Fig. 3.

(a) Imaging targets ($T_1$ to $T_6$) of similar cross-sections ($1.0\mathrm{mm}\times 0.5\mathrm{mm}$ in $xz$-plane) with variation in elastic coefficient were embedded in background phantom [$25\times 20\times 20{\mathrm{mm}}^3$ ($x\times y\times z$)]. (b) Targets of different cross-sections ($0.5\mathrm{mm}\times 0.5\mathrm{mm}$ to $3.0\mathrm{mm}\times 0.5\mathrm{mm}$ for $T_1$ to $T_4$ in $xz$-plane) with optical and mechanical properties similar to that of background phantom. (c) Contrast in $E$ (with similar ${\mu }_a$ for $t_1$) and ${\mu }_a$ (with similar $E$ for $t_2$) with respect to that of background sample.