Positive meniscus lenses are designed to minimize spherical aberration and are usually used in small focus numerical applications; meniscus lenses can also improve image quality and reduce spot size, without an undue increase in the aberrations.
Negative Meniscus lenses are the best lens form where one conjugates is relatively far from the lens or where both conjugates are the same size of the lens. They are commonly used in beam expanding applications where minimal spherical aberration is desired.

Specifications