Single-Pixel Photoacoustic Microscopy with Speckle Illumination

Wide-field optical-resolution microscopy with structured illumination and single-pixel detection has been the topic of a number of research investigations. Its advantages over point scanning approaches are many and include a faster acquisition rate for sparse samples, sectioning, and super-resolution features. Initially introduced for fluorescence imaging, structured illumination approaches have been adapted and developed for many other imaging modalities. In this paper, we illustrate how speckle illumination, as a particular type of structured illumination, can be exploited to perform optical-resolution photoacoustic microscopy with a single-pixel imaging approach. We first introduce the principle of single-pixel detection applied to photoacoustic imaging and then illustrate in 2 different situations how photoacoustic images may be computationally reconstructed from speckle illumination: In the first situation where the speckle patterns are known through a prior calibration, various reconstruction approaches may be implemented, which are demonstrated experimentally through both scattering layers and multimode optical fibers; in the second situation where the speckle patterns are unknown (blind structured illumination), the so-called memory effect can be harnessed to produce calibration-free photoacoustic images, following the approach initially proposed for fluorescence imaging through thin scattering layers.