New capabilities for supervising high-power CO 2 laser-beams in research and industry

Abstract

During the last years a variety of devices for beam diagnostics of high-power CO2 lasers have been developed enabling to measure different parameters like the beam power, the spatial intensity distribution, the state of polarization or different geometrical values such as beam diameter and beam divergence. This paper gives a short overview of the state-of-the-art in CO2 laser beam diagnostics, points out future perspectives and presents two new measuring systems. In search of facilities for a cost-efficient measurement of the beam position and beam diameter in industrial laser beam delivery systems a flexible device for this task has been developed. The apparatus operates with moving thermocouples and is small and rigid. Under aspects of mirror-allgnement and the control of significant beam parameters during processing the system has a modular design with the ability to connect several measuring devices with one central control unit. The investigation of dynamic interactions between the laser beam and the process in case of laser beam welding and cutting reveals the necessity of measuring the intensity profile with a time resolution up to several kHz. Due to the lack of time resolution of available diagnostic systems the development of a high-speed laser beam intensity-profiler based on a room-temperature MCT detector-array and real-time data analysis will be described. By the use of a partially transmitting mirror in the beam delivery system it is possible to perform beam diagnostics during materials processing. Measurements of the intensity profile can be obtained with repetition rates up to 10 kHz and will be analyzed on-line to characterize the temporal stabifity of the laser beam.