Adaptive optics & wavefront shaping

Methods that measure or infer how tissue distorts a light wavefront and then pre-compensate it with a deformable mirror or a spatial light modulator, partially undoing aberration and scattering to recover a tight focus at depth. Adaptive optics extends the usable depth and restores resolution for both imaging and holographic stimulation. More aggressive wavefront-shaping techniques — guidestar-based focusing, iterative or transmission-matrix optimization — aim to focus light through scattering rather than merely correcting mild aberration around it.

The correction is fundamentally local: it is valid only over a small isoplanatic patch and must be re-measured whenever the focus moves, so it does not scale trivially to a large volume. Focusing deep through thick scattering remains largely a demonstration rather than a routine tool, and the achievable gains fall off steeply with depth. It is an important frontier for pushing optical access beyond the native scattering limit, not a solved problem.