OSC Colloquium: Lambertus Hesselink, "Recent Advances in Differential Phase Contrast 3-D X-ray..."

Jan. 4, 2022
Michael Raymer
Title: Recent Advances in Differential Phase Contrast 3-D X-ray Imaging with Applications to Medical Imaging and Aviation Security 
 
Abstract: 
Differential phase contrast imaging can provide direct access to electron density, and dark field (or small angle scatter) contrast enables access to surface and texture details significantly below the detector resolution. These new imaging capabilities offer the opportunity to image soft tissue for medical applications, or liquids and low density powders for aviation security applications. In contrast to sources for optical interferometers, X-ray sources are incoherent, requiring external means to create partially coherent photons. The standard grating based approach uses three gratings, G0, G1 and G2 to create a Talbot-Lau interferometer. The first grating G0 provides the partial coherence required for X-ray interference; the second grating G1 provides the interference of waves that generates a spatially modulated set of fringes at some distance away; the final grating G2 provides the means to interrogate the fringes before the coarse pixelated detector. We will review the basic theory, implementation challenges, progress made in our lab, and present applications. 
 
Speaker Bio: 
Dr. Lambertus Hesselink is Professor of Electrical Engineering and Applied physics, by courtesy. He has presented over 270 keynote and invited presentations at scientific meetings, has organized over 80 scientific meetings, published over 500 papers in scientific journals and over 15 book chapters, and was an editor of Applied Optics, Applied Scientific Research, and IEEE Transaction on Visualization. He has over 100 issued and pending patent applications worldwide. He pioneered 3-D optical data storage technology, demonstrating world-record performance in 2000. He built the first Internet controlled laboratory in 1998. His group pioneered the field of topological matrix and tensor visualization techniques in the middle 1990’s. He has founded three startup companies. He was VP, CTO and Chief Strategist for Branded Products at Western Digital Corporation. Among other honors, he is a Member of the Royal Dutch Academy of Arts and Sciences, Fellow of the OSA and SPIE, and he studied at Caltech as a Fulbright scholar.
 

 

 

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Past Speakers

donna strickland colloquium
3:30 – 5 p.m., Dec. 5, 2024

OSC Colloquium: Donna Strickland, "High Intensity Fiber lasers for Nonlinear Optics"

Ti:sapphire lasers offer the largest bandwidths and therefore the shortest pulses.   The highest laser intensities have been achieved using Chirped Pulse Amplification (CPA) of large diameter solid state lasers.  CPA was needed to avoid damage from the nonlinear process of self-focusing.  The disadvantage of solid-state lasers is the limited average power.  On the other hand, diode pumped fiber laser systems offer significantly higher average power than solid state lasers. Self-focusing is eliminated in single mode fibers by guiding and so nonlinear optics can be beneficial rather than detrimental and used to broaden the gain bandwidth.  Single fiber laser amplifiers will not reach the highest intensities offered by solid state lasers, but in this talk, I will discuss developing fiber laser amplifiers for nonlinear optical interactions such as mid-infrared generation and laser acceleration of electrons that require high intensity and benefit from high average power.
Hendra Nurdin
3:30 – 5 p.m., Nov. 21, 2024

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