Two-part aspherical condensing lens system - for illumination purposes in projectors has Fresnel lens and Meniscus lens

摘要

The aspherical condenser lens (4), which is in close proximity to the slide, is a Fresnel lens. The Fresnel's rings (7) have been adapted to the pupil positions of the projection objective used and feature an alternately different gradation of refraction. The different gradations of refraction is mounted on one or both surfaces of the Fresnel lens (4). The condenser lens (3), which is in close proximity to the lamp, is designed as an aplanatic meniscus lens consisting of heat absorbing glass and has a thickness roation of centre to edge thickness of less than 5. The condenser lenses (3, 4) are arranged at a fixed distance.