Wide-angle Applications Research Articles

Wideband Sherman–Morrison–Woodbury Formula-Based Algorithm for Electromagnetic Scattering Problems

In this paper, a wideband Sherman-Morrison-Woodbury formula-based algorithm (WSMWA) is proposed to efficiently compute the wideband and wide-angle electromagnetic scattering problems. In the proposed algorithm, the standard adaptive cross approximation (ACA) decomposition is only performed at the highest frequency of the frequency band of interest to find the dominant basis functions for each far-block pair. Then, at any frequency within the entire frequency band, the approximate compression of the impedance matrix can be efficiently constructed by using the impedance interpolation method with the dominant basis functions selected at the highest frequency. As a result, the WSMWA avoids performing the standard ACA repeatedly and saves a lot of computational time in comparison with the conventional Sherman-Morrison-Woodbury formula-based algorithm (SMWA) for wideband and wide-angle applications. Numerical results for electromagnetic scattering are given to demonstrate the efficiency and accuracy of the proposed algorithm.

Novel “Ionology Art for Art Ionology Methods” in 4π plasma focus device space: Bridging art, science and technology

Novel “Ionology Art for Art Ionology (IAAI) Methods” were invented by us and presented for the first time in this paper by successfully bridging art, science and technology for producing “Positive and Negative Art Ionograms” or “Art Ion Shadowgrams” using 4π ion beams of a plasma focus device (PFD). As recently discovered by us, a PFD emits 4π high intensity heavy charged ions isotropically in PFD space which was used for the first time in this study for producing “Art Ionograms” which is a wide-scale wide-angle application. Art patterns to be ionographed were transferred and cut on vinyl decal sheet which was stuck onto a panorama polycarbonate ion image detector, and then bombarded by helium ions in 4π PFD space in order to form “Hidden Art Patterns”. The polycarbonate detectors with “Hidden Art Patterns” have been developed in panorama single-cell mega-size electrochemical ion image processing systems. High resolution “Art Ionograms” such as thin flat art patterns, poems and even portraits were produced, sharply observed by the unaided eyes and framed as beautiful art pieces. This study while introduced novel “IAAI Methods” by using full-scale 4π PFD ion beams, it also demonstrated how scientifically and efficiently ion beams in 4π PFD space can be used for large-scale wide-angle applications with a high prospect for applications in medicine, industry, science and technology. On the other hand, it is hoped that the novel inventions made, the unique framed art pieces produced as presented here and those being further produced for setting up a “Gallery of Particle-bombarded Arts” are remained as a worldwide cultural heritage of bridged art, science and technology.

Design and Fabrication of Moth-Eye Subwavelength Structure with a Waist on Silicon for Broadband and Wide-Angle Anti-Reflection Property

Reflection loss on the optical component surface is detrimental to performance. Several researchers have discovered that the eyes of moths are covered with micro- and nanostructured films that reduce broadband and wide-angle light reflection. This research proposes a new type of moth-eye subwavelength structure with a waist, which is equivalent to a gradient refractive index film layer with high–low–high hyperbolic-type fill factor distribution. The diffraction order characteristics of a moth-eye subwavelength structure are first analyzed using a rigorous coupled wave analysis. The moth-eye structural parameters are optimized within the spectral range of 2–5 μm using the finite-difference time-domain method. The experimental fabrication of the moth-eye structure with a waist array upon a silicon substrate is demonstrated by using three-beam laser interferometric lithography and an inductively coupled plasma process. The experimental and simulation results show good agreement. The experimental results show that the reflectivity of the moth-eye structure with a waist is less than 1.3% when the incidence angle is less than 30°, and less than 4% when the incidence angle is less than 60°. This research can guide the development of AR broadband optical components and wide-angle applications.

Study of broadband polarization conversion with metallic surface-relief gratings by rigorous coupled-wave analysis

The conical rigorous coupled-wave analysis (RCWA) is employed to calculate the polarization conversion through the excitation of surface plasmons on metallic gratings. Various examples are examined with this numerical scheme. Our calculated results are consistent with those obtained from experiment and from other numerical methods. Three types of subwavelength surface-relief gratings are studied for the capability of broadband polarization conversion in the visible region. For wide-angle applications, various incident angles are studied and high polarization conversion efficiency is achieved.

