| periscopic | Viewing all around, or on all sides. <optics> Periscopic spectacles, spectacles having concavo-convex or convexo-concave lenses with a considerable curvature corresponding to that of the eye, to increase the distinctness of objects viewed obliquely. Origin: Cf. F. Periscopique. Source: Websters Dictionary (01 Mar 1998) |
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| periscopic lens | A lens with 1.25 D base curve. (05 Mar 2000) |
| periscopic meniscus | A lens designed to correct spherical aberration and coma (q.v.). Synonym: periscopic meniscus. (05 Mar 2000) |