  Versatile, sterically accessible imaging systems capable of in vivo rapid
volumetric functional and structural imaging deep in the brain continue to be a
limiting factor in neuroscience research. Towards overcoming this obstacle, we
present integrated one- and two-photon scanned oblique plane illumination
(SOPi) microscopy which uses a single front-facing microscope objective to
provide light-sheet scanning based rapid volumetric imaging capability at
subcellular resolution. Our planar scan-mirror based optimized light-sheet
architecture allows for non-distorted scanning of volume samples, simplifying
accurate reconstruction of the imaged volume. Integration of both one-photon
(1P) and two-photon (2P) light-sheet microscopy in the same system allows for
easy selection between rapid volumetric imaging and higher resolution imaging
in scattering media. Using SOPi, we demonstrate deep, large volume imaging
capability inside scattering mouse brain sections and rapid imaging speeds up
to 10 volumes per second in zebrafish larvae expressing genetically encoded
fluorescent proteins GFP or GCaMP6s. SOPi flexibility and steric access makes
it adaptable for numerous imaging applications and broadly compatible with
orthogonal techniques for actuating or interrogating neuronal structure and
activity.
