Rubbing Out Roughness

Daniel S. Burgess, News Editor

Problem:
Does anyone have information about testing methods for optical mirror surfaces with microroughness of 1 nm rms or less?

Yuri Petrunin, President
Telescope Engineering Co.
Lakewood, Colo.
March 1997

Solution:
The team at Telescope Engineering Co. had a problem. In 1997, potential institutional customers asked the company to document how it approaches issues of scattered light and surface micro-roughness. The company, which produces mirrors, optical elements and telescopes -- mainly for experienced amateur astronomers -- prides itself on the quality of its products. Its test metrology lab was equipped with Fizeau and Twyman-Green interferometers and a goniometer but did not have a method in place to measure the roughness of its optical surfaces. The company, now in Golden, Colo., turned to the readers of Photonics Spectra…