Abstract: A coating composition which results from hydrolyzing 40 to 70 weight per cent tetraethyl orthosilicate and 60 to 20 weight per cent of certain silane is useful for providing abrasion resisting coatings for plastics after curing. Optionally, up to 20 weight percent of a silane having a reactive polar site or, in the alternative, a small percentage of a surfactant may be used to provide a dyeable coated article.

Abstract: There is disclosed a glass ophthalmic lens including an ion-exchanged antireflection coating. Metal oxide films including TiO.sub.2, CeO.sub.2, ZrO.sub.2, La.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Al.sub.2 O.sub.3, and SiO.sub.2 when evaporated on glass lenses in a vacuum chamber by electron-beam techniques form hard optical coatings which are chemically stabile at high temperatures and allow potassium and sodium ions to traverse the thickness thereof without changing chemical composition or physical integrity thereby enhancing ability of glass lenses to be ion-exchanged in a conventional ion-exchange treatment. This allows antireflection coated glass lenses to pass impact-resistant standards ANZI Z80.1 for prescription ophthalmic lenses and USAS Z87.1 for safety lenses.

Abstract: The annular reflector for a dark-field, vertically-illuminated microscope objective must have a peculiar curvature to obtain a uniform distribution of the light on the object surface being viewed. Four reflectors are disclosed. Each reflector is suitable for use in a respective microscope objective.

Abstract: A pair of identical bi-convex triplets, a mirror, and a pentaprism are used to extend the parallel light zone between the objective and the telescope lens of a conventional infinity corrected microscope system. Specific values for the components and spacings between the same are given.