Publications de Theo Lasser | EPFL Graph Search

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We present a 3D time-lapse imaging method for monitoring mitochondrial dynamics in living HeLa cells based on photothermal optical coherence microscopy and using novel surface functionalization of gold nanoparticles. The biocompatible protein-based biopoly ...

Parallel optical coherence tomography in scattering samples is demonstrated using a 58 x 58 smart-pixel detector array. A femtosecond mode-locked Ti:Sapphire laser in combination with a free space Michelson interferometer was employed to achieve 4 mum longitudinal resolution and 9 mum transverse resolution on a 260 x 260 mum field of view. We imaged a resolution target covered by an intralipid solution with different scattering coefficients as well as onion cells. (C) 2002 Published by Elsevier Science B.V.

We report a bioinspired multifunctional albumin derived polypeptide coating comprising grafted poly(ethylene oxide) chains, multiple copies of the HIV TAT derived peptide enabling cellular uptake as well as mitochondria targeting triphenyl-phosphonium (TPP ...

There is a continuous demand for imaging probes offering excellent performance in various microscopy techniques for comprehensive investigations. of cellular processes by more than, one technique. FluoreScent nanodianiond gold nanoparticles (END Au) consti ...

We developed a dual-color total internal reflection fluorescence (TIRF) system for single molecule imaging and fluorescence fluctuation spectroscopy (FFS). For a performance analysis, we measured a synthetic binding assay with dual-color global fluorescence correlation spectroscopy (2CG-FCS) and dual-color fluorescence intensity distribution analysis (2D-FIDA). We show that dual-color TIR-FFS is a suitable method for measuring coincidence assays at the surface. In particular, our setup has a very high fluor

Method for detecting amyloidogenic proteinaceous material induced by a proteopathy, for instance Alzheimer's disease, characterized by the fact that said amyloidogenic proteinaceous material is detected in a mammal waste product, such as feces. ...

A new numerical a posteriori dispersion compensation technique for partial coherence interferometry and optical coherence tomography depth-scan signals is presented. This technique is based on numerical correlation of the depth-scan interferometer signal with a depth-variant kernel. Examples of dispersion compensated depth-scan signals obtained from microscope cover glasses are presented. (C) 2002 Elsevier Science B.V. All rights reserved.

We introduce a simple and cheap method for phase-shifting Fourier domain optical coherence tomography (FDOCT) that does not need additional devices and can easily be implemented. A small beam offset at the fast beam-scanning mirror introduces a causal phase shift, which can be used for B-scan-based complex image reconstruction. We derive the conditions for optimal conjugate suppression and demonstrate the method on human skin in vivo for spectrometer-based FDOCT operating at 1300nm employing a handheld scan

An optical method is presented that allows the measurement of the triplet lifetime of a fluorescent molecule. This is a characteristic specific to each fluorophore. Based on differences in triplet lifetimes of two fluorescent species (autofluorescence vers ...

We demonstrate a simple and cheap method for phase shifting that does not need additional devices. A small beam offset at the fast scanning mirror introduces a causal phase shift which can be used for recently introduced B-scan based complex image reconstruction as well as for enhancing flow signals with resonant Doppler imaging. It can be directly implemented in any FDOCT setup without additional cost. The method is demonstrated on human skin in vivo for spectrometer based FDOCT operating at 1300nm employi

The diffusion of charged proteins in liquid-filled nanometer-sized apertures with charged surfaces has been investigated with fluorescence correlation spectroscopy (FCS). Based on a two-dimensional (2D) multicomponent diffusion model, key parameters such a ...

Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing. (C) 2003 Optical Society of America.

It is important to characterize and quantify the imaging performance of optical coherence tomography (OCT) and especially optical coherence microscopy (OCM) systems for validation and calibration of the setup. We suggest using a simple rubber surface, presented to the setup at different focal positions, to measure the system’s lateral resolution and depth of field. Rubber is a nearly perfect scatterer and produces a fully developed speckle pattern. The speckle size and shape are directly defined by the opti

Optical coherence microscopy (OCM) is an interferometric technique providing 3D images of biological samples with micrometric resolution and penetration depth of several hundreds of micrometers. OCM differs from optical coherence tomography (OCT) in that i ...

We present a novel concept for optical spectroscopy called nonlinear correlation spectroscopy (NLCS). NLCS analyses coherent field fluctuations of the second and third harmonic light generated by diffusing nanoparticles. Particles based on noncentrosymmetr ...

Diabetes is characterized by hyperglycemia that can result from the loss of pancreatic insulin secreting β-cells in the islets of Langerhans. We analyzed ex vivo the entire gastric and duodenal lobes of a murine pancreas using extended-focus Optical Cohere ...

Fluorescence correlation spectroscopy (FCS) has emerged as a powerful technique for measuring low concentrations of fluorescent molecules and their diffusion constants. In FCS, the experimental data is conventionally fit using standard local search techniq ...

Alzheimer's disease (AD) is characterized by amyloidosis of brain tissues. This phenomenon is studied with genetically-modified mouse models. We propose a method to quantify amyloidosis in whole 5xFAD mouse brains, a model of AD. We use optical projection ...

Comparison of two illumination modes for wide-field optical coherence tomography has revealed that spatially coherent illumination generates coherent cross talk, causing significant image degradation, and that spatially incoherent illumination, with an adequate interferometer design, provides an efficient mechanism for suppression of coherent cross talk. This is shown by comparison of a pulsed laser with a thermal light source for a U.S. Air Force resolution target covered with a scattering solution made fr

Theo Lasser

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3D Time-lapse Imaging and Quantification of Mitochondrial Dynamics

Parallel optical coherence tomography in scattering samples using a two-dimensional smart-pixel detector array

NIR-emitting and photo-thermal active nanogold as mitochondria-specific probes

Fluorescent Nanodiamond–Gold Hybrid Particles for Multimodal Optical and Electron Microscopy Cellular Imaging

Dual-color Total Internal Reflection Fluorescence Fluctuation Spectroscopy

Use of waste products for detecting amyloidogenic proteinaceous material in living mammals

Dual-color Total Internal Reflection Fluorescence Fluctuation Spectroscopy

Dispersion compensation for optical coherence tomography depth-scan signals by a numerical technique

Complex ambiguity-free Fourier domain optical coherence tomography through transverse scanning

Assessment of transferrin recycling by Triplet Lifetime Imaging in living cells

Phase manipulation without phase shifter for complex FDOCT signal reconstruction and resonant Doppler imaging

Direct Observation of Transitions between Surface-Dominated and Bulk Diffusion Regimes in Nanochannels

Optical sectioning in wide-field microscopy obtained by dynamic structured light illumination and detection based on a smart pixel detector array

Measurement of the coherent transfer function

Interferometric synthetic aperture microscopy for extended focus optical coherence microscopy

Nonlinear Correlation Spectroscopy (NLCS)

Diabetes imaging — quantitative assessment of islets of Langerhans distribution in murine pancreas using extended-focus optical coherence microscopy

Stochastic Approach to Data Analysis in Fluorescence Correlation Spectroscopy

Supervised learning to quantify amyloidosis in whole brains of an Alzheimer's disease mouse model acquired with optical projection tomography

Spatially incoherent illumination as a mechanism for cross-talk suppression in wide-field optical coherence tomography