Paper
12 March 2014 Analysis of phase conjugation in a turbid medium
Author Affiliations +
Abstract
The ability to focus light in most tissue degrades quickly with depth due to high optical scattering. Recently, researchers have found they can concentrate light tightly despite these scattering effects by using a guidestar and optical phase conjugation to focus light to greater distances in tissue. An optical or probe signal is transmitted through a scattering medium and its resulting wavefront is detected. The wavefront is then conjugated and utilized as a new optical source or delivery wave that focuses back to the guidestar's location with minimal scattering. The power in the delivery wave may be greatly increased for enhanced energy delivery at the focus. Modulation by an ultrasound (US) beam may be utilized to generate the guidestar dynamically and allow for US-resolution at depths of several millimeters. The delivery wave is successful at focusing light back at the guidestar because it creates constructive interference at the desired focus. However, if the phases of the field contributions change, we expect the delivered power at the focus to be reduced. This paper will analyze the robustness of this method when the probe beam is at one wavelength and the delivery wave is at another. This will allow us to characterize the deleterious effects of varying the phase contributions at the focus.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Joseph L. Hollmann, Sergio Cantero, Snow Tseng, and Charles A. DiMarzio "Analysis of phase conjugation in a turbid medium", Proc. SPIE 8949, Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXI, 89490O (12 March 2014); https://doi.org/10.1117/12.2041165
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KEYWORDS
Scattering

Wavefronts

Phase conjugation

Tissue optics

Laser beam diagnostics

Laser scattering

Light scattering

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