Dr. Brett Spivey Profile

Dr. Brett Spivey

at Jasr Systems

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Publications (8)

Proceedings Article | 12 June 2023 Presentation + Paper

Lidar tomography for remote sensing

Andre Van Rynbach, Sarah Krug, Andrew Reinhardt, Brett Spivey

Proceedings Volume 12537, 1253702 (2023) https://doi.org/10.1117/12.2663164

KEYWORDS: Tomography, LIDAR, Image restoration, Reconstruction algorithms, CT reconstruction, Remote sensing, Image resolution, Convolution, Computed tomography, Point spread functions

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Proceedings Article | 8 September 2006 Paper

Phase closure and object reconstruction algorithm for Fourier telescopy applied to fast-moving targets

Brett Spivey, James Stapp, David Sandler

Proceedings Volume 6307, 630702 (2006) https://doi.org/10.1117/12.682179

KEYWORDS: Reconstruction algorithms, Transmitters, Spatial frequencies, Fourier transforms, Signal to noise ratio, Algorithm development, Telescopes, Phase shifts, Receivers, Image restoration

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Proceedings Article | 7 September 2006 Paper

Simulation of a Fourier telescopy imaging system for objects in low Earth orbit

James Stapp, Brett Spivey, Laurence Chen, Lisandro Leon, Kevin Hughes, Dave Sandler, E. Louis Cuellar

Proceedings Volume 6307, 630701 (2006) https://doi.org/10.1117/12.676284

KEYWORDS: Transmitters, Receivers, Sensors, Speckle, Telescopes, Atmospheric modeling, Imaging systems, Space telescopes, Signal detection, Spatial frequencies

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Proceedings Article | 30 September 1999 Paper

Recovery of images from two-color pupil-plane speckle data using object-plane root matching and pupil-plane error minimization

Richard Holmes, Brett Spivey, Adlai Smith

Proceedings Volume 3815, (1999) https://doi.org/10.1117/12.364141

KEYWORDS: Speckle, Signal to noise ratio, Fourier transforms, Reconstruction algorithms, Reflectivity, Speckle pattern, Point spread functions, Convolution, Coherence imaging, Atmospheric turbulence

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Proceedings Article | 24 July 1998 Paper

Integrated CMOS-selenium x-ray detector for digital mammography

Michael Andre, Brett Spivey, Peter Martin, Arthur Morsell, Eugene Atlas, Tony Pellegrino

Proceedings Volume 3336, (1998) https://doi.org/10.1117/12.317019

KEYWORDS: Sensors, Selenium, X-rays, Mammography, Image sensors, Breast, X-ray detectors, Digital mammography, CMOS sensors, Transistors

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This paper describes a novel area detector for direct conversion and readout of the x-ray energy that eliminates multiple conversions and coupling stages which degrade performance. The pixel array and readout electronics are fabricated on the same piece of silicon. The detector consists of a uniform layer (approximately 300 micrometers) of amorphous selenium alloy vapor-deposited on an electronic readout array fabricated using conventional complementary metal oxide semiconductor (CMOS). The CMOS array features 66 micrometer pixels in a 1024 X 832 array providing a 5.5 X 6.75 cm image area. Each pixel has active circuitry including signal amplification, pixel selection and reset, while peripheral circuitry on one end of the array provides shift registers, sample and hold and multiplexing. The CMOS readout array was fabricated at a standard facility on a 10-cm diameter silicon wafer using 2 micrometer CMOS process. Fifteen separate image sensors were assembled for evaluation in a 3 X 5 format to provide a 20 X 27 cm composite field of view. Missing data between sensors is recovered by acquiring three sub-exposures, between which the array is translated diagonally approximately 2 mm. Total exposure time for an average breast is less than one second. Conversion efficiency was found to be approximately 120 electrons per absorbed x-ray (19 keV average). Electronic readout noise was measured to be 2.4 ADU corresponding to approximately 500 electrons. Detective quantum efficiency was found to be 0.65 at low spatial frequency (0.25 lp/mm) and at 0.2 at high spatial frequency (8 lp/mm) for x-ray fluence ranging from 5 - 35 mR. Images of an ACR phantom show visualization of all of the fibers, specks and masses when displayed with a linear lookup table on a high-resolution monitor. These studies demonstrated that there is a slight but measurable image retention evident as 'ghost' images. The two most effective means to reduce this effect are flushing the sensors with infrared light or x-rays between exposures and reversing the applied voltage on the selenium layer. A number of improvements designed to increase sensitivity and reduce noise also have been identified and are being implemented. Sample images were acquired from four volunteer human subjects at exposure factors identical to their film-screen mammograms. The results suggest that the detector performance is suitable for further clinical investigation.

Proceedings Article | 2 May 1997 Paper

Optimization of tungsten x-ray spectra for digital mammography: a comparison of model to experiment

Michael Andre, Brett Spivey

Proceedings Volume 3032, (1997) https://doi.org/10.1117/12.274009

KEYWORDS: Breast, Signal to noise ratio, Optical filters, X-rays, Tin, Molybdenum, Silver, Tungsten, Digital mammography, Quantum efficiency

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Proceedings Article | 14 November 1996 Paper

Image processing techniques for digital breast imaging

Gregory Otto, Douglas Palmer, Jean-Marie Tran, Brett Spivey, Stuart Clark

Proceedings Volume 2847, (1996) https://doi.org/10.1117/12.258251

KEYWORDS: X-rays, Image processing, Breast, Digital imaging, X-ray imaging, Cameras, Charge-coupled devices, Digital mammography, Sensors, Distortion

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Proceedings Article | 14 November 1996 Paper

Sheared-beam coherent image reconstruction

Steven Stahl, Richard Kremer, Paul Fairchild, Kevin Hughes, Brett Spivey, Robert Stagat

Proceedings Volume 2847, (1996) https://doi.org/10.1117/12.258219

KEYWORDS: Turbulence, Receivers, Image restoration, Signal to noise ratio, Sensors, Beam splitters, Modulation, Fourier transforms, Speckle, Atmospheric turbulence

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Showing 5 of 8 publications

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