Publications de Theo Lasser | EPFL Graph Search

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Super-resolution optical fluctuation imaging (SOFI) provides an elegant way of overcoming the diffraction limit in all three spatial dimensions by computing higher-order cumulants of image sequences of blinking fluorophores acquired with a classical widefi ...

A system for full-field laser Doppler blood flow imaging has been developed and tested on biomedical samples. The new imaging system allows 2D flow maps or monitoring flux signals to be obtained from a plurality of measured points simultaneously by using a ...

In this paper we present recent single molecule detection experiment using a solid immersion lens (SIL) for fluorescent correlation spectroscopy measurements. We compared the performance of the SIL in combination with an air objective (40×, numerical aperture (NA)=0.6) with a water immersion objective (40×, NA=1.15) in a confocal microscope system (ConfoCorr 1). Important parameters for single molecule experiments such as collection efficiency and excitation field confinement were investigated. Although the

We report on the fabrication of two-dimensional arrays of nano-optical apertures in gold layers by electron beam lithography (EBL) on a transparent glass substrate. 30 x 30 μ m(2) large arrays of high aspect ratio sub-wavelength cylinders (400 nm diameter ...

One of the main drawbacks of Fourier domain optical coherence tomography (FDOCT) is the limited measurement depth range. Phase shifting techniques allow reconstructing the complex sample signal resulting in a doubled depth range. In current complex FDOCT r ...

The invention relates to an interferometer system (41), especially for use in a co-ordinate measuring system. Said interferometer system comprises, disposed in an illumination beam path, a pair of spaced-apart boundary surfaces (52, 53). A boundary surface (53) facing an object (9) is arranged in a detection beam path, a detector (61) being additionally disposed in said detection beam path. The invention also relates to an interferometer system, especially one of the above-described type, which is provided

Dispersive samples introduce a wavelength dependent phase distortion to the probe beam. This leads to a noticeable loss of depth resolution in high resolution OCT using broadband light sources. The standard technique to avoid this consequence is to balance the dispersion of the sample by arranging a dispersive material in the reference arm. However, the impact of dispersion is depth dependent. A corresponding depth dependent dispersion balancing technique is diffcult to implement. Here we present a numerica

Aims/hypothesis It is generally accepted that structural and functional quantitative imaging of individual islets would be beneficial to elucidate the pathogenesis of type 1 diabetes. We here introduce functional optical coherence imaging (FOCI) for fast, ...

Odorant receptors are an excellent example of natural superiority in binding specific small and hydrophobic molecules. Difficulties in expression, isolation and solubilisation of these receptors have been overcome recently by in vitro synthesis and incorporation of receptors into a planar lipid membrane [1,2]. The incorporation density and the mobility of the membrane embedded receptors were analyzed at the single-molecule level by means of image correlation spectroscopy [3,4]. Instead of a confocal scannin

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-resolution by applying Gaussian-based fitting algorithms to in-focus images of individual fluorophores; when applied to fixed dipoles, this can lead to a bias in the range of 5-20 nm.We introduce a method for the joint estimation of position and orientation of d

The invention relates to a method and device for identifying luminescent molecules according to the fluorescence correlation spectroscopy method. The inventive method comprising the following steps: a) preparing a sample (12) containing luminescent molecul ...

Fluorescent nanodiamonds (fNDs) represent an emerging class of nanomaterials offering great opportunities for ultrahigh resolution imaging, sensing and drug delivery applications. Their biocompatibility, exceptional chemical and consistent photostability r ...

We introduce a novel microscopy method of probing the spatial frequencies of a two dimensional sample with a single point detector allowing for sub- micron resolution with low NA lenses as well as for lateral phase resolution in the nanometer range. We synthesize the spatial frequency coordinate space by illuminating a sample with a TIR configuration and lateral interference fringes generated by a wavelength tunable light source. Similar to OCT the temporal coherence defines the resolution up to the illumin

During open brain surgery we acquire perfusion images non-invasively using laser Doppler imaging. The regions of brain activity show a distinct signal in response to stimulation providing intraoperative functional brain maps of remarkably strong contrast. ...

