Ulrike Schulz, Uwe B. Schallenberg, and Norbert Kaiser
„Symmetrical periods in antireflective coatings for plastic optics” in Applied Optics / Vol. 42, No. 7 / 1 March 2003

Abstract:
Plastic optical parts require antireflective as well as hard coatings. A novel design concept for coating plastics combines both functions. Symmetrical three-layer periods with a phase thickness of 3/2? are arranged in a multilayer to achieve a step-down refractive-index profile. It is shown mathematically that the equivalent index of symmetrical periods can be lower than the lowest refractive index of a material used in the design, if the phase thickness of the symmetrical period is set equal to 3/2? instead of the usual ?/2. The straightforward application of the concept to the design of antireflection coatings in general is demonstrated by example.
© 2003 Optical Society of America
OCIS codes: 310.1210, 310.1860