We research and develop compact and robust optical devices for the fluorescence measurement of biochemical signals in live animal models for human diseases in pre-clinical investigations and basic science. The key characteristic of the fluorscence signal that we focus on is the excited state lifetime. The core technology that underlies our in vivo measurement devices is time-correlated single photon counting. It is a technology that gives rise to dynamic information that is super-resolution in time (picoseconds to nanoseconds). When it is combined with Förster resonance energy transfer, it provides super-resolution information on the spatial scale of 2 - 8 nanometers.