  Oblique plane microscopy (OPM) is a single objective light-sheet microscopy
which performs three dimensional (3D) imaging by axial scan of the generated
light-sheet. Recently, multiple techniques for lateral scan of the generated
light-sheet in OPM have emerged. However, their suitability for geometrically
distortion free 3D imaging, which essentially requires a constant tilt
light-sheet scan, has not been evaluated. In this work, we use a geometrical
optics approach and derive analytical relationship for the amount of tilt
variance in planar mirror based scanned oblique plane illumination (SOPi)
arrangement. We experimentally validate the derived relationship and use it to
arrive at an optimized scanner geometry and to understand its associated
limitations. We also discuss the effects of scanning on optical aberrations and
3D field of view in optimized, tilt invariant, lateral scanning OPM systems.
