ZEMAX-EE supports a complete polarisation ray-tracing and analysis capability. Any input polarisation may be defined, and the polarised light may be traced through any optical system. ZEMAX accounts for and reports transmission, reflection, absorption, polarisation state, diattenuation and retardance.

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.

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.

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.

Reflection versus angle shown for the s- and p- polarisations

ZEMAX computes, tabulates and graphs the following:

	Transmission
	Reflection
	Absorption
	Diattenuation (differential absorption)
	Retardance

for any ray or as a function of wavelength or incident angle. ZEMAX supports arbitrary input polarisation states for rays, and computes transmission, polarisation of output, polarisation aberrations, and more. Detailed modelling of internal transmittance as a function of path length and wavelength is also available.

A Jones matrix surface supports arbitrary polarising devices such as polarisers or waveplates. ZEMAX even accounts for the dispersion of thin-film coatings and thin-film effects on coated GRIN lenses. This very extensive capability is documented in an entire chapter in the manual.

All analysis features whose results may be affected by polarisation effects now support a "Use Polarisation" check box on their settings dialog boxes. The Use Polarisation switch causes ZEMAX to trace two orthogonally polarised rays through the system to keep track of the transmitted intensity. All surface, thin film, pupil apodisations, user defined apodisations, and bulk transmittance effects are thus accounted for. This capability has been added to the various MTF, PSF, encircled energy, RMS, image analysis, and other features.

An Example: Frustrated Total Internal Reflection

Frustrated Total Internal Reflection (FTIR) occurs when a ray of light travelling through glass strikes an interface at an angle exceeding the critical angle. It should be totally-internally-reflected at the glass/air interface.

If another piece of glass is placed close to (but not touching) the interface, some light will evanescently couple through the thin gap and propagate. Both the reflected and transmitted beams will be affected, depending on the thickness of the gap. In the limit of the gap having zero thickness, the light will continue as if there were no boundary. In the limit of a large gap, more than a fraction of a wavelength, then virtually all the light is perfectly reflected.

Here is a glass prism, showing total internal reflection at the 45° interface:

Now we bring up a second piece of glass:

with a coating defined as 0.1 waves of air (refractive index unity) at the interface. Repaeting the transmission calculation gives:

showing frustrated Total Internal Reflection. As we increase the thickness of the gap, the result returns to the Total Internal Reflection case. Here is transmission with an air gap of one wavelength:

Note that ZEMAX can correctly compute both the transmitted or reflected ray. The same techniques can be used to model thin-film coatings, polarising coatings, interference filters etc.