This chapter focuses upon a pair of specific imaging techniques: speckle interferometry and nonlinear imaging. Both techniques provide methods to not only vastly improve image quality but also provide for correction of images taken through irregular media. Both techniques rely upon using advanced averaging methods, in particular using the phase space of the Fourier and Hilbert transforms to achieve their goals. In the case of speckle interferometry, the chapter examines the version of used in astronomy. The position of the object is altered by a secondary factor, which in addition may also blur and distort the image. The scattering from the flowing media creates dynamic noise in the image. Similar to speckle interferometry it is the random reflections, or speckles, that are used to create the image. Both speckle interferometry and the nonlinear imaging flow detection methodologies discussed have proven to be powerful and reliable techniques to improve imaging results.

Controlled Vocabulary Terms

electronic speckle pattern interferometry; Fourier transforms; Hilbert transforms