An apparatus for observing dynamic systems by time-resolved microscopy has an optical microscope including a cryo stage for receiving a cryo sample and maintaining the cryo sample at a cryogenic temperature, a heating system configured to temporarily heat at least a portion of the cryo sample such that the portion of the cryo sample melts to a liquid state, temporarily resides in the liquid state, and then revitrifies, and an image detector associated with the optical microscope for detecting magnified images of the cryo sample generated by the optical microscope. Detected images may be recorded and analyzed to inform on-the-fly adjustment of heating power level delivered to the cryo sample. In a correlative light-electron microscopy method, the revitrified cryo sample is observed using an electron microscope.