Negative Meniscus lenses can be used to increase the focal length of another lens while maintaining the angular resolution of the optical assembly. This lens shape is best used when one conjugate is relatively far from the lens.

The UV Grade Fused Silica negative meniscus lenses are commonly used in beam expanding applications; they increase the divergence of the beam without introducing any significant spherical aberration. Combining a negative meniscus to another lens will increase the focal length, and decrease the NA of the system.