Apochromatic lenses for near-infrared astronomical instruments

A method based on the Herzberger approach has been investigated for the selection of glasses for the apochromatic correction at near-infrared (NIR) wavelength. The method avoids the algebraic complexity and simplifies the glass selection processes. Doublet and triplet glass combinations can be chosen directly from the plot of partial dispersion versus V number. Good combinations of NIR doublets and triplets are given. Design examples show that the method is practical and efficient.