Figure 4
From: Optimizing the precision of laser speckle contrast imaging
Effects of the exposure time on speckle noise and measurements precision. (A) Per-pixel relative error in contrast measurements, estimated from the simulated independent frames with \(T/\tau _c\) ranging from 0.05 to 40. Lines colour reflects the pixel’s neighbourhood size used in the contrast calculation. Solid lines correspond to simulations where the noise is defined only by speckle statistics. Dashed lines correspond to simulations that additionally include a typical camera-related noise. (B–D) Experimentally measured contrast variation around the mean \(\frac{\sigma (K)_{cardiac}}{<K>}\), which is dominated by cardiac pulsatility rather than noise. Grey lines show measurements from 3 animals, 3 regions of interest each. Blue lines show the average across all animals and regions of interest. In (B–D), larger values mean higher sensitivity to the physiological signal. Therefore, they confirm that the LSCI signal quality peaks at \(T/\tau _c\) between 2 and 10.
