Dispersion of Some Optical Glasses in the Visible and Infrared

Indices of refraction of a number of Bausch & Lomb optical glasses are given for the wavelength region 0.4 μ to 2.5 μ. Dispersion curves for different glasses are more similar in the infrared than they are in the visible. Infrared indices may be calculated from measured values of indices in the visible for a particular glass if visible and infrared indices are known for two or more other glasses. The expected error in the calculated infrared index is less than one unit in the third decimal place if the glass is similar in composition to those whose indices were measured, and of the order of two in the third place if far different in composition.