Callam completed a PhD focused on optical metrology, where he explored the weak signal limits of inter-spacecraft interferometers. His research sits in the sweet spot between fundamental research and applied science, giving him experience in tackling the difficult problems that arise when we try to translate theoretical concepts out of the lab. His day-to-day work in this area of study saw him develop a technical mastery of: optical physics, statistics, mathematical and numerical modelling and digital signal processing on high-speed electronics.