Abstract: A lighting device with variable angle of emission includes a light source, and a lens system comprising two lenses, a primary lens and a secondary lens. The two lenses and the light source are arranged along an optical axis and the distance between the primary lens and the secondary lens is variable, in order to vary the angle of emission of the cone of light rays generated by the lighting device. In one example, the primary lens has a numerical aperture of at least 0.7, the primary lens is an aplanat, and the secondary lens is designed so as to image to infinity, at a certain distance of the secondary lens from the primary lens, a virtual image of the light source generated by the primary lens. According to a second aspect, the illumination factors are distinguished by the fact that the primary lens has a numerical aperture of at least 0.

Abstract: An arrangement for turning an image projected on an image screen has an image screen, a trapezoidal prism for image turning, and an optical system for image producing. The prism has an entry surface, a base surface and an exit surface. The entry surface of the prism encloses with the base surface an angle which is different from an angle enclosed by the exit surface of the base surface. A light beam extending on an optical axis of the optical system for image producing is offset on the exit surface relative to the optical axis and encloses an angle with the optical axis which is not equal to zero, and a transmission filter is located between the prism and the image screen.