Abstract-Terahertz to mid-infrared dielectric properties of polymethacrylates for stereolithographic single layer assembly

Serang Park, Yanzeng Li, Daniel B. Fullager, Stefan Schöche, Craig M. Herzinger, Glenn D. Boreman, Tino Hofmann

https://arxiv.org/abs/1907.13299

The fabrication of terahertz (THz) optics with arbitrary shapes via poly-methacrylate-based stereolithography is very attractive as it may offer a rapid, low-cost avenue towards optimized THz imaging applications. In order to design such THz optical components appropriately, accurate knowledge of the complex dielectric function of the materials used for stereolithographic fabrication is crucial. In this paper we report on the complex dielectric functions of several polymethacrylates frequently used for stereolithographic fabrication. Spectroscopic ellipsometry data sets from the THz to mid-infrared spectral range were obtained from isotropically cross-linked polymethacrylate samples. The data sets were analyzed using stratified layer optical model calculations with parameterized model dielectric functions. While the infrared spectral range is dominated by a number of strong absorption features with Gaussian profiles, these materials are found to exhibit only weak absorption in the THz frequency range. In conclusion, we find that thin transmissive THz optics can be efficiently fabricated using polymethacrylate-based stereolithographic fabrication.

Abstract-Metalized Poly-methacrylate Off-Axis Parabolic Mirrors for Terahertz Imaging Fabricated by Additive Manufacturing

Daniel B. Fullager, Serang Park, Clark Hovis, Yanzeng Li, Jesse Reese, Erin Sharma,  Susanne Lee,  Christopher Evans, Glenn D. Boreman, Tino Hofmann

https://link.springer.com/article/10.1007/s10762-019-0568-9

Terahertz radiation sources are currently one of the most widely used non-ionizing illumination mechanisms for security applications and also find increasing utilization in quality control of commercial products. Presently, a majority of these applications rely on scanning rather than direct imaging and implicitly suffer from temporal latency due to post processing. The monetary and temporal cost associated with procuring commercially manufactured optics that are suitable for imaging leads to fundamental limitations in the ability to rapidly develop application-specific imaging modalities using terahertz sources. Herein, we show a novel method for the rapid prototyping of metallic coated poly-methacrylate parabolic reflectors fabricated by stereolithographic 3D printing. Images comparing the performance of a commercially available off-axis parabolic reflector to our metalized poly-methacrylate prototype, which was designed to be identical to the commercially available mirror, are subsequently presented. The images show that at 530 GHz it is possible to produce a metalized poly-methacrylate off-axis paraboloid whose spatial beam profile is nearly identical to that of a commercially available equivalent.