Methods and systems for single beam scanning capable of imaging the surface of a spherical body of arbitrary radius of curvature are provided. The spherical imaging methods and systems utilize one or more off-axis parabolic (OAP) mirror to perform a geometrical transformation of the spherical surface to a flat rectilinear imaging coordinate grid such that the single scanning beam maintains a normal incidence across the curved field of view of the spherical body. The imaging methods and systems project the spherical surface to a Cartesian plane and then the remapped surface is rapidly imaged by raster-scanning an illumination beam in the rectangular coordinate such that the OAP mirror produces a rectilinear image of the target. The imaging of the spherical surface is accomplished while maintaining the target, illumination source, and detector in a stationary position. The imaging systems and methods may utilize a single source and a single detector, and may incorporate a THz illumination source. The beam scanning imaging systems and methods may be applied to corneal tissue imaging.