Browsing by Author "Katkus, T"

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    Femtosecond laser fabrication of diffractive optics for spatial and spectral imaging at synchrotron infrared beamlines
    (Society of Photo-Optical Instrumentation Engineers (SPIE), 2021-03-06) Anand, V; Katkus, T; Ng, SH; Vongsvivut, JP; Maksimovic, J; Klein, AR; Bambery, KR; Lundgaard, S; Linklater, D; Ivanova, EP; Tobin, MJ; Juodkazis, S
    Infrared (IR) microspectroscopy is a powerful molecular fingerprinting tool widely used for the identification of structural and functional composition of biological and chemical samples. The IR microspectroscopy beamline at the Australian Synchrotron can be operated either with a single-point narrow-band mercury cadmium telluride (MCT) detector or a focal plane array (FPA) imaging detector with 64 × 64 pixels. For the implementation of indirect nonscanning imaging technology, the system was operated with the FPA detector. In this study, we propose an indirect IR imaging technique based on the principles of correlation optics using diffractive optical elements such as random pinhole array (RPA) and Fresnel zone plate (FZP). The spatial and spectral variations of point spread functions (PSFs) of the RPA and FZP were simulated for the synchrotron configuration. Intensity responses for 2D objects were simulated using the same simulation conditions and reconstructed using Lucy-Richardson algorithm. Fabrication of diffractive elements for IR wavelengths is often a challenging task as the IR transparent material substrates, such as barium fluoride and calcium fluoride, are highly susceptible to thermal shocks and brittle by nature. The diffractive elements were fabricated by ablating directly on a 100 nm thick gold coated substrate using femtosecond laser pulses. The simulation results and the fabrication outcomes demonstrate the feasibility of indirect imaging at the synchrotron IR beamline. © 2021 Society of Photo-Optical Instrumentation Engineers (SPIE)
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    Single-shot mid-infrared incoherent holography using Lucy-Richardson-Rosen algorithm
    (Institute of Optics and Electronics, Chinese Academy of Sciences, 2022-03-18) Anand, V; Han, Ml; Maksimovic, J; Ng, SH; Katkus, T; Klein, AR; Bambery, KR; Tobin, MJ; Vongsvivut, JP; Juodkazis, J
    In recent years, there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional (3D) information into a two-dimensional intensity distribution without two-beam interference (TBI). Most of the incoherent 3D imagers without TBI are based on scattering by a random phase mask exhibiting sharp autocorrelation and low cross-correlation along the depth. Consequently, during reconstruction, high lateral and axial resolutions are obtained. Imaging based on scattering requires an astronomical photon budget and is therefore precluded in many power-sensitive applications. In this study, a proof-of-concept 3D imaging method without TBI using deterministic fields has been demonstrated. A new reconstruction method called the Lucy-Richardson-Rosen algorithm has been developed for this imaging concept. We believe that the proposed approach will cause a paradigm-shift in the current state-of-the-art incoherent imaging, fluorescence microscopy, mid-infrared fingerprinting, astronomical imaging, and fast object recognition applications. © The Author(s) 2022. Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License.