Mr. William Derrick Edwards Profile

William Derrick Edwards

IR Engineer at Dynetics Inc

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Author

Publications (5)

Proceedings Article | 9 June 2014 Paper

Reporting NETD: why measurement techniques matter

Ryan Rogers, W. Derrik Edwards, Caleb Waddle, Christopher Dobbins, Sam Wood

Proceedings Volume 9071, 90710T (2014) https://doi.org/10.1117/12.2050559

KEYWORDS: Cameras, Imaging systems, Collimation, Black bodies, Sensors, Collimators, Long wavelength infrared, Infrared imaging, Staring arrays, Infrared sensors

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Proceedings Article | 29 May 2014 Paper

Low-cost computational imaging infrared sensor

Kyle Bryant, W. Derrick Edwards, Ryan Rogers

Proceedings Volume 9071, 90710H (2014) https://doi.org/10.1117/12.2054609

KEYWORDS: Modulation transfer functions, Sensors, Optical filters, Convolution, Computational imaging, Prototyping, Image filtering, Image processing, Detection and tracking algorithms, Imaging systems

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Proceedings Article | 5 June 2013 Paper

Data analysis tools for imaging infrared technology within the ImageJ environment

Ryan Rogers, W. Derrik Edwards, Caleb Waddle, Christopher Dobbins, Sam Wood

Proceedings Volume 8706, 870608 (2013) https://doi.org/10.1117/12.2016043

KEYWORDS: Modulation transfer functions, Image processing, 3D image processing, Infrared imaging, Sensors, Excel, Image quality, Signal to noise ratio, Imaging systems, Infrared sensors

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Proceedings Article | 5 June 2013 Paper

Compensation for instrument anomalies in imaging infrared measurements

Christopher Dobbins, James Dawson, Jay Lightfoot, William Edwards, Ryan Cobb, Amanda Heckwolf

Proceedings Volume 8706, 870606 (2013) https://doi.org/10.1117/12.2015473

KEYWORDS: Sensors, Thermography, Black bodies, Temperature metrology, Staring arrays, Calibration, Quantum efficiency, Infrared imaging, Nonuniformity corrections, Infrared radiation

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Infrared imaging is commonly used for performing thermography based on field calibration that simply relates image levels to apparent temperature levels using field blackbodies. Under normal conditions, the correlation between the image levels and blackbody temperature is strong, allowing conversion of the raw data into units of blackbody-equivalent temperature without consideration of other factors. However, if certain instrument anomalies are present, a compensation procedure that involves more in-depth sensor characterization may be required. The procedure, which uses an analysis of temperature-dependent dark current, optical emissions, and detector response, is described along with results for a specific case. The procedure involves first cold soaking a thermal camera and then observing the cooldown behavior of the sensor under non-stressing conditions. Variations in environmental temperature levels are then used to observe cooler performance and dark current levels. A multi-variate linear regression is performed that allows temperature-dependent dark current, lens emission, lens transmission, and detector quantum efficiency to be fully characterized. The resulting data describe for each image pixel a relationship between the scene temperature and the observed values of image signal, detector temperature, and camera temperature. The procedure has been applied successfully to a thermal imager used to collect field data while suffering from instrument anomalies due to a faulty cooler. Using the resulting characterization data for the pixel-dependent dark current, image data collected with the thermal imager was compensated. The compensation involved using spatial filtering to determine temperature shifts caused by the faulty cooler based on the predictable pattern of pixel-to-pixel variations in dark current. The estimated temperature shift was used to compute a compensation offset for each pixel based on its known dark current coefficient. The compensated image data, while still degraded, was sufficiently corrected for the predictable effects of dark current variations to allow valid thermography to be performed.

Proceedings Article | 4 May 2010 Paper

Uncooled infrared development for small unmanned aerial vehicles

Timothy Pitt, Sam Wood, Caleb Waddle, William Edwards, Ben Yeske

Proceedings Volume 7660, 76600I (2010) https://doi.org/10.1117/12.855134

KEYWORDS: Cameras, Sensors, Infrared radiation, Systems modeling, Algorithm development, Infrared sensors, Computing systems, Microbolometers, NVThermIP, Neodymium

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