| 摘要 |
A projection-lens system for projecting a magnified image of a scene formed by means of a reproduction element onto a projection screen, which system has two correction groups and one main group which provides substantially the entire power of the system. The main group includes a glass preform of which at least one of the outer surfaces is provided with a layer of a transparent plastics having an aspheric outer profile. This projection-lens system is substantially temperature-independent, provides a satisfactory correction for aberrations, and has a short focal length and a comparatively large numerical aperture.
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