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Coloured Digital Terahertz Holography Within 1.39-4.25 THz range
preprintposted on 2023-11-09, 17:00 authored by Rusne Ivaskeviciute-Povilauskiene, Linas Minkevicius, Ignas Grigelionis, Agnieszka Siemion, Domas Jokubauskis, Kestutis Ikamas, Alvydas Lisauskas, Gintaras Valusis
Terahertz coloured digital holography ranging from 1.39 THz up to 4.25 THz is demonstrated. It is shown that it can be applied for the investigation of low-absorbing objects, and it is illustrated via inspection of stacked graphene layers placed on high-resistivity silicon substrate. Holograms are recorded using an optically-pumped molecular THz laser operating at discrete emission lines of 1.39 THz, 2.52 THz, 3.11 THz, and 4.25 THz frequencies and it unveiled that phase-shifting methods allow to qualitatively reconstruct coloured THz holograms with improved quality achieved by removing unwanted information related with so-called DC term and conjugated beam forming virtual image.