Tech Spec high-index ball lenses are made from LaSFN9 glass that has an index of refraction of 1.850. Edmund Industrial Optics designed the lenses to help increase the efficiency of coupling light into optical fibers. The ball lenses are available in 10 diameters ranging from 1 to 10 mm, with diameter tolerances of less than or equal to 3 µm. The surface quality of the lenses is 40-20, and sphericity is at least 0.4 µm. Available uncoated, the lenses also come with a broadband near-IR antireflection coating that offers more than 99.5% transmission at 1310 and 1550 nm.