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Meniscus lenses have a combination of concave on one side and convex on the other side surfaces. They are also known as convex-concave lenses. Depending on the relative sharpness of the curvature between the outer and inner surfaces these lenses can be positive or negative. The key properties of these lenses are the minimized spherical aberrations and increased numerical aperture, which makes them critical for optical corrective applications such as optical glasses, various optical systems and multi lens focussing objective in photo cameras.