This program develops technology to advance the field of optical intensity interferometry using single photon detectors coupled to small telescopes. Measurement of photon correlation signals between multiple telescopes leverages advances in time-to-digital converters, ultra-fast imaging and optical communications, and novel approaches to high resolution spectroscopy. Near term science opportunities include characterizing the diameters of stars and material around stars, as well as characterizing the properties of binary star systems. The program sets the stage for intensity interferometers with 10s of kilometers of baseline separation reaching micro-arcsecond angular resolution, thereby opening a new discovery space for extragalactic and galactic astronomy. This program supports the education of undergraduate and PhD students and training of a STEM workforce through both laboratory research and contribution to courses on digital signal processing and astronomical instrumentation. Community outreach presentations take advantage of institutional and local museum venues, as well as local secondary schools and Astronomy clubs. This program pursues advances in optical intensity interferometry in three areas: (i) Development of a time calibration system to enable automated measurements of photon correlations on small telescopes using commercial room temperature single photon counting detectors and time to digital converters; (ii) multi-band measurements of photon correlations on