Ralf Widenhorn
Assistant Research Professor
Portland State University
Department of Physics
Phone:(503) 725-8486
Lab: SB1 #42 (Basement Observatory)
e-mail: ralfw@pdx.edu


Research





 My research at Portland State University focuses on digital imagers:
Charge-Coupled Devices (CCDs)
and and more recently
Complementary Metal–Oxide–Semiconductors (CMOS)

CCDs are digital imagers found in most  digital cameras but also in high-end applications in science and astronomy. CMOS sensors are more common in consumer or cell phone cameras. They have also found their way into higher-end applications in recent years.

At PSU we have characterized digital imagers since 1996.
Recent projects include: 
Residual images and the Point spread function (PSF) in a CCD.
Dark current in CCD and CMOS cameras from lower grade consumer cameras to high end scientific cameras.


Teaching

General Physics
Workshops for General Physics
General Physics Laboratory
Physics in Biomedicine

Selected Publications

Justin C. Dunlap, Oleg Sostin, Erik Bodegom, and Ralf Widenhorn, Dark current behavior in DSLR cameras, Proceedings of SPIE Volume: 7249 (2009)

Ralf Widenhorn, Ines Hartwig, Justin C. Dunlap, and Erik Bodegom, Measurements of dark current in a CCD imager during light exposures, Proceedings of SPIE Volume: 6816 (2008)

William Porter, Bradley Kopp, Justin C. Dunlap, Ralf Widenhorn, and Erik Bodegom, Dark Current Measurements in a CMOS Imager, Proceedings of SPIE Volume: 6816 (2008)

Ralf Widenhorn; Armin Rest; Morley M. Blouke; Richard L. Berry; Erik Bodegom,  Computation of dark frames in digital imagers, Proceedings of SPIE Volume: 6501 (2007)

Erik Bodegom, Matthias Loch, and Ralf Widenhorn, Dual Meyer-Neldel Rules for Infrared Light in a Charge-Coupled Device, International Symposium, Optro 2005, Paris, France

Matthias Loch, Ralf Widenhorn, and Erik Bodegom, Infrared response of charge-coupled devices, Proceedings of SPIE Volume: 5677 (2005)

Ralf Widenhorn, Michael Fitzgibbons, and Erik Bodegom The Meyer-Neldel rule for diodes in forward bias, J. Appl. Phys. 96, 7379 (2004) 

E. Bodegom, R. Widenhorn, and D. A. Iordache, New Meyer-Neldel relations for the depletion and diffusion dark currents in some CCDs, Presented at International Semiconductor Conference (CAS) 2004, Sinaia, Romania

Ralf Widenhorn, Richard Berry, Armin Rest, and Erik Bodegom, Computation of dark frames, patent pending

Ralf Widenhorn, Ph. D. Thesis, “Characterization and modeling of dark current, residual images, and the point-spread function in charge-coupled devices”  (2004)

E. Bodegom, R. Widenhorn, D. A. Iordache, and V. Iordache, Numerical analysis of experimental data concerning the temperature dependence of dark current in CCDs, Proceedings of the 28th Annual Congress of the American-Romanian Academy of Arts and Sciences (ARA), vol.2, 763, (2003) 

Ralf Widenhorn, Morley M. Blouke, Alexander Weber, Armin Rest, and Erik Bodegom, Proc. 2003 IEEE Workshop on Charge-coupled Devices and Advanced Image Sensors (Schloss Elmau, Germany, May 2003)

Ralf Widenhorn, Alexander Weber, Morley M. Blouke, Albert J. Bae, and Erik Bodegom, PSF measurements on back-illuminated CCDs, Proc. SPIE Int. Soc. Opt. Eng. 5017, 176 (2003)

Ralf Widenhorn, Erik Bodegom, Interpreting fitting parameters, Proceedings of the second edition of the Colloquium "Mathematics in engineering of numerical physics", Bucharest, 26 (2002)

Ralf Widenhorn, Armin Rest, and Erik Bodegom, The Meyer-Neldel rule for a property determined by two transport mechanisms, J. Appl. Phys. 91, 6524 (2002)

Armin Rest, Lars Mündermann, Ralf Widenhorn, Erik Bodegom, and T. C. McGlinn, Residual images in charged-coupled device detectors, Rev. Sci. Instrum. 73, 2028 (2002)

Ralf Widenhorn, Morley M. Blouke, Alexander Weber, Armin Rest, and Erik Bodegom, Temperature dependence of dark current in a CCD, Proc. SPIE Int. Soc. Opt. Eng. 4669, 193 (2002)

Ralf Widenhorn, Lars Mündermann, Armin Rest, and Erik Bodegom, Meyer-Neldel rule for dark current in charge-coupled devices, J. Appl. Phys. 89, 8179 (2001)

Ralf Widenhorn, M. S. Thesis “Spectroscopy of dark current in CCD imagers”, 2000