Cosmic Microwave Background (CMB) experiments are a great tool to probe the universe's history and content. In the recent decade, great progress in large format detector array technologies has allowed increased sensitivity and sky coverage, which has enabled very precise measurements. The next generation of CMB experiments will offer larger focal planes, which will allow measurements with exquisite precision. In this thesis, the following studies are presented: The development of a silicon meta-material deep reactive ion etched anti-reflection coating for use in sub-millimeter wavelengths. Characterization of the aliased detector noise performance of the Atacama Cosmology Telescope (ACT), a current polarization sensitive six-meter telescope that observes the CMB at arcminute resolution. Optical models developed to describe the pickup and sidelobes characteristics of the ACT. These models are currently being used to optimize the design of the Simons Observatory, a next generation six-meter telescope with increased sensitivity. Studies of the motions of clusters of galaxies via the pairwise kinetic Sunyaev-Zeldovich effect (the frequency-distortion of the cold CMB light due to the interaction with the hot inter-cluster ionized gas), with data from ACT.