Dr. Thomas J. Karr Profile

Dr. Thomas J. Karr

Consultant

SPIE Involvement:

Conference Program Committee | Author | Editor

Area of Expertise:

Remote Sensing , Optical Communications , Active EO Sensors , Quantum Information , Laser Radar , Space Astronomy

30 years' experience in applied physics R&D
12 years as a scientist and manager at Lawrence Livermore National Lab
Advisor to DARPA
Founder of a commercial remote sensing company
Executive Director of a satellite communications company
Many scientific publications in refereed journals
Former editor of the journal Applied Optics

Proceedings Article | 14 May 2018 Paper

Propagation of infrared ultrashort pulses in the air

Thomas Karr, Larry Stotts, Jason Schmidt, Jason Tellez, Justin Mansell

Proc. SPIE. 10684, Nonlinear Optics and its Applications 2018

KEYWORDS: Ultrafast phenomena, Transmitters, Mid-IR, Short wave infrared radiation, Dispersion, Kerr effect, Turbulence, Infrared radiation, Atmospheric propagation, Plasma

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Proceedings Article | 31 October 2014 Paper

The future dynamic world model

Thomas Karr

Proc. SPIE. 9254, Emerging Technologies in Security and Defence II; and Quantum-Physics-based Information Security III

KEYWORDS: Defense and security, 3D surface sensing, Data modeling, Sensors, Satellites, Sensing systems, Defense technologies, Systems modeling, Situational awareness sensors, Compressed sensing

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SPIE Journal Paper | 1 January 2008

Operational characteristics of a long-wavelength IR multispectral imager based on an acousto-optic tunable filter

Narsingh Singh, David Kahler, David Knuteson, M. Gottlieb, D. Suhre, Andre Berghmans, Brian Wagner, Jerry Hedrick, Thomas Karr, Jack Hawkins

OE Vol. 47 Issue 01

KEYWORDS: Crystals, Long wavelength infrared, Imaging systems, Acousto-optics, Thallium, Transducers, Cameras, Mercury, Acoustics, Infrared imaging

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Proceedings Article | 26 September 2007 Paper

Phase and frequency stability for synthetic aperture LADAR

Thomas Karr, John Glezen, Henry Lee

Proc. SPIE. 6712, Unconventional Imaging III

KEYWORDS: Oscillators, Imaging systems, LIDAR, Sensors, Synthetic aperture radar, Fourier transforms, Image resolution, Chromium, Image quality, Phase measurement

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Proceedings Article | 26 September 2007 Paper

Signal-to-noise ratios of coherent imaging LADAR

Thomas Karr

Proc. SPIE. 6712, Unconventional Imaging III

KEYWORDS: Target detection, Radar, Signal to noise ratio, Coherence imaging, Imaging systems, Speckle, LIDAR, Synthetic aperture radar, Interference (communication), Signal analyzers

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Proceedings Article | 26 April 2007 Paper

Operational characteristics of LWIR AOTF based multispectral imager

N. Singh, M. Gottlieb, D. Suhre, D. Kahler, D. Knuteson, A. Berghmans, B. Wagner, J. Hedrick, T. Karr, J. Hawkins

Proc. SPIE. 6554, Chemical and Biological Sensing VIII

KEYWORDS: Microbolometers, Long wavelength infrared, Imaging systems, Cameras, Crystals, Transducers, Gas lasers, Thallium, Acoustics, Acousto-optics

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Proceedings Article | 10 November 2003 Paper

Synthetic aperture ladar for planetary sensing

Thomas Karr

Proc. SPIE. 5151, Earth Observing Systems VIII

KEYWORDS: Imaging systems, LIDAR, Sensors, Synthetic aperture radar, Image resolution, Receivers, Heterodyning, Phase measurement, Planets, Microwave radiation

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Proceedings Article | 30 April 2003 Paper

Synthetic aperture ladar resolution through turbulence

Thomas Karr

Proc. SPIE. 4976, Atmospheric Propagation

KEYWORDS: Transmitters, Point spread functions, LIDAR, Video, Image resolution, Receivers, Wave propagation, Turbulence, Modulation transfer functions, Atmospheric propagation

