Source: NOVA: "Galileo's Battle for the Heavens" This resource was adapted from NOVA: "Galileo's Battle for the Heavens." As early as the 1300s, eyeglasses made from convex, or outward-curving ...

3. Shape of Optical lens: Plano lens,bi convex lens,bi concave lens, ball lens,Spherial lens 4. Inside quality of Optical lens: clear and transparent, no mold marks, no inside bubble and dirts, 5.