Hiding an image with a light-scattering medium and use of a contrast-discrimination method for readout

Hiding image data with a material such as a light-scattering medium is useful as an initial stage of data protection, because the hidden image can be detected only by observation with a specific technique. A light-scattering medium is used to hide the image data, and a low-temporal-coherence interferometer performs the readout processing. A new readout method for detecting pixel values of the image is proposed to overcome spatial variation of the light intensity and distortion of the interference fringes. The introduction of spatial coding further improves the performance by overcoming spatial variations of the light-scattering medium and variations in the reflectance of given pixels.     

All-optical wavelength conversion in a GaInAsP/InP optical gate loaded with a Bragg reflector

All-optical wavelength conversion employing a GaInAsP/InP nonlinear distributed-feedback waveguide switch is investigated. The device has the advantages of simple structure, compactness, polarity-noninverted operation, and feasibility of integration with other photonic devices such as semiconductor optical amplifier and modulators. We show that the device exhibits constant conversion efficiency around -9.2 dB in a signal-wavelength range of 1530-1560 nm. Furthermore, this device can potentially be made polarization independent.     

Basic study about cooperative movement between a human and an agent with entrainment

The use of an agent in the environment, as in medical treatment, welfare, the construction field, and the home, is examined. It is necessary for the agent to be able to work cooperatively with a human, and that may be a problem. Therefore, this study pays attention to the phenomenon that is called entrainment. This is the phenomenon where the rhythm of a certain person and the partner in the communication is synchronized. The purpose of this study is to perform a basic examination into applying an entrainment in order to realize cooperation in operations between a human and an agent. Since many human rhythms are expressed by a nonlinear oscillator, we simulated limited cycle oscillators, which are one of two nonlinear oscillators that cause interactions between agents, as the basic examination for this achievement. Consequently, entrainment of limited cycle oscillators with rhythms which differ has been checked in certain conditions. As a result, the possibility that cooperative movement could be gained was suggested.     

Effects of Solvents in the Polyethylene Glycol Series on the Bonding of Copper Joints Using Ag2O Paste

The effects of reducing solvents on the bonding process using silver oxide paste in a copper joint were investigated. Three solvent types were tested: diethylene glycol (DEG), triethylene glycol (TEG), and polyethylene glycol (PEG). The strength of the joints was assessed by fracturing, which occurred at the interface of the copper oxide layer and the copper substrate in DEG and TEG samples and at the bonded interface in the PEG sample. Analysis of the samples revealed that, in the DEG and TEG samples, the copper substrate was oxidized during the bonding process, which compromised the shear strength of the joints. In contrast, the PEG sample exhibited nonuniform sintering of the silver layer while retaining good shear strength. It was found that the combination of DEG and PEG produced optimum shear strength in the copper joint, as PEG suppressed the growth of copper oxide and DEG promoted the formation of a dense sintered silver layer. The bonding strength achieved was higher than that of the gold-to-gold joint made using standard Pb-5Sn solder.     

Distribution of double bonds in thermally degraded polyisobutylene

The distribution of double bonds in thermally degraded polyisobutylene was determined quantitatively by using pulsed Fourier transform ¹H n.m.r. spectroscopic analysis. The double bonds in the degraded polymer did not exist in the interior but at the terminal positions of the polymer chain. These olefins were of the terminal trisubstituted and terminal vinylidene types. The content of the former was much greater than that of the latter. This shows that radical chain transfer predominantly occurs at the methylene hydrogen rather than at the methyl groups of the polymer chain. The average number of double bonds per molecule, f, was greater than 1 and tended to be near 2. Thereby most of the degraded polyisobutylene was shown to have two terminal unsaturations per molecule.     

Intrinsic diffusion coefficients and the vacancy flow factor in Dilute Cu-Zn Alloys

Interdiffusion coefficients in copper-rich copper-zinc solid solutions containing up to 8 at. pct of Zn at 1168 K have been determined by Matano's analysis using semi-infinite diffusion couples consisting of pure copper and Cu-Zn alloys with Kirkendall markers. From the marker shift and Darken's relation, intrinsic diffusion coefficients, D_Zn and D_Cu, in the alloys containing 3.2 and 4.7 at. pct of Zn have been determined. Further, using thin plate couples, D_Zn and D_Cu in Cu alloys containing 0.9, 2.3, 3.5, and 4.6 at. pct of Zn at 1168 K have been determined by Heumann's method. The ratio of the intrinsic diffusion coefficients, D_Zn/D_Cu, has been found to be about two for all the compositions examined. Using the values of the intrinsic diffusion coefficient of copper at infinite dilution of zinc obtained by extrapolating the concentration dependence of D_Cu, and the self- and impurity diffusion coefficients in pure copper, the vacancy flow factor has been estimated to be - 0.22_-0.15 ^+0.06 at 1168 K. By combining this value of the vacancy flow factor with the solute enhancement factor of solvent diffusion determined by Peterson and Rothman, the correlation factor for impurity diffusion of Zn in Cu at 1168 K has been evaluated to be 0.5, which is in good agreement with the value of 0.47 determined by Peterson and Rothman based on the isotope effect measurement. KAZUTOMO HOSHINO, formerly Graduate Student, Tohoku University is now with Materials Science Division, Argonne National Laboratory, Argonne, IL 60439. YOSHIAKI IIJIMA, Instructor, and KENICHI HIRANO, Professor, are both with the Department of Materials Science, Faculty of Engineering, Tohoku University, Sendai 980, Japan.     

Ultra light-weight and high-resolution X-ray mirrors using DRIE and X-ray LIGA techniques for space X-ray telescopes

We are developing novel ultra light-weight and high-resolution X-ray micro pore optics for space X-ray telescopes. In our method, curvilinear micro pore structures are firstly fabricated by silicon deep reactive ion etching (DRIE) or X-ray LIGA processes. Secondly, side walls of the micro structures are smoothed by magnetic field assisted finishing and/or hydrogen annealing techniques for high reflectivity mirrors. Thirdly, to focus parallel X-ray lights from astronomical objects, these structures are elastically or plastically bent into a spherical shape. Fourthly, the bent structures are stacked to form a multi-stage X-ray telescope. In this paper, we report on fabrication and X-ray reflection tests of silicon and nickel X-ray mirrors using the DRIE and LIGA processes, respectively. For the first time, X-ray reflections were confirmed on both of the mirrors. Estimated rms roughnesses were 5 nm and 3 nm for the silicon and nickel mirrors, respectively.