A ray-tracing diagram uses a set of drawing conventions and labels to visualise the path that rays of light take in order to understand what happens as they encounter different media, materials or objects.
- Ray-tracing diagrams are used in geometric optics which treats light as rays that travel in straight lines and change speed and/or direction when they encounter different transparent media.
- The aim of a ray-tracing diagram is to demonstrate optical phenomena such as absorption, dispersion, polarization, reflection, refraction, scattering and transmission.