Recent Progress in Plasmonic Colour Filters for Image Sensor and Multispectral Applications

Using nanostructured thin metal films as colour filters offers several important advantages, in particular high tunability across the entire visible spectrum and some of the infrared region, and also compatibility with conventional CMOS processes. Since 2003, the field of plasmonic colour filters has evolved rapidly and several different designs and materials, or combination of materials, have been proposed and studied. In this paper we present a simulation study for a single- step lithographically patterned multilayer structure able to provide competitive transmission efficiencies above 40% and contemporary FWHM of the order of 30 nm across the visible spectrum. The total thickness of the proposed filters is less than 200 nm and is constant for every wavelength, unlike e.g. resonant cavity-based filters such as Fabry-Perot that require a variable stack of several layers according to the working frequency, and their passband characteristics are entirely controlled by changing the lithographic pattern. It will also be shown that a key to obtaining narrow-band optical response lies in the dielectric environment of a nanostructure and that it is not necessary to have a symmetric structure to ensure good coupling between the SPPs at the top and bottom interfaces. Moreover, an analytical method to evaluate the periodicity, given a specific structure and a desirable working wavelength, will be proposed and its accuracy demonstrated. This method conveniently eliminate the need to optimize the design of a filter numerically, i.e. by running several time-consuming simulations with different periodicities. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Kennesaw State University Wind Ensemble

KSU School of Music presents Wind Ensemble featuring KSU Trumpet Ensemble, guest conductor James David Collins, and KSU Composition Winner Andrew Niehoff\u27s world premiere, Flowers in the Dark.https://digitalcommons.kennesaw.edu/musicprograms/1239/thumbnail.jp

High performance, accelerometer-based control of the Mini-MAST structure at Langley Research Center

Many large space system concepts will require active vibration control to satisfy critical performance requirements such as line of sight pointing accuracy and constraints on rms surface roughness. In order for these concepts to become operational, it is imperative that the benefits of active vibration control be shown to be practical in ground based experiments. The results of an experiment shows the successful application of the Maximum Entropy/Optimal Projection control design methodology to active vibration control for a flexible structure. The testbed is the Mini-Mast structure at NASA-Langley and has features dynamically traceable to future space systems. To maximize traceability to real flight systems, the controllers were designed and implemented using sensors (four accelerometers and one rate gyro) that are actually mounted to the structure. Ground mounted displacement sensors that could greatly ease the control design task were available but were used only for performance evaluation. The use of the accelerometers increased the potential of destabilizing the system due to spillover effects and motivated the use of precompensation strategy to achieve sufficient compensator roll-off

Exploitation of magnetic dipole resonances in metal–insulator–metal plasmonic nanostructures to selectively filter visible light

Significant improvement in using plasmonic nanostructures for practical color filtering and multispectral imaging applications is achieved by exploiting the coupling of surface plasmons with dielectric optical cavity resonances within a hexagonal array of subwavelength holes in a thin CMOS-compatible metal–insulator–metal stack. This polarization-independent architecture overcomes the limitations of all previously reported plasmonic color filters, namely poor transmission and broad band-pass characteristic, effectively providing a compact approach for high color accuracy multispectral and filtering technologies. Measured transmission efficiencies up to 60% and full-width at half-maximum between 45 and 55 nm along the entire visible spectrum are achieved, an impressive and unique combination of features that has never been reported before. The nanostructure exploits the phenomenon of extraordinary optical transmission and magnetic dipole modes to efficiently filter visible light. The presence of magnetic resonances in the optical regime is an unusual property, previously reported in photonic metamaterials or dielectric nanoparticles. The physical insights established from the electromagnetic near-field patterns are used to accurately tailor the optical properties of the filters. The nonideality of the fabrication at the nanoscale is addressed, the issues encountered highlighted, and alternative solutions proposed and verified, demonstrating that the working principle of the MIM structure can be successfully extended to other materials and structural parameters

Age and Growth of King Mackerel, \u3cem\u3eScomberomorus cavalla\u3c/em\u3e, from the Atlantic Coast of the United States

Whole sagittae from 683 and sectioned sagittae from 773 adult (age\u3e 0 ; 437-1.310 mm FL), and lapilli from 29 larval (2-7 mm SL) and 69 young-of-the-year (79-320 mm FL) king mackerel, were examined. All fish were from waters off the Atlantic coast of the southeastern United States (Cape Canaveral, Florida to Cape Fear. North Carolina). Back-calculated lengths at ages and von Bertalanffy growth equations were calculated from both whole and sectioned sagittae. Ages determined from sectioned sagittae were significantly greater than ages determined from whole sagittae, and the magnitude of the difference increased with age (from sections). Rings on sectioned sagittae are considered to be true annual increments, forming during June-September. There was no clear pattern to ring formation on whole otoliths. The oldest fish examined was age 21. The daily nature of rings on lapilli of age 0 king mackerel was not validated, but if the marks are formed daily they suggest growth rates of approximately 0.47 mm/d for early larvae and 2.9 mm/d for fish 1-3 months of age

3D Studies of Damage by Combined X-ray Tomography and Digital Volume Correlation

AbstractThe combined use of high resolution X-ray computed tomography with digital image correlation allows quantitative observations of the three-dimensional deformations that occur within a material when it is strained. In suitable microstructures, the displacement resolution is sub-voxel (a voxel is the three-dimensional equivalent of a pixel), and both elastic and plastic deformations can be studied. This paper reviews recent work in which three-dimensional in situ observations of deformation have provided unique insights that support both continuum and heterogeneous microstructure-dependent models of damage development in a range of materials. The examples presented include; crack propagation in a quasi-brittle porous material (polygranular graphite), sub-indentation radial and lateral cracking in a brittle polycrystalline ceramic (alumina); plastic deformation and damage development underneath indentations in a ductile metal (Al-SiC composite) and a ceramic matrix composite (SiC-SiCfibre). These examples show how material properties can be obtained by analysis of the displacement fields, how such measurements can be used to better define the applied loading on small test specimens and how crack opening magnitude and mode may be extracted also. Some new directions for research are outlined, including the combined use of diffraction and imaging techniques on synchrotron X-ray facilities to map both elastic and inelastic strains