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It is well known that light can carry two different kind of angular momentum that together form the total angular momentum of photons. These two forms are the spin orbital angular momentum, associated with the circular polarisation of light, and the orbital angular momentum of light associated with a wavefront tilted with respect to the propagation axis. Any tilted wavefront generates an orbital component of the angular momentum but there are some special cases in which this property becomes particularly interesting. It is the case of optical vortices which form when the waveform is continuously and uniformly tilted to the propagation axis forming a spiral structure.

O presente trabalho trata do estudo, projeto, desenvolvimento, construção e medida de lentes discretas planares (DLAs). Estes dispositivos atuam como sistemas irradiantes, especialmente com características multi-feixes. A construção destas lentes utiliza tecnologias compatíveis com a fabricação de circuitos impressos, com alguns detalhes que são característicos da área de antenas e circuitos planares. O estudo aborda as equações de projeto e considerações gerais relativas ao atendimento de especificações técnicas preliminares. Foram desenvolvidas duas lentes discretas, uma na frequência de 8GHz (banda X) e outra na frequência de 40GHz (banda Ka- faixa de ondas milimétricas). São apresentados os resultados de medidas destas duas lentes, que comprovam a possibilidade de uso em aplicações multi-feixes, bem como seu efeito de foco, análogo ao observado em lentes óticas comuns. / The object of this work is the study, design, development, fabrication and measurement of discrete lens arrays (DLAs). These devices act as radiant systems, especially with multi-beam characteristics. Their construction follows the same procedures and techniques normally found in printed circuit fabrication, with some further details that are pertinent to the antenna and planar circuit field. This study contains the design equations and general remarks as to fulfill preliminary technical specifications. Two real designs were developed, one in the X-band (8GHz) and another in the millimeter range, Ka band (40GHz). Their respective measurement results are presented, which proved their possible application in multi-beam systems, as well as their focusing effect, which is analogous to that observed in common optical lenses.

O presente trabalho trata do estudo, projeto, desenvolvimento, construção e medida de lentes discretas planares (DLAs). Estes dispositivos atuam como sistemas irradiantes, especialmente com características multi-feixes. A construção destas lentes utiliza tecnologias compatíveis com a fabricação de circuitos impressos, com alguns detalhes que são característicos da área de antenas e circuitos planares. O estudo aborda as equações de projeto e considerações gerais relativas ao atendimento de especificações técnicas preliminares. Foram desenvolvidas duas lentes discretas, uma na frequência de 8GHz (banda X) e outra na frequência de 40GHz (banda Ka- faixa de ondas milimétricas). São apresentados os resultados de medidas destas duas lentes, que comprovam a possibilidade de uso em aplicações multi-feixes, bem como seu efeito de foco, análogo ao observado em lentes óticas comuns. / The object of this work is the study, design, development, fabrication and measurement of discrete lens arrays (DLAs). These devices act as radiant systems, especially with multi-beam characteristics. Their construction follows the same procedures and techniques normally found in printed circuit fabrication, with some further details that are pertinent to the antenna and planar circuit field. This study contains the design equations and general remarks as to fulfill preliminary technical specifications. Two real designs were developed, one in the X-band (8GHz) and another in the millimeter range, Ka band (40GHz). Their respective measurement results are presented, which proved their possible application in multi-beam systems, as well as their focusing effect, which is analogous to that observed in common optical lenses.

abstract: Fingerprints have been widely used as a practical method of biometrics authentication or identification with a significant level of security. However, several spoofing methods have been used in the last few years to bypass fingerprint scanners, thus compromising data security. The most common attacks occur by the use of fake fingerprint during image capturing. Imposters can build a fake fingerprint from a latent fingerprint left on items such as glasses, doorknobs, glossy paper, etc. Current mobile fingerprint scanning technology is incapable of differentiating real from artificial fingers made from gelatin molds and other materials. In this work, the adequacy of terahertz imaging was studied as an alternative fingerprint scanning technique that will enhance biometrics security by identifying superficial skin traits. Terahertz waves (0.1 – 10 THz) are a non-ionizing radiation with significant penetration depth in several non-metallic materials. Several finger skin features, such as valley depth and sweat ducts, can possibly be imaged by employing the necessary imaging topology. As such, two imaging approaches 1) using quasi-optical components and 2) using near-field probing were investigated. The numerical study is accomplished using a commercial Finite Element Method tool (ANSYS, HFSS) and several laboratory experiments are conducted to evaluate the imaging performance of the topologies. The study has shown that terahertz waves can provide high spatial resolution images of the skin undulations (valleys and ridges) and under certain conditions identify the sweat duct pattern. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2017

