Thursday, May 27, 2010

Specular Reflection vs. Diffuse Reflection

Specular vs. Diffuse Reflection

When a ray of light hits a surface, it bounces off or reflects and then reaches our eyes. This phenomenon by which a ray of light changes the direction of propagation when it strikes a boundary between different media through which it cannot pass is described as the reflection of light.

Or in simpler words reflection is the bouncing of light from a smooth surface.

There are two types of reflection of light:

Reflection off of smooth surfaces such as mirrors or a calm body of water leads to a type of reflection known as specular reflection. Reflection off of rough surfaces such as clothing, paper, and the asphalt roadway leads to a type of reflection known as diffuse reflection. Whether the surface is microscopically rough or smooth has a tremendous impact upon the subsequent reflection of a beam of light. The diagram below depicts two beams of light incident upon a rough and a smooth surface.
Why Does a Rough Surface Diffuses A Beam of Light?

For each type of reflection, each individual ray follows the law of reflection. However, the roughness of the material means that each individual ray meets a surface which has a different orientation. The normal line at the point of incidence is different for different rays. Subsequently, when the individual rays reflect off the rough surface according to the law of reflection, they scatter in different directions. The result is that the rays of light are incident upon the surface in a concentrated bundle and are diffused upon reflection. The diagram below depicts this principle. Five incident rays (labeled A, B, C, D, and E) approach a surface. The normal line (approximated) at each point of incidence is shown in black and labeled with an N. In each case, the law of reflection is followed, resulting in five reflected rays (labeled A,, B,, C,, D,, and E,).


Hope you like the above explanation of Specular Reflection vs. Diffuse Reflection
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