Theo Lasser | EPFL Graph Search

De nationalité allemande, né en 1952 à Lauchheim (Baden-Württemberg, Allemagne).

Après des études de physique à l'Université Fridericiana de Karlsruhe il y obtient son diplôme de physique en 1978.

En 1979, il rejoint l'Institut de Recherches franco-allemand à Saint-Louis (France) comme collaborateur scientifique. En 1986, il entre à la division de recherche de Carl Zeiss à Oberkochen (Allemagne) où il développe principalement divers systèmes laser principalement pour des applications médicales. Dès 1990, il dirige le laboratoire laser de la division médicale. En 1993, il prend la direction de l'unité "laser d'ophtalmologie". En 1995, il est chargé de restructurer et regrouper les nombreuses activités d'ophtalmologie chez Carl Zeiss et de son transfert à Jena. Durant cette période, il réalise des nouveaux instruments de réfraction, des biomicroscopes et des caméras rétiniennes.

Dès janvier 1998, il dirige la recherche de Carl Zeiss à Jena où il initie de nouveaux projets en microscopie, en métrologie optique, en microtechnique et en recherche médicale. En juillet 1998, il est nommé professeur ordinaire en optique biomédicale à l'Institut d'Optique Appliquée. Au sein du Département de microtechnique, son activité de recherche porte sur la optique biomédicale et en particulier la microscopie. Il participe à l'enseignement de l'optique et de microscopie.

Short CV

1972 Physics University of Karlsruhe (Germany)

1979 l'Institut de Recherches franco-allemand à Saint-Louis (France)

1986 central research division Carl Zeiss, Oberkochen (Germany)

1990 Med - Division, ophthalmic lasers

1994 Ophthalmology division, Carl Zeiss Jena

1998 Head of Central research Carl Zeiss Jena

1998 full Professor Ecole Polytechnique Federale Lausanne, Switzerland

High-speed multiplane structured illumination microscopy of living cells using an image-splitting prism

Adrien Charles-François Raymond Descloux, Theo Lasser, Tomas Lukes, Vytautas Navikas, Aleksandra Radenovic

Super-resolution structured illumination microscopy (SR-SIM) can be conducted at video-rate acquisition speeds when combined with high-speed spatial light modulators and sCMOS cameras, rendering it particularly suitable for live-cell imaging. If, however, three-dimensional (3D) information is desired, the sequential acquisition of vertical image stacks employed by current setups significantly slows down the acquisition process. In this work, we present a multiplane approach to SR-SIM that overcomes this slowdown via the simultaneous acquisition of multiple object planes, employing a recently introduced multiplane image splitting prism combined with highspeed SIM illumination. This strategy requires only the introduction of a single optical element and the addition of a second camera to acquire a laterally highly resolved 3D image stack. We demonstrate the performance of multiplane SIM by applying this instrument to imaging the dynamics of mitochondria in living COS-7 cells.

2020

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

Theo Lasser, Tomas Lukes, Aleksandra Radenovic

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 that switch spontaneously between an open, fluorescent "on" state and a closed, colorless "off" state were introduced. Here, we exploit the synergy between super-resolution optical fluctuation imaging (SOFI) and spontaneously switching fluorophores for 2D and 3D imaging. SOFI analyzes higher order statistics of fluctuations in the fluorophore emission instead of localizing individual molecules. It thereby tolerates a broad range of labeling densities, switching behavior, and probe brightness. Thus, even dyes that exhibit spontaneous blinking characteristics that are not suitable or suboptimal for single molecule localization microscopy can be used successfully for SOFI-based super-resolution imaging. We demonstrate 2D imaging of fixed cells with almost uniform resolution up to 50-60 nm in 6th order SOFI and characterize changing experimental conditions. Next, we investigate volumetric imaging using biplane and eight-plane data acquisition. We extend 3D cross-cumulant analysis to 4th order, achieving super-resolution in 3D with up to 29 depth planes. Finally, the low laser excitation intensities needed for single and biplane self-blinking SOFI are well suited for live-cell imaging. We show the perspective for time-resolved imaging by observing slow membrane movements in cells. Self-blinking SOFI thus provides a more robust alternative route for easy-to-use 2D and 3D high-resolution imaging.

AMER CHEMICAL SOC2020

Spectral cross-cumulants for multicolor super-resolved SOFI imaging

Adrien Charles-François Raymond Descloux, Kristin Stefanie Grussmayer, Theo Lasser, Marcel Leutenegger, Tomas Lukes, Aleksandra Radenovic

Super-resolution opticalfluctuation imaging provides a resolution beyond the diffraction limitby analysing stochasticfluorescencefluctuations with higher-order statistics. Usingnthorderspatio-temporal cross-cumulants the spatial resolution and the sampling can be increased upton-fold in all spatial dimensions. In this study, we extend the cumulant analysis into thespectral domain and propose a multicolor super-resolution scheme. The simultaneousacquisition of two spectral channels followed by spectral cross-cumulant analysis andunmixing increases the spectral sampling. The number of discriminablefluorophore species isthus not limited to the number of physical detection channels. Using two color channels, wedemonstrate spectral unmixing of threefluorophore species in simulations and experimentsinfixed and live cells. Based on an eigenvalue/vector analysis, we propose a scheme for anoptimized spectralfilter choice. Overall, our methodology provides a route for easy-to-implement multicolor sub-diffraction imaging using standard microscopes while conservingthe spatial super-resolution property.

2020