We report the design, fabrication, and characterization of bianisotropic Huygens' metasurfaces (BHMSs) for refraction of normally incident beams towards 71.8 degrees. As previously shown, all three BHMS degrees of freedom, namely, electric polarizability, magnetic polarizability and omega-type magnetoelectric coupling, are required to ensure no reflections occur for such wide-angle impedance mismatch. The unit cells are composed of three metallic layers, yielding a printed-circuit-board (PCB) structure. The fabricated BHMS is characterized in a quasi-optical setup, used to accurately assess specular reflections. Subsequently, the horn-illuminated BHMS' radiation pattern is measured in a far-field chamber, to evaluate the device's refraction characteristics. The measured results verify that the BHMS has negligible reflections, and the majority of the scattered power is coupled to the desirable Floquet-Bloch mode. To the best of our knowledge, this is the first experimental demonstration of such a reflectionless wide-angle refracting metasurface.
There is an established equivalence between Huygens' metasurfaces and lattice networks. This paper proposes an extension to this equivalence for bianisotropic Huygens' metasurfaces, where bianisotropy refers to the magnetoelectric coupling between the effective electric and magnetic responses. A modified version of the lattice network is proposed that exhibits a one-to-one mapping to the bianisotropic sheet transition conditions by incorporating ideal transformers. A possible realization of bianisotropic Huygens' unit cells is also proposed that relies on offsetting the wire with respect to the loop in the wire/loop topology. This is followed by deriving analytical expressions for the image impedances and the corresponding transfer function of bianisotropic Huygens' metasurfaces. Inverse analytical expressions are also derived that govern the required effective electric and magnetic responses and the magnetoelectric coupling for achieving wideband electrical transparency (symmetric case) and wideband impedance transformation (bianisotropic case) with these Huygens' metasurface unit cells. Moreover, it is shown that these expressions can be realized with transmission-line stubs. These expressions are then used to design subwavelength thin Huygens' metasurfaces immersed in an air gap between two dielectric media. It is shown, through full-wave simulations, that wideband electrical transparency and impedance transformation are realized for a normally impinging plane wave.
An isostructural series of transition metal-formate-chloride-hydrate compounds, M3(OOCH)5Cl(OH2) (M = Fe, Co, Ni), have been synthesized using a solvothermal method. These compounds crystallize in the chiral and polar space group P31 and are comprised of three different types of helical chains of edge-sharing M2+-centered octahedra. All three compounds undergo 3D ferrimagnetic ordering at low temperature, and the iron and cobalt analogues exhibit field-induced metamagnetic transitions. The magnetic structure was determined by neutron powder diffraction, revealing ferromagnetic intrachain coupling and antiferromagnetic interchain interactions, with the three chains arranged in a two-up/one-down triangular lattice. As all three chains contain one type of metal in the same spin state, these compounds are rare examples of homospin topological ferrimagnets.
In addition to reviewing the major alignment and inspection procedures in producing miniaturized electronic components, this paper describes a 3D automated vision system used in the inspection of TAB (Tape Automated Bonding) products. This multi-sensor system utilizing four solid-state cameras is aliased IBIS Intelligent Bump-tape Inspection System. Besides the capabilities to measure the major planar geometric features, the key features of this system include (1) structured-light 31) vision for etch depth measurement, (2) data-base driven inspection, (3) close coupling of microsensing and micropositioning, (4) sequential usage of multiple resolution cameras and computer controlled illumination for optimal micromeasurements, and ( 5 ) statistical analysis of measured data for process trend monitoring.
Polarization independent liquid crystal (LC) microlens arrays based on controlling the spatial distribution of the Kerr constants of blue phase LC are simulated. Each sub-lens with a parabolic distribution of Kerr constants results in a parabolic phase profile when a homogeneous electric field is applied. We evaluate the phase distribution under different applied voltages, and the focusing properties of the microlens arrays are simulated. We also calculate polarization dependency of the microlenses arrays at oblique incidence of light. The impact of this study is to provide polarizer-free, electrically tunable focusing microlens arrays with simple electrode design based on the Kerr effect.
Mathematical modeling is used to examine the unsteady problem of heating and pulling an axisymmetric cylindrical glass tube with an over-pressure applied within the tube to form tapers with a near uniform bore and small wall thickness at the tip. To allow for the dependence of viscosity on temperature, a prescribed axially varying viscosity is assumed. Our motivation is the manufacture of emitter tips for mass spectrometry which provide a continuous fluid flow and do not become blocked. We demonstrate, for the first time, the feasibility of producing such emitters by this process and examine the influence of the process parameters, in particular the pulling force and over-pressure, on the geometry. There is not a unique force and over-pressure combination to achieve the desired geometry at the tip but smaller over-pressure (hence force) yields a more uniform bore over the entire length of the emitter than does a larger over-pressure (and force). However, the sensitivity of the geometry to small fluctuations in the parameters increases as the over-pressure decreases. The best parameters depend on the accuracy of the puller used to manufacture the tapers and the permissible tolerances on the geometry. The model has wider application to the manufacture of other devices.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)