All-optical photoacoustic tomography via beam deflection

TL;DR

This paper introduces an all-optical photoacoustic tomography method that uses beam deflection to detect pressure gradients, potentially improving sensitivity and reducing distortion compared to traditional ultrasound-based systems.

Contribution

The work presents a novel all-optical detection technique for photoacoustic imaging using optical deflection and advanced reconstruction algorithms, bypassing conventional transducer arrays.

Findings

Demonstrates the Radon transform relationship between deflection signals and pressure gradients.

Uses optimization and Galerkin methods for accurate image reconstruction.

Shows potential for enhanced sensitivity and reduced distortion in photoacoustic imaging.

Abstract

Photoacoustic imaging (PAI) uniquely combines the advantages of optical contrast with deep tissue penetration capability of acoustic waves, enabling imaging at depths of several centimeters. Conventional photoacoustic imaging methods have relied on pulsed lasers to induce the photoacoustic effect, coupled with arrays of pressure transducers to detect the resulting ultrasound signals. In this work, we propose an alternative all-optical approach that leverages optical deflection to record photoacoustic waves by an array of detection beams. The measured signal is shown to be the Radon transform of the pressure gradients. An optimization-based inversion procedure is used to reconstruct the initial time pressure gradient field. Subsequently, a Galerkin method is used to reconstruct the pressure field from the pressure gradient field. The new modality offers the potential for enhanced sensitivity and reduced signal distortion, advancing the capabilities of photoacoustic imaging beyond traditional transducer-based systems.