Mr. Derek J. Griffith Profile

Derek J. Griffith

Optical Engineer

SPIE Involvement:

Author

Area of Expertise:

Optical Design , Radiometry , Atmospheric Radiative Transfer

Websites:

Personal Website | Company Website

https://orcid.org/my-orcid?orcid=0000-0003-4498-9212

Proceedings Article | 24 January 2019 Paper

Flight hardware verification and validation of the K-line fire sensor payload on ZACube-2

Donovan Cogan, Derek Griffith, Edwin Magidimisha, Robert van Zyl

Proceedings Volume 11043, 110431A (2019) https://doi.org/10.1117/12.2503094

KEYWORDS: Sensors, Cameras, Satellites, Collimators, Flame detectors, Potassium, Imaging systems, Modulation transfer functions, Optical filters, Lenses

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Proceedings Article | 24 January 2019 Paper

Measurement of the thermal-vacuum defocus of an objective lens for an imaging payload on a CubeSat

Edwin Magidimisha, Derek Griffith

Proceedings Volume 11043, 1104318 (2019) https://doi.org/10.1117/12.2502328

KEYWORDS: Modulation transfer functions, Imaging systems, Satellites, Commercial off the shelf technology, Refractive index, Sensors, Thermal modeling, Cameras, Temperature metrology

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Proceedings Article | 7 September 2017 Paper

Investigation of the height dependency of optical turbulence in the surface layer over False Bay (South Africa)

Detlev Sprung, Alexander M. van Eijk, Willie Günter, Derek Griffith, Christian Eisele, Erik Sucher, Dirk Seiffer, Karin Stein

Proceedings Volume 10408, 104080U (2017) https://doi.org/10.1117/12.2275859

KEYWORDS: Optical turbulence, Atmospheric propagation, Atmospheric turbulence, Electro optics, Scintillation, Laser systems engineering, Optical testing, Meteorology, Turbulence

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Proceedings Article | 3 February 2017 Paper

Remote optical observations of actively burning biomass fires using potassium line spectral emission

Edwin Magidimisha, Derek Griffith

Proceedings Volume 10036, 1003611 (2017) https://doi.org/10.1117/12.2244284

KEYWORDS: Combustion, Potassium, Aerosols, Absorption, Chemical species, Image filtering, Atmospheric particles, Transmittance, Atmospheric modeling, Earth's atmosphere

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Proceedings Article | 19 October 2016 Paper

FESTER: a propagation experiment, overview and first results

Christian Eisele, Dirk Peter Seiffer, Karin Stein, Erik Sucher, Willem Gunter, Faith February, George Vrahimis, Carl Wainman, Benita Maritz, Mokete Koago, Alexander M. van Eijk, Miranda van Iersel, Leo Cohen, Sven van Binsbergen, H. J. M. (Eric) Heemskerk, Armin Sternberg, Helmut Schulte, Arthur van Rheenen, Erik Brenthagen, Jan Thomassen, Derek Griffith

Proceedings Volume 10002, 1000208 (2016) https://doi.org/10.1117/12.2240771

KEYWORDS: Atmospheric propagation, Aerosols, Atmospheric particles, Sensors, Mid-IR, Long wavelength infrared, Environmental sensing, Turbulence, Halogens, Temperature metrology

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Proceedings Article | 19 September 2016 Presentation + Paper

The FESTER field trial

Alexander M. van Eijk, Willie Gunter, Faith February, Benita Maritz, George Vrahimis, Mokete Koago, Carl Wainman, Christian Eisele, Dirk Seiffer, Erik Sucher, Karin Stein, Miranda van Iersel, Leo Cohen, Sven Van Binsbergen, H. J. M. (Eric) Heemskerk, A. Sternberg, H. Schulte, Arthur van Rheenen, Erik Brenthagen, Jan Thomassen, D. Griffith

Proceedings Volume 9979, 99790Q (2016) https://doi.org/10.1117/12.2240642

KEYWORDS: Electro optics, Environmental sensing, Long wavelength infrared, Turbulence, Sensors, Mid-IR, Atmospheric propagation, Aerosols, Temperature metrology, Metals

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Proceedings Article | 21 October 2014 Paper

Exploration of satellite-derived data products for atmospheric turbulence studies

Derek Griffith, Arshath Ramkilowan, Detlev Sprung, Erik Sucher, Cornelius Willers, Gert J. Coetzee, Ryno van Staden

