Negative meniscus lenses are designed to minimize spherical aberration. These N-BK7, UV fused silica, calcium fluoride, and zinc selenide lenses consist of a convex surface and a concave surface where the concave surface has the greater radius of curvature. In combination with another lens, a negative meniscus lens will decrease the NA of the system. A negative meniscus lens is a common element in beam expanding applications. For more information on these substrates, please visit our Optical Substrates page.