Materials

This section provides a comprehensive overview of the materials available in Optiland. A material is a set of properties that define the optical behavior of a medium. Specifically in Optiland, a material defines the refractive index and extinction coefficient of a medium at any wavelength. A material may be described simply by refractive index and abbe number, or it may be a more complex model based on Sellmeier, or other, coefficients. Optiland provides a wide range of materials, which are outlined here.

Optiland includes a database of common materials based on refrativeindex.info. Any material in this database can be accessed by name via the Material class.

Abbe Material Model

The AbbeMaterial class utilizes a robust, data-driven statistical dispersion model to resolve the ambiguity of the two-parameter ($n_d, V_d$) definition. While standard approximations like the “Normal Line” rule often fail for anomalous glasses, Optiland’s model is derived from a principal component analysis (PCA) of over 1,000 commercial optical glasses.

The model construction involves: 1. Dimensionality Reduction: Using PCA to quantify the effective degrees of freedom in standard optical glasses. 2. Basis Selection: Applying Sparse Regression (LassoLarsIC) to the Buchdahl dispersion formula to identify the minimum set of coefficients required for accurate spectral reconstruction.

This approach allows for accurate refractive index prediction across the visible and near-infrared spectrum, even for glasses that deviate from the standard “normal line”.

For a detailed walkthrough of the model derivation and validation, please refer to the Abbe Material Model Building notebook.

Catalog-Scoped Lookup

Material accepts an optional catalog= keyword (e.g. "schott", "ohara") to restrict lookup to a specific manufacturer. The match_policy keyword controls fuzzy-match behavior:

from optiland.materials import Material, MatchPolicy

glass = Material("N-BK7", catalog="schott")              # exact-catalog lookup
glass = Material("N-BK7", match_policy=MatchPolicy.BEST) # silent fuzzy
glass = Material("N-BK7", catalog="schott",
                 match_policy=MatchPolicy.STRICT)         # raise on non-exact

Discovery and User Catalogs

MaterialCatalog is a read-only view into any registered catalog:

from optiland.materials import MaterialCatalog

MaterialCatalog.available()              # list all catalogs
MaterialCatalog("schott").list()         # all Schott glass names
MaterialCatalog("schott").search("bk7") # fuzzy search within catalog
MaterialCatalog("schott").get("N-BK7")  # returns a Material instance

MaterialRegistry is the global singleton that manages built-in and user-registered materials:

from optiland.materials import MaterialRegistry

reg = MaterialRegistry.instance()
reg.register("MyGlass", "internal", yaml_payload_dict)  # programmatic
reg.register_file("path/to/my_glass.yml")               # single YAML file
reg.load_catalog("~/.optiland/catalogs/my_company/")    # directory

User YAML files must follow the refractiveindex.info format. Files placed under ~/.optiland/catalogs/<catalog_name>/ are auto-discovered on the first registry access.

`materials.abbe`	Abbe Material
`materials.ideal`	Ideal Material
`materials.material_file`	Material File
`materials.material`	Material
`materials.material_spec`	MaterialSpec and MatchPolicy for the Optiland materials system.
`materials.material_utils`	Utility functions for working with materials.
`materials.catalog`	MaterialCatalog — read-only view into one catalog within the MaterialRegistry.
`materials.registry`	MaterialRegistry — global singleton for material lookup.