title: Photo-acoustic concave transmitter for generating high frequency focused ultrasound.
abstract: 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.
authors.affiliation: Dept. of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 USA.
authors.forename: Hyoung Won
authors.initials: HW
authors.lastname: Baac
authors.forename: Tao
authors.initials: T
authors.lastname: Ling
authors.forename: Shai
authors.initials: S
authors.lastname: Ashkenazi
authors.forename: Sheng-Wen
authors.initials: SW
authors.lastname: Huang
authors.forename: L Jay
authors.initials: LJ
authors.lastname: Guo