A schematic diagram of the experimental setup.
(a) Raw CCD images corresponding to a phase shift of (i) 0°, (ii) 90°, (iii) 180°, and (iv) 270° of the modulated laser diode with respect to ultrasound beat signal . (b). The one-dimensional intensity profile along the dotted line for the intensity images given in (a). The legend indicates the corresponding phase shifted image.
Contribution to phase change (in %) from the background (excluding the focal region) compared to the focal region.
(a) Plots of normalized DPF [given by Eq. (3)] measurements versus ultrasound pressure in the focal region. The error in the measurements is in the range of 1%–4%. (b) Plots showing the enhancement factor in effective [using Eq. (4)] with ultrasound drive voltage. The error in the enhancement is in the range of 2%–7%. The four different curves correspond to values of 100, 400, 800, and 1200 Hz (as given in legend) using a viscoelastic phantom corresponding to a storage modulus of 11.39 kPa.
Plots of enhancement in effective versus ultrasound pressure in the focal region with for storage modulus of 11.39 and 40.35 kPa. The error in the measurements is in the range of 1%–7%.
Comparison of experimental and Monte-Carlo simulation results in the enhancement of effective corresponding to increase in the ultrasound pressure in the focal region.
Change in measured phase (numerically and experimentally) due to increase in at the focal region with kept constant at the background value of for .
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