The quality of optical simulations may critically depend on the choice of the underlying optical constants. SPRAY contains very powerful dielectric constant models as well as a large database of literature data and pre-defined models.

The definition of optical constants (or dielectric functions) in SPRAY is exactly the same as in our spectrum simulation program SCOUT. Please refer to the SCOUT technical manual (online version: www.mtheiss.com/docs/scout2/index.html) for details. A printed version of the SCOUT manual is included in your SPRAY documentation.

Optical constants enter SPRAY simulations in the following ways:

•Each light source is embedded in a certain material. Its optical constants are assigned to the light source object by drag&drop from the list of materials. The ray continues to move in that medium unless it crosses an interface which defines a change of the optical constants.

•Interfaces may consist of layer stacks. An optical constant object from the list ofmaterials must be assigned to each layer of a layer stack. The stack of layers is embedded between a top and a bottom 'halfspace'. If the materials assigned to top and bottom halfspace are different and a ray crosses the interface, it continues its motion in the new material.