OPTICAL-SYSTEMS FOR HIGH-POWER LASER APPLICATIONS - PRINCIPLES AND DESIGN ASPECTS

Starting from the optical properties of laser beams, the requirements of optical systems for manipulating laser radiation in industrial appl ications are derived. The relevant parameters, relations to the diffra ction limit and the state-of-the-art design techniques are discussed. The three important types of lasers for use in industrial materials pr ocessing operate at wavelengths ranging from the infrared (10.6 mu m, CO2 laser; 1.06 mu m, Nd:YAG) to the ultraviolet region (excimer laser s). Each wavelength range is associated with specific design challenge s. The scarcity of suitable refractive materials for the 10 mu m wavel ength range and the ultraviolet below 300 nm is a major constraint. Re flective systems are used widely at the longer wavelength, but some de signs suffer from coma. The 1.06 mu m radiation from the Nd:YAG laser can make use of many well-developed optical means for handling visible light. Energy transport by optical fibres is commonly used. Optical s ystems for excimer laser applications are specific in that they image a mask onto a workpiece, and use the high photon energy and the high d efinition possible with the short wavelength for precision micro-machi ning.