PhD thesis supervisor: dr. Linas Minkevičius (apply for recommendation)
Terahertz imaging based on beam shaping and spatial filtering approaches
The expanding range of applications of terahertz (THz) imaging systems poses significant challenges, including the influence of packaging materials and the detection of objects with low THz absorption. The aim of this doctoral research is to develop innovative THz imaging systems capable of identifying weakly absorbing materials. The novelty of the proposed approach lies in the application of THz beam-shaping techniques and phase-contrast and dark-field spatial filtering to enhance image contrast. While these methods are well established in optical microscopy, they have not yet been widely explored in THz imaging systems. Most of the existing research on spatial filtering in the THz range has been conducted by the group of dr. A. Siemion (Warsaw, Poland). Their work primarily focuses on theoretical aspects of digital THz holography [M. Surma et al., Applied Sciences, 2019], THz diffractive optics, and spatial filtering techniques [A. Siemion et al., Sensors, 2020]. However, experimental incoherent THz imaging and THz beam engineering remain largely unexplored. A pioneering experimental study in the 0.6 THz frequency range was carried out in 2021 by the proposed supervisor and collaborators [A. Siemion et al., Optics and Lasers in Engineering, 2021]. This work demonstrated that spatial filtering techniques can significantly extend the dynamic range of THz imaging systems and enable enhanced visualization of edges and structural inhomogeneities in weakly absorbing samples.
The proposed doctoral topic represents a continuation of this research, focusing on THz beam forming, advanced spatial filtering strategies, and the development of compact, high-contrast THz imaging systems, thereby opening new perspectives for practical applications.