Geometrical Aberration Suppression for Large Aperture Sub-THz Lenses

• Published in: Journal of infrared, millimeter and terahertz waves Vol. 38; no. 3; pp. 347 - 355
• Main Authors: Rachon, M., Liebert, K., Siemion, A., Bomba, J., Sobczyk, A., Knap, W., Coquillat, D., Suszek, J., Sypek, M.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2017; Springer Nature B.V; Springer Verlag
• Subjects: Aberration; Algorithms; Classical Electrodynamics; Design optimization; Diffractive optical elements; Electrical Engineering; Electronics and Microelectronics; Engineering; General Physics; Instrumentation; Narrowband; Numerical aperture; Optical components; Phase distribution; Physics; Three dimensional printing; Sub-terahertz; Kinoform; Double-sided lens; Diffractive lens; 3D printing; Narrowband
• ISSN: 1866-6892; 1866-6906
• DOI: 10.1007/s10762-016-0342-1

Advanced THz setups require high performance optical elements with large numerical apertures and small focal lengths. This is due to the high absorption of humid air and relatively low efficiency of commercially available detectors. Here, we propose a new type of double-sided sub-THz diffractive optical element with suppressed geometrical aberration for narrowband applications (0.3 THz). One side of the element is designed as thin structure in non-paraxial approach which is the exact method, but only for ideally flat elements. The second side will compensate phase distribution differences between ideal thin structure and real volume one. The computer-aided optimization algorithm is performed to design an additional phase distribution of correcting layer assuming volume designing of the first side of the element. The experimental evaluation of the proposed diffractive component created by 3D printing technique shows almost two times larger performance in comparison with uncorrected basic diffractive lens.