Fiber optics offer better photoacoustic detection

Optical coherence tomography (OCT) provides 3D morphological information about a sample. Noninvasive photoacoustic microscopy (PAM) visualizes chromophore distribution. Combining the two techniques into an optical coherence photoacoustic microscopy (OC-PAM) system allows for noninvasive, high-resolution imaging in vivo.

For the first time, Deng et al. demonstrated the feasibility of an OC-PAM system using a fiber-based dome sensor as the PAM detector. OC-PAM systems usually use piezoelectric transducers as the PAM detector, which have a limited field of view. The small size, broad detection bandwidth and wide, almost omnidirectional detection angle of the fiber optic sensor allowed a large field of view with a stationary sensor.

The authors tested their system by imaging zebrafish larvae, an animal model with significance in developmental biology and disease research. The OC-PAM system comprehensively visualized zebrafish larvae anatomy and vasculature, demonstrating the benefits of a small and flexible sensor. The system could be applied to a variety of preclinical studies that use zebrafish larvae as an animal model.

“The work is important, because it shows an alternative, if not better, method to incorporate OCT and PAM,” said author Mengyang Liu. “It broadens the applicability of the fiber-based dome sensor in preclinical imaging.”

Currently, the OC-PAM system works in transmission mode. While this mode works for studies of zebrafish embryos, it has limitations when applied to other types of animal models.

The authors plan to improve the system’s performance by extending the applicability of the system with development of a reflection mode OC-PAM system.

Source: “An optical coherence photoacoustic microscopy system using a fiber optic sensor,” by Shiyu Deng, Richard Haindl, Edward Zhang, Paul Beard, Eva Scheuringer, Caterina Sturtzel, Qian Li, Abigail J. Deloria, Harald Sattmann, Rainer A. Leitgeb, Yi Yuan, Leopold Schmetterer, Manojit Pramanik, Martin Distel, Wolfgang Drexler, and Mengyang Liu, APL Photonics (2021). The article can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0059351 .