Photo-acoustic concave transmitter for generating high frequency focused ultrasound.
We present a photo-acoustic concave transmitter to generate and subsequently focus high frequency ultrasound. Owing to a short time-duration of pulse laser beam, high frequency acoustic waves and tight focusing can be easily achieved. The transmitter consists of a light-absorbing film coated on a concave spherical structure. For detection, we used an optical microring ultrasound detector capable of covering a broadband and high frequency spectrum of photo-acoustic source. A spot width of ∼44 μm was obtained at the focal plane. As the finite size and the specific shape of the microring cause a geometrical effect on the detection process, especially for high frequency components, we performed a 2-D spatial signal processing to remove this effect and extract a pure pressure distribution. The aperture for acoustic focusing could be optically controlled by changing the size of pulse laser beam.
Baac
Hyoung Won
HW
Dept. of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 USA.
Ling
Tao
T
Ashkenazi
Shai
S
Huang
Sheng-Wen
SW
Guo
L Jay
LJ