Using Speckle Contrast as a Tool to Track Static and Dynamic Modifications of the Surface

A rough surface when illuminated by a monochromatic source of light produces a speckle pattern. Pattern contains a large number of dark and bright spots, due to constructive and destructive interferences of light waves reflected from the surface under observation. Surface deformation of any kind can cause changes in the phase of reflected light waves. This will change the speckle pattern accordingly. Hence, deformations can be quantitatively analyzed if the corresponding phase change is known. However, qualitative information regarding the object under study can be gathered by calculating speckle parameters such as speckle contrast. Speckle contrast is a degree of speckleness of the image. Any modifications in the surface even if it is tiny can lead to fluctuations in the speckle pattern. Hence by observing changes in these speckle patterns, we can monitor surface activities provided we monitor a statistical parameter related to the speckleness of the pattern. In this paper, we demonstrate the interesting application of speckle contrast monitoring in the field of agriculture sciences which corresponds to static modifications in the surface and to monitor rotational motion which corresponds to dynamic modifications in the surface.