| Summary: | 碩士 === 國立臺灣師範大學 === 資訊工程學系 === 104 === This research aims to implement the design of “Autofocusing System for 3D Digital Holography Reconstruction” on FPGA ( Field Programmable Gate Array ).
With the use of Holography to record the phase and amplitude of the samples, the system can execute the 3D reconstruction by the hologram. The change of the observed samples during the observation process caused by the application of holography microscope and the need to adjust the focal length manually for clear 3D reconstruction images were time and labour consuming. Therefore, the system highlights the importance of autofocusing.
Autofocusing System for 3D Digital Holography Reconstruction includes diffraction computation (Fresnel transform), phase unwrapping (DCT-based minimum mean square algorithm) and numerical evaluation (Normalized Variance). Diffraction computation reconstructs the wrapped phase and phase unwrapping reconstructs the unwrapped phase. Processing numerical evaluation with unwrapped phase demonstrates whether the 3D reconstructed images are in of focus or not. This system uses multiple I/O technology to decrease the time when the system changes focal length and loads the original hologram.
The experimental results and performance analysis indicates that the system has the ability to reconstruct large size hologram. And the DCT-based phase unwrapping algorithm provides competitive reconstructing time. Comparing this system implementation on FPGA, MATLAB, CPU and GPU, the system implementation on FPGA has less reconstructing time and lower power consumption.
Keyword: FPGA, Autofocusing, Hologram reconstruction, Discrete cosine transform
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