What the animation is actually showing

The moving axis controls a variable in an equation. Brightness on screen is a visual encoding of the computed transmission fraction. Its colour or luminance is not a calibrated detector measurement.

At a middle angle of 45°, the three filter model computes:

The value follows directly from the model. It does not include alignment error, leakage, detector background or source drift unless these are explicitly added as separate model parameters.

Three kinds of accuracy need separate attention:

- Floating point and rounding accuracy.

- Search or plotting resolution.

- Uncertainty in a physical inference.

A 0.1° inverse search can return 37.0° from exact synthetic data. That grid spacing does not establish a ±0.1° experimental uncertainty. A fit to data generated by the same equation primarily checks computational consistency.