Danko O. Controlled formation and analysis of optical images in disordered media

The dissertation aims to analyze light propagation through scattering media, light focusing with the help of a controlled modification of the incident wavefront, and to determine the features of the flow of charged colloidal rods suspension that belongs to the “soft matter” class. The last part may be useful since numerous potential applications deal with dynamic media. The investigation of the suspension flows has been performed utilizing rheological methods and laser Doppler velocimetry. This has allowed determining the features of the flow of this suspension at different shear rates. The data obtained may be useful for further researches on light focusing in dynamic media. To study light focusing through a multiple scattering medium with the help of adaptive optics, a computer model has been developed. The main idea of this model is the determination of eigen transmission channels using singular value decomposition of the linear operator that describes the light scattering by the medium. The advantage of this model is the possibility of using different programs for calculating fields that are scattered on a disordered medium of a defined microscopic configuration. The peculiarities of light propagation through disordered media during focusing have been determined with the help of this model. Also, light focusing algorithms have been investigated utilizing the computer simulation and a modification to one of the algorithms that allow increasing its efficiency has been proposed. Besides, a light focusing algorithm that consists in recovering the real part of the medium transmission matrix has been analyzed and a method for reducing the effect of noise on it has been proposed. The experimental investigations of light focusing have also been performed. It has been found that the imaging pipeline noise significantly influences the light focusing algorithm's performance and the final result. The noise properties of the imaging pipeline have been studied and based on the investigation results, the recommendations on the reducing of the influence of noise in the experiment have been developed.