title: Non-Contact Photoacoustic Imaging Using a Commercial Heterodyne Interferometer.
abstract: Most current photoacoustic imaging (PAI) systems employ piezoelectric transducers to receive photoacoustic signals, which requires coupling medium to facilitate photoacoustic wave propagation and are not favored in many applications. Here, we report an all-optical non-contact PAI system based on a commercial heterodyne interferometer working at 1550 nm. The interferometer remotely detects ultrasound-induced surface vibration and does not involve any physical contact with the sample. The theoretically predicated and experimentally measured noise equivalent detection limits of the optical sensor are about 4.5 and 810 Pa over 1.2 MHz bandwidth. Using a raster-scan PAI system equipped with the non-contact design, stereotactic boundaries of an artificial tumor in a pig brain were accurately delineated. The non-contact design also enables the tomographic PAI of biological tissue samples in a non-invasive manner. The preliminary results and analyses reveal that the heterodyne interferometer-based non-contact PAI system holds good potential in biomedical imaging.
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 USA.
authors.forename: Chao
authors.initials: C
authors.lastname: Tian
authors.affiliation: Department of Electronic Science and Engineering, Nanjing University, Nanjing 21000, China, and also with the Department of Radiology, University of Michigan, Ann Arbor, MI 48109 USA.
authors.forename: Ting
authors.initials: T
authors.lastname: Feng
authors.affiliation: School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.affiliation: College of Physical Science and Technology, Heilongjiang University, Harbin 150080, China.
authors.forename: Shengchun
authors.initials: S
authors.lastname: Liu
authors.affiliation: Institute of Acoustics, Tongji University, Shanghai 200092, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: Polytec, Inc., Irvine, CA 92618 USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Oliver
authors.affiliation: Department of Biomedical Engineering and the Department of Radiology, University of Michigan, Ann Arbor, MI 48109 USA, and also with the Institute of Acoustics, Tongji University, Shanghai 200092, China.
authors.forename: Xueding
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, MI 48109 USA.
authors.forename: Guan
authors.initials: G
authors.lastname: Xu
keywords: Biophotonics; interferometry; photoacoustic imaging; remote sensing