Coating Library

The Coating Library window holds coatings as objects of their own, separate from designs. A coating here is a layer stack together with the substrate and incident medium it was designed on, the wavelength band, angle and polarization it is specified for, and the specification it meets. Any coating in the library can be put onto the front or the back of the active design.

The window has two shelves. Built-in is the set of starting designs that ships with TFStudio. My coatings is what you have saved yourself.

Built-in coatings

Every built-in coating uses materials from the built-in library, or carries its own material definitions, so it computes the same on every installation. The source of each design is recorded in the entry, and the shipped thicknesses are the ones that meet the entry’s specification with TFStudio’s own material data. A design taken from a book in idealized indices has been mapped to real materials and re-optimized before shipping.

The built-in shelf is meant to be small and trustworthy rather than long. Use an entry as a starting point: apply it, then refine or synthesize from there.

Reading an entry

Select a coating in the list to see:

Use this when and Limitations: what the coating is for and where it stops being a good answer.
Spectrum: the coating alone on its substrate, seen from its incident medium, computed at the entry’s own angle of incidence and polarization, which the plot states above the curves. At normal incidence it shows T, R and A; at an angle it shows the s and p components separately (solid s, dashed p), since that is what a beamsplitter or polarizer is specified by. The range is somewhat wider than the design bands, which are shaded.
Stack: the layers from the substrate up, numbered the same way as in the Design Editor, with thicknesses in nm.
Properties in the design band: the numbers that matter for that family, computed at the entry’s angle. An antireflection coating shows its average and maximum R; a mirror its minimum R and its absorptance; an edge filter its pass and stop transmittance and the wavelength where T crosses 50 %; a band-pass its peak, centre wavelength and FWHM; a notch the same for its dip; a polarizer Ts, Tp and their ratio. At an angle, R and T are given for s, p and their average. A coating specified over several bands gets one column per band; layer count and total thickness close the list. These are the same numbers the merit function operands and the qualifiers would report.
Specification: each claim the entry makes, with the angle and polarization it is stated at, its computed value and a pass or fail mark. The claims are evaluated with the same qualifiers the Specification window uses.
Source: where the design came from.

Finding a coating

Every entry has a type and a set of tags. The type is the family: antireflection, mirror, edge filter, band-pass, notch filter, beamsplitter, cold and hot mirror, polarizer, low-E, chirped mirror, neutral density. The tags say the rest: the spectral region (visible, NIR, MWIR and so on), how many bands it covers, what it is for (laser, telecom, CWDM and DWDM grids, imaging, solar), what it does (short-pass, long-pass, high-reflector, non-polarizing), how it is built (quarter-wave stack, V-coat, metal-dielectric, the material pair), the geometry and the substrate. Hover a tag to read what it means.

The list keeps one folder per family, each with its own color and a count of what it holds. Folders start folded; click a header to unfold or fold it. Every row carries a strip of its stack in the materials’ own colors, the same colors the Design Editor uses, substrate side on the left.

The list can be narrowed by type, by substrate, by any number of tags (an entry must carry all of them), by a wavelength that must lie inside one of its design bands, by a maximum layer count, and by a text search over the name, the use text, the tags, the substrate and the layer materials. The Tags button unfolds the tags of the entries the other filters leave, one line per kind of tag, each chip colored by its kind and showing how many entries choosing it would keep. The tags you have chosen stay in the bar when the panel is folded again.

Applying a coating

Pick Front or Back, then Replace the stack or Add on top of the stack, and press Apply. Replace swaps the chosen side’s stack for the coating. Add on top deposits the coating over what is already there, so the new layers are the outermost ones. The design’s substrate and media are not changed; compare them with the substrate the entry was designed on before you rely on the numbers.

Applying is one undoable edit: Undo brings the previous stack back.

If the coating brings a material definition under an id the design already uses with different data, the design’s own definition is kept and the window says so. The coating may then compute differently than it does in the library.

Saving a coating

Save current coating… in this window, or Save coating to library… in the Design Editor’s Tools menu, saves the front or back stack of the active design into My coatings. Give it a name, a type and a short use note, and set the band, angle and polarization it is meant for. Non-built-in materials are embedded in the saved entry, so it stays usable when the catalog it came from is renamed or removed.

Saved coatings are plain JSON files with the .tfsc extension in the Coatings folder (Settings, Data Folders). Saving under an existing name replaces that coating. Delete removes the selected saved coating.

Share a coating… sends one of your coatings to the project for the built-in library. With one of My coatings selected, the dialog opens a GitHub issue prefilled with the layer table and the design conditions, or an email with the same text, and Save file for sending… writes the coating with its embedded material data as one file to attach to either. With nothing selected it only points at the two ways to send a design.

Anything with a layer table and a stated purpose is welcome, in whatever form you have it: a .tfs or .tfsc file, a table typed by hand, or a design exported from another program, with or without a description. A contributed coating ships in the next release with a credit in its source line.