Meniscus Lens are available in either positive or negative from MT-Optics,Inc. Positive Meniscus Lenses may be used to increase the numerical aperture of a positive lens assembly, without an undue increase in the aberrations. Negetive 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.

Specifications:
Material:-------------------------------------------------N-BK7, Fused Silica,N-SF10, CaF2 etc.
Diameter Tolerance:--------------------------------+0.0/-0.15mm (General), +0.0/-0.02mm (High Precision)
Focal Length Tolerance (mm):--------------------+/-2%
Centration:-----------------------------------------------<3 arc minutes
Clear Aperture:---------------------------------------->80% (Small Size), >95% (Large Size)
Surface Figure X (per 25mm@632.8nm)------λ/2 (General), λ/4 (High Precision)
Surface Figure Y (per 25mm@632.8nm)------2λ (General), λ (High Precision)
Surface Quality:---------------------------------------60/40 (General), 10/5 (High Precgaision)
Protected Bevel:---------------------------------------<0.25mmx45deg
Coating:-------------------------------------------------Upon request

Note: Other sizes, material and coating are available upon request.