### Changing optical properties

Optical properties

Unit

Explanation

Transparency

Model describing the interaction of light with the material.

The list box in CrysMAS offers four models for four different optical material behaviours types:

• Opaque

Fully opaque, no transparency at all.

• Transparent

Fully transparent.

• Visibility bands

CrysMAS uses the n-Band model for treatment of the spectral behaviours.

Material is absolutely transparent only in the defined spectral bands and is totally opaque in the rest of the spectrum.

• Semitransparent

It is the most general case of the optical model. The spectrum can be subdivided into bands which are either fully opaque or fully transparent or have a finite absorption coefficient. In the latter case the spectral band is treated as a semitransparent and the ray tracing model is applied to compute the radiative heat transport.

Emissivity

The emissivity of the material in the approximation of gray bodies is needed for materials at the border of a radiation cavity and must be a real number between 0 and 1.

For the n-band model the emissivity means the absorption and emission of the radiated energy only in the opaque spectral band of the material. The radiation is propagated in this case outside of the material.

Transparent windows

μ m

If transparency is Visibility bands, you need to specify the visibility band windows by entering a list of wavelengths or a formula, e.g. 0-1 1-4 4-1e+10.

A fully transparent material has the Visibility bands list 0-1e+10, an opaque material 0-0, i.e. no transparency window.

Semitransparent windows

μ m

If transparency is Semitransparent , you need to specify the semitransparent spectral windows by entering a list of wavelengths or a formula, e.g. 0-1 1-4 4-1e+10. The rules are the same like in the previous case of Visibility bands.

The defined semitransparent windows coincide with the semitransparent bands, it means bands where the absorption coefficient should be specified. The absorption coefficient and other properties are hold constant within of one semitransparent or one transparent band.

1. Place the cursor in the phase column of the property that you want to change.

2. Type respectively overwrite the value.

or

Select Yes in the list box of the Anisotrop property to specify Conductivity -z and/or Phi.

3. Click on or press the Enter key and continue with the next property.

or

Click on to apply the changes and to close the dialog.

The next computation will consider the changed properties.