Fluorescence lifetime imaging microscopy (FLIM), especially based on the most accurate and frequently used technique called time-correlated single photon counting (TCSPC), has been widely employed for it gives not only morphological information but also chemical information. Chemical properties such as pH value (Hanson et al., 2002), ion or oxygen concentration (Gilbert et al., 2007), molecular dynamics and even the disease progression (Park et al., 2012) can be investigated and studied by TCSPC-FLIM. This powerful traits of FLIM has led many researchers and developers to include FLIM into their imaging system. Even though TCSPC-FLIM technique gives precise and accurate measurement of fl uorescence decay curves, its core technology, called single photon counting (SPC), inherently limits the system from high speed imaging. In the case of the state-of-art single channel TCSPC-FLIM, more than one minute is required to produce an image of 512 by 512 pixels with 10% accuracy. The acquisition time could be lengthened up to five minutes for 3% accuracy (Kollner & Wolfrum, 1992). To overcome such drawback of the long acquisition time of TCSPC-FLIM, analog mean-delay FLIM (AMD-FLIM) was recently developed (Moon et al., 2009; Won et al., 2009). Rather than using the stochastic reconstruction used in SPC techniques, AMD method extracts a decay constant directly by subtracting the mean-delay time (or mean-arrival time) of reflected photon flux from that of fluorescence photon fl ux. The total amount of alterations in the mean-delay time