ABSTRACT
Aberrations, in their many forms, comprise the need for real-time adaptive optics. For fifty years, atmospheric turbulence has been the center of attention for astronomical or laser beam propagation adaptive optics. Starting with a discussion of refractivity and the statistics applied to random processes, this chapter discusses the details of the Kolmogorov spectrum, the refractive index structure constant, and the seeing cell size, also known as Fried’s coherence length. Scintillation, phase tears, and branch points also are explored. In addition to turbulence, thermal blooming, beam jitter, and beam wander are discussed. Related topics such as the marine environment and underwater propagation are presented along with the boundary layer turbulence effects of aero-optics. Non-atmospheric sources, as they apply to adaptive optics, are introduced. These include optical misalignments, vibration induced jitter, large optics and gravity sag, thermal distortions and manufacturing errors. Special problems with laser resonators and lasing media are identified. With the expanding applications involving retinal imaging, the aberrations related to the fluid within the eye are presented.
