الفهرس 
English CoverOnly 14 pages are availabe for public view
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Abstract
Holography is a technique of imaging which involve using Coherent light sources, interference and diffraction phenomena .The hologram is not a real image but an interference pattern which represent the intensity distribution of the object interfering with a reference beam. Rather than latent images, the hologram is not a fixed shot which includes only intensity of the objects inside the image frame but includes the phase and amplitude which make it recordable and gives different views with different angles of view. Holography involves recording and reconstructing processes. Recording can be performed on different holographic films materials and reconstructing can be done by illuminating the hologram with a reference beam. The process can be done conventionally by constructing a mach-zender interferometer and recording the interference pattern on different recording material but this process demands complex lab preparations including motion free tables, dark room settings and time to chemically process the films and the cost of photographic films and processing chemicals. The use of many optical elements can also distort the output image details due to diffraction, scattering and uncleanness of the element. Respectively, the disposable output means that the film is for one time use. To eliminate these complexities, two solutions were promoted. First, computer generating the pattern using computer algorithms like Lohmann detour phase encoding algorithm and Gsaxtron algorithm. Second, the use of spatial light modulators which are liquid crystals that use electrical voltage to encode each pixel of object image to each pixel on the Crystal display, it uses Electro-Optical modulation technique and voltage polarity variation in transmission and absorption of light to formulate the image eliminating the use of holographic films and chemicals. SLMS can be over written, achieve high resolutions and reach real time speeds. Two types of SLMS were used (Reflection”1980*1080 pixels resolution and transmission “600*800 pixels resolution). The two SLM differ since the transmission demands two polarizers to polarize the input light and the modulated laser pattern which is screened behind the SLM in a fully horizontal alignment. The transmission SLM has a low resolution which reflects on output image quality and demands higher power laser. On the other hand, the reflection SLM reflects the patters on its surface with an angle therefore the IFT can be obtained by two methods, with a lens in a distance equal the focal distance of the lens creating the IFT of the pattern or without a lens on a distance equal infinity to the input wavelength creating the IFT. The hologram technique applied in thesis was the Fourier hologram and the algorithm implemented was the GSaxtron algorithm or the kinoform. The results were applied on various types on input medical images (X ray- Computed tomography- Magnetic resonance imaging). The holographic reconstructions displayed adequate image representation and quality especially with the higher laser power (one watt Nd: Yag laser source). The black and white components of the image were clear and give more details than the grey scale areas due to input image quality, the coherence length of the input laser and the laboratory lighting conditions upon reconstructing. The medical images with defects (fractured bones or masses) were tested and the reconstructed holograms showed the defects in good quality making it possible to be used by physicians to diagnose these defects using holographic imaging similar to any other imaging modalities. An alternative technique is the optical scanning hologram method which is a technique that divides the input 3D object into a number of slices and apply Fourier transform on every slice to create the cosine hologram, the sine hologram, combined complex hologram. These three holograms are reconstructed then the real part of the complex hologram is extracted.. In the end, holography can be used as a visualization tool for physicians to diagnose defects without the disadvantages of using goggles. The future research in this filed will be on higher resolution SLMs, faster computer algorithms, and faster processing units .On the other hand, the most important disadvantage that limits the use of CGH in commercial use is the high cost. However, the mentioned problems can be solved in the future by the efforts of the research group and the advanced technologies invented every day.