Recently, flexible and lightweight optical devices are desired from the practical viewpoint. We demonstrated roll-to-roll type Anti Reflection (AR) film fabricated by layer-by-layer (LBL) adsorption process. When deposition time was 2.5 min and repeating cycle was 8 cycles, refractive index of LBL layer was 1.499 at 632 nm and thickness was 93.1 nm, which are almost the same as those of batch type LBL layer. The minimum reflectance was about 0.6% at 600 nm and transmittance was over 75% at visible region. However as compared with batch type, roll type AR film has lower reflectance and transmittance. This reason is that the flow of solution and rinse and quantity of rinse was smaller, a number of bathes of roll type was lower than that of batch type. Furthermore, comparing the deposition time and film speed, LBL layer was fabricated clearly long deposition time and slow film speed. The roll-to-roll film had a problem of peeling off during the deposition process. By increasing the contact area between film and guided roll, vertical pressure was decrease and friction force was decreased. Furthermore, as rotational speed of guided roll and film speed was decreased, LBL layer was not peeled by friction force between film and guided roll. Because rotational speed of guided rolls and films were almost same in the range of less than about 30 mm/min. There was the problem that polymer complexes were likely to appear on the substrate when the surface was dried during moving between solution and rinse bath. This phenomenon was observed during the roll-to-roll as well as batch process. The quality of roll-to-roll LBL process was depending on deposition time and film speed and drying at moving process critically compared with batch type. It is necessary to design the roll-to-roll machine with care: important points are deposition time and film speed, drying at moving process.

A double surface light emission backlight that uses single light-guide plate, has been developed for illumination of two liquid-crystal displays (LCD) on its front and rear, to be used in a cellular phone. The light-guide plate has a trapezoid cross-section with arrays of optical micro deflector and micro prism on the front and the rear surfaces, respectively. Propagated light, forward and backward, inside the light-guide plate are controlled and directed toward LCDs using only two prism sheets with internal reflection characteristic, each for the front and the rear. Only three optical components and four light-emitting diodes (LEDs) are used in the new structure compared with ten components and six LEDs of the current type. Comparing with the current type, the thickness and power consumption of the new backlight are reduced by a factor of 0.59 and 0.67, respectively.

This letter develops a practical sectorized antenna array using center-fed half-wavelength dipole antennas that are parallel to and a distance in front of a large ground plane reflector. Each element in the array is designed to provide coverage to isolate each 120sector from adjacent sectors. We derive a closed-form expression for spatial correlation function that can be used as guides in evaluating the effects of array spatial correlation on diversity performance in sectorized cellular communications.

This paper is concerned with the application of ray tracing method (RTM) to field analysis in bended and branched tunnels. On the line of sight, direct wave from a source and reflected waves at the tunnel walls are dominant compared with diffracted waves, but off the line of sight, diffraction can not be ignored especially beyond an abrupt bending. As a result, a detailed attention should be focused on the RTM analysis when dealing with propagation in the region off the line of sight. In this paper, we take into account of the diffraction rays which are originally reflection rays, next diffracted at a bending edge, and again converted to reflection rays. It is shown that numerical results are in good agreement with the experimental data.

Recently, dielectric lens antennas are paid attentions in ITS applications. Many lens shape designing methods were already developed. And electrical performances were estimated through a ray tracing method. Here, arbitral lens shapes were expressed by a system of power series. In the case of ray tracing, time-consuming three-coordinate root-finder programs were needed to find intersection points of rays on the lens surfaces. In order to calculate complicated structures such as zoned lenses and complicated rays such as multiple reflections between lens surfaces, simple ray tracing methods are requested. In this paper, a simple ray tracing method that utilizes directly designed discrete points of lens surfaces is developed. In this method, a refracted ray is automatically determined for a given incident ray. As for an intersecting point of a lens surface for an outgoing ray, the nearest point to the refracted vector is found out by employing a simple searching procedure. This method is time-saving compared to the previous three-coordinate root-finding program. Through calculated results of focal points and radiation patterns in wide angle beam steering, effectiveness of a developed method is ensured. Application of the developed ray tracing method of complicated multiple reflections are studied. Reflecting points are found out speedily by the same searching procedure. A calculated example of doubly reflected rays is obtained. Through comparing calculated and measured results of wide angle radiation patterns, effectiveness of a developed method is ensured.

