Thin Film Coatings
Zemax has an extensive thin film modeling capability to support the polarization analysis. Multilayer film dielectric and metallic coatings may be defined, from either a predefined or user defined material database. Many thin film codes, like The Essential Macleod and Film-Star export coating designs directly in Zemax format.
Coatings may be applied to either dielectric or metallic substrates. Coatings may be composed of arbitrary layers of arbitrary material, each defined with a complex index of refraction, with full dispersion modeling in the coating materials. Substrates may be glass, metallic, or user defined. Coating layers may be of uniform or varying thickness, and loops of replicated coating stacks can be easily created.
Zemax automatically reverses the coating layer order if surfaces go from air to glass then glass to air, so the same coating may be applied on many surfaces without the need to define "mirror image" coatings.
With the coating data in place, Zemax computes the diattenuation, phase, retardance, reflection, transmission, or absorption of any coating as a function of wavelength or angle. Here for example is the reflectivity of a metallic beamsplitter coating with N-BK7 glass on either side:
Zemax can model performance exactly from the coating prescription data, but often this is not available to the optical designer because of commercial confidentiality. In these cases, Zemax has a powerful TABLE coating capability that allows Zemax to read in tables of either measured or predicted coating performance. Zemax also supports a powerful encrypted coating capability, that uses 256-bit encryption to export a coating in a format that can be freely distributed without revealing details of the prescription. The coating is modeled exactly, with no approximation or interpolation to tabular data.
Also, in many cases detailed coating data is not required: it is enough to say that some fraction of the input energy is reflected, some is transmitted and the rest absorbed by the coating. The IDEAL coating lets you specify this type of coating quickly.
Related Knowledge Base articles:
How To Model a Dichroic Beam Splitter
How To Model a Partially Reflective and Partially Scattering Surface
How to Add Coating and Scattering Functions to Non-Sequential Objects