THIN-FILM MULTILAYER OPTICAL FILTERS; SENSIIVITY ANALYSIS

Thin-film multilayer optical filters play an important role in many aeronautic applications. The selection of a specific wavelength signal is very important for aircraft communication, guidance and control. Aerial imaging and reconnaissance require optical filters to reject background radiation. The performance of optical filters is affected by many parameters: The materials' indices of refraction, the layers' thicknesses and the anges of incidence are the most important parameters. During production, these parameters have tolerances within which they can be produced. Here, a sensitivity study is done to show the effect of these parameters on the filter performance. The study covered single-layer, two-layer and three-layer filters. For all the investigated filters neither a variation of up to 5% of the indices of refraction and the thickness of layers nor angles of incidence up to 100 showed considerable effect on both the peak transmission and the shape of transmission curve. The sensitivity analysis helps greatly in studying the mutual relationship between the filter performance and the tolerance of its parameters.