Movies demonstrating the response time of our Newport FSM20XY fast steering mirror. At a 50 Hz signal, the mirror cannot respond as quickly as the signal leading to a wobble in the laser beam. This causes a flickering in the intensity (cf. video 1) of the TIRF beam as it sweeps through 360 degrees of incident angle. When the signal frequency is reduced to 30 Hz, the mirror can keeps up with the signal providing a clean circular input and even illumination at all angles (cf. video 2) . We find that as long as the frame rate is no faster than 4x the sweep rate, Disco TIRF is sufficient to reduce or remove the intensity fringes observed in standard laser-illuminated fluorescent micrsocopy.
Fluorescently labeled myosin XI molecules walking along actin filaments.