World's fastest high-speed cameras were built to take photos of specific objects. What kind of objects?

The rapatronic cameras are capable of recording a still image with an exposure time as brief as 10 nanoseconds (that would give 100 million frames per second if the camera was capable to do multiple pictures). The camera uses two polarizing filters mounted with their polarization angles at 90° to each other and a Faraday cell which briefly changes the polarization plane of light passing through it, acting as a shutter.