Publications de Ramachandra Rao

Field confinement with aberration correction for solid immersion lens based fluorescence correlation spectroscopy

Theo Lasser, Jelena Mitic, Ramachandra Rao, Rainer Leitgeb

The solid immersion lens (SIL) as a tool for increasing the field confinement as well as providing optimal performance by aberration compensation in a confocal fluorescence correlation spectroscopy (FCS) system is illustrated here. Using Zernike polynomial ...

2007

Fast focus field calculations

Marcel Leutenegger, Theo Lasser, Ramachandra Rao, Rainer Leitgeb

We present a fast calculation of the electromagnetic field near the focus of an objective with a high numerical aperture (NA). Instead of direct integration, the vectorial Debye diffraction integral is evaluated with the fast Fourier transform for calculat ...

2006

Stochastic Approach to Data Analysis in Fluorescence Correlation Spectroscopy

Theo Lasser, Ramachandra Rao, Rajesh Langoju

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 ...

2006

Fluorescence correlation spectroscopy : simulations and bio-chemical applications based on solid immersion lens concept

Ramachandra Rao

Fluorescence Correlation Spectroscopy (FCS) has become an important tool for measuring diffusion, concentration and molecular interactions in biomolecular systems. Two major requirements for FCS are good collection efficiency and a small and well defined e ...

EPFL2006

Total internal reflection fluorescence correlation spectroscopy (TIR-FCS) with low background and high count-rate per molecule

Marcel Leutenegger, Theo Lasser, Kai Hassler, Ramachandra Rao

We designed a fluorescence correlation spectroscopy (FCS) system for measurements on surfaces. The system consists of an objective-type total internal reflection fluorescence (TIRF) microscopy setup, adapted to measure FCS. Here, the fluorescence exciting ...

2005

Solid immersion lens used in a microscope with a lens system is made of a material having a refractive index that is selected so that the numerical aperture of the lens system

Theo Lasser, Ramachandra Rao

The invention relates to a solid immersion lens (SIL) for a microscope, comprising a lens system with a predetermined numerical aperture. The refractive index of the material of the solid immersion lens is selected in such a way that the numerical aperture ...

2005