常用作聚焦镜的红外平凸镜，材料包括BaF2,CaF2，Si，Ge，Al2O3，ZnSe以及其他各种材料。此材料为CaF2.
产品指标如下：
Diameter tolerance +0,-0.005” (+0,-0.13 mm)
Center Thickness tolerance ±0.008” (±0.2 mm)
Design Wavelength 5.0 microns
Focal Length Tolerance ±2%
Surface Quality 60/40
Clear Aperture 90% Central Diameter
Wedge Angle < 3 arc min
Surface Irregularity 1 l at 633 nm
