The difference between light reflection, light refraction, and light diffraction is simple. In reflection, the light rays striking a surface return towards the originating source of light as the waves spring or bounce off the surface. In refraction, the waves go through a clear medium, and as they travel though, their speed and direction are altered. In other words, refraction is the bending of light as it passes though a medium, while reflection is the return of that light. Diffraction is the process by which a beam of light is spread out as a result of passing through a narrow aperture or across an edge. In diffraction, light is both spread out, and its direction is changed.
Reflection = Bounce Light. Refraction = Bend Light. Diffraction = Bend and Spread Light. Reflection, refraction, and diffraction change the direction of light, but in different ways.
A mirror, like the one on your car or in your master bath is an example of reflectivity. The distortion of a pencil in a glass of water, a mirage in the desert, or light through a glass lens, are examples of refraction. The sun behind a cloud and the rays that result are an example of diffraction. What happens to light when you shine it on a mirror is reflectivity. What happens to light when you shine it through a glass of water is refraction. What happens to light when you shine it through an aperture or the edge of a solid object is diffraction.
Here are some examples of Reflection and Refraction:
1. Mirror (reflection)
2. High gloss surface (reflection)
3. Oil in a glass bottle (refraction)
4. Light beams around a cloud (diffraction)
5. Telescope Lens (refraction)
6. Shiny aluminum foil (reflection)
7. Light shining through a small hole (diffraction)
8. Glass Prism (refraction)
9. Glass of water with a fork in it (refraction)
10. Sheet of Glass (refraction)
Retro Reflectivity is a form of reflection that returns light from a surface, but only back to the source of the light. Refraction is a part of reflectivity in that bending light is an element of that process. Diffraction is not a part of retro reflectivity, but is a part of the manipulation of light.
Steven Cole (Economics, MBA – University of West Florida , Business & Innovation – Stanford University) 25 years of experience in the reflective safety business. Specializing in vehicle accident and rear end collision reduction through increased visibility.