No description available.

Thesis (M.S.)--Rochester Institute of Technology, 1992. / Typescript. Includes bibliographical references (leaves 59-61).

Thesis (Ph. D.)--Lehigh University, 1996. / Includes vita. Includes bibliographical references (leaves 174-179).

This study was aimed at broadening the knowledge of aspects of holography by examining three areas of importance, namely: i) qualitative holographic nondestructive testing, as applicable to flaw detection, ii) quantitative holographic interferometry and iii) white-light transfer reflection holography, with particular emphasis on the multiplexing principle. The objects used to evaluate the viability of qualitative holographic nondestructive testing were various carbon fibre airframe sections, a ceramic tube and a ceramic mould. The real-time and double-exposure holographic techniques were used to investigate the objects. Hot air was employed as the stress application medium. The results obtained clearly show the viability of holography as a nondestructive testing technique for the detection of debonds, delaminations, cracks, etcetera. In the second part of the study, the zero-order and fringe-counting techniques were applied to a cantilever loading experiment as a means of quantitatively determining the cantilever's displacement. It was determined that displacements with an accuracy of circa 85 % could be obtained by using the abovementioned techniques. In the final part of this study the transfer and multiplexing principles were rigorously examined. As a result, it was found that when reflection holograms were used as masters, excessively dim transfer holograms were produced. Transmission masters produced much brighter transfer holograms and displayed the capability of individually reproducing the images recorded. However, the angle of visibility of the individual images produced was found to be unsatisfactory and therefore warrants further investigation.

published_or_final_version / Physics / Master / Master of Philosophy

No description available.

Chapter 1 contains an introduction to holography, holographic optical elements and coupled wave theory. Chapter 2 contains a detailed review of dichromated gelatin based on published literature and on experimental observations made during work for this thesis. In Chapter 3 the non-linearity of the recording characteristic and changes in the bulk properties of the material during processing are determined. In Chapter 4 the non-uniformity of planar gratings is investigated by making a detailed comparison with a coupled wave theory in which the grating parameters are functions of depth. The effect of different processing procedures on these non-uniformities is demonstrated. In Chapter 5 the mechanism behind the formation of real-time gratings in dichromated gelatin is determined by applying a dynamic form of coupled wave theory. The source of diffraction is found to be a pure absorption grating. In Chapter 6 the use of dichromated gelatin as a medium for copying holograms and for recording efficient noise gratings is demonstrated. In Chapter 7 a theoretical model of holographic optical elements based on vectorial coupled wave theory is presented and is used to investigate the effects of polarisation. In Chapter 8 an optical method for the measurement of distance is developed using the dispersive properties of an on-axis holographic lens. Conclusions are then presented in Chapter 9.

An investigation is conducted into the suitability of thirteen different silver halide hologram development schemes with a view towards their use in underwater hologrammetry. To this end the image fidelity indicators of resolution, reconstructed irradiance, noise, signal-to-noise ratio and contrast are extracted from a representative, diffusely reflecting object. Both amplitude and phase holograms are recorded, utilising a range of post-development treatments, on Agfa-Gevaert 8E56 emulsion. In addition, silver halide sensitised gelatin holograms are examined and evaluated. The major conclusion drawn is that suitably chosen phase development schemes are able to outperform amplitude development schemes in each fidelity indicator. A smaller number of development schemes are selected and characterised in terms of repeatability, beam ratio variations, Hurter-Driffield curves, 'amplitude transmittance versus exposure' curves and hologrammetric suitability. Pulsed holograms are recorded of the representative object both in-air and underwater. These holograms are evaluated with a view to determining their comparability and the conclusion is drawn that underwater holograms, in ideal conditions, are equivalent to 'in-air' holograms. It is concluded that, of those tested, the most suitable development scheme for underwater hologrammetry is Tetenal Neofin Blue bleached (without fixation) with ferric EDTA rehalogenating bleach. The optimum beam ratio is when K=5 and the optimum exposure for maximum signal-to-noise ratio, accurate contrast reproduction and high resolution is H = 25 muJ cm-2. Should maximum resolution be required then exposures as low as H = 5 muJ cm-2 should be employed.

This thesis details the investigation, design, implementation and testing of an underwater holographic camera ("HoloCam"). The system has been optimised for the recording of plankton and marine particles located within the upper water column of the sea. The ultimate aim of the system is to provide marine biologists with an effective means of enhancing their knowledge and understanding of these organisms and their environment. The HoloCam utilises both in-line and off-axis holographic techniques and facilitates an overlapping volume between the two geometries. This provides a recording range of a few microns for the in-line to large opaque subjects with the off-axis. The in-line system records a volume of 3000 cm3 whilst the off-axis records 47000 cm3. The HoloCam allows recording to a depth of 100 m. The development and optimisation of both holographic systems is detailed with regard to implementation in the HoloCam assembly and the recording of high resolution images of plankton. Special attention is directed towards optimisation of the off-axis illumination system. A new recording medium is also identified and processing schedules for the material are evaluated. The design of all major aspects of the HoloCam system is detailed and the philosophy behind the design is discussed. Rigorous testing of the system is completed under both laboratory and open water conditions. Laboratory trials using the complete HoloCam system have allowed resolutions of 14.3 1p mm-1 to be reconstructed using the off-axis arrangement and 71 1p mm-1 using the in-line. A large number of holograms have been recorded during the open water trials and laboratory replay has allowed many high-resolution images of aquatic particles to be reconstructed. The maximum resolvable detail on the reconstructed images is of the order of 50 mm for the off-axis and 3 mm for the in-line.

by Liu Chi Kin. / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1986