Using the bench
The ray inspector
When a measurement surprises you, this is how you find out why. The inspector follows a single ray through the whole bench and lists everything that happens to it.
Opening it
Ctrl + click any beam in the viewport — including a faint ghost reflection — and the inspector opens on that exact path. Or open it from View → Ray inspector and choose a beam line and wavelength by hand.
Branches
Light splits. A beam splitter creates two paths, total internal reflection folds one back, a grating sends orders in different directions. Each of those is a branch, listed with the share of the original power it carries and where it ends up — a screen, out of the scene, or absorbed.
Turn on ghost reflections to include the faint Fresnel reflections that bounce between surfaces. These are the ghosts that show up as flare in real photographs.
The event table
| Column | Means |
|---|---|
| At | Which part, and what happened: refract, TIR, mirror, split, polariser, wave plate, grating, screen |
| n in / n out | Refractive index before and after — the exact numbers Snell was applied with |
| Incidence / exit | Angles to the surface normal, in degrees |
| R / T | The Fresnel split at that surface, as percentages |
| Segment | Geometric length of the leg that ended here, and its optical path (n × length) |
| Power | Fraction of the launch power still left |
| Time | Arrival time at this event, in picoseconds since leaving the source |
| Polarisation | The Stokes vector after the event |
At the top of each branch you also get its total optical path, geometric length and time of flight — the fastest way to compare two arms of an interferometer.