Right, he used a microscope based on crystal lenses to observe which specific frequencies had an effect on virus particles and other microbes.
So in reality, the key is to be able to observe the virus while it is being zapped or "irradiated" as in the case of Rife. Doing this allows direct observation that could be used to determine the MOR rather than use the Synchrometer which was Clark's favored tool.
This brings to point that Morris Fishbein was a success at his goal of setting microscopy back so that the Science of vibrational treatment could not be fulfilled.
So what the US and the World needs today is to build the modern Rife microscope project. If the people of the world want a true cure for cancer and many other illnesses, a high powered optical microscope is the answer.
It will take a concerted effort to replace the genius of Rife. If undertaken by the US, it could be called the NMSA ( National Microscopic and Submicroscopic Administration ).