The press release (edit: and I) skipped a step: "A portion of the laser beam is split off with a glass plate and directed to a photodetector that provides the syn- chronization signal for the camera. The camera images the incoming light on a slit and this slit on a photocathode where photons excite electrons. These electrons are accelerated in a vacuum tube and deflected by an electric field perpendicular to their direction of motion and perpendicular to the direction of the slit. The signal generating this field is obtained by filtering and amplifying the synchronization signal from the laser. The image is thus spread out over time in a “streak” that hits a micro channel plate at the far end of the vacuum tube that further amplifies the electrons and directs them to a phosphor screen where they are converted back to photons. The screen is than imaged on a conventional low noise CCD camera. The complete time interval captured in this way spans about 1 nanosecond." [Picosecond Camera for Time-of-Flight Imaging]

So a photo cathode generates electrons which are deflected.