An illumination system for illuminating a line on a document which illumination, when reflected and focused via a lens on a sensor (or image plane), has substantially uniform light intensity along the length of the line. The illumination system includes means for compensation for lens cosine to the fourth power fall-off and an illumination cosine fall-off phenomenon, which has classically been treated as proportional to cosine to the fourth power but in the example of lamps made of coiled tungsten filaments located along the axis of the foci, is more nearly cosine to the 2.8th power. The compensation apparatus includes a cylindrical ellipse for focusing light from two lamps located on an axis which is one foci of the ellipse and the line on the document is located at the other foci of the ellipse. Reflected light from the line on the document is then reflected and focus via a lens onto a sensor. At the sensor, the image is captured for analysis or other uses, e.g., using conventional techniques for character recognition or image processing. The uniform intensity at the sensor can be facilitated by the use of appropriate dimensional relationships between components of the imaging system.

An illuminating device for use with an imagewise exposing arrangement of an electrophotographic copier, electrostatic printer or similar image recording equipment. A delimited area of a glass platen is illuminated by a light source and a main reflector which is implemented by a mirror. The main reflector is located outside of one end of the delimited area. Three auxiliary reflectors are individually associated with, among four sides which are individually associated with the outer edges of the delimited area, a side facing the one end where the main reflector is provided and two facing sides which adjoin the above-mentioned side. Light reflected by the main reflector is redirected by the auxiliary reflectors toward the delimited area.

The present invention concerns with a slit illumination system for use in a copying machine or the like, which includes a light source, a first and second elliptical mirrors, a third plane mirror, and a supplemental mirror positioned behind the light source and between the first and second mirrors. The supplemental mirror directs the light which does not contribute to the illumination by the first and second mirror to the original through a light path extending directly to the original and/or a light path extending to the original through the third mirror.

An illumination system for a document copying machine including an optical cavity having interior walls coated with a white, diffusely reflecting material. One end of the cavity contains a platen for positioning a document to be copied while the opposing end contains a lens for forming an image of the document on a light sensitive image plane. Illumination from a single flash illumination source located within the cavity, undergoes multiple reflections from the walls resulting in a uniform diffuse illumination of the document. An optical element is positioned above the lamp to prevent direct light from striking the platen and, in a preferred embodiment, has an aperture therein for increasing illumination of the platen area overlying the lamp-blocker mounting.

An illumination system having a light source disposed along a central axis of the system is provided with a conical reflector coaxially disposed about the light source for forming an annular virtual image of an arc of the light source. A toroidal lens is coaxially disposed about the central axis for forming a circular real image of the annular virtual image of the arc at the input port of a utilization device.