In situ optical monitoring of Fabry-Perot multilayer structures: analysis of current techniques and optimized procedures

Single cavity Fabry-Perot filters are one of the most popular designs for the production of narrow bandpass filters. The usual deposition strategy to create such filters based on optical monitoring at the filter central wavelength is well-known and has proven its strength over decades. We review in this paper the possible optical methods to monitor such a filter during production and analyze their strengths and weaknesses. Then, we discuss a new monitoring procedure, mixing different methods, to minimize the production errors of this filter while maintaining a precise filter centering. This strategy is applied on different bandpass filter designs.