Publications de Theo Lasser | EPFL Graph Search

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An instrument for high-speed laser perfusion imaging comprises a laser source, a detector, a signal-processing unit, data memory, and a screen to display the results. A section of the sample surface is illuminated with laser light; the reemitted light from ...

There have been three basic approaches to optical tomography since the early 1980s: diffraction tomography, diffuse optical tomography and optical coherence tomography (OCT). Optical techniques are of particular importance in the medical field, because these techniques promise to be safe and cheap and, in addition, offer a therapeutic potential. Advances in OCT technology have made it possible to apply OCT in a wide variety of applications but medical applications are still dominating. Specific advantages o

Optical coherence tomography (OCT) and optical coherence microscopy (OCM) allow the acquisition of quantitative three-dimensional axial flow by estimating the Doppler shift caused by moving scatterers. Measuring the velocity of red blood cells is currently ...

Research on synthetic delivery vectors is of major interest for cell imaging and manipulation, as they allow an efficient transfer of nucleic acids, therapeutic proteins or small drugs into the cells. We have developed a library of L-lysine analogues that allow for highly efficient gene delivery with low cytotoxicity. However little is known on the exact mechanism of uptake and the final intracellular destination of the synthetic carriers. Therefore we have developed a novel optical technique based on a mod

PURPOSE: To perform high speed and completely non-invasive 3D angiography at the optic nerve head region and to reconstruct vectorial 3D blood flow from optically segmented blood vessel structure as a pre-requisite for testing retinal function and physiolo ...

Spectral domain optical coherence tomography (OCT) is a widely employed, minimally invasive bio-medical imaging technique, which requires a broadband light source, typically implemented by super-luminescent diodes. Recent advances in soliton based photonic ...

Most diffraction-unlimited super-resolution imaging critically depends on the switching of fluorophores between at least two states, often induced using intense laser light and specialized buffers or UV radiation. Recently, so-called self-blinking dyes tha ...

A targeting device (35) determines a first location in an area under examination with reference to a system (13) of coordinates and makes coordinates for the first location available as a first coordinate set allocated to the first location. A topology capture device (37) produces a record of topological data in a 3D expanded area around the first location. An Independent claim is also included for a device for displaying the extent of a section produced from a section under examination. A device for detect

We present a novel Fourier domain method for microscopic imaging - so- called k-microscopy - with lateral resolution independent of the detection numerical aperture. The concept is based on sample illumination by a lateral fringe- pattern of varying spatial frequency, which probes the lateral spatial frequency or k- spectrum of the sample structure. The illumination pattern is realized by interference of two collimated coherent beams. Wavelength tuning is employed for modulation of the fringe spacing. The u

Endocrine beta cells produce and release insulin in order to tightly regulate glucose homeostasis and prevent metabolic pathologies such as Diabetes Mellitus. Optical imaging has contributed greatly to our current understanding of beta cell structure and f ...

With the use of a Bessel-like illumination beam produced by an axicon lens an extended depth of field can be achieved. The resulting illumination pattern exhibits a strong central lobe extending over 300um along the optical axis without diffraction. Here we present a fast digital focusing algorithm to correct for remaining out of focus artifacts, manifest in sidelobes for out of focus scatterers, due to the decoupled Gaussian detection. The waist of the detection in the focal plane is 2.1um, with a Rayleigh

We derive the behavior of the average exit time (i.e., the number of reflections before escape) of a ray path traveling between two perfect mirrors subject to dynamic random-tilt aberrations. Our calculation is performed in the paraxial approximation. When small random tilts are taken into account, we may consider an asymptotic regime that generically reduces the problem to the study of the exit time from an interval for a harmonic, frictionless oscillator driven by Gaussian white noise. Despite its apparen

Membrane protein research depends largely on the availability of functional protein in an instrumental set- up for application of biophysical investigations. We used an in vitro synthesis strategy in the presence of a solid supported lipid membrane as a new experimental strategy for the expression and membrane insertion of complex membrane proteins. Thus we realized the insertion of such a complex membrane protein, the odorant receptor OR5 from rat, which belongs to the highly important class of G-Protein c

