Abstract

Microroughness for profile lengths of 1 mm or less can be measured with several very sensitive mechanical contact and optical noncontact instruments.^1-5 These instruments are sensitive enough to measure roughnesses of less than 1 Å rms. Lateral resolutions vary from a few tenths of a micron for a mechanical contact type instrument^1,2 to one or more microns for optical non-contact profilers.^3-5 The best polished optical surfaces have microroughnesses of less than 10 Å rms, and values of 1 - 2 Å rms have been measured for specially polished samples of Zerodur, silicon carbide, and sapphire². On the other hand, optical figure measurements are routinely made on samples ranging from diameters of a few centimeters to several meters. Flatness of a few hundredths of a wavelength of visible light can be achieved in the best cases. For example, an rms figure error of one hundredth of a wavelength at a wavelength of 5000 Å is 50 Å.

© 1987 Optical Society of America