Design of a fluorescence-lifetime imaging microscope workstation

One of the promising recent developments in fluorescence microscopy is fluorescence lifetime imaging microscopy. This type of microscopy images the lifetime of fluorescence molecules (in the nano second range) rather than the amount of light emitted by these molecules. This physical property is of interest while it gives information about the local environment of the molecule, such as molecular concentration of O2, Ca2+, pH, and conjugation. Our goal is to design a affordable, robust and easy-to-use FLIM workstation which is completely automated and does not need any difficult calibration. Therefore we are developing a workstation which applies a homodyne detection scheme (frequency range: 1 - 100 MHz) with use of an intensity modulated laser-diode (635 nm) and a gain modulated intensified CCD camera to image fluorescence lifetimes in the range of 1 - 100 ns. Using these components it is possible to make a FLIM workstation based on a normal fluorescence microscope by just replacing the light source and image detector. The FLIM image acquisition procedure in software allows automatic optical measurements of fluorescence lifetimes in different ranges and mixtures of lifetimes by adjusting the modulation frequency.