Gradient-index rod lens with a high acceptance angle for color use by Na(+) for Li(+) exchange

The relationship between the characteristics of gradient-index rod lenses obtained by ion exchange and their mother glass compositions is studied. It is observed that Li(2)O content, R(2)O (Li(2)O + Na(2)O) content, and the Li(2)O/Na(2)O ratio are important factors in attaining a high acceptance angle and a small field curvature. Thus the gradient-index lens array is fabricated by the use of a newly developed glass composition and its optical performance; the modulation transfer function, luminous intensity, and chromatic aberration are precisely evaluated. The array is found to have a sufficiently high performance to be applicable for color use.     

Reconstruction of a complex-valued object in double-passage coherent imaging through a random-phase screen

We consider the reconstruction of a complex-valued object that is coherently illuminated and viewed through the same random-phase screen. The reconstruction is based on two intensity measurements: the intensity of the Fourier transform of the image and the intensity of the Fourier transform of the image when modulated with an exponential filter. The illumination beam has a Gaussian intensity profile of arbitrary width, and the phase screen is assumed to be described by a Gaussian random process of large variance and arbitrary correlation length. Computer-simulated examples of the reconstruction of a two-dimensional complex object demonstrate that the reconstruction is robust.     

Angular displacement fiber-optic sensor: theoretical and experimental study

An optical-fiber sensor based on twist-induced optical activity has been developed for measuring angular displacements at low temperature. The sensing part is composed of a fiber coil rotated between two points, which induces a twist of two sections of fiber. A theoretical study of the evolution of a general input state of polarization in the sensor gave us its main characteristics. Then experimental investigations permitted the construction of a sensor to take angular measurements over a 100-deg range with an accuracy of 0.2 deg. The thermal sensitivity of this kind of sensor is also briefly reported.     

Fiber-optic array algebraic processing architectures

A high-accuracy fiber-optic array processor (FOAP) based on the algorithm of digital multiplication by analog convolution is proposed. The FOAP architecture is a local regularly interconnected processor that utilizes an array of identical all-optical elemental-processing lattice units, namely, an optical splitter, an optical combiner, and a binary programmable fiber-optic transversal filter. Various FOAP matrix multipliers are proposed for nonnegative and twos-complement binary arithmetic matrix-vector, matrix-matrix, triple-matrix, and high-order matrix operations. The overall performances of the FOAP matrix multipliers are compared with the time-integrating and space-integrating architectures and with the digital multipliers. Extension of the digital-multiplication-by-analog-convolution algorithm is also considered.     

Packing products for customers: an ergonomics evaluation of three supermarket checkouts

The introduction of laser scanners at supermarket checkout areas has resulted in previous ergonomics studies focusing specifically on the scanning process and associated cumulative trauma disorders in the hands and arms. Few studies have evaluated the increased musculoskeletal load and exertion of checkout staff when they are also expected to pack the products into bags for the customers. This paper describes an ergonomics evaluation of three different designs of checkout workstation, which require the operator to stand when they scan the products, pack them into plastic bags and transfer the packed bags to the customer. Musculoskeletal load and exertion associated with the different checkouts were measured using OWAS, heart rate recordings and ratings of perceived exertion. In addition, subjective rankings of the workstations were obtained and the productivity associated with each design examined as part of the evaluation. Some of the variables measured showed significant differences in postural load between the workstations. The results of the evaluation formed the basis of recommendations for an improved workstation design. Some of the suggestions made to reduce postural load and increase productivity include positioning the weigh scale to the side and the bag frame beneath the scanner.     

A nano-plasmonic HMIM waveguide based concurrent dual-band BPF using circular ring resonator

This article analyzes the transmission line characteristics of plasmonic hybrid metal insulator metal (HMIM) waveguide, circular ring resonator (CRR) based dual-band band-pass filters with two transmission poles in both pass-bands in the optical regime using coupled line feed. The transmission line characteristics of an HMIM waveguide, such as characteristic impedance (ZPV), effective refractive index (neff) and propagation length (Lspp), have been obtained by using full wave simulation. Using basic HMIM slot waveguide, a CRR with periodic loading of double- and triple-ring CRR is numerically analyzed. Two input ports have been used for excitation, which are located at the separation of 180° positions along the CRR, and are coupled with the ring by parallel coupled lines, producing the dual pass-bands with the synchronous excitation of two transmission poles. The proposed double-ring dual-band band-pass filter (DR-DB-BPF) offers 35 dB extinction ratio (ER), 299.69 nm free spectral range (FSR) and narrow band full width half maximum (FWHM) of 78.057—112.43 nm. The triple-ring DB-BPF (TR-DB-BPF) has 22.5 dB ER, FSR of 292.18 nm and FWHM of 42.751—59.58 nm. The proposed filters are very useful in the development of dual-band filters for electronic photonic integrated circuits (EPICs), as the optical signals are filtered at two wavelengths simultaneously.     

Effect of substrate bias on the properties of plasma deposited organosilicone (pp-HMDSN) thin films

Organosilicone thin films have been deposited by plasma polymerization (pp) in a plasma enhanced chemical vapor deposition (PECVD) system using hexamethyldisilazane (HMDSN:C6H19Si2N) as a monomer precursor, at different biases of the stainless-steel substrate holder. The substrate bias affected film thickness, surface morphology, chemical composition and photoluminescence (PL) emission. For a negatively biased substrate, it is found that the film thickness is the minimum, while the porosity and PL emission are the maximum. For a positively biased substrate, the thickness and the ratio of Si/N are the maximum which correspond to a blue shift of the PL emission in comparison with the case of non-biased grounded substrate. In addition, the characterization of the plasma using a single cylindrical Langmuir probe has been performed to obtain information about both the electron density and the positive ion energy, where it can be concluded that the ion energy plays a major role in determining film thickness.     

Oblique incidence of gaussian beams on waveguide gratings with the four-wave coupled-mode theory

Diffraction of obliquely incident Gaussian beams on waveguide gratings with infinitely long grooves is described. The analysis is based on the angular spectrum of the beam and on the grating response derived from the four-wave coupled-mode theory, which simultaneously considers all four (approximately) synchronous waves. Results concerning the shapes of the emerging beams and their directions, the power content, and the possibility of beam splitting could differ significantly from those obtained by means of two-wave coupling. The analysis method is general and can be performed on many kinds of realistic beam shapes and applications.     

Refracted Near-Field Measurements of Refractive Index and Geometry of Silica-on-Silicon Integrated Optical Waveguides

The standard refracted near-field technique for measuring the refractive-index profile of optical fibers cannot be directly used for silica-on-silicon integrated optical waveguides because of the opacity of silicon. A modified method is thus presented to characterize this kind of waveguide. The resolution it gives, both spatially and in the refracted index, is practically as good as that obtained with the standard technique for measuring optical fibers.