Low-power coherent light and wavefront shaping for reducing photobleaching effect in fluorescence based imaging

Abstract

Photobleaching is a light-induced effect where a fluorophore loses its fluorescence property due to light-induced damage. Controlling photons of light inside the scattering media is a challenging task due to refractive index inhomogeneity, multiple scattering of light, and formation of speckle noise. In this work, we have digitally transferred the coherent light of 0.74 mW power and concentrated the photon intensity in a controlled manner using the principle of constructive interference at the target location inside a tissue media, which is stained with fluorescence for generating pathological signals. The localized fluorescence signal extraction from the deep chicken tissue has been demonstrated with the developed binary-phase modulation based wavefront shaping system. The low-intensity coherent light has been re-localized from a large field of view to a spatio-temporal focused point, and fluorescence light emission has been detected from the fluorophores embedded in chicken tissue even after being exposed to light for a few hours. The fluorescence emission photons are obtained from the tissue by the developed experimental setup in the reflection mode.