Which surface of a typical meniscus lens is concave?

• A. Front
• B. Back
• C. Both surfaces
• D. Neither surface

Answer: (B)

A meniscus lens has one surface that is convex and the other that is concave. This shape is chosen to produce the desired optical power while using less material than a full bi-convex or bi-concave lens. In common lens design, the concave surface is on the back of the lens. That back-surface concavity allows the front surface to remain convex and carry most of the optical power, yielding a lighter lens with a thinner profile overall. If both surfaces were concave or both were convex, you wouldn’t have a true meniscus shape.