Design of optical coatings for two widely separated spectral regions

A systematic method for the design of antireflection coatings for two widely separated spectral regions has been previously described. This method, based on the buffer layer concept, has been extended to the design of optical coatings with virtually any spectral characteristics in the two regions. To demonstrate the principle, coatings with all possible combinations of the properties of antireflection coatings, neutral filters, reflectors, edge filters and narrow-band filters in the visible and in the infrared spectral regions are presented.