Progress of the 3He neutron spin filter project at HMI

Recent progress in the various fields related to the project will be described. On the one hand, the development of suitable and reliable filter cells is a crucial task. Especially further decrease of the wall relaxation rate continues to be important. Therefore, we embarked on coatings made out of Cs suboxides, in particular, Cs 7O, and compared such cells in an elementary neutron experiment with those simply coated with Cs. To enable wide-angle applications of the 3He neutron spin filter technique, like reflectometry or small angle scattering, the cell design has been modified in order to get access to scattering angles up to 18°. A new type of transportation unit, well adapted to the requirements of those cells, has been constructed and tested. On the other hand, the construction of a filling station to supply filter cells is indispensable. Although a 3He polarization degree of 80% during optical pumping had been achieved reliably, further improvements for a novel optical pumping cell has been evaluated prepared and tested. Moreover, progress in the compressor completion is discussed. To integrate it, the rebuilding of the filling station for a flow-through type of operation has been evaluated and afterwards the construction of certain parts upgraded, allowing determination of the polarization in each of the four optical pumping cells which will be part of the filling station in the future.

Calibration procedures for charge-coupled device x-ray detectors

Calibration procedures are described for use with electronic x-ray detectors, with an emphasis on detectors based on fiber-optically coupled charge-coupled devices. Methods are detailed for removing spurious events, pixel pedestals, dark-current, spatial distortion, and intensity response variations for both small-angle and wide-angle applications. The accuracy of the calibration procedures is discussed.

Characteristics of polymer light conduits from different manufacturing processes

The characteristics of polymer light conduits (PLCs) prepared from three different processes are compared: (1) a bulk polymerization and melt spinning process (PLC1), ( 2 ) a thermal polymerization (PLC2 ), and (3 ) a UV curing photopolymerization (PLC3-PLC4) of a monomer mixture in a fluorinated ethylene propylene tube. PLC1 and PLC2 were obtained from Toray and Lumenyte, respectively. New PLCs, PLC3 and PLC4, were prepared from the monomer mixtures consisted of methyl methacrylate, 2-ethyl-hexyl acrylate, and the crosslinking agent polyethylglycol 200 diacrylate and diallyl phthalate, respectively. All four polymer light conduits contain the acrylic moiety. PLC2 may also contain the plasticizer additives, which resulted in an excellent flexibility but with a poor thermal stability. The flexibilities of PLC2 and PLC3 were significantly improved from that of PLC1 due to the insertion of a plasticizer and the long alkyl chain monomer 2-EHA, respectively. The much larger numerical apertures of PLC2-PLC4 than that of PLC1 suggest that PLC2-PLC4 can have a wide angle application. The transmitted distance of PLC1 is larger than those of PLC2-PLC4. However, the illumination intensity of PLC1 is worse than those of PLC2-PLC4. This result indicates that PLC1 is suitable for the applications as PLCs with the characteristics of long distance and low illumination intensity, while PLC2-PLC4 are suitable for short distance and high illumination intensity applications.

Novel polymer optical couplers based on symmetry mode mixing

Emerging mixed signal modules will contain microwave, digital, and photonic circuits requiring efficient interconnect technology due to space limitation. Polymers are envisioned to perform optical interconnections via waveguides, and distribution networks via optical couplers. A novel polymer optical coupler, using center-fed mode mixing for multimode waveguide, is demonstrated experimentally for use in a mixed-signal mode environment. This coupler has lower loss and space requirement than the traditional Y-junction coupler. A limitation of this type of coupler is the small separation of the output beams. To circumvent this a microprism is introduced for wide-angle applications. >

A simplified technique for the photography of lightning in daylight

A variation of the Salanave and Brook (1965) technique of daytime lightning photography that uses a Kodak #92 filter in conjunction with Kodak 2476 Sheelburst film to restrict the spectral sensitivity to a narrow region near the Hα line in the lightning spectrum is described. The lack of an interference filter makes this approach simpler and more suitable for wide-angle applications.