Inside a connector an interface with low insertion force and contact resistance is required, utilizing low cost materials such as copper alloys surrounded by tin coating. Relating to the application, the operating parameters have a wide range of values of currents, forces and materials. In this paper, we present a new experimental method based on non-intrusive probing of the deflection of the spring terminal with a laser technique. The main feature is that the reflection of the Laser beam onto the spring allows the determination of the contact force of the lamella-spring inside the female part. The technique requires the following insertion parameters during the insertion stroke: contact deflection δ, which allows contact force Fc, insertion force Fi and contact resistance Rc. It was found that the insertion force has a maximum value which decreases to the stable value, and depends on the size and the material of the pin. However contact resistance decreases sharply when first inserting, and tends to stable values on completing the insertion process, which is less sensitive to the pin diameter. Furthermore the final value which is important for the connector characterization is related and discussed. Finally, discrepancies were observed between the experimental and calculated data with simple numerical models. More complex models are in progress, which should improve the convergence of the theoretical approach to experimental results and proceed to the optimization of the connector parameters.

Iris recognition is used to identify a user based on the iris texture information which exists between the white sclera and the black pupil. For fast iris recognition, it is very important to capture user's focused eye image at fast speed. If not, the total recognition time is increased and it makes the user feel much inconvenience. In previous researches and systems, they use the focusing method which has been used for general landscape scene without considering the characteristics of iris image. So, they take much focusing time sometimes, especially in case of the user with glasses. To overcome such problems, we propose a new iris image acquisition method to capture user's focused eye image at very fast speed based on the corneal specular reflection. Experimental results show that the focusing time for both the users with glasses and without glasses is average 480 ms and we can conclude our method can be used for the real-time iris recognition camera.

Packet loss is a serious problem due to the shortage of optical buffers in all-optical packet switched networks. In order to reduce packet losses, a dynamic routing method called 'deflection routing' has been proposed. Deflection routing, however, requires an optical switch to modify routing tables and packet labels for overflowing packets, so this routing method may also lead to other implementation problems in packet routing and forwarding. This paper proposes a simple routing method called 'reflection routing' which utilizes optical transport links as optical buffers to improve the quality of service in optical packet switched networks in terms of packet loss ratio. We numerically demonstrate the effectiveness and applicability of reflection routing.

In this letter, we show that a key agreement and password authentication protocol proposed by Kwon and Song is potentially vulnerable to a reflection attack, and then suggest simple improvements.

In a two-microphone approach, interchannel differences in time (ICTD) and interchannel differences in sound level (ICLD) have generally been used for sound source localization. But those cues are not effective for vertical localization in the median plane (direct front). For that purpose, spectral cues based on features of head-related transfer functions (HRTF) have been investigated, but they are not robust enough against signal variations and environmental noise. In this paper, we use a "profile" as a cue while using a combination of reflectors specially designed for vertical localization. The observed sound is converted into a profile containing information about reflections as well as ICTD and ICLD data. The observed profile is decomposed into signal and noise by using template profiles associated with sound source locations. The template minimizing the residual of the decomposition gives the estimated sound source location. Experiments show this method can correctly provide a rough estimate of the vertical location even in a noisy environment.

A novel method for measuring microwave reflection coefficients without the open and load standards is proposed. In this method, a single probe is inserted into an air line and the output wave is detected by a vector detector. Offset shorts are used for the calibration. The measurement system is constructed using 7 mm coaxial line and APC7 connectors. The result of the measurement in the frequency range 1-9 GHz shows the possibility of the proposed method. All the major systematic errors can be estimated from the data that is easily obtainable.

Low-loss optical coupling structures between photonic crystal waveguides and channel waveguides were investigated. It was emphasized that impedance matching of guided modes of those waveguides, as well as field-profile matching, was essential to achieving the low-loss optical coupling. We developed an impedance matching theory for Bloch waves, and applied it to designing the low-loss optical coupling structures. It was demonstrated that the optical coupling loss between a photonic crystal waveguide and a Si-channel waveguide was reduced to as low as 0.7 dB by introducing an interface structure for impedance matching between the two waveguides.

