Optical imaging into deep tissue

Abstract Biologists have long pursued the ability to probe living systems with high spatial resolution and molecular specificity in order to elucidate fundamental biological structures and processes. An optimal imaging modality would also provide high temporal resolution, enabling real‐time visualization of dynamic cellular activities and biochemical reactions. Conventional clinical imaging techniques such as X‐ray imaging offer substantial tissue penetration, yet these are inherently limited in spatial resolution. In contrast, optical imaging techniques can achieve ultrafast acquisition rates and resolution at the single‐molecule or even single‐atom level; however, their application is restricted to superficial tissue layers owing to substantial light scattering and intrinsic autofluorescent effects. The inherent trade‐off between penetration depth and spatial resolution continues to motivate the development of advanced optical imaging modalities capable of achieving deeper tissue access without sacrificing imaging precision.