Research On Particle Field Holographic Reconstruction Technology With GPU

Digital hologram is a kind of new modern science and technology. It combines the traditional optical holography with digital image processing technology. The hologram is recorded by the photoelectric detector, and reconstructed in the computer. The optical system of the particle field is simple. In the process of reconstructing hologram, the velocity and three-dimensional information of the particle image can be showed efficiently by the GPU parallel acceleration algorithm. This topic is widely used in chemical industry, medical imaging, environmental protection, military field and so on. The main work as follows has been done in this thesis:1 . The basic principles of the particle field holographic technology have been studied.The wavefront recording and reconstructing systems and the basic principles have been introduced in detail. Based on the theory of light diffraction, three commonly used algorithms for reconstruction, named Fresnel diffraction method, convolution method and the angular spectrum method have been studied. The 2D sparse particle field and dense particle field have been simulated by these three commonly used reconstruction algorithm in the computer. Due to the angular spectrum method is better than the others, so the angular spectrum method is used in this thesis as the reconstruct algorithm.2. Acceleration algorithm, including preprocessing algorithm, fast Fourier transform algorithm and phase unwrapping algorithm for processing the hologram on GPU has been studied. Median filter algorithm and mean filter algorithm is used in order to depress the noise for the hologram. Meanwhile, quality-guided phase unwrapping algorithm is used to restore the phase. Every algorithm has been proved on the CPU and GPU. By comparing with relevant results, it can be found that the parallel computing ability of GPU can effectively improve the image processing speed. Finally, the process of reconstructing particle hologram on the GPU by the angular spectrum method have proved that the angular spectrum algorithm is exact and efficient on coaxial holographic particle field.3. It introduces an experimental procedure of system. Take the brine shrimp eggs'hologram for example. First, preprocessing the hologram. Then, reconstructing the hologram.In the end, subtracting the two reconstructed images to restrain most of the background noise.The experiment have been proved that the reconstruction algorithms of digital holographic technique have the advantages of rapidly, accurately, easily to reconstruct.4. The software of reconstructing the particle field hologram has been completed in Visual Studio 2010 software development platform and Windows 7 system. This application is usually used to the optical image processing field. In addition, user interface is made so that it is easier to process images.