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The Gauss lens is a compound achromatic lens that uses two uncemented elements; in its most basic form, a positive meniscus lens on the object side and a negative meniscus lens on the image side.
Meniscus lenses: negative (top) and positive (bottom) Convex-concave (meniscus) lenses can be either positive or negative, depending on the relative curvatures of the two surfaces. A negative meniscus lens has a steeper concave surface (with a shorter radius than the convex surface) and is thinner at the centre than at the periphery.
A: The bottom of a concave meniscus. B: The top of a convex meniscus . In physics (particularly fluid statics ), the meniscus ( pl. : menisci , from Greek 'crescent') is the curve in the upper surface of a liquid close to the surface of the container or another object, produced by surface tension .
The innermost element in each group is a positive meniscus, the outermost is biconvex, and there is a biconcave element between them. The Plasmat lens is made in many variants, e.g. departing from exact symmetry, adding a lens to one or both groups, or separating the innermost or outermost element from the rest of the group.
Development of the Double Gauss. The earliest double Gauss lens, patented by Alvan Graham Clark in 1888, consists of two symmetrically-arranged Gauss lenses.Each Gauss lens is a two-element achromatic lens with a positive meniscus lens on the object side and a negative meniscus lens on the image side.
The cornea is considered to be a positive meniscus lens. [19] Some species of birds and chameleons, and one kinown species of fish, also have corneas which can focus.
In 1804 William Hyde Wollaston invented a positive meniscus lens for eyeglasses. In 1812 Wollaston adapted it as a lens for the camera obscura [1]: 23–26, 307 by mounting it with the concave side facing outward with an aperture stop in front of it, making the lens reasonably sharp over a wide field. Niépce began using Wollaston Meniscus in 1828.
The meniscus lens on the bottom is a positive element. The negative (diverging) meniscus lens has a thicker edge than the center, and represents the case where the concave surface (shown in red) has a smaller radius than the convex surface (shown in green). The meniscus lens on the top is a negative element.