Magnetic guidestar assisted light focusing through scattering media

Abstract

Optical scattering of biological tissue limits the working depth of conventional biomedical optics, which relies on the detection of ballistic photons. Recent developed optical phase conjugation (OPC) technique breaks through this depth limit by harnessing the scattered photons and shaping an optical wavefront that can "undo" the optical scattering. The OPC system measures the complex light field exiting the tissue and reconstructs a phase conjugated copy of the measured wavefront, which propagates in the reversed direction to the source of the light. To focus light inside a scattering medium, an embedded light source or "guidestar" is often required. Therefore, developing guidestar mechanisms plays an important role in advancing the OPC technique for deep tissue optical focusing and imaging. In addition to having strong optical modulation efficiency and compact size, a favorable guidestar for biomedical applications should also have good biocompatibility, fast response time, and be noninvasive or require only minimally invasive procedure. While a number of guidestar mechanisms have been developed and showed promising for various biomedical applications, they all have their own limitations. We have been developing new guidestars and tailoring them to meet the need for biomedical imaging and therapies. We are going to present our recent progress in novel guidestar development, compare them with established guidestar mechanisms, and discuss their potential in biomedical applications.

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