Although the default material catalogs in OpticStudio are extensive, it is sometimes the case that a desired material is not available in the catalog. This article describes how to create a Materials Catalog to load in your own material or glass data.

Authored By Mark Nicholson, Kristen Norton

Introduction

In OpticStudio, material data is managed within catalogs, which are defined via ASCII text files with the extension. AGF. These catalogs contain refractive, thermal, transmission and other data for each material inside the catalog. Catalog data is provided to Zemax by a variety of materials vendors, including Schott, Ohara, and Edmund Optics.

Adding a custom materials catalog

Before adding a custom materials catalog in OpticStudio, you should heed this important reminder: never edit or change the materials catalogs supplied with OpticStudio. When you update OpticStudio at its next release, all files included with the installation (including materials catalogs) are overwritten with the versions supplied with that release. For this reason, when you want to add your own materials, the first step is to create your own catalog. Then, add as many materials as you want to your catalog. Your private catalogs will not be affected by updates to OpticStudio.

All materials catalogs are saved in the GLASSCAT user data folder, which is defined under the Setup...Project Preferences...Folders.

By default, English-language versions of Windows will use the file path {Zemax}\Glasscat.

Catalog files are text files with the extension .agf (ASCII glass file). Note that for every AGF there may be a BGF (binary glass file) file also. The BGF files are created by OpticStudio when the AGF is used, and these files should not be edited or used by the user in any way. These files can be ignored: only the AGF file is important for user concerns.

There are two methods to create a new materials catalog.

1. Use Windows Explorer to navigate to the Glasscat user data folder. Copy and paste one of the existing agf files, then rename the file to MyCatalog.agf. This creates a new catalog with the same materials as the copied catalog, and within the OpticStudio UI these materials can be deleted, edited or left alone.
2. Within OpticStudio, go to Libraries...Materials Catalog. Select one of the existing catalogs and then press the Save Catalog As button to save the catalog with a new name. This will save the catalog and all materials inside it, which can then be deleted, edited or left alone.

Use one of these methods to create a new materials catalog named MYCATALOG.AGF. Here, we have used the second method to copy the default ANGSTROMLINK.AGF catalog.

Adding materials to a custom materials catalog

Run OpticStudio, and go to the Libraries...Materials Catalog. Select MYCATALOG.AGF from the Catalog drop-down menu.

All materials listed in the Glass section are from "ANGSTROMLINK.AGF" because I copied this catalog to create the new one. The data shown in this window will update depending on which material is selected. The data can be separated into useful sections:

1. Refractive Index Data: Dispersion data is entered via dispersion formulae (Schott, Sellmeier, Conrady, etc). If you have raw index data, OpticStudio can fit this to the various formulae for you. Just press the Fit Index Data button to enter index versus wavelength data and have OpticStudio fit it or use the Glass Fitting tool. See the separate article "Fitting index data in OpticStudio" for full details. If you do not use the fitting tools, you must enter the minimum and maximum wavelengths of operation of the glass by hand.
2. Thermal Variation data: OpticStudio can compute the refractive index at temperatures different to the reference temperature. The data values D0, D1, D2, E0, E1, Ltk and TCE are used by the thermal model. The glass fitting tool will take data at multiple temperatures and produce not only a fit to the refractive data but also a fit to the thermal data. See the article "How OpticStudio calculates Refractive Index at arbitrary temperatures and pressures," and the Help Files section called "Thermal Analysis of Optical Systems" for full details.
3. Transmission data: Press the Transmission button to enter the internal transmission of the material. This data should ignore surface reflections and represents the absorption of the bulk material. (Surface reflections depend only on the index of the glasses, the angle and wavelength of the incoming ray, and the ray's polarization state, and are not affected by bulk absorption losses.)
4. Other data: You can tell OpticStudio 'non-optical' data, like relative cost, stain resistance, climate resistance etc. In addition, you can also provide a comment for the material itself. The Status entry is usually Standard or Preferred for easily available materials. 'Special' is available to describe unusual materials, and 'Obsolete' should be used to represent materials that are no longer available (materials should never be deleted once entered, as this would render designs that use that data useless). The status flag 'Melt' should normally only be used by OpticStudio's Melt Data fitting tool, although it can be used by hand if desired.

In order to add a material to the catalog, you must first select the Insert Glass option in the Materials Catalog window. You may then enter the relevant data for the material and rename it to whatever you desire. You can also delete materials from the catalog using the Cut Glass button.

After data entry, and after cutting the materials from the ANGSTROMLINK.AGF catalog, the Materials Catalog window with MYCATALOG.AGF will appear as below.

There may be multiple materials inside the catalog, and the data displayed represents whatever material is highlighted in the Glass control below the catalog name. It is a good idea to give the catalog itself a descriptive comment, and a date or version number.

Testing materials catalog data

After you have entered material data in a materials catalog, it is a good idea to test it before use. OpticStudio provides multiple tools for this, including the Glass Report and Catalog Report which provide comprehensive listings of all the entered data. You can also analyze materials individually based on their various qualities, including dispersion. To do this, you first must add your customer materials catalog to an existing design by navigating to System Explorer...Materials Catalogs and moving the new catalog from Catalogs Available to Catalogs To Use.

Then, go to the Libraries...Materials Analyses...Dispersion Diagram to check the index versus wavelength values.

You can also go to the Libraries...Materials Analyses...Internal Transmission vs. Wavelength to check this data.

Using custom materials in a design

To use the newly added material, simply type its name in the Material cell of the Lens Data Editor, or the Non-Sequential Component Editor if you are using Non-Sequential Mode. After typing in the full name, press [Enter] or [Tab], and you should see the row color change, indicating that the surface is no longer air.

As an important note, never delete a material from a catalog once it has been used in a design. If you delete a material from the catalog, any file that used the now-deleted material will fail to trace. The correct approach is to mark the glass as 'Obsolete', and to use the comment field to explain why the glass should not be used. Both of these are discussed later in this article. The System Check utility will detect and warn the user if an obsolete glass is used, but the file will still ray-trace correctly. 

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