Comparing free-space and fiber-coupled detectors for Fabry-Pérot-based all-optical photoacoustic tomography.

Significance: Highly sensitive detection is crucial for all-optical photoacoustic (PA) imaging. However, free-space optical detectors are prone to optical aberrations, which can degrade the pressure sensitivity and result in deteriorated image quality. While spatial mode-filtering has been proposed to alleviate these problems in Fabry-Pérot-based pressure sensors, their real functional advantage has never been properly investigated.

Aim: We rigorously and quantitatively compare the performance of free-space and fiber-coupled detectors for Fabry-Pérot-based pressure sensors.

Approach: We develop and characterize a quantitative correlative setup capable of simultaneous PA imaging using a free space and a fiber-coupled detector.

Results: We found that fiber-coupled detectors are superior in terms of both signal level and image quality in realistic all-optical PA tomography settings.

Conclusions: Our study has important practical implications in the field of PA imaging, as for most applications and implementations fiber-coupled detectors are relatively easy to employ since they do not require modifications to the core of the system but only to the peripherally located detector.