An approach to cell characterization for Filtered Rayleigh scattering used in high speed flow diagnostics

Abstract

This thesis looks at the design of developing laser technology that can be used for nonintrusive diagnostics by approaching cell characterization for molecular filters used for Filtered Rayleigh scattering (FRS). First, the thesis looks at an existing injection- seeded and frequency-tripled Titanium:sapphire laser that has been used for FRS experiments in the past. This laser is selected for the filter cell characterization because of its narrow linewidth capability and the wide gain bandwidth of Ti:sapphire, which is advantageous for tuning. The selected filter cell made of mercury has a transition wavelength in the ultraviolet region at 254 nm, which provides good overlap with the Ti:sapphire laser. To make the existing laser more robust for scattering experiments, a data acquisition system is designed to be used in conjunction with the system for cell characterization. This acquisition system incorporates a Boxcar integrator to receive the fast analog signals from the detectors incorporated into the laser’s design. The design, comprised of the laser system along with the data acquisition methods, was insufficient for the complete characterization of the cell to be used for further FRS experiments due to certain instabilities in the laser design. However, this thesis discusses the adjustments to the system for more robustness as well as steps to be taken for this project to proceed.