How a Camera Lens is Made
This video from the Discovery Channel shows how a camera lends is made.
It all starts with a design. A diamond blade slices up a block of optical glass. A drill cuts the glass into disks. Optical glass is very expensive. A device spins one of the disks while a wheel overhead sculpts it into a lens. Each lens is checked for chips. The underside of the lens is coated with pitch. The pitch is melted on the lens. Grinding makes the surface of the lends uniform and smooth. The lens are polished and lubricated. Polishing makes the lens smooth and transparent.
Any residue is wiped away. A technician optically centers the lens. The lens is cleaned again. It is very important to keep the lens clean and free from dust particles. The F number and other technical details are carved into the side of the lens. It takes 6 weeks to make one of these optical lens’.