Vector beam mapping at millimeter wavelengths using a robot arm

Presently, experiments aimed at mapping the cosmic microwave background (CMB) and further constraining the energy scale of cosmic inflation require extensive studies of potential systematic effects. Typically operating in the 40-400 GHz frequency range, these experiments are particularly sensitive to optical systematics of various form. Near-field vector beam mapping, or holography, is now employed in a variety of CMB-focused experimental efforts due to the technique's ability to provide full details of electromagnetic field propagation through complex systems. In this proceeding, we describe the development of a millimeter-wave system for phase-sensitive beam mapping with the goal of characterizing telescopes and telescope components for CMB experiments. We discuss the testing of a scanning mechanism based on a 6-axis robot arm, the software we have written for interacting with it, the readout architecture and the overall validation of the system through various testing procedures.