Development of non-invasive techniques to measure blood sugar level is strongly required. The application of millimeter waves has a great potentiality to realize the measuring technique. Nevertheless, the practical method of the technique is not yet reported. In this paper, a new technique is proposed to measure blood sugar level using millimeter waves. The technique proposed here is very rapid and safety way to obtain blood sugar level.

A C-Ku band 5-bit MMIC phase shifter using optimized reflective series/parallel LC circuits is presented. The proposed circuit has frequency independent characteristics in the case of 180 phase shift, ideally. Also, an ultra-broad-band circuit design theory for the 180 optimized reflective circuit has derived, which gives optimum characteristics compromising between loss and phase shift error. The fabricated 5-bit MMIC phase shifter with SPDT switch has successfully demonstrated a typical insertion loss of 9.4 dB 1.4 dB, and a maximum RMS phase shift error of 7 over the 6 to 18 GHz band. The measured results validate the proposed design theory of the phase shifter.

We propose an analysis method for Franz-Keldysh (FK) oscillations appearing in photoreflectance (PR) spectra of heterojunction device structures, which enables precise and simultaneous evaluation of the built-in electric field strength and band-gap energy. Samples for PR measurements were n+-GaAs/n-Al0.3 Ga0.7 As/i-GaAs heterostructures with different Al0.3Ga0.7As-layer thickness. We have found that the phase of the FK oscillations originating from the i-GaAs buffer layer depends on the Al0.3 Ga0.7 As-layer thickness. We have derived a calculation model for FK oscillations that includes the interference of probe light. From the comparison of the calculated spectra with the measured spectra, we conclude that mixing of the real and imaginary parts of a modulated dielectric function, which is caused by the probe-light interference, gives rise to the phase shift of the FK oscillations. Our FK-oscillation analysis method reduces ambiguity in the estimation of band-gap energy that is considerable in a conventional analysis.

The present paper deals with the frequency-dependent finite difference time domain ((FD)2TD) method analysis of the light-beam diffraction from a land/groove recording phase-change (PC) disk model with a metal (Al or Au) reflective layer in order to improve the conventional analysis for PC optical disk models with a perfectly conducting reflective layer. The diffracted fields are numerically calculated for both recorded and non-recorded states of the recording layer, and the comparison of the detected signal characteristics between two states is discussed. The crosstalk between the recording marks on lands and grooves are evaluated and the optimum groove depth is examined for Al,Au and perfectly conducting layer models.

Optical Burst Switching (OBS) is one of the most important switching technologies in future optical Internet. One of critical design issues in OBS is how to reduce burst dropping resulting from resource contention. Especially when traffic load is high, there should be frequent deflection routing as well as more contentions in an optical burst-switched network. The burst loss performance can be improved by implementing a proper deflection routing scheme. In this paper, we propose a limited deflection routing scheme to prevent injudicious deflection routing. The proposed scheme reduces unnecessary contentions resulting from deflection routing itself, increasing the utilization of network resource such as channels. Simulation tests were performed to evaluate the performance of the proposed scheme.

We demonstrate a mode-locked fiber laser (MLFL) method for measuring the chromatic dispersion of long transmission fiber. In this method, device under test (DUT) is inserted in the laser cavity, and the chromatic dispersion is measured by the shift of mode-locking frequency when the lasing wavelength is changed. The experimental results of the MLFL method for a 5km-long single-mode fiber had good agreement with the conventional phase-shift method.

A blind source separation problem in a solicitations context is addressed. The mixture stems from several telecommunication signals, the symbol periods of which are unknown and possibly different. Cost functions are introduced, the optimization of which achieves the equalization for a user, i.e. estimation of the symbol period and the associated sequence of symbols. The method is iterated by implementing a deflation. The theoretical results are validated by simulations.

The paper overviews and surveys Japan's reflector antennas for earth stations and radio telescopes since the 1960's. Some interferometers for radio astronomy are included. Japanese original technologies regarding reflector antenna design and measurement are also described. There are 35 figures and 3 tables.