Optical near field microscope for use with different, including differential contrast, methods. Microscope has a near field illuminating light source probe (3) and a photo-detector for detection of light from the object (6). Said detector has electronics for processing the detected signals to yield details of object structures. The photo-detector (9) is a structured photo-receiver and outputs photo-receiver signals to the evaluation electronics. The invention also relates to a corresponding method.

Laser Doppler (LDI) and laser speckle imaging (LSI) are two optical non-invasive techniques that are used to obtain 2D maps of blood flow in biological tissues. Each of these techniques has some benefits and drawbacks for measuring the blood flow. LSI is a true real-time imaging technique, but less sensitive to changes of flow parameters such as speed and concentration. In contrast, LDI has superior measurement accuracy but it is not a real-time technique. Recently we have developed a blood-flow imaging sys

We introduce a photoswitchable O6-benzylguanine derivative and demonstrate its use for super-resolution microscopy of SNAP-tagged proteins based on single fluorophore localization. Stochastic Optical Reconstruction Microscopy (STORM) reveals SNAP-tagged mi ...

Dual-color cross-correlation spectroscopy allows the detection and quantification of labeled biomolecules at ultra-low concentrations, whereby the sensitivity of the assay correlates with the measurement time. We now describe a parallel multifocal dual-col ...

We present a combination of topography measurements based on digital fringe projection and blood flow imaging based on Laser Doppler Imaging (LDI). Both techniques are optical, non-contact and high-speed whole-field methods well suited for in-vivo measurements on the skin. Laser Doppler perfusion imaging is an interferometric technique used for visualization of two-dimensional (2D) maps of blood flow. Typically the measured sample has a surface with a specific 3D relief. In many cases the sample relief can

Triplet imaging is a novel optical technique that allows investigating oxy- gen metabolism at the single cell and the sub-cellular level. The method combines high temporal and spatial resolution, which are required for the monitoring of fast kinetics of ox ...

Theo Lasser

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Live-cell multiplane three-dimensional super-resolution optical fluctuation imaging

Full-field laser Doppler perfusion imaging and monitoring with an intelligent CMOS camera

High light field confinement for Fluorescence Correlation Spectroscopy using a Solid Immersion Lens

Fabrication of arrays of sub-wavelength nano-apertures in an optically thick gold layer on glass slides for optical studies

Heterodyne Fourier domain optical coherence tomography for full range probing with high axial resolution

Interferometer coordinate measurement system for use in measurement and machining tools has partially reflecting boundary surfaces within its measurement head with a separation shorter than the coherence length

Numerical dispersion compensation for Partial Coherence Interferometry and Optical Coherence Tomography

Longitudinal three-dimensional visualisation of autoimmune diabetes by functional optical coherence imaging

Single molecule imaging of odorant receptors in supported planar lipid membranes

Super-resolved position and orientation from defocused images of fluorescent dipoles

Identification of luminescent molecules comprises fluorescence correlation spectroscopy

High-Contrast Imaging of Nanodiamonds in Cells by Energy Filtered and Correlative Light-Electron Microscopy: Toward a Quantitative Nanoparticle-Cell Analysis

k-Microscopy: resolution beyond the diffraction limit

See the Brain at Work—Intraoperative Laser Doppler Functional Brain Imaging

Scanning optical near field microscope for use with different contrast methods, including phase contrast microscopy, has an improved photo-detector design that improves resolution and imaging of the smallest structures

Combined laser Doppler and laser speckle imaging for real- time blood blow measurements

Targeted Photoswitchable Probe for Nanoscopy of Biological Structures

Parallel dual-color fluorescence cross-correlation spectroscopy using diffractive optical elements

Laser Doppler blood-flow imaging combined with topographical imaging of the sample

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