Technology Of Active Optics

A review of present active (or adaptive) optics technology is provided. By active optics wavefront aberrations in optical systems are measured and corrected in real time. Particular emphasis is given here on active optics applications to laser systems. The sources and properties of beam aberrations are described and basic concepts for their correction are discussed. Different types of active optics systems are compared, characterized by typical wavefront correction devices and wavefront sensors. Characteristic technical features of active mirrors developed as wavefront correctors for a high power CO₂-laser system are presented. Finally, performance and limitations of active optics are examined.