Fluorescence lifetime imaging module LIMO for CLSM

摘要

The Fluorescence Lifetime Module (LIMO) from Nikon is a versatile device for time domain Fluorescence Lifetime Imaging (FLIM). The high efficiency and high sample speed make LIMO ideal for the fast acquisition of fluorescence lifetime images using a confocal scanning laser microscope (CSLM) or multi-photon excitation microscope. We employed LIMO to acquire fluorescence lifetime images with the Nikon PCM 2000 CLSM.Measuring FLIM images with LIMO requires a pulsed excitation source. The unit was used both with short and long excitation pulses. The fast excitation pulses come from a femto-second mode-locked Titanium:Sapphire (Ti:Sa) laser. The combination of LIOM with expensive laser yields a high lifetime-resolution and fast acquisition rate. In addition, LIMO was used in combination with a much cheaper pulsed light source consisting of an Acoustic Optic Modulator (AOM) and the standard CW Ar-ion laser of the PCM 2000. This combination produces brief, nanosecond light pulses at a 50 MHz repetition rate.Compared with the AOM solution, the expensive Ti:Sa laser yields better timing characteristics. However, the performance of the cheap AOM based pulsed light source is sufficient for biological FLIM applications.