ABSTRACT
The author devotes some paragraphs to a brief historical review of structures, concerning the physical properties of speckle patterns. Sir Isaac Newton describes such random effect as it occurs at the focus of (Earth-based) telescopes; he explaines the trembling points by the action of atmospheric movement. Instead of going too deep into mathematics, the authors outlines here the main assumptions and steps to arrive at the description of the intensity statistics of a speckle diagram. He consider another point P located at the same plane as PGǦ0 but laterally displacing a small distance y, the wavelets arriving at P will present some phase difference. Another approach in the field of speckle metrology, known as speckle interferometry, was first proposed by Leendertz at the beginning of the 1970s; in it the desired information is codified in the correlation fluctuations of the involved speckle patterns. Considering again the sketch of , a laser beam is divided into two beams by the BS1.
