The diffraction gratings produced by the researchers are 5 x 5 centimeters in size; their surface consists of periodically repeating structures. In order to analyze the diffraction of the radiation, a precise production of the gratings is a prerequisite. This is why a stereolithography printer is being used at the Institute for Electrical Measurement Technology and the Fundamentals of Electrical Engineering (EMG) at Braunschweig Technical University under the direction of Professor Meinhard Schilling.
After printing, the diffraction gratings are coated with a thin gold layer, which increases the reflectivity of the structures. In stereolithography, liquid photosensitive resins are solidified with a laser. This can be done with extremely high precision in the micrometer range. In this way, very precise plastic objects can be produced - quickly and reproducibly.
To ensure quality, the surface of the 3D-printed diffraction grating is closely examined: Scientists at the EMG examine their roughness and measure the diffracted radiation. A terahertz scanning microscope developed at the institute is available for this purpose, which records the radiation distribution three-dimensionally and makes it measurable.
In the past, the terahertz frequency range was rarely used for technical applications due to a lack of RF sources and sensors. These extremely high frequencies promise exciting application scenarios, such as fast transmission technology in mobile radio and, in medicine, the analysis of tissue and breathing air. Terahertz waves are used in the form of detectors at airports: radiation that is harmless to humans achieves good spatial resolution and can penetrate many non-metallic materials.
The further development of optical components is being promoted in the nanometrology research centre LENA (Laboratory for Emerging Nanometrology) and in the Institute for Electrical Measurement Technology and Fundamentals of Electrical Engineering at the Technical University of Braunschweig together with the Physikalisch-Technische Bundesanstalt (PTB) and within the framework of the "Quantum Frontiers" cluster of excellence.
More information: www.emg.tu-bs.de