Paraxial

This section provides an overview of the paraxial optics module in Optiland. This module enables the user to perform paraxial analysis of the optical system.

Conventions

Location quantities follow Optiland’s reference-surface convention, where object-space quantities are measured relative to the first physical surface (index 1) and image-space quantities relative to the image surface:

• EPL() (entrance pupil location) is relative to the first physical surface (surface 1).

• XPL() (exit pupil location) is relative to the image surface.

• The focal, principal, nodal, and anti-nodal planes (F1/F2, P1/P2, N1/N2, P1anti/P2anti, N1anti/N2anti) follow the same per-surface convention, where 1 denotes object space and 2 denotes image space.

When the entrance pupil is needed on the same axial coordinate as surface positions — for instance to compare it against object or surface positions — use entrance_pupil_axial_position(), which re-anchors EPL() in one place (entrance_pupil_z is its deprecated legacy alias). Internally, every ray-aiming, ray-tracing, and aperture consumer that mixes the pupil location with axial coordinates routes through this helper. For the pupil’s real-space location in a folded system, use entrance_pupil_point_gcs() and exit_pupil_point_gcs().

The scalar first-order model itself is written on the signed unfolded axial coordinate carried by ParaxialPath (see the developer’s guide page Folded Systems and the Scalar Paraxial Domain).

paraxial	Paraxial Module
paraxial_path	Folded-path paraxial metadata.