With the introduction of Additive Manufacturing, many industrial sectors benefit from the freedom of design and capabilities of this technology. Components can be individually designed and extended with different functions. However, high effort in the post-processing is necessary, since surfaces have to be processed and support structures have to be removed. This post-processing usually takes place outside the Additive Manufacturing machine. Therefore an additional effort is necessary for the machining process, but also for pre- and post-processing of the components. For example, positioning in a CNC milling machine has to be done. It is not feasible to fabricate complete systems consisting of multiple components in a single manufacturing operation. Especially optical systems require high surface qualities. The surfaces usually have to be milled or polished. In order to install the optical system afterwards, an enormous adjustment and assembly effort is needed. This can be bypassed, when both optics and mechanics are manufactured during the same process. However, integrating subtractive post-processing should be avoided as it may cause contaminants that cannot be removed from the system. Transformative processes like laser polishing do barely cause contaminants and are more suited for parallel processing. In this work the integration of a laser polishing system is evaluated, which can be used to reduce surface roughness. The requirements for the light source, manufacturing accuracy, etc. are clarified and concepts, how the integration can be implemented are developed. In addition, possibilities for processing additional materials to manufacture optical systems in one machine are discussed.
Individually shaped light distributions become more and more important in lighting technologies and thus the importance of additively manufactured reflectors increases significantly. The vast field of applications ranges from automotive lighting to medical imaging and bolsters the statement. However, the surfaces of additively manufactured reflectors suffer from insufficient optical properties even when manufactured using optimized process parameters for the Selective Laser Melting (SLM) process. Therefore post-process treatments of reflectors are necessary in order to further enhance their optical quality. This work concentrates on the effectiveness of post-process procedures for reflective optics. Based on already optimized aluminum reflectors, which are manufactured with a SLM machine, the parts are differently machined after the SLM process. Selected finishing methods like laser polishing, sputtering or sand blasting are applied and their effects quantified and compared. The post-process procedures are investigated on their impact on surface roughness and reflectance as well as geometrical precision. For each finishing method a demonstrator will be created and compared to a fully milled sample and among themselves. Ultimately, guidelines are developed in order to figure out the optimal treatment of additively manufactured reflectors regarding their optical and geometrical properties. Simulations of the light distributions will be validated with the developed demonstrators.
Optical techniques are effective tools for diagnostic applications in medicine and are particularly attractive for the noninvasive analysis of biological tissues and fluids in vivo. Noninvasive examinations of substances via a fiber optic probe need to consider the optical properties of biological tissues obstructing the optical path. This applies to the analysis of the human perilymph, which is located behind the round window membrane. The composition of this inner ear liquid is directly correlated to inner ear hearing loss. In this work, experimental methods for studying the optical properties of the human round window membrane ex vivo are presented. For the first time, a comprehensive investigation of this tissue is performed, including optical transmission, forward scattering, and Raman scattering. The results obtained suggest the application of visible wavelengths (>400 nm) for investigating the perilymph behind the round window membrane in future.