Microwavephysics and Atmospheric Physics
Biomedizinische Photonik
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HS 2017  ·  FS 2017
HS 2016  ·  FS 2016
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HS 2012  ·  FS 2012
Ultrafast Science and Technology
Last update: 19.07.2018
HS 2013: Seminare über Biomedizinische Photonik
Wednesday 10-12
Vorträge, die innerhalb der nächsten Tage stattfinden, sind speziell markiert.
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Mittwoch, 02.10.2013

Monte Carlo modeling of polarized light propagation: Stokes vs Jones

Zeit: 10:15 Uhr
Hörsaal: B116
Dr. Hidayet Günhan Akarçay
Institute of Applied Physics
University of Bern

Half a century after their emergence, the "Stokes-Mueller" and "Jones" calculi have arguably gained a new momentum with the development of polarized Monte Carlo simulations. Most groups opt for the Stokes vector -- hence dealing with intensities -- whereas only few authors prefer to use the Jones one -- involving amplitudes. The popularity of the Stokes formalism could be explained by several reasons, of which a recurrent claim which assumes that the Jones formalism does not allow the treatment of depolarizing effects. Is this claim still relevant in the modern context of Monte Carlo simulations? What are the (dis)similarities between "Stokes-Mueller" and "Jones" when modeling unpolarized light / fluctuations? A comparative study was conducted between the Universities of Bern and Ulm to answer these questions.

Mittwoch, 09.10.2013

Towards global brain connectivity analysis by diffusion MRI

Zeit: 10:15 Uhr
Hörsaal: B116
Prof. Jean-Philippe Thiran
EPFL / Signal Processing Laboratory (LTS5)
and University Hospital Center (CHUV) and University of Lausanne (UNIL)
Department of Radiology

In this talk I will discuss diffusion MR imaging as a tool for in-vivo study of brain macroscopic connectivity. I will first explain how MR imaging can be used to measure diffusion in the human brain and how the diffusion phenomenon is related to white matter architecture. Several diffusion MR protocols will be presented, including Diffusion Tensor Imaging (DTI) and Diffusion Spectrum Imaging (DSI). Then I will show advanced image analysis techniques developed to infer information on brain connectivity from diffusion MR images, and how this can be applied to study global brain connectivity both in normal and pathological cases.

Mittwoch, 16.10.2013

Electrospinning: Methods and the way to applications in medicine and technology

Zeit: 10:15 Uhr
Hörsaal: B116
Dr. Roland Dersch
Macromolecular Chemistry
University of Bayreuth

Several methods for the defined production of structured Micro- and Nanofibers by electrospinning will be presented. These include the modification of the electrospinning process itself, like co-electrospinning but also the use of water-based systems that allow the production of water-stable fibers without the use of harmful solvents. Diferent areas of application, like tissue engineering, will be shown.

Mittwoch, 06.11.2013

Localised Vibration tagging for clutter reduction in optoacoustic imaging

Zeit: 10:15 Uhr
Hörsaal: B116
Sara Peeters
Institute of Applied Physics
University of Bern

Clutter, caused by strong off-plane OA transients and acoustic echoes, significantly limits imaging depth in clinical epi-mode optoacoustic (OA) imaging. Localised vibration tagging – LOVIT – is a clutter reduction method in which acoustic radiation force (ARF) in the focus of an ultrasonic beam “tags” the OA signal at its origin. Past experiments employing a separate transducer for ARF have shown that the resulting localised displacement allows the retrieval of optical absorbers within the clutter background. In this talk, the combination of ARF and imaging using the same ultrasound probe is investigated in simulations and experiments. This combination offers several advantages over a separate ARF transducer, and is a significant step towards clinical application.

Mittwoch, 27.11.2013

Characterization of clutter in optoacoustic signals of human forearms

Zeit: 10:15 Uhr
Hörsaal: B116
Stefan Preisser
Institute of Applied Physics
University of Bern

Optoacoustic imaging is a clinical imaging modality that is sensitive to local variations of optical absorption. Tissue is illuminated with a laser pulse of a length of a few nanoseconds, and naturally occurring optical absorbers, such as red blood cells, serve as localized sources of optoacoustically generated ultrasound signals: the absorbed energy is released to the tissue by thermalization, leading to a small temperature rise and, thus, a localized pressure increase. This pressure perturbation propagates as an ultrasound wave through the tissue and can be detected on the tissue surface using an ultrasound transducer. In theory, an imaging depth of 5 cm can be achieved by using near infrared light, limited by optical attenuation. However, in vivo measurements have shown that a depth larger than 2 cm is difficult to achieve because the localized optoacoustic signal are obscured by clutter signals. In this seminar I will discuss the characteristics of these clutter signals on the example of optoacoustic measurements of the human forearm, the impact on the imaging depth and the possibilities to reduce these clutter signals.

Donnerstag, 05.12.2013

Basics of OCT and some Projects at optolab, BUAS Biel

Zeit: 10:15 Uhr
Hörsaal: A4
Prof. Christoph Meier
Berner Fachhochschule Technik und Informatik
Standort Biel, Mikrotechnik

In a short introduction, the basics of Optical Coherence Tomography OCT are presented, including some more engineering related aspects of the OCT signal processing. The second part of the presentation is dedicated to current R&D projects running at optoab.

Mittwoch, 11.12.2013

Analysis of Street Cocaine with Infrared Spectroscopy

Zeit: 10:15 Uhr
Hörsaal: B116
Tigran Petrosyan
ETH Zürich
Laser Spectroscopy and Sensing Laboratory

We present a new method for cocaine detection in saliva based on attenuated total reflection (ATR) spectroscopy and quantum cascade laser (QCL) spectroscopy combined with simple one-step extraction. It demonstrates an efficient cocaine base extraction out of street samples and minor extraction of cutting agents and leads to limit of detection (LOD) of ~1µg cocaine per 1ml of saliva. Preconcentration ensures a further reduction of LOD. This method of cocaine extraction and detection is an important step towards a compact, easy-to-use, hand-held device for semi-quantitative on-road-side testing of cocaine. It can also be applied for extraction of other substances from liquids for other optical sensor schemes.

Mittwoch, 18.12.2013

Internship presentation:
Integration of spacial light modulation into a reflective contrast setup

Zeit: 10:15 Uhr
Hörsaal: B116
Willi Stepp
Internship IAP, Biomedical Photonics