We describe the design and performance of a new full-field high-speed laser Doppler imaging system developed for mapping and monitoring of blood flow in biological tissue. The total imaging time for 256x256 pixels region of interest is 1.2 seconds. An integrating CMOS image sensor is utilized to detect Doppler signal in a plurality of points simultaneously on the sample illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to- nois

Fluorophores that are fixed during image acquisition produce a diffraction pattern that is characteristic of the orientation of the fluorophore’s underlying dipole. Fluorescence localization microscopy techniques such as PALM and STORM achieve super-resolu ...

The invention relates to an adjustable pinhole, especially for the illumination beam path and/or detection beam path of a laser scanning microscope. Said pinhole consists of at least two planar basic components comprising articulation points in the form of connecting elements, to which at least one cutting edge that can be displaced in one direction is applied. The basic components advantageously contain at least one integrated preferably optical or electromagnetic positioning element, and a device for pref

The measurement of tissue and cell oxygenation is important for understanding cell metabolism. We have addressed this problem with a novel optical technique, called triplet imaging, that exploits oxygen-induced triplet lifetime changes and is compatible with a variety of fluorophores. A modulated excitation of varying pulse widths allows the extraction of the lifetime of the essentially dark triplet state using a high-fluorescence signal intensity. This enables the monitoring of fast kinetics of oxygen conc

Odorant receptors are an excellent example of natural superiority in binding specific, small and hydrophobic molecules, and therefore are of particular interest in the development of a sensor platform for G protein-coupled receptors (GPCRs). Odorant receptors (OR5) of Rattus norvegicus were incorporated into model membranes by in vitro synthesis and vectorial incorporation for achieving natural receptor function. The vectorial insertion of OR5 into the planar membrane and their lateral distribution, their i

We present optical coherence correlation spectroscopy (OCCS), a novel method to study the motion dynamics of nanoparticles within many observation volumes simultaneously. For this purpose, OCCS combines the key features of dark-field optical coherence microscopy (dfOCM) and fluorescence correlation spectroscopy (FCS). dfOCM is a Fourier domain optical coherence microscopy technique offering micrometer three-dimensional spatial resolution and microseconds temporal sampling. The rapid temporal sampling is ach

Theo Lasser

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High speed laser Doppler perfusion imaging system e.g. blood flow imaging system, detects laser Doppler signal and/or laser speckle signal from light reflected from selected blood vessel area, to obtain flow data

Optical coherence tomography - principles and applications

Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography

Assessing the cellular uptake pathway for poly-Lysine analogues using triplet lifetime imaging

Vectorial retinal blood flow and optical vessel vivisection for 3D angiography with high resolution resonant Doppler OCT

Laser perfusion imaging system for acquiring flow-related images of object for medical diagnosis comprises coherent light source and image sensor(s) made by randomly addressed two-dimensional array of integrating photodetectors

Soliton microcomb based spectral domain optical coherence tomography

Self-Blinking Dyes Unlock High-Order and Multiplane Super-Resolution Optical Fluctuation Imaging

Method for defining a location in a section under medical examination refers to a system of coordinates and subsequently to a collection of topological data

k-Microscopy: resolution beyond the diffraction limit

Towards high resolution optical imaging of beta cells in vivo

Enhancement of extended depth of field by digital focusing

Resonator stability subject to dynamic random-tilt aberration

In vitro Synthesis of GPCRs in a Solid Supported Planar Lipid Membrane System

Full-field high-speed laser Doppler imaging system for blood-flow measurements

Super-resolution orientation estimation and localization of fluorescent dipoles using 3-D steerable filters

Adjustable illumination or detection beam pinhole for laser scanning microscope has two knife blades with triangular apertures moving in front of slit with lamp and optical detector

Triplet imaging of oxygen consumption during the contraction of a single smooth muscle cell (A7r5)

Imaging of G protein-coupled receptors in solid-supported planar membranes at the single molecule level

Optical Coherence Correlation Spectroscopy (OCCS)