... : 30 days 1, Techniques of Optical lens: by Molding, Grinding, Polishing 2, Shape of Optical lens: Plano lens,bi convex lens ... concave lens, ball lens,Spherial lens 3, Inside quality of Optical lens: clear and transparent, no mold marks, no inside bubble ... and dirts, 4, Function of Optical lens : Lighting splitting,magnifying etc. 5, High transimission ...