  Light sheet fluorescence microscopy provides optical sectioning and is widely
used in volumetric imaging of large specimens. However, the axial resolution
and the lateral Field of View (FoV) of the system, defined by the light sheet,
typically limit each other due to the spatial band product of the excitation
objective. Here, we develop a simple multi-focus scheme to extend the FoV,
where a Gaussian light sheet can be focused at three or more consecutive
positions. Axially overlapped multiple light sheets significantly enlarge the
FoV with improved uniformity and negligible loss in axial resolution. By
measuring the point spread function of fluorescent beads, we demonstrated that
the obtained light sheet has a FoV of 450 um and a maximum axial FWHM of 7.5
um. Compared with the conventional single-focus one, the multi-focus Gaussian
light sheet displays a significantly improved optical sectioning ability over
the full FoV when imaging cells and zebrafish.
