Turning tissues transparent by optical phase conjugation

Elastic optical scattering in biological tissue typically dominates over absorption by an order of magnitude or more. Being the dominant light interaction process, scattering prevents tissue from being transparent. Although the spectral properties [1] and angular profiles [2] of scattered light can reveal useful physiological information about a given tissue sample, scattered light is generally regarded as poor in imaging information. This is due to the severe deterioration of the incident light field, caused by disordered amplitude and phase modulation of its wavefront as it propagates through the tissue. Yet, it is also known that elastic optical scattering is a deterministic and time reversible process. In other words, if we can record the phase and amplitude of the propagating scattered light field completely and reproduce a back propagating optical phase conjugate (OPC) field or a time‐ reversed light field this field should be able to retrace its trajectory through the scattering medium and return the original input light field.