Meniscus Lens can increase the NA of the system while only adding slightly to the total spherical aberrations. The Negative Meniscus Lens is 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.
Material: Optical Glass
Surface Flatness: < λ/5 @ 633nm
Scratch/Dig: < 40/20 (both sides)
Eccentricity: ≤ 1arcmin
Focal Length Tolerance < ± 1%
Diameter Tolerance: < + 0.00/ - 0.10mm
Thickness Tolerance: < ± 0.1
Clear Aperture: ≥ 90% of diameter
Coating: AR OR BBAR
Diameter Range: 5~260mm