How do they make the reflecting surface of giant telescopes barabolic mirrors?

Query by alfajoe127: How do they make the reflecting surface of giant telescopes barabolic mirrors?
For the glass base, they make it rotate in an oven, but how do they make the completely reflecting surface following?
I was also surprised by doug’s post. I am preatty certain that it makes a parabola result in I eared it a lot of times but I red the demo on the hyperlink you gave Lioni and i just never get why they say Ekin = Ecin

Greatest answer:

Answer by Rob L
its parabolic, but anyway

I never know… excellent question
I know that they have actual people polish mirrors for lasers

Add your personal answer in the comments!