Ibn al-Haytham (Alhacen), in his Book of Optics (1021), expanded the principle to both reflection and refraction, and expressed an early version of the principle of least time.
For the study of astronomical refraction he developed an unusual method of calculating the vertical gradient of air temperature together with his Assistent Felix Hausdorff.
In astronomy, Long-slit spectroscopy involves observing an elongated celestial object (such as a nebula or along the major axis of a disc galaxy at high inclination) through an elongated slit aperture, and refracting this light with a prism or diffraction grating.
Project Mogul was conceived by Dr. Maurice Ewing who had earlier researched the deep sound channel in the oceans and theorized that a similar sound channel existed in the upper atmosphere: a certain height where the air pressure and temperature result in minimal speed of sound, so that sound waves would propagate and stay in that channel due to refraction.
Hess observed, from previous seismic velocity experiments with olivine crystals, that if the crystals had even a slight statistical orientation this would be extremely evident in the seismic velocities recorded using seismic refraction.
Willebrord Snellius (1580–1626), a Dutch astronomer and mathematician, most famous for the law of refraction now known as Snell's law
Problems of atmospheric refraction were addressed by Vahe Gurzadyan in a 2003 publication.
Also known as the Warp Refraction Principle, warp refraction is a term coined by guitarist Jon Finn, in his 1999 publication, Advanced Modern Rock Guitar Improvisation.