Scientific boundaries
Proxima Centauri: NASA gives the nearest star at about 4.25 light-years. Across a tens-of-meters lens, its wavefront curvature is negligible here, so incoming rays are modeled as parallel.
This is geometric optics. The simulation calculates 3D refraction at both spherical surfaces and the detector spot geometry. It reports a diffraction Airy radius separately, but does not perform wave propagation, interference, stellar-coronagraph contrast, detector noise, or measured long-path PDMS attenuation.