Material Editor

The Material Editor is where you manage every refractive-index source TFStudio knows about. Each material provides a refractive index n(λ) and an extinction coefficient k(λ); absorbing materials have k > 0. Every dropdown in the app that asks you to pick a material reads from here.

Materials are grouped into catalogs by source:

Catalog	Source	Editable
Built-in	A curated set of 16 common optical materials.	Read-only
AGF	Zemax .agf files placed in your TFStudio materials folder.	Via the file
User	Materials and catalogs you create inside TFStudio.	Yes
RefractiveIndex	Materials you import from the refractiveindex.info database.	Yes

The left panel holds a catalog selector, a search box, and the material list; the right panel shows the selected material. Built-in and AGF materials show read-only details (properties, dispersion formula, tabulated data, and an n/k chart); user and imported materials open in an editable form.

Settings

Catalog selector: choose a single catalog or All. The selector shows each catalog’s material count, and beneath it sit the actions for managing the selected catalog.

Search: filter the list by name (case-insensitive). The filter respects the catalog you have selected.

Import AGF: load a Zemax .agf glass file as a new catalog. AGF files store internal transmittance versus wavelength; TFStudio converts that to k(λ) automatically. AGF files you place in your TFStudio materials folder are also picked up automatically when the app starts.

Import material files: load materials written by other coating programs, any mix of them in one pick:

Program	Files
TFCalc	.mat from the MATERIAL and SUBSTRAT folders
Essential Macleod	.tfx from a materials database folder, or .mtx written by File → Export → Material
OptiLayer	.lm and .sub

The import dialog lists every material it read with its program and data type (table with its point count, or the formula in the program’s own name), and previews the highlighted one: formula and coefficients or the table rows, and an n/k chart. Untick what you do not want, choose the catalog to add to, or create a new one.

TFCalc and Essential Macleod files do not record their wavelength unit. The dialog assumes nanometres, reads the unit from an Essential Macleod database’s own settings when the .tfx file sits in its database folder, and has a switch to micrometres for when the preview shows the curve in the wrong place.

Formula materials keep their formula where TFStudio has the same form. The TFCalc forms it lacks (Hartmann, Drude, and every k formula) are sampled onto a table over the range the file states. An Essential Macleod internal-transmittance table has no equivalent here and is left out; the k column is imported as it is. The compressed files of the Essential Macleod materials library cannot be read: open such a material in Essential Macleod and save it into your database first.

Browse RII: open the refractiveindex.info browser to pick from the online database (an internet connection is needed the first time you fetch a material). The material is added to your chosen user catalog and then lives locally.

New Catalog: create an empty user catalog to organize your own materials.

Duplicate: copy the selected catalog (from any source) into a new, editable user catalog. Copy to catalog copies a single material into a user catalog, which is the way to make an editable variant of a read-only material.

Creating a material

Open a user catalog and choose New material, then pick a data type:

1. Tabular: paste or type a λ, n, k table. You can paste directly from a spreadsheet (Ctrl+V), and the grid supports keyboard navigation, sorting and per-cell editing.
2. Formula: choose a dispersion formula (Sellmeier, Cauchy, Conrady, Schott, Herzberger and other standard forms), enter its coefficients, and optionally add a λ, k table for absorption. The formula is rendered in full so you can confirm the convention. The Cauchy and general Sellmeier forms take as many terms as you add; a term left at zero is dropped when the material is saved.

A live n/k chart updates as you edit, and the wavelength range you set bounds where the material is valid and the span the chart shows. Under the chart, type a wavelength to read n and k there, and a sampled table lists the curve’s numbers. The same probe and table sit under the chart of a read-only material.

TFStudio evaluates every tabulated n and k column with shape-preserving PCHIP interpolation. The curve passes through every supplied point and stays inside the values of each bracketing pair, so a non-negative k table cannot acquire optical gain from interpolation overshoot. Outside the tabulated range, the nearest endpoint value is held constant. PCHIP defines the values between measurements; it does not add measured information that is absent from the table.

Smooth dispersion fit

An editable tabular material can store an explicit smooth fit for calculations that need higher derivatives. Transparent materials can use Cauchy or a one- to three-term Sellmeier model for n; k uses a non-negative Urbach form when the table contains enough positive values, otherwise it remains zero. Metals can use a coupled Drude or Drude-Lorentz dielectric model, which fits n and k together. The fit uses the material’s stated wavelength range, never the range of an analysis window.

Choose Fit or Refit to calculate it. TFStudio shows RMS and maximum residuals for both n and k, plus a residual plot. Inspect those errors before using the model. The fit is not created silently. It is stored on the material, travels with an embedded user material, and is removed automatically when its source table changes. Built-in materials remain read-only; copy one to a user catalog before fitting a different representation.

How to read it

For a built-in or imported material, the n/k chart shows the real index n (left axis) and, when present, the extinction coefficient k (right axis, dashed). The properties panel lists the d-line index, Abbe number, density and wavelength range when the source provides them, and the dispersion formula and coefficients when the material is formula-based. A material with a flat, zero k is non-absorbing across the plotted range.

Catalogs are saved to your TFStudio materials folder and persist between sessions, so an imported or hand-built material is available the next time you open the app.

References

• M. N. Polyanskiy, refractiveindex.info (public-domain dispersion data).
• F. N. Fritsch and J. Butland, “A Method for Constructing Local Monotone Piecewise Cubic Interpolants,” SIAM Journal on Scientific and Statistical Computing 5, 300-304 (1984).
• A. D. Rakić et al., “Optical properties of metallic films for vertical-cavity optoelectronic devices,” Applied Optics 37, 5271-5283 (1998), doi:10.1364/AO.37.005271.
• Beer–Lambert relation for extinction from internal transmittance: k(λ) = −λ / (4π d) · ln τ_int(λ).