| The optically assisted ultrasonic velocity-change imaging method was applied to obtain the spectroscopic image of nano-particles, which were expected as markers for drug delivery system and photo-thermal therapy, in tissue mimic phantoms. Phantoms including gold nano-rods or semiconductor nano-particles were prepared. The ultrasonic velocity-change images of phantoms were obtained using illumination of laser diodes with various emission wavelengths corresponded to the absorption spectrum of nano-particle. Experimental results showed that our method has the potential to find the optical absorption agent in biological tissue. |