THz microscopy of additive manufactured microstructures

THz microscopy was employed to investigate reflection and diffraction properties of additive manufactured structures in this thesis. These structures were irradiated by a far-infrared laser. The THz microscope was developed at the Institut für Elektrische Messtechnik und Grundlagen der Elektrotechnik. It generates three dimensional images by moving a sensor above a sample. The sensors are Josephson cantilevers, which consist of the high temperature superconductor YBa2Cu3O7 on LaAlO3 bicrystal substrates. These sensors are sensitive to high frequency electromagnetic radiation, static magnetic fields and temperature fields. A pre-characterization of the sensors is necessary. It can be performed in the THz microscope or in a separate setup. A scanning force procedure can be employed to collect topological data in addition. Furthermore, the Josephson cantilever can be complemented by other sensors such as pyroelectric detectors. These are also sensitive for high frequency radiation and are available at favorable prices. Though, they cannot reach the spatial resolution of the Josephson cantilever and not their frequency resolution. The far-infrared laser is optically pumped by a carbon dioxide laser. The Gaussian beam is quasi-optically coupled into the THz microscope by multiple mirrors and lenses. The calculated beam parameters are verified by measurements. Additive manufacturing processes offer the opportunity to manufacture prototypes for optical components very fast. The printing processes stereolithography (SLA), fused deposition modeling (FDM) and ceramic paste extrusion can be employed for different applications. Metrology is gaining importance in the field off additive manufacturing to obtain reproducible results. Diffraction gratings are optical components which are particularly suited for beam manipulation. Multiple diffraction gratings were calculated, constructed and eventually additively manufactured. These objects were implemented into the THz microscope and the diffraction patterns were investigated.