Deep tissue space-gated microscopy via acousto-optic interaction

Abstract

To extend the imaging depth of high-resolution optical microscopy, various gating operations—confocal, coherence, and polarization gating—have been devised to filter out the multiply scattered wave. However, the imaging depth is still limited by the multiply scattered wave that bypasses the existing gating operations. Here, we present a space gating method, whose mechanism is independent of the existing methods and yet effective enough to complement them. Specifically, we reconstruct an image only using the ballistic wave that is acousto-optically modulated at the object plane. The space gating suppresses the multiply scattered wave by 10–100 times in a highly scattering medium, and thus enables visualization of the skeletal muscle fibers in whole-body zebrafish at 30 days post fertilization. The space gating will be an important addition to optical-resolution microscopy for achieving the ultimate imaging depth set by the detection limit of ballistic wave.

In ideal diffraction-limited optical microscopy imaging depth is limited by the multiply scattered wave. Here, the authors present a space gating method, based on an acoustic focus in the object plane and reconstruction using only the acousto-optically modulated ballistic wave, and demonstrate increased imaging depth in scattering samples.