ABSTRACT
When observing through a turbulent transparent medium, the image quality can be strongly deformed, making it impossible to observe small details. This effect is especially important in astronomical observations and also when looking at the retina of the human eye through an ophthalmoscope.
The active and adaptive optics methods work by measuring the distorted light wave and then compensating this wave deformation with a flexible mirror, controlled by an electronic system connected to a computer. This chapter describes these methods in some detail and their application to astronomy and ophthalmology.
