, Atmospheric turbulence, Reflectivity, Sensors, Signal processing, Spatial frequencies

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Proceedings Article | 1 June 2011 Paper

Underwater laser serial imaging using compressive sensing and digital mirror device

Bing Ouyang, Fraser Dalgleish, Frank Caimi, Thomas Giddings, Joseph Shirron, Anni Vuorenkoski, Gero Nootz, Walter Britton, Brian Ramos

Proceedings Volume 8037, 803707 (2011) https://doi.org/10.1117/12.884156

KEYWORDS: Imaging systems, Matrices, Image processing, Binary data, Digital micromirror devices, Laser scattering, Receivers, Compressed sensing, Scattering, Modulation

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Proceedings Article | 19 May 2011 Paper

Experimental imaging performance evaluation for alternate configurations of undersea pulsed laser serial imagers

Fraser Dalgleish, Anni Vuorenkoski, Gero Nootz, Bing Ouyang, Frank Caimi

Proceedings Volume 8030, 80300B (2011) https://doi.org/10.1117/12.888640

KEYWORDS: Receivers, Scattering, Photons, Sensors, Imaging systems, Signal attenuation, Laser scattering, Pulsed laser operation, Target detection, Particles

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This paper examines imaging performance bounds for undersea electro-optic identification (EOID) sensors that use pulsed laser line scanners to form serial images, typically utilizing one laser pulse for each formed image element. The experimental results presented include the use of two distinct imaging geometries; firstly where the laser source and single element optical detector are nearly co-aligned (near monostatic) and secondly where the laser source is deployed on a separate platform positioned closer to the target (bistatic) to minimize source-to-target beam spread, volumetric scatter and attenuation, with the detector being positioned much further from the target. The former system uses synchronous scanning in order to significantly limit the required instantaneous angular acceptance function of the detector and has the desired intention of acquiring only ballistic photons that have directly interacted with the target element and the undesirable property of acquiring snake photon contributions that indirectly arrive into the detector aperture via multiple forward scattering over the two-way propagation path. The latter system utilizes a staring detector with a much wider angular acceptance function, the objective being to deliver maximum photon density to each target element and acquire diffuse, snake and ballistic photon contributions in order to maximize the signal. The objective of this work was to experimentally investigate pulse-to-pulse detection statistics for both imaging geometries in carefully controlled particle suspensions, with and without artificially generated random uncharacterized scattering inhomogeneities to assess potential image performance in realistic conditions where large biological and mineral particles, aggregates, thin biological scattering layers and turbulence will exist. More specifically, the study investigates received pulse energy variance in clear filtered water, as well as various well-characterized particle suspensions with and without an artificial thin random scattering layer. Efforts were made to keep device noise constant in order to assess the impact of the environment on extrapolated image quality.

Proceedings Article | 2 March 2010 Paper

Two-photon absorption and multi-exciton generation in lead salt quantum dots

Lazaro Padilha, Gero Nootz, Scott Webster, David Hagan, Eric Van Stryland, Larissa Levina, Vlad Sukhovatkin, Edward Sargent

Proceedings Volume 7600, 760008 (2010) https://doi.org/10.1117/12.842287

KEYWORDS: Lead, Absorption, Quantum dots, Semiconductors, Solar cells, Signal to noise ratio, Ultrafast phenomena, Femtosecond phenomena, Spectroscopy, Luminescence

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Proceedings Article | 31 August 2006 Paper

Two-photon absorption in direct bandgap semiconductors quantum dots

Lazaro Padilha, Jie Fu, G. Nootz, David Hagan, Eric Van Stryland, D. Buso, A. Martucci, Carlos Cesar, Luiz Barbosa, Carlos H. B. Cruz

Proceedings Volume 6327, 63270M (2006) https://doi.org/10.1117/12.681160

KEYWORDS: Quantum dots, Absorption, Semiconductors, Data modeling, Nanocrystals, Oscillators, Quantum optics, Nonlinear optics, Borosilicate glass, Glasses

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Proceedings Article | 27 December 2001 Paper

Structural analysis of chalcogenide waveguides using Rutherford backscattering spectroscopy (RBS)

Clara Rivero, Patricia Sharek, Gero Nootz, Cedric Lopez, Kathleen Richardson, Alfons Schulte, Richard Irwin, Tigran Galstian, Vincent Hamel, Karine Turcotte, Alain Villeneuve, Real Valee

Proceedings Volume 4468, (2001) https://doi.org/10.1117/12.452559

KEYWORDS: Arsenic, Waveguides, Multilayers, Ions, Glasses, Sulfur, Raman spectroscopy, Annealing, Backscatter, Selenium

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Showing 5 of 15 publications

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