Figure 11.

(A) Schematic of image-based biplane active feedback 3D tracking. One part of fluorescence is transmitted through a 50:50 beamsplitter and imaged onto the EMCCD camera while the other part of fluorescence is reflected by beamsplitter and imaged on a different side of the EMCCD. The reflected fluorescence has a longer path so that two axial planes can be monitored synchronously. The piezo mirror and Z piezo stage are used to move the laser focus in 3D. Adapted from reference [100]. Copyright 2010 American Chemical Society. (B) Schematic of astigmatic imaging active feedback 3D tracking. A high NA objective is used for light sheet illumination and the 3D information of the particle is encoded in the astigmatic image. The image is analyzed and a feedback control is applied to the Z piezo stage to maintain the particle in focus. Adapted from reference [101] under Creative Commons CC BY Licence.