When the pulse-fluorescence method is used to measure molecular fluorescence-lifetime

and if it is near to or smaller than the instrumental response time

the observed fluorescence decay curve is a convolution of the true fluorescence decay curve and the instrumental response function. That is

if the true fluorescence decay curve is

G(t)

and the instrumental response function is

F(t)

then the observed fluorescence decay curce will be

D(t)=∫

0

t

G(t′)F(t-t′)dt′

.Therefore

it needs to carry out deconvolution proceeding for obtaining the true fluorescennce decay curve. In deconvolution method. the calculation is very strenuous and its result is dependent on the accuracy in measuring the instrumental response function:a small deviation of

F(t)

may produce a iserious deviation or wrong result for calculating fluorescence lifetime.