Figure 1: Diffuse reflection
Diffuse reflection is the reflection of light or other waves or particles from a surface such that a ray incident on the surface is scattered at many angles. When light is reflected from a mirror, the angle of reflection equals the angle of incidence. When light is reflected from a piece of plain white paper (its surface is rough compared to the wavelength); however, the reflected beam is scattered, or diffused. Because the surface of the paper is not smooth, the reflected light is broken up into many light beams that are reflected in all directions.
This form of reflection is of particular importance for remote sensing of the Earth using synthetic aperture radar (SAR).