On Phase Retrieval Based On Wave Field Transport Of Intensity Equation

When the light wave exposure on the object, the object will have effect on the three properties of the wave:amplitude, wavelength and phase. We are familiar with the first two corresponding to the brightness and color. The latter carries the relevant details of the physical shape of the object, location. However, we know that because the light wave of oscillation frequency is about 1015Hz, phase changes too fast, the existing optical sensing device cannot directly to measure them, so that many of the key information is buried in the intensity information. Therefore, the phase retrieval technology of the wave field in the surface reconstruction, microscopy, position detection and other different branch of physics and has a very important significance in engineering applications.By the known wave field intensity information to recover the phase information of the object phase retrieval technology mainly includes the deterministic algorithm that based on the transport of intensity equation(TIE) and Gerchberg-Saxton-Fienup iterative algorithm. In certain physical and geometrical(paraxial approximation) conditions, the relation of amplitude and phase of the wavefront propagation can be connected by TIE, therefore since the TIE in the early 1980s proposed by Teague et al., has been the theory and application communities attention.The thesis studied on the fast Fourier transform algorithm based on the three kinds of boundary conditions, and gives the simulated and real experiment results.The derivation of the classical TIE phase retrieval algorithm is based on the coherent light field, therefore, the conventional TIE algorithm cannot be directly applied to the phase retrieval of partially coherent light field. In this thesis, the current phase retrieval algorithm of partially coherent light field is introduced, and the key research and analysis of the uniform and non-uniform illumination conditions of the corresponding phase retrieval equation. In this thesis, the main research work and innovation are as follows:(1) Under the conditions of coherent light illumination TIE retrieval algorithm is particularly fast Fourier transform algorithm is summarized, presented three boundary conditions (including periodic boundary, Dirichlet and Neumann boundary) derive the formula and the specific solution algorithm. Build the coherent lighting conditions (laser as the light source) optical experimental system, the simulation and real experiment results are given.(2) Using the spatial coherence and temporal coherence is deduced the wave function, the wave function with an angular spread spectrum function representation. Made from the description of partially coherent field mutual intensity function deduced expansion transport intensity equation of the partially coherent light field, and is used to uniform and non-uniform illumination conditions of phase retrieval. Build the partially coherent light illumination condition(LED as the light source) of the optical experiment system, the real intensity of the image was recorded using the experiment system for experiments, the experimental results demonstrate the proposed algorithm to recover the effectiveness of the partially coherent light field phase.(3) Design an integrated multi-CCD camera taking readings, the camera is simple structure, easy to carry, while the real-time acquisition of the image can be accurately reading the distance of focused image and defocused images, thus to provide the necessary information for the TIE solution.