English: Meniscus lenses have one concave surface (illustrated here on the right side) and one convex surface (illustrated here on the left side).
The positive (converging) meniscus lens has a thicker center than edge, and represents the case where the convex surface (shown in green) has a smaller radius than the concave surface (shown in red). 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.
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