Phase_Recovery Thermal Imaging
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In my research work, I explored several extensions of the Fourier ptychography microscopy (FPM) technique, which is a promising but well-known phase-recovery imaging technique. First, I extended from microscopy to photography the scanning-diffracted-light (SDL) microscopy technique recently demonstrated in our research group, which permits to implement the Fourier ptychography (FPM) technique using a single illumination direction and can have applications where microscopes or telescopes are used for imaging the phase of the optical disturbance (OD). I conducted proof-of-concept experiments and simulations demonstrating the SDL photography technique, which permits to image the intensity and phase of the optical disturbance when the sample is illuminated by a collimated beam from either white-light or thermal radiation source. A rotating slit placed in the FP of the optical system scanned the direction of the light that was diffracted by the sample. Images of the sample obtained for different slit orientations are different. This provides the required image diversity for the successful convergence of the presented SDL imaging algorithm. Second, I explored the coherent illumination-direction multiplexing (IDM) FPM technique, also recently demonstrated in our research group, using thermal radiation. We explained the observed Moiré patterns in terms of the mutual coherence of the diffraction beams produced by the interaction of a thermal beam with a diffractive element with periodic structure. It was demonstrated the capability of the coherent IDM-FPM technique for obtaining, from a set of Moiré patterns, intensity images with the correct structure of a sample. We found the numerical algorithm to be stable when the phase of the optical disturbance at the sample’s plane is known, but it fails to determine the correct phase when it is unknown. This indicates that further convergence-improvement of the numerical algorithm is necessary. Finally, I demonstrated by scanning the Fourier plane of the optimal system in different forms, the SDL imaging technique can be implemented in a variety of ways.