Read · 1 min
The shadow of an obstacle of finite dimensions,which is formed by a very small origin of light, is practically its geometrical projection; and we are inevitably led to the idea that the light travels from its origin in straight lines.These straight lines are called rays.
Source: A Treatise on Geometrical Optics by Robert Alfred Herman.
Read · 1 min
"There is only 1 Ray" -- Ray Li
"Do you speak of the great Ray? The one who created the universe, laid out its geometry, decided how the rays reflect, refract, and enter our eyes." -- Anonymous
Illustrated · 1 min
In optics a ray is an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow. Rays are used to model the propagation of light through an optical system, by dividing the real light field up into discrete rays that can be computationally propagated through the system by the techniques of ray tracing. This allows even very complex optical systems to be analyzed mathematically or simulated by computer. Ray tracing uses approximate solutions to Maxwell's equations that are valid as long as the light waves propagate through and around objects whose dimensions are much greater than the light's wavelength. Ray theory does not describe phenomena such as interference and diffraction, which require wave theory (involving the relative phase of the rays).
Definition: A light ray is a line (straight or curved) that is perpendicular to the light's wavefronts; its tangent is collinear with the wave vector. Light rays in homogeneous media are straight. They bend at the interface between two dissimilar media and may be curved in a medium in which the refractive index changes. Geometric optics describes how rays propagate through an optical system. Objects to be imaged are treated as collections of independent point sources, each producing spherical wavefronts and corresponding outward rays. Rays from each object point can be mathematically propagated to locate the corresponding point on the image.
A slightly more rigorous definition of a light ray follows from Fermat's principle, which states that the path taken between two points by a ray of light is the path that can be traversed in the least time.
the image here is describing an incident ray of light is being reflected off the surface and into the atmosphere but the reflected ray in being reflected in the same angle on the other side of the incident ray. this image is also showing if light enters any substance with a higher refractive index (such as from air into glass) it slows down. The light bends towards the normal line. If light travels enters into a substance with a lower refractive index (such as from water into air) it speeds up. The light bends away from the normal line
