Fig. 1.

Tissue-like phantom experiments to verify the feasibility of applying the noise model in homogeneous media with semi-infinite geometry. DCS measurements were performed in three liquid phantoms with different μ_a (0.075, 0.100, 0.150 cm⁻¹) to test the noise model under different noise levels. Higher μ_a was associated with lower number of photons detected (I), thus leading to higher measurement noise [σ(τ)] and lower signal-to-noise ratio [SNR(τ)]. (a) Comparison of the measurement noises between the measured autocorrelation curves from the phantoms (dots) and calculated noises predicted by the noise model (solid curves). The measurement noise decreased as the delay time τ increased. The “steps” were due to the multi-tau arrangement of the correlator. (b) Comparison of the SNRs between the measured autocorrelation curves and model predictions. Although the measurement noise decreased as the delay time τ increased, the SNR of DCS measurement also decreased because the “signal” dropped even faster than the noise as τ increased.