• beam quality
• laser
• marble
• roughness
• speckle
• stones

This thesis discusses the design and the realization of a Beam Propagation Analyzer apparatus and the application of laser beams in surface characterization.
Most of this work has been performed at the University of Erlangen-Nürnberg, Chair of Photonics Technologies (Germany). Today laser beams are widely used in a large number of industrial applications. Mechanical Machining, Electronics Industries, Communication Engineering and Medical Application are some areas in which the laser technologies play a key role. The design of optical system is treated with powerful simulation software but it requires at the same time a good knowledge of basic rules of Optics. These beam propagation and transformation can be defined by two critical parameters: the beam waist (the smallest beam radius achieved in the beam trajectory) and the divergence angle (the ratio at which the beam enlarges far away from the waist). These parameters are strongly related and they are important indicators of the beam quality. The beam quality can be measured with an apparatus composed by a beam profiler (instrument able to measure the intensity profile of the beam) and a translation stage that permits the measurement of the beam intensity at different positions. Such a type of apparatus has been realized.
The apparatus has been designed and realized with commercial elements, the hardware interacts with the laser beam and PC software controls the image acquisitions and analyzes the data.
Laser beams are also widely used in surface characterization. A novel method, based on the speckle effect and normally applied in roughness characterization of metallic surfaces, is tested on Carrara marble stones to investigate a possible new field of applications.