However, when an object is moving, the speckle pattern is disrupted.  Thus, by comparing consecutive recorded images of an object, stationary objects and regions of motion can be distinguished.   

For high-precision imaging systems, wavelength-stabilized single-mode lasers with intrinsically high coherence produce speckle images with the greatest contrast and fidelity. For example, a recent optimization study notes that speckle size is proportional to the f-number. This means that a single-mode laser does not automatically produce larger speckles if the imaging aperture is unchanged; it more reliably produces fully developed, high-contrast speckles.

For imaging applications or for measuring rough surfaces, multi-mode lasers are the ideal choice, especially for in vivo and in vitro studies, where the additional longitudinal modes of the laser help compensate for the variability in the scattering of tissues and other structures.

Since speckle imaging is also an illumination technique,  it is important to have a uniform “flat-top” intensity profile, which can be obtained with various types of round or rectangular core optical fiber. IPS laser systems can be customized for these specific applications and requirements.