Prism shaped pavement light redirecting sunlight through total internal reflection. Credit: glassian.org In the beginning, vault covers used round plano-convex lenses or even just flat glasses.

They reflect off the rear face ... This means that the light leaving the prism is spread out into its different colours, a process called dispersion. This experiment is recorded as first being ...

Newton was also the first to understand the rainbow, and to refract white light with a prism into its component ... Newtonian telescopes use a reflecting mirror to avoid the colour distortion ...