Quasi-optical components for the THz-regime: Fabrication and characterization
BIAS-Bremer Institut für angewandte Strahltechnik GmbH, Klagenfurter Str. 5, 28359 Bremen, Germany;
2 Aswan University, Faculty of Science, Department of physics, 81528 Aswan, Egypt;
3 Faculty of Physics and Material Sciences Center, Philipps-Universitat Marburg, Renthof 5, 35032 Marburg, Germany;
4 University of Bremen, MAPEX Center for Materials and Processes and Faculty of Physics and Electrical Engineering, 28359 Bremen, Germany
Abstract
Computational Shear-interferometry (CoSI) has recently been used in the visible band of the electromagnetic spectrum for wave field sensing. Extending this concept into the THz-regime would allow broadening the concept of wave field sensing into this band. Yet, one has to fabricate, characterize and evaluate quasi-optical components suitable for the THz-regime. In this paper, we demonstrate the construction of lenses with different focal lengths and Ronchi phase gratings with different periods and heights. For this purpose, we use two different fabrication schemes: Firstly, mechanical milling from bulk High-Density Polyethylene (HDPE-block) using a computer numerical control (CNC) machine, and secondly, 3D printing of polystyrene and TOPAS copolymer will be compared. For the characterization, we use a tactile probe for measuring the radius of curvature of the lenses and a scanning confocal microscope for measuring the period and the height of the phase Ronchi gratings. The measured radius of curvature of the lenses deviates about 0.23% from the design value while the grating period length and the height profile are fabricated with ±50 µm and ±25 µm precision, respectively.