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Proceedings Article | 1 May 1990 Paper

Effect of a random wind field on thermal blooming instabilities

James Morris, James Viecelli, Thomas Karr

Proc. SPIE. 1221, Propagation of High-Energy Laser Beams Through the Earth's Atmosphere

KEYWORDS: Refractive index, Laser beam propagation, Wave propagation, Phase compensation, Turbulence, Earth's atmosphere, Atmospheric propagation, Thermal blooming, Neptunium, Absorption

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We have numerically investigated the effect of random fluctuations on uncompensated (open-loop) and phase-compensated (closed-loop) small -scale thermal blooming instabilities of a collimated beam propagating through refractive index turbulence. We used the ORACLE time-dependent, three space-dimensional, wave-optics code on a Cray X-MP. The Monte Carlo random wind fields, v(z), were exponentially correlated along the propagation direction, z. The small scale instabilities are present up to a threshold value of the rms random wind, beyond which beam propagation appears to be stable; the threshold value is nearly independent of the correlation length as long as the latter is much shorter than both the length of the thermal blooming region and the Rayleigh range of dominant perturbations. We describe our results with a dimensionless shear parameter, S, that is directly proportional to the ratio of the turbulence scintillation rate to the thermal blooming rate. S is defined as: (formula available on paper) is the one-axis variance of the random wind and N is the time derivative of the thermal blooming optical path difference (OPD) in waves/sec. The open-loop calculations use a plane wave “beam” and a uniform medium. The Strehl ration at 50 waves of thermal blooming OPD remains approximately constant while S ≥ 2.3 and then it decreases rapidly as S decreases. The closed-loop calculations use a large Fresnel number finite beam, a non-uniform medium of length sL, absorption - exp(-z/L), and a Hufnagel-Valley typ On2 profile whose r0 Fresnel number was 24. For 10 is less than or equal to Np is less than or equal to 40 we see no evidence of the closed-loop instability at a wind clearing time (20 waves) for S ≥ (54 ± 2)/Np, where (formula available on paper) is twice the actuator spacing simulated by a Fourier filter. This rresult suggests that the ration of the turbulence scintillation rate to the closed-loop gain for a uniform wind determines the threshold.

Proceedings Article | 1 May 1990 Paper

Measurement of the stimulated thermal Rayleigh scattering instability

Thomas Karr, Michael Rushford, John Murray, James Morris

Proc. SPIE. 1221, Propagation of High-Energy Laser Beams Through the Earth's Atmosphere

KEYWORDS: Scattering, Diffusion, Laser scattering, Laser beam propagation, Wave propagation, Rayleigh scattering, Earth's atmosphere, Atmospheric propagation, Beam propagation method, Thermal blooming

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Proceedings Article | 1 May 1990 Paper

Linear theory of thermal blooming in turbulence

David Chambers, Thomas Karr, James Morris, P. Cramer, James Viecelli, A. Gautesen

Proc. SPIE. 1221, Propagation of High-Energy Laser Beams Through the Earth's Atmosphere

KEYWORDS: Refractive index, Laser beam propagation, Wave propagation, Phase compensation, Turbulence, Wind energy, Earth's atmosphere, Atmospheric propagation, Thermal blooming, Absorption

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Proceedings Article | 1 May 1990 Paper

Turbulent mixing effects in models of thermal blooming

David Chambers, James Viecelli, Thomas Karr

Proc. SPIE. 1221, Propagation of High-Energy Laser Beams Through the Earth's Atmosphere

KEYWORDS: Refractive index, Laser beam propagation, 3D modeling, Turbulence, Scintillation, Earth's atmosphere, Atmospheric propagation, Thermal blooming, Thermal modeling, Atmospheric modeling

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Proceedings Article | 1 May 1990 Paper

Instabilities of atmospheric laser propagation

Thomas Karr

Proc. SPIE. 1221, Propagation of High-Energy Laser Beams Through the Earth's Atmosphere

KEYWORDS: Laser beam propagation, Adaptive optics, Deformable mirrors, Computer simulations, Wave propagation, Turbulence, Rayleigh scattering, Earth's atmosphere, Atmospheric propagation, Thermal blooming

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