Figure 4. Image scanning of a fluorescent bead.

(a) Experimental setup. The ultrasound focus scanned the sample in the x-y plane. At each step, 6 iTRUE iterations were implemented. The fluorescence intensity was measured at each iteration using the photodetector. (b–c) Microscopic images of the fluorescent bead without and with the scattering film. (d–i) Intensity map of the fluorescent signals (11 × 11 scanning points with cubic interpolation). A Gaussian profile was fitted to the data points across the centre of the bead in both the x and y directions. (j, k) The resolution (FWHM of the Gaussian profile) in the y direction and the x direction of the fluorescent bead image over 6 iterations. The error bars indicate the 95% confidence bound. All scale bars are 20 μm.