Glancing angle ion beam sputtering of optical thin films

Abstract

Optical thin films are essential for many laser applications in industry and science. The increasing demand for highest quality laser optics, requires the enhancement of existing coating technology as for example Ion Beam Sputtering (IBS). By facing new challenges like the large area deposition for line beam optics with up to two-meter edge length, LASEROPTIK is already pushing the limits of coating technology. This contribution describes an approach to combine Glancing Angle Deposition (GLAD) with IBS utilizing the MAXIMA deposition machine. To analyse the dependence of the refractive index, the ultra violet absorption edge, the mechanical stress and the laser damage resistance on the mean deposition angle to the substrate surface, single layers as well as multilayer coatings are realized at five different mean deposition angles between 30° and 90°. By coating one substrate at each of the five different mean deposition angles in the same batch the influence of run to run process variations is minimized. Besides fundamental research regarding this coating technology the results of this experiment will gain further insight into the deposition of thin films on strongly curved surfaces applying curvature dependent velocity profiles.