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Coating Material

Overview​

Coating Material is the material library used by thin-film design, refractive-index fitting, and other optical calculation modules.

There are two valid material types:

  1. Tabulated material
  2. Model material

The two types are both stored in the same material library, but they are used differently.

Material Types​

Tabulated Material​

Tabulated material stores refractive index directly as wavelength points.

Use this type when:

  1. You already have a measured or edited n/k table.
  2. You want to compare or calculate directly from discrete refractive-index data.
  3. You want to import the material into the refractive-index table editor.

Model Material​

Model material stores refractive index as a model structure, such as Cauchy, Sellmeier, Drude, NK, TabulatedNK, or custom expressions.

Use this type when:

  1. You need to preserve the model form itself.
  2. You want to continue editing model parameters later.
  3. You want to import the material into the model editor of the refractive-index fitting module.

Important Rule​

Each material record should keep a single valid optical meaning.

That means:

  1. A tabulated material should be saved as a tabulated material.
  2. A model material should be saved as a model material.
  3. Users should not rely on the system to guess which payload is the real one.

How to Create or Save Materials​

Save a Tabulated Material​

Typical sources:

  1. Manual editing in the refractive-index table
  2. Imported refractive-index text data
  3. Fitted point-by-point refractive-index results

Recommended workflow:

  1. Open the refractive-index editing table.
  2. Confirm that the wavelength-point data is correct.
  3. Click the upload button in the table area.
  4. Save the material as a new or existing Coating Material record.

Save a Model Material​

Typical sources:

  1. Model-parameter fitting results
  2. Manually configured dispersion models
  3. Existing model materials edited and re-saved

Recommended workflow:

  1. Open the model parameter editor.
  2. Confirm the model type and all coefficients.
  3. Click the upload button in the model editor.
  4. Save the material as a model material record.

How Materials Are Used Later​

Structure-sensitive usage​

Some modules need to preserve the material structure, not just the final refractive-index curve.

Examples:

  1. Importing a material into the table editor
  2. Importing a material into the model editor
  3. Restoring a fitting configuration that must rebuild the model UI

In these cases:

  1. Tabulated material should be selected from the tabulated-material entry.
  2. Model material should be selected from the model-material entry.

Calculation-oriented usage​

Other modules only need a valid refractive-index result for calculation.

Examples:

  1. Spectrum calculation
  2. Thin-film calculation
  3. Runtime optical evaluation

In these cases:

  1. Tabulated material can be used directly.
  2. Model material can also be used, because the system evaluates the model at the target wavelengths.

To avoid confusion, use the following rule:

  1. If you care about editable wavelength points, save a tabulated material.
  2. If you care about editable model coefficients, save a model material.
  3. When importing into Index Fit, always use the matching import entry instead of a generic material picker.

Quick Help​

If you are not sure which material type to choose, start with the quick decision guide: