Robust and adjustable dynamic scattering compensation for high-precision deep tissue optogenetics

Abstract

The development of high-precision optogenetics in deep tissue is limited due to the strong optical scattering induced by biological tissue. Although various wavefront shaping techniques have been developed to compensate the scattering, it is still a challenge to non-invasively characterize the dynamic scattered optical wavefront inside the living tissue. Here, we present a non-invasive scattering compensation system with fast multidither coherent optical adaptive technique (fCOAT), which allows the rapid wavefront correction and stable focusing in dynamic scattering medium. We achieve subcellular-resolution focusing through 500-μm-thickness brain slices, or even three pieces overlapped mouse skulls after just one iteration with a 589 nm CW laser. Further, focusing through dynamic scattering medium such as live rat ear is also successfully achieved. The formed focus can maintain longer than 60 s, which satisfies the requirements of stable optogenetics manipulation. Moreover, the focus size is adjustable from subcellular level to tens of microns to freely match the various manipulation targets. With the specially designed fCOAT system, we successfully achieve single-cellular optogenetic manipulation through the brain tissue, with a stimulation efficiency enhancement up to 300% compared with that of the speckle.

Single-shot digital optical fluorescence phase conjugation through forward multiple-scattering samples

“…Laser light focusing inside or through aberrant and scattering sample is a major challenge which is of interest for in-depth imaging ( 1 ), photostimulation ( 2 ), or phototherapy ( 3 ). At depth larger than the scattering mean free path ℓ s [typically ≃100 μm in brain tissues ( 4 )], light is scrambled into a complex random-like speckle pattern.…”