Fig. 9
From: Visualising varnish removal for conservation of paintings by fluorescence lifetime imaging (FLIM)
Phasor analysis separated varnish samples by their ageing conditions. Point clouds from phasor analysis of fluorescence intensity decays were produced for samples of A dammar and B mastic natural resin varnishes. Varnish aged under ambient conditions is shown in green and varnish undergoing accelerated ageing in brown. Points closer to the right end of the unity semicircle (accelerated ageing) correspond to shorter lifetimes. Points inside the unity circle (all) indicated multi-exponential fluorescence intensity decays. Plots were derived from the same data used in producing Fig. 6. g(ω) is the real part and s(ω) is the imaginary part of the Fourier transform of the fluorescence intensity decay in each pixel