Monitoring error compensation in general optical coatings.

Error compensation in optical monitoring was demonstrated many years ago for narrow bandpass and edge filters. It is shown here that the compensation effects can apply to a broader range of more general coatings. This is illustrated with a very broadband antireflection coating design of 20 layers and a ramp design of 13 layers. The choice of monitoring wavelength and monitoring strategy are important, and suggestions are made concerning those choices. The results are derived from and demonstrated by computer simulations of the monitoring processes. The importance of monitoring directly on only one part and with one wavelength throughout the process in order to obtain the benefits of error compensation is emphasized.