Simulation of controlling focus spot in the scattering medium by using optical phase conjugation technique
Date Issued
2015
Date
2015
Author(s)
Tseng, Chia-Ta
Abstract
Focusing light through the scattering medium is the optical application due to penetration of biomedical optics. In this thesis, we introduce the novel method of optical phase conjugation (OPC) to focus light inside the scattering medium. In order to observe this phenomenon, we provide the numerical method of pseudospectral time-domain (PSTD) technique to simulate the OPC focusing. PSTD simulation technique is employed to obtain numerical solutions of Maxwell’s equations. PSTD technique is good for simulating large space problems and reducing the computer storage. In this thesis, we demonstrate the derivative of PSTD algorithm and the simulation of OPC focusing. In the OPC theory, amplitude and phase of the outgoing light is recorded and later used to generate phase-conjugated light which back-propagates through the scattering medium, and focuses inside. Then, we introduce the application of OPC theory which called time-reversed ultrasonically encoded (TRUE). TURE is the novel technique which use the light and ultrasound to focus inside the scattering medium. In our results, by changing the angular span of phase conjugate mirror (PCM) which generates the phase-conjugated light, we can analyze back-propagation of light for different angular spans. The simulation results may help determine the optimal angular span for practical back-propagation of light. In addition, we also analyze the influence of the resolution to the focusing phenomenon. In this simulation, we understand property of light focusing through the scattering medium.
Subjects
Optical Phase Conjugation (OPC)
Pseudospectral Time-Domain (PSTD)
Time-Reversed Ultrasonically Encoded (TRUE)
light focusing
Type
thesis
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ntu-104-R02941089-1.pdf
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