Abstract: A symmetrical type four-component lens system comprises, in the direction of incidence of light, a first lens component, a second lens component, a stop, a third lens component and a fourth lens component. Each lens component is a combination of a positive and a negative lens element, the concave surface of each element facing the stop. The surfaces of the first and fourth components facing the stop have shorter radii of curvature than the surfaces of the second and third components facing away from the stop. The first and fourth components have greater focal lengths than the second and third components. The second and third components satisfy certain conditions relating to the materials forming them.

Abstract: A device for providing an illumination of an object includes first and second optical integrators disposed on an optical axis in spaced-apart relationship. Light rays emitted from a point light source formed by an elliptical reflector mirror having a light-emitting source are incident on the first optical integrator, which forms a plurality of secondary images of the point light source. The second optical integrator receives luminous fluxes emitted from the secondary light source images to form a multiplicity of secondary images of the secondary light source images formed by the first optical integrator. Luminous fluxes from the secondary images formed by the second optical integrator are superimposed by a condenser lens on the object for illuminating the latter with light beams of uniform intensity.