We made two very steep parabolas, one in quartz and one in a water-soluble salt. We well know that our use of Grandfather's pantograph is as out of date in the Eighties as the dinosaur; but that is what we have and it is simple to set up. The results speak for themselves, as they are adequate.
© 1980 Optical Society of America
Frank Cooke, "Making two very steep parabolas," Appl. Opt. 19, 1016-1019 (1980)