This video is a fascinating look at the Hikari Glass factory in Akita Japan which is part of the Nikon Group. It shows the production of glass, that later becomes Nikkor lenses, in its earliest stages. The precision, dedication, and craftsmanship is incredible.
The interviews with engineers and production staff are insightful and interesting. Each person seems to have an acute understanding of their job. Check out the video and I hope you enjoy it.