Data imprinting device for camera

摘要

An optical piece for a data imprinting device for a camera having beam incident and beam emerging areas. Beam incident and beam emerging areas have an effective aperture for passing a main beam of light and a peripheral beam refracting surface around and defining the effective aperture. This structure eliminates ghosts or flares generated by light rays passing through the peripheral portion of the optical piece. The peripheral beam refracting surface is equivalent to the surface of a lens having a negative index of refraction or one of the bilateral plane surfaces of a triangular prism with its apex pointing toward the optical axis of the optical piece. The lens geometry is controlled by a set of four inequalities. The effective aperture may use convex, planar or concave shapes.