Cushman, Darby & Cushman
Cata-dioptric objective lens system
 A compact cata-dioptric objective lens system comprising a first, second, third and fourth lens components in which the first lens component is a positive meniscus lens, the second lens component has a primary mirror formed on its surface on the image side by leaving a transparent central portion, the third lens component has a secondary mirror formed on its surface on the object side and the fourth lens component is cemented to the second lens component. The cata-dioptric objective lens system is arranged so that the rays entered through the first lens component are reflected by the primary and secondary mirrors, pass through the transparent central portion of the second lens component and are imaged thereafter and so that the fourth lens component has a large thickness in order to eliminate detrimental rays. 
Olympus Optical Co., Ltd.
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inventional inventional inventional inventional
Toru
Fujii