Diplomová práce se zabývá návrhem a sestavením nového spektrometru opticky detekované magnetické rezonance (ODMR) modifikací stávajícího spektrometru magnetického kruhového dichroismu (MCD) přivedením mikrovlnného ozařování. Je navrhnut nový držák vzorku umožnující osvětlení jak viditelným světlem, tak mikrovlnným zářením. Pro přivedení vlnění o nižších frekvencích je navržena anténa, určená k umístění pod vzorkem. Schopnosti celého systému jsou demonstrovány na sloučenínách kovových komplexů.

With the recent rise of 3D-printing as a form of manufacturing and their advantages for quick prototyping there is an interest for 3D-printed optical components. This thesis tests how well 3D-printed quasi-optical components preform and verify measurements with electromagnetic simulations. Measurements were made using a 60GHz FM-CW radar as well with a trihedral reflector, and tested on 3D-printed PLA lenses printed using an Ultimaker 2+. The measurements made are of the refractive index of the material, as well as the focal length of the lenses. Results showed PLA having a refractive index close to n = 1.654 in the 60GHz region. Results also showed the lenses having consistent properties like focal length and gain, two lenses having focal length of 23.7 and 23.9 mm which are close to the simulation of 24.05 mm. These findings shows 3D printed quasi-optical components have sufficient performance for use of prototyping or production depending on use. There are also some questions that have arisen like how does crystallisation in the plastic affect the components properties? And how does the PLA degrading affect the quality of the lenses over time? / På grund av framgångar inom 3D-utskrivning på senaste tiden som en form av tillverkning och dess fördelar med snabb framtagande av prototyper finns det ett intresse för utskrivna optiska komponenter. Detta examensarbete testar hur väl 3D-utskrivna kvasioptiska komponenter funger\-ar och verifierar testresultat med elektromagnetiska simuleringar. Mät\-ning\-arna gjordes med en FM-CW radar och en trihedral reflektor, och testade PLA linser utskrivna med en Ultimaker 2+. Mätningar\-na gjordes på materialets brytningsindex samt linsernas brännvidd. Resultaten visade att PLA har ett brytningsindex nära n = 1.654 i 60GHz området. Resultaten visade även hur linserna har konsekventa egenskaper som brännvidd och förstärkning. De två slutgiltiga linserna hade en brännvidd på 23.7 and 23.9 mm vilket är nära simuleringen på 24.05 mm. Dessa resultat visar att 3D-utskrivna komponenter har tillräcklig prestanda för användning i framtagande av prototyper eller produktion beroende på användning. Det finns en del frågor som kommit till, som hur påverkar plastens kristallisation komponentens egenskaper? Och hur påverkar PLAs nedbrytande linsernas kvalité?

Cílem diplomové práce je navrhnout konstrukční řešení držáků vzorků pro vysokofrekvenční elektron paramagnetickou resonanci. Předmětem návrhu je vytvořit jednoduchý zamykací systém pro spojování mikrovlnného vlnovodu a držáku vzorku. Dále navrhnout systém s řešením držáku pro více vzorků. Toto unikátní provedení držáku povede k několikanásobné úspoře celkového času měření vzorků. Poslední návrh spočívá v optimalizaci držáku vzorku s možností naklápění osy, kterou lze díky přímému napojení na piezoelektrický rotátor pootáčet s přesností na miliradiány. Oba typy držáku vzorku jsou navrženy s ohledem na automatizaci měření.