When light passes through a calcite crystal, double refraction produces two images of the object viewed through it.

Astronomic refraction causes stars to appear slightly higher above the horizon than their true positions.

Astronomers must correct for atmospheric refraction when measuring the precise positions of stars, because the Earth's atmosphere bends starlight and makes celestial objects appear higher than they truly are.

Astronomical refraction caused the star's apparent position to shift slightly above the horizon.

The optometrist explained that the lens's refractive power determines how sharply images are focused on the retina.

The optometrist compared the refractive powers of the two lenses before recommending one to the patient.

The refractive index of diamond causes light to bend sharply and sparkle.

The refractive indices of the composite materials were measured at multiple wavelengths to determine their dispersion.