Fluorescence correlation spectrometer (FCS) Hamamatsu Photonics

Hammamatsu's FCS (fluorescence correlation spectroscopy) system, the C9413, consists of:

Main Unit (detection unit).
The FCS unit consists of a laser to excite fluorescence molecules, a confocal optics to focus laser beams onto a very small volume and a high sensitivity photodetector to detect fluorescence. The laser is a compact, LD-pumped low-noise solid-state laser. The confocal has a simple structure that minimizes optical loss and allows easy alignment of the optical axis. The photodetector is a specially designed module comprised of a photomultiplier tube using a GaAsP photocathode with high quantum efficiency, a cooling element, a high-voltage power supply and a photon counting circuit. The signal output from the photodetector is transferred to a digital correlator installed in a PC for arithmetic operation and analysis.

Digital correlator.
Measurement data counted by the digital correlator is transferred and stored into the main memory of a PC through the PCI interface. Using this data, autocorrelation is then calculated by the CPU in the PC. A molecular model is then fitted to the calculated autocorrelation function to find the number of molecules and translational time. Fitting can be performed on 3 components and a triplet. For example, bound molecules and free molecules have different diffusion times so their fitting profile contains two components being mixed. All measurement data are stored in the memory of the PC and can be further analyzed with your own calculation algorithm.

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