Ray Optics Simulation

You place light sources, lenses, mirrors, prisms and surfaces on a canvas, and the rays are drawn in real time. Focal points, aberration, refraction, total internal reflection and wavelength-dependent dispersion are all visible.

This is not a professional optical design tool — dedicated packages exist for that — but for understanding a system, testing an idea or explaining a principle it is the fastest route there is. Useful in lighting design, optical sensing and teaching. It runs in the browser with no installation, and a scene can be saved and shared as a link.