  An experimental strategy has been developed specifically for the study of
composition-dependent phase behavior in multi-component artificial membranes.
The strategy is based on steady-state measurements of fluorescence resonance
energy transfer between freely diffusing membrane probe populations, and it is
well suited for the rapid generation of large data sets. Presented in this
paper are the basic principles that guide the experiment's design, the
derivation of an underlying mathematical model that serves to interpret the
data, and experimental results that confirm the model's predictive power.
