Fiber-based remote photoacoustic imaging utilizing a Mach Zehnder interferometer with optical amplification

We present a remote photoacoustic imaging system without the need of a physical contact to the specimen. The setup is based on a Mach-Zehnder interferometer using optical wave guide technology as usually used in telecommunication industries, thus guaranteeing long life times and relatively low costs. A detection beam is transmitted through an optical fiber to a lens system which focuses the beam to the surface of a specimen. The back reflected light is than collected by the same lens system and coupled into the same optical fiber. As the collected light intensity is less than 0.1% of the transmitted intensity in forward direction an optical amplifier is used for amplifying the collected light. After amplification the light is brought to interference with a reference beam for demodulation of the ultrasound signals. The modulated light intensity is converted into electrical signals by a self-built balanced photo detector. We present noncontact photoacoustic imaging of a tissue-mimicking phantom and on chicken skin.