High time-resolution confocal microscopy (HTRCLSM) requires fast scanning devices. Whereas non-resonant galvo scanners allow full position control, but only at slow speed, resonant scanners allow ~25,000 lines per second, but offer much less positioning freedom. To still allow zoom and pan functions, several approaches have been tried, with varying success. The Leica confocal microscopes od the TCS
series use a very smart solution that enables stepless zooming with short switching times.