  Fluorescent observation of cells generally suffers from the limited axial
resolution due to the elongated point spread function of the microscope optics.
Consequently, three-dimensional imaging results in axial resolution being
several times worse than the transversal. The optical solutions to this problem
usually require complicated optics and extreme spatial stability. A
straightforward way to eliminate anisotropic resolution is to fuse images
recorded from multiple viewing directions achieved mostly by the mechanical
rotation of the entire sample. In the presented approach, multiview imaging of
single cells is implemented by rotating them around an axis perpendicular to
the optical axis by means of holographic optical tweezers. For this, the cells
are indirectly trapped and manipulated with special microtools made with
two-photon polymerization. The cell is firmly attached to the microtool and is
precisely manipulated with 6 degrees of freedom. The total control over the
cells position allows for its multiview fluorescence imaging from arbitrarily
selected directions. The image stacks obtained this way are combined into one
3D image array with a special image processing algorithm resulting in isotropic
optical resolution. The presented tool and manipulation scheme can be readily
applied in various microscope platforms.
