Abstract: A relief image-forming composition having an acidic pH comprises a photosensitive component and an indicator capable of existing in two states differing in actinic opacity dependent upon pH. A relief image is formed by (1) exposing to light selected areas of a layer of the composition, the indicator being in its state of lower actinic opacity, (2) removing layer material from the exposed areas or from the unexposed areas and (3) shifting the pH in the remaining layer material to a value at which the indicator exists in its state of higher actinic opacity. The resultant image can then be used as an intermediate original in diazotype copying processes.

Abstract: The invention relates to electrostatographic copiers and in a first embodiment an optical arrangement is provided in which the image of an original placed on a part-cylindrical platen is reflected via a first mirror through a movable scanning lens onto a second, rotating mirror and thence onto a photoconductive surface of a drum. The platen may be either cylindrical or flat and have the image of the original reflected from a first mirror which is so inclined and dimensioned that substantially the whole of the perpendicular projection of the original falls on the first mirror, the arrangement being such that the optical path length between the original and the drum surface is maintained substantially constant.