Book excerpt: Increasing worldwide energy demand has necessitated the building of more power generation facilities. These facilities often consume pollution emitting fossil fuels (coal, gas, etc.) or generate dangerous radioactive byproducts (nuclear fission). Much research has been done to find new, more environmentally conscious ways of providing energy; some of which are promising. An outstanding candidate for clean energy production is nuclear fusion; the process of binding atoms together to release energy in the same process stars use to power the universe. Nuclear fusion can provide clean reliable energy with an almost inexhaustible fuel supply: Hydrogen. However, commercial fusion power cannot start without first understanding the complex processes occurring within burning (self-perpetuating) plasmas. Multiple fusion research reactors have been built around the world to study plasma behavior. The most promising reactor types for the advancement of commercial fusion are Tokamaks.Plasmas which exist in fusion reactors can reach temperatures in the many millions of Kelvin. Microwave and milli-meter wave diagnostic devices provide the capability to monitor various plasma parameters and visualize plasma phenomena without requiring direct contact with the plasma. Outlined in this dissertation are two different Microwave Imaging Reflectometer (MIR) systems designed for the DIII-D and EAST Tokamak fusion reactors. Reflectometry is a technique by which radio frequency (RF) signals are transmitted into the plasma and the reflection phase and amplitude is measured. Special imaging optics are employed to focus the sampled plasma volume onto the RF detector arrays to enhance signal coherence. The Super-Heterodyne down-conversion electronics of the presented MIR systems are highlighted.