Thesis (doctoral)--Universität zu Köln, 1974.

The Bismuth Silicon Oxide (BSO) single crystal can be obtained both in a large size and with good optical quality. It has been demonstrated that the BSO (Bi₁₂SiO₂₀) crystal is a practical holographic recording medium. BSO is a semiconductor and has a large electro-optic coefficient. These two properties of the BSO crystal are responsible for its capability to record. In this study, the linear and circular birefringence of the BSO crystal under an electric field were investigated. The measurement method is by passing a linearly polarized wavefield through the crystal. The transmitted wavefield is written in parametric expressions using Jones calculus, and the wavefield is probed by a simple ellipsometer. The two parameters in the Jones matrix, the linear and circular birefringence, are solved from the experimental data. The electro-optic coefficient is determined from the resulting linear birefringence to be 3.57 x 10⁻¹⁰ cm/V at λ = 632.8 nm. The diffraction efficiency and temporal response of the BSO crystal in the transverse electro-optic configuration were studied. The crystal was then coated with a single layer antireflection coating to investigate the effect of a multi-reflections inside the crystal. The result showed that although the visibility improved only about 20%, the diffraction efficiency and temporal response improved two times. The BSO crystal is used as the recording medium in a two-wavelength holographic interferometer. An optical edge filter is used in the interferometer to adjust the beam ratio, and a prism is used to incorporate tilt in the interferometer and to deviate the two wavelengths to satisfy the Bragg's condition for the volume hologram. The 488 and 514.5 nm lines of an argon-ion laser are used to give an equivalent wavelength of 9.45 μm. The interferograms obtained are of high contrast.

In this study, the pulse laser was used as writing beam, and He-Ne laser as the probe beam. The liquid-crystal has several mesomorphic phase: Smectic C, Smectic A, Nematic and Isotropic. The laser-induced holographic gratings in the azo-dye-doped liquid crystals have been investigated by changing the temperature, and the polarization of the probe beam.

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Several optical information processing tasks are implemented using photorefractive BSO as a dynamic holographic medium. The physical basis for the mechanism which allows the implementation of these devices is studied. The properties of BSO which make it particularly attractive as a processing medium are highlighted, and experimental results are presented to demonstrate its practical limitations. An extensive study is presented of the influence of optical bias on the grating formation characteristics. This leads to a documentation of the optimum conditions for transient enhancement of a beam diffracted from such a grating. This transient enhancement can be controlled to provide ideal characteristics for the implementation of transient devices such as a novelty filter. A novelty filter utilising this transient enhancement is subsequently demonstrated. It exhibits good temporal discrimination through the choice of suitable external optical conditions, and the use of digital thresholding. The overall device operates at T.V. frame rates. Results are also presented of various optical correlators using BSO. These include the optical intensity correlator. The unique properties of the intensity correlator are stressed by practical demonstration. Specifically, the relative intolerance of the intensity correlator (compared with coherent correlators) to the position of the various components is demonstrated. Also, the spatially incoherent readout light allows the use of a low-optical quality liquid crystal television (LCTV) as a low-cost spatial light modulator. Output results are then presented from the correlator using the LCTV as a dynamic readout device. This provides an updateable hologram as the reference of the correlator which is interrogated at frame rates by the LCTV. Finally, the temporal discrimination of the novelty filter is combined with the character recognition ability of the intensity correlator. This produces an optical processor which will recognise a particular object but will only register it at the output stage when it is moving.

This study is focus on solute concentration ahead of solidification front and base on holographic method by using holographic interferometry. Heterogeneous nucleation of bubbles on an advancing solidification front during freezing of water containing a dissolved gas has been experimentally and analytically studied. The formation of bubbles resulting from supersaturation of liquids is commonly encountered in different fields such as heat transfer, manufacturing, and bioscience.

We study the dynamical behavior of the holographic grating formed in polymer-dispersed liquid crystal ( PDLC ) films. The grating is written by two coherent Ar+ laser ( l=514.5nm ) , while probed by a He-Ne laser ( l=632.8nm ).