Turning point monitoring of narrow bandpass filters: the enormous strength of the error self-compensation effect

Abstract

It is generally accepted that turning point optical monitoring provides a very strong error self-compensation effect when used to control the deposition of narrow bandpass filters with quarter-wave or multiple-quarter-wave layer optical thicknesses. However, how strong this effect is has never been assessed before, to our knowledge. A recently developed general approach to estimating the strength of thickness error correlation and the strength of the associated error self-compensation effect allows, possibly for the first time, such an assessment. In this work, it is proved that, indeed, in the case of monitoring narrowband filters, the latter effect has enormous strength, many times greater than the strength of the error self-compensation effects when manufacturing all other types of optical coatings using various monochromatic and broadband monitoring techniques.