Specification of half ball lens as follow: Diameter (mm):0.5mm-100mm Radius Tolerance (μm):+0/-0.01 Center Thickness Tolerance:(mm) ±0.01 Surface Quality:20-10 Substrate:N-BK7 or other optical material Coating:None or as requested RoHS Compliant Half-ball (hemispherical) lens are ideal for applications such as fiber communication, endoscopy, microscopy, optical pick-up devices, and laser measurement systems.