Abstract

Antireflection (AR) coatings are important components of optical instruments and many papers have been published on their design. However, few deal with the design of dual band AR coatings except for the special case of wavelength doubling or tripling. There is, in addition, a need for AR coatings that act in widely separated spectral regions. For example, when visible lasers are used for the alignment of infrared lasers, the optical surfaces should have AR coatings that are effective at both laser wavelengths. In the case of CO₂ and He-Ne lasers, the wavelength ratio is about 17 to 1. Two methods for the design of such AR coatings are described. One is based on the elimination of visible light reflection at the interfaces of the AR coating for the infrared region. The other method uses the concept of a thickness-independent buffer layer.¹

© 1991 Optical Society of America