Distortion correcting apparatus for line-scanning system

Claim 1

Apparatus for scanning an area emitting a given kind of radiation, and for processing the radiation thus collected into a form suitable for reproduction and recording, which comprises one or more surfaces reflecting the radiation, which surfaces are rotatable about an axis of rotation; a configuration of detector elements with an array of n elements for simultaneously scanning n field lines transversely to said axis of rotation; and n light modular units each responsive to an output signal derived from an associated one of said n detector elements; and characterized in that each of said reflecting surfaces is at a fixed angle, of preferably 45°, to said axis of rotation; each of a plurality of the detector elements is coupled to a separate delay device serving to delay the signal from the associated detector element by a time interval varying with the scanning angle φ according to a pre-determined function, said delay devices being such that radiations from points in the scanned area located in rows parallel to said axis of rotation and horizontally spaced from a vertical line through the apparatus, are effective to produce isochronous signals at the respective outputs of the delay devices; and in that said light modulator units are optically coupled at their output ends to prism means for combining the n separate beams of radiation generated by the n light modulator units, each of which light beams has been modulated with the appropriately delayed output signal from an associated one of said detector elements, to form a beam comprising n rotation-symmetrical component beams co-axially shifted together.