Optical-resolution photoacoustic imaging with speckle illumination

Abstract

Conventional approaches for optical-resolution photoacoustic microscopy generally involves raster scanning a focused spot over the sample. Here, we show that a full-field illumination approach with multiple speckle illumination can also provide diffraction-limited optical-resolution photoacoustic images. Two different proof-of-concepts are demonstrated with micro-structured test samples. The first approach follows the principle of ghost imaging [1], and is based here on solving a linear inverse problem under sparsity assumptions: the object is reconstructed through a pseudo-inverse computation of a reference matrix made of speckle patterns measured during a calibration step. The second approach is a speckle scanning microscopy technique, which adapts the technique proposed in fluorescence microscopy by Bertolotti et al. [2]: in our work, spatially unresolved photoacoustic measurements are performed for various translations of unknown speckle patterns. Because speckle patterns naturally appear in many vari...