Some concentrating dishes ( such as satellite dishes ) that do not require a precise focus opt for a spherical curvature over a paraboloid.
2.
Additionally, aperture grille displays tend to be vertically flat and are often horizontally flat as well, while shadow mask displays usually have a spherical curvature.
3.
Developed by Sir David Brewster, this magnifier was a simple plano-convex lens of such thickness that the focus of its spherical curvature coincides with the flat surface of the lens.
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