Patent ID: 8520268

Claim:
An apparatus for scanning a surface with electromagnetic radiation, the apparatus comprising: a base plate having a planar support surface extending in a longitudinal direction and a transverse direction for supporting a medium having a marginal edge and a scanning surface to be scanned; an optical head unit shiftable relative to the base plate in the longitudinal direction, and adapted to scan the scanning surface in both the longitudinal direction and the transverse direction with electromagnetic radiation propagating along an optical axis which is oriented generally perpendicular to both the longitudinal direction and the transverse direction; a fluid film generation unit movably connected to the optical head unit and having at least one gliding surface with means through which pressurized air is ejected to generate a fluid film between the scanning surface of the medium and the gliding surface of the fluid film generation unit for maintaining a predetermined distance along the optical axis between the gliding surface and the scanning surface during scanning operation of the optical head unit across the scanning surface; wherein the fluid film generation unit is movably connected to the optical head unit for sliding, linear translational movement in the longitudinal direction independently of and relative to the optical head unit, such that the optical head unit can slidingly shift linearly beyond the marginal edge of the medium, while the fluid film generated by the fluid film generation unit remains fully over the scanning surface of the medium to accurately maintain the predetermined distance between the gliding surface and the scanning surface, and thereby facilitate scanning the entirety of the scanning surface without any margins; and wherein the apparatus further comprises an automated control operably connected to the optical head unit and the fluid film generation unit, wherein the automated control is configured to automatically detect the marginal edge of the medium, and automatically control the position of the fluid film in the longitudinal direction relative to the optical axis of the optical head unit in synchronization with the scanning operation, whereby the optical head unit can slidingly shift linearly beyond the marginal edge of the medium, while the fluid film generated by the fluid film generation unit remains fully over the scanning surface of the medium to accurately maintain the predetermined distance between the gliding surface and the scanning surface, and thereby facilitate scanning the entirety of the scanning surface without any margins.