We present a multimodal optical setup, allowing non-contact photoacoustic imaging (PAI) and optical coherence tomography (OCT). Optical coherence tomography is sensitive to changes in the specimen’s refractive index, thereby offering complementary information to photoacoustic signals which are induced by light absorption. A multimodal setup, allowing OCT and photoacoustic measurements, should ideally not rely on any physical contact to a specimen and, thus, commonly used transducers for photoacoustic signal detection which require acoustic coupling to the specimen should be avoided. In this work photoacoustic signals are acquired by measuring the surface displacement of a specimen using a fiber-optic Mach-Zehnder interferometer. Photoacoustic signals are excited with a Nd:YAG pulse laser. The interferometer for non-contact photoacoustic detection and the OCT system are realized in the same fiber-optic network. Light from the PAI detection laser and the OCT source are multiplexed into a single optical fiber and the same objective is used for both imaging modalities. Light reflected from specimens is demultiplexed and guided to the respective imaging systems. To allow fast non-contact PAI and OCT imaging the detection spot is scanned across the specimens’ surface using a galvanometer scanner. As the same fiber-network and optical components are used for photoacoustic and OCT imaging the obtained, images are co-registered intrinsically. Imaging is demonstrated on a tissue mimicking sample.

Date Published: 15 February 2017
PDF: 8 pages
Proc. SPIE 10057, Multimodal Biomedical Imaging XII, 100570I (15 February 2017); doi: 10.1117/12.2250863

Published in SPIE Proceedings Vol. 10057:
Multimodal Biomedical Imaging XII
Fred S. Azar; Xavier Intes, Editor(s)