Applications
When lasers were first invented, the speckle effect was considered to be a severe drawback in using lasers to illuminate objects, particularly in holographic imaging because of the grainy image produced. It was later realized that speckle patterns could carry information about the object's surface deformations, and this effect is exploited in holographic interferometry and electronic speckle pattern interferometry. The speckle effect is also used in stellar speckle astronomy, speckle imaging and in eye testing using speckle.
Speckle is the chief limitation of coherent imaging in optical heterodyne detection.
In the case of near field speckles, the statistical properties depend on the light scattering distribution of a given sample. This allows the use of near field speckle analysis to detect the scattering distribution; this is the so-called near-field scattering technique.
When the speckle pattern changes in time, due to changes in the illuminated surface, the phenomenon is known as dynamic speckle, and it can be used to measure activity, by means of, for example,an optical flow sensor (optical computer mouse). In biological materials, the phenomenon is known as biospeckle.
Read more about this topic: Speckle Pattern