They cut glass, they refract light into perfect hearts-and-arrows, and they have superlative fire and brilliance.
Spectacles and contact lenses refract the light before it enters the eye, helping the eye to focus objects sharply.
Metamaterial research is an emerging field that uses manmade substances to alter the way materials refract light or electromagnetic radiation.
The cornea and the crystalline lens refract light that enters the eye.
The cornea and lens refract the incoming light rays to focus them on the retina at the back of the eye.
Ideally we would like to refract the shadow ray too, but mathematically this is a much more difficult problem to solve.
The rays were detected by a calcium sulfide thread that glowed slightly in the dark when the rays were refracted through a 60-degree angle prism of aluminum.
The wavelength of light affects how much it is refracted on entering the atmosphere, with red light refracted the most and blue least (as in rainbows).
The hotter, denser air refracts the light coming from the horizon and the viewer sees an image of the sky near the horizon.
Color is important: one sees the reds, tans and browns of skin color, the blue of water and the wavy white lines of light refracted through the water.