The Research On The Imaging Through Turbid Media And Its Application

The scattering effect of strongly scattering medium makes the traditional optical imaging system can not detect the internal targets of scattering medium. To solve this problem, a method using wavefront shaping theory is proposed to real-time detect the object locates in the strongly scattering medium with high resolution. Compared with the existed detection methods, some depend on complicated and time consuming recovery algorithm so that they need off-line image restoration, some need the prior knowledge of the target which results in the low generality, the new proposed method can detect the internal target of strongly scattering medium noninvasively with high resolution in real time just by changing the way of lighting, this simple operation causes the new method to be more pratical.In this paper, the content mainly involves spatial light modulator, imaging restoration of a spot light and a way of detecting target in the scattering medium.Firstly, As we use spatial light modulator to correct the irregular wavefront in the experiments, in order to have a better understanding to the device, after introducing its concept, classification and application, birefringence phenomenon and electronically controlled birefringence effect are used to analyze the phase modulation characteristics of twisted nematic spatial light modulator. Through the Twyman-Green interference experiment, the relationship between the gray of modulate image and movement of the interference strip are obtained and corresponding phase shift curves are plotted.Secondly, in order to have a better understanding of the wavefront shaping theory, after analyzing the principle of it, we construct an experiment of the imaging restoration of a spot light to prove the theory. In terms of phase optimization algorithm of wavefront, phase measurement method and local phase matching method are introduced, then the way how the software is designed to control the phase correction is elaborated. The experiment results verify the feasibility of this technology at the same time make sufficient preparation to the realization of the new detecting method both in theory and in practice.Finally a new detecting method for real-time and high resolution imaging of target located in the strongly scattering medium is proposed. It uses wavefront shaping technology and optical memory effect to expand spot imaging to regional imaging within a certain range, so it can realize real-time imaging that avoids off-line image reconstruction. At the same time, it doesn’t need spot light pre-placement or prior knowledge of target, only by changing the converging lighting to extending lighting, the goal can be achieved. The related experiment proves the validity of the new method. The results also show that the scattering imaging system has a better imaging acuity than the conventional optical imaging system.