THz Beam Shaping Based on Paper Diffractive Optics

Agnieszka Siemion ; Andrzej Siemion ; Jaroslaw Suszek ; Adam Kowalczyk ; Jaroslaw Bomba ; Artur Sobczyk ; Norbert Palka ; Przemysław Zagrajek ; Andrzej Kolodziejczyk ; Maciej Sypek

Abstract:

Fast and intensive development of terahertz (THz) technology requires designing dedicated optical elements. Here, we generated complicated THz field distribution thanks to simple binary diffractive optical elements (DOEs) made from paper. The paper fabricated structures are lightweight, inexpensive, feasible for fast-prototyping purposes and they have high transparency in the THz range. Structures were designed and simulated in nonparaxial approach which suppresses the influence of geometrical aberrations and enables large apertures in comparison with their focal lengths. Such DOEs can be used in THz tomography, scanners, radiation sources collimation, focusing and gathering the radiation on the detector.

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Analysis of Wire-Grid Polarisers in Terahertz Spectral Range

Mičica ; Martin ; Bucko ; Václav ; Postava ; Kamil ; Vanwolleghem ; Mathias ; Lampin ; Jean-François ; Pištora ; Jaromír

Abstract:

Polarisers are important components in many optical applications working with polarised radiation, therefore it is need to know their behaviour at specified spectral range. Interest in terahertz (THz) radiation and its application in science, where we need polarisers was our motivation for study of commonly used polarisers this spectral range. In our paper we present THz measurement of free standing wire-grid (5 μm tungsten wire, 12.5 μm period) and polyethylene foil wire-grid (0.5 μm metallic stripes, 1.2 μm period) polariser.

Measurements were performed by terahertz time domain spectroscopy in the range from 60 GHz to 3 THz (2–100 cm−1) at different rotation of azimuth angle. For quality evaluation was from measured data calculated extinction ratio and phase shift. Both polarisers were compared and their suitability for THz application is discussed. Results show better properties of free standing wire-grid polariser in the range up to 60 cm−1 while properties of polyethylene polariser are better at higher wavenumbers. Polarisers are described in the frame of Jones matrix calculus.

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Moisture contamination detection in adhesive bond using embedded FBG sensors

Magdalena Mieloszyka ; Wiesław Ostachowicza

Abstract:

The paper presents an application of embedded fibre Bragg grating (FBG) sensors for moisture contamination detection in an adhesive bond between two composite elements. FBG sensors are a great tool to Structural Health Monitoring of composite structures due to their high corrosion resistance as well as their small size and weight. Adhesive bonds are very popular in many industrial branches. One of the major problem limits the use of an adhesive joints is they sensitivity on water form ambient. Even the 1% of moisture affects an adhesive bond layer strength. FBG sensors can be use for detection of even a small amount of moisture concentration (1–3% of sample weight). It can be also used for determination of moisture concentration changes during both soaking and drying processes.

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