Optional Step: The Olympus Fluoview 300 laser scanning confocal microscope has two computers, the ‘power supply unit’ (PSU) and the ‘trigger unit’(TU) (Supplementary Figure 3). To observe the ramp-like scan signal, connect pin 11 and pin 15 of the DB-15HD connector (situated at the back of the TU) to the. On the Fluoview software, set the scan area to ‘512x512’ and zoom to ‘10’. Run the software in ‘XY repeat’ mode.