of space vehicles. In the 1960s, doctoral students who were trained in these sampled-data control system programs became the core of leading researchers in industry and education in the field of digital computer control.9
Atom Probe Field Ion Microscope (1953-1967) The co-inventor of the Atom Probe Field Ion Microscope, Dr. Erwin Mueller, was a principal investigator for AFOSR from 1953 until his retirement from Pennsylvania State University in 1977. Prior to his arrival at Penn State in 1953, he had invented the Field Emission Electron Microscope (1936) and the Field Ion Microscope (1951), which was the first instrument employed to observe single atoms. In 1953, AFOSR issued two contracts with Mueller: one to refine the Field Emission Electron Microscope, and the other to develop an even more effective device: the Field Ion Emission Microscope, which was later termed the Atom Probe Field Ion Microscope. Invented in 1967, and commonly referred to as the atom probe microscope, this device is unlike optical or electron microscopes, because the magnification is the result of a highly curved electric field that removes ions from a sample surface in order to image and identify them. In successively sophisticated models, the instrument allows three-dimensional reconstruction of millions of atoms.10
Dr. Erwin Mueller, Atom Probe Field Ion Microscope
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1950s
field of control systems theory. The objective was to formulate theories for the marriage of new advances in the fledgling field of digital computers, as well as data links, to automatic control systems. In addition, there was a dedicated AFOSR effort to train research engineers to further develop and advance control systems theory. Control systems are essentially devices that regulate the output of a system in accordance with information originating from within or outside of the system, and as the information that is used to control the output of a system is in the form of electronic signals, a discrete portion can also be used to track the overall performance of a system. Early in the 1950s, it became apparent that computers would soon dominate the control system field, and AFOSR endeavored to develop basic underlying theory and rational design principles for the development of control systems that use digital processing of control information. In 1960, AFOSR funding resulted in three papers describing two significant mathematical developments in sampled-data theory under Professor E.I. Jury at the University of California, Berkeley: the Modified z-Transform Theory and the p-Transform Method. This research was subsequently utilized for NORAD’s massive Semi-Automatic Ground Environment (SAGE) system, a digitally automated control system for tracking and intercepting enemy bomber aircraft, which was operational from 1959 to 1983, as well as being employed in guided missile control systems and the trajectory and rendezvous control