Proceedings Volume 9242, 92421J (2014) https://doi.org/10.1117/12.2071893

KEYWORDS: Satellites, Heat flux, MODIS, Shortwaves, Reflectivity, Soil science, Humidity, Data modeling, Turbulence, Aerosols

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Proceedings Article | 21 October 2014 Paper

Investigation of optical turbulence in the atmospheric surface layer using scintillometer measurements along a slant path and comparison to ultrasonic anemometer measurements

D. Sprung, E. Sucher, A. Ramkilowan, D. Griffith

Proceedings Volume 9242, 92421I (2014) https://doi.org/10.1117/12.2070257

KEYWORDS: Optical turbulence, Atmospheric optics, Turbulence, Laser sintering, Meteorology, Light emitting diodes, Temperature metrology, Cameras, Electro optical systems, Imaging systems

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Optical turbulence represented by the structure function parameter of the refractive index C_n ² is a relevant parameter for the performance of electro-optical systems and characterization of the atmospheric influence on imaging. It was investigated during a field trial above an Highveld grassland in the atmospheric surface layer at the Rietvlei Nature Reserve close to Pretoria in South Africa from 18th June to 30th June 2013. This campaign was performed to compare different measurement techniques analyzing the diurnal formation of the vertical distribution of optical turbulence up to a height of 16 m above ground. The chosen time period was characterized by a pronounced diurnal cycle of the meteorological conditions, i.e. low variations from day to day. Ultra sonic anemometers were used to measure high frequency time series (50 Hz) of temperature at single points. From the statistical analysis of these time series C_n ² was derived. Three instruments were mounted at a portable mast in the center of slant path measurements over a horizontal distance of 1000 m using large aperture scintillometers (Boundary layer scintillometer BLS 900). Averaging over a time period of 5 minutes, the results of both methods are compared. The agreement in the results of optical turbulence is quite good. Discrepancies and agreement are analyzed with respect to the atmospheric stability and other meteorological parameters. Lowest values of C_n ² at 4.6 m above ground amount to about 8*10^-17 m^-2/3, daily maxima to 6*10^-13 m^-2/3. Additional to the nearly constant meteorological conditions in the diurnal cycle, the uniformity of the terrain let the results of this measurement campaign an ideal data set for investigating methodological questions regarding a comparison of single point measurements with integrated measurements over a horizontal distance. Four stability regimes were identified in the diurnal cycle and investigated. These are convective conditions during the day, neutral conditions about sunrise and sunset, and two different stable regimes at night.

Proceedings Article | 17 October 2013 Paper

Comparison of slant-path scintillometry, sonic anemometry and high-speed videography for vertical profiling of turbulence in the atmospheric surface layer

Derek Griffith, Detlev Sprung, Erik Sucher, Arshath Ramkilowan, Lufuno Vhengani

Proceedings Volume 8890, 889014 (2013) https://doi.org/10.1117/12.2032674

KEYWORDS: Turbulence, Video, Laser sintering, Cameras, Receivers, Light sources, Atmospheric turbulence, Environmental sensing, Atmospheric modeling, Light emitting diodes

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Proceedings Article | 2 October 2008 Paper

Measurement of atmospheric MTF in a littoral environment

Derek Griffith, Francois le Roux, Piet Schwering, Mark Holloway

Proceedings Volume 7113, 711308 (2008) https://doi.org/10.1117/12.799797

KEYWORDS: Modulation transfer functions, Scintillation, Telescopes, Image quality, Cameras, Turbulence, Receivers, Point spread functions, Atmospheric scintillation, Light emitting diodes

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SPIE Journal Paper | 1 May 2006

Estimating uncertainty in resolution tests

Duarte Goncalves, Derek Griffith

OE, Vol. 45, Issue 05, 053601, (May 2006) https://doi.org/10.1117/12.10.1117/1.2202914

KEYWORDS: Spatial frequencies, Image resolution, Quantization, Spatial resolution, Collimators, Optical engineering, Modulation, Optical components, Chemical elements, Estimation theory

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Proceedings Article | 1 April 1991 Paper

New approach to synchroballistic photography

Maurice McDowell, Heinz Klee, Derek Griffith

Proceedings Volume 1358, (1991) https://doi.org/10.1117/12.24020

KEYWORDS: Photography, Cameras

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