Marcus Oliver Held

Short Bio and Projects Description

As physicist we tend to seek the optimal result possible within the given laws of physics and I am also enthusiastic about it. My area of interest is photonic, the field I did my studies, before I specialised in my PhD on fluorescence microscopy to measure single fluorescent molecules. In my thesis, I could show that using complex but optimal illumination conditions the localization precision of a single molecule reached previously unattained values for a low number of detected photons.

In our group at IIT, we are working with a photon detector (Single Photon Avalanche Diode array) that performs under optimal physical parameters with respect to the detection side. It provides a spatial sampling of a small camera with temporal information of a SPAD, which is sufficiently fast to study fluorescence processes.

In my research, I want to use this detector to track single fluorescent molecules in space. Here, the temporal performance of the array detector does not impose a limit to the tracking speed nor the spectroscopic information of the emitter, e.g. its fluorescence lifetime. The setup I’m working on was developed by Andrea Bucci for tracking fluorescent particles, which are much brighter than single molecules, in a biological environment. The challenge I’m facing is to detect enough information from the rather dim single molecules with the SPAD array, which has high dark counts and low detection efficiency than single pixel SPAD detectors.

Publications with our group