Environment

This section covers Optiland’s environment subpackage, which calculates the refractive index of air. This is used to account for the effect of ambient temperature, pressure, humidity, and CO2 concentration on an optical system’s performance, as opposed to the fixed reference-air assumption used elsewhere in the package.

The main entry point is refractive_index_air(), which dispatches to one of several well-established empirical models based on an EnvironmentalConditions instance. Each model - Ciddor, Edlén, Birch & Downs, and Kohlrausch - is implemented in its own module under environment.models and can also be called directly.

from optiland.environment import EnvironmentalConditions, refractive_index_air

conditions = EnvironmentalConditions(
    temperature=15.0,
    pressure=101325.0,
    relative_humidity=0.0,
    co2_ppm=400.0,
)
n = refractive_index_air(0.55, conditions, model="ciddor")

environment.air_index	Unified Interface for Air Refractive Index Models.
environment.conditions	Dataclass for Environmental Conditions.

environment.models.ciddor	Ciddor (1996) Air Refractive Index Model.
environment.models.edlen	Edlén (1966) Air Refractive Index Model (with NIST Modification).
environment.models.birch_downs	Birch and Downs Air Refractive Index Model (with NIST Modification)
environment.models.kohlrausch	Kohlrausch Air Refractive Index Model (Zemax Implementation).