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Advances in Fingerprint Technology.pdf

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Figure 6.4 Phase shift and demodulation of lum<strong>in</strong>escence vs. excitation (Φ =<br />

phase shift, ω = modulation angular frequency, τ = lum<strong>in</strong>escence lifetime, m =<br />

demodulation).<br />

1<br />

<strong>in</strong>tensity<br />

φ<br />

b<br />

fluorescence<br />

time<br />

excitation<br />

tan φ = ωτ m = b/B = (1 + ω 2 τ 2 ) -1/2<br />

m φ<br />

0 0<br />

Figure 6.5 Phase and demodulation vs. modulation angular frequency.<br />

ω<br />

block diagram of the pert<strong>in</strong>ent imag<strong>in</strong>g apparatus is shown <strong>in</strong> Figure 6.6.<br />

More sophisticated versions are described elsewhere. 9 Here, one is primarily<br />

concerned with f<strong>in</strong>gerpr<strong>in</strong>t treatments that yield lum<strong>in</strong>escence lifetimes<br />

appropriate to the time-gated and phase-resolved doma<strong>in</strong>s, rather than the<br />

details of <strong>in</strong>strumentation.<br />

B<br />

90 0

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