Design and development of a pulsed ruby laser system for an underwater holographic camera
This thesis presents a design of a ruby laser system which would form the heart of an underwater holographic camera. The design principally emphasised upon simplicity, compactness and lightweight construction, in addition to the achievement of the necessary coherence length. The research was mainly focused on Q-switching and longitudinal mode selection which were identified as the key elements in achieving our goal. A fresh insight into dye Q-switching was made with the view of its implementation in the laser. Two major experiments were carried out on a dye Q-switch consisting of cryptocyanine dye dissolved in methanol. The first trial explored the lifetime performance of the Q-switch with regards to the number of laser pulses fired and the elapsed time. It gave an indication of the suitability of this Q-switch for the application. The second experiment concentrated on evaluating the operational characteristics of a dye Q-switched ruby laser with regards to pump energy, dye absorbance, output energy and timing of the pulse emergence. The results of this experiment clearly defined the effects of variation of one parameter on another. Consequently, these results displayed in a number of graphical plots could form the basis for the selection of optimum parameters for such lasers. In addition to its primary role of creating a giant pulse, the performance of a Q-switch could be optimised or modified to enhance the longitudinal mode selection property of a laser. The mode selection properties of Pockels cell and dye Q-switched ruby lasers were theoretically developed before experimentally confirming the derived predictions to a good degree.