In this thesis, we characterize and test a new MiM cavity for use in the Bouwmeester Optomechanics group. The cavity seems stable over time, though alignment offers some issues. The tip/tilt...Show moreIn this thesis, we characterize and test a new MiM cavity for use in the Bouwmeester Optomechanics group. The cavity seems stable over time, though alignment offers some issues. The tip/tilt alignment of the membrane was achieved to within 700 arcs eventually however. We also explore the use of finesse measurements to determine the absorbance of our membranes. We conclude that optical ring down measurements are preferable in our system and suspect that the PSG4 membranes have higher absorbance as compared to later generations. We present a scheme to determine the thermal gradient of our membrane in-situ, without any modifications required to the principle of the system. We do find, however, that the measurement is very sensitive to drift of the laser detuning. Finally, we explore the observed short term drift in our mechanical mode frequencies. We suspect the thermal expansion of some part of the system of adding additional strain to the membranes, and in doing so raising their mode frequencies, though the exact pathway remains unclear.Show less