A new approach to 3-D profilometry for the white light interferometric (WLI) is presented. The proposed method is the extended depth from focus (EDFF) that determine the zero optical path difference (OPD) from the quantity of fringe contrast degradation of white light interferometer. In the method, the variance of the mismatch function and the modified local variance function are used as the focus measures. The method has a theoretically unlimited range and can profile with subpixel accuracy both optically rough and smooth surfaces without changing algorithm.

A passive branched optical network unified for broadcasting and communication utilizing a set of Fabry-Perot etalons with different cavity lengths is proposed and its basic operation including thermal stability of broadcasting channel is demonstrated. It is confirmed that a high transmission frequency in common for a pair of fiber Fabry-Perot etalons is always found however environmental temperature changes.

We formalize a model of "demonstration of program result-correctness," and investigate how to prove this fact against possible adversaries, which naturally extends Blum's theory of program checking by adding zero-knowledge requirements. The zero-knowledge requirements are universal for yes and no instances alike.

The head tissue heterogeneity required in the spatial peak specific absorption rate (SAR) assessment for portable telephones was investigated by using the FDTD method in conjunction with an MRI-based human head model. The tissue heterogeneity of the head model was changed from one type of tissue to 17 types of tissue. The results showed that, at 900 MHz and 2 GHz, the homogeneous modeling results in an underestimate about 20% for the λ/2 monopole antenna portable telephones and an overestimate to the same extent for the λ/4 monopole or helical antenna portable telephones. A head model with a simple skin-fat-muscle-bone-brain structure seems to be sufficient to obtain a fairly accurate one-gram or ten-gram averaged spatial peak SAR value in computational dosimetry for portable telephone compliance.

We propose an adaptive complex-amplitude texture classifier that takes into consideration height as well as reflection statistics of interferometric synthetic aperture radar (SAR) images. The classifier utilizes the phase information to segment the images. The system consists of a two-stage preprocessor and a complex-valued SOFM. The preprocessor extracts a complex-valued feature vectors corresponding to height and reflectance statistics of blocks in the image. The following SOFM generates a set of templates (references) adaptively and classifies a block into one of the classes represented by the templates. Experiment demonstrates that the system segments an interferometric SAR image successfully into a lake, a mountain, and so on. The performance is better than that of a conventional system dealing only with the amplitude information.

In Synthetic Aperture Radar Interferometry (InSAR), phase unwrapping holds the key to accurate inversion of digital elevation data. Two new techniques are introduced in this paper that can perform automatic phase unwrapping. The first one is an "optimal" branch-cut algorithm and the second one a hybrid branch-cut/least-square technique, in which pole locations form the weighting basis for the weighted least-square approach. Application of both techniques to ERS-1 data indicates that the height inversion errors are comparable and offer over fifty percent reduction in root mean square (rms) height error compared to the straight least squares method and over thirty-five percent reduction in rms height error compared to the weighted least squares method based on coherence data weighting schemes. The hybrid technique is especially appealing due to its computational efficiency and robustness when compared to traditional branch-cut algorithms.

The aim of this study is to examine the effectiveness of various open-ended resonators. According to the required filter responses, the application to microwave filters based on presented open-ended resonators is systematically examined as well. First, the resonance property of the basic open-ended resonator is discussed based on even-and odd-mode analysis. The intrinsic property of a tapped open-ended resonator is also discussed here. Second, the basic properties of a stepped impedance resonator (SIR) and a loaded-element resonator are examined theoretically for improvement of spurious responses and the dual-passband response. The basic operations of these resonators are also explained based on even- and odd-mode analysis. Examples for filter applications based on presented resonators are also provided. We found that the intrinsic properties of the open-ended resonators are very useful for practical filter responses.

This paper investigates noise enhancement factors of a zero-forcing detector and a decision feedback detector for synchronous Multiple Input Multiple Output (MIMO) channels. It is first shown that the zero-forcing and decision feedback detectors can be implemented in a vector digital filter form, and the noise enhancement factors with the detectors can easily be calculated by using the vector digital filter form. This paper then applies the zero-forcing and decision feedback detectors to the signal detection of a frequency-overlapped multicarrier signaling (FOMS) system. The normalized noise enhancement factor, which is given as a product of the noise enhancement and bandwidth reduction factors, is shown to be smaller with the decision feedback detector than the zero-forcing detector. Results of computer simulations conducted to evaluate bit error rate (BER) performances with the two detectors are also shown together with the BER performance with a conventional channel-by-channel detector.

This paper describes an individual effect of soil moisture (mg) and surface roughness (hrms) of bare soil on the back scattering coefficient (σ0) at the X-band frequency. The study contributes to the design of an efficient microwave sensor. For this purpose, experimentally observed data was utilized to provide a composite σ0 equation model accounting for individual effect in regression analysis. The experimental data are compared with Small Perturbation Method. It is observed that the X-band gives better agreement up to incidence angle 50 for HH-polarization and 60 for VV-polarization as compared to the C-band. The lower angles of incidence give better results than the higher angles for observing mg at the X-band. The multiple and partial regression analyses have also carried out for predicting the dependence of scattering coefficient (σ0) on mg and hrms more accurately. The analyses suggest that the dependence of dielectric constant (i.e., mg) is much more significant in comparison to surface roughness at lower angles of incidence for both like polarizations. The results propose the suitable angle of incidence for observing bare surface roughness and soil moisture at the X-band. All these data can be used as a reference for satellite or spaceborne sensors.

The development of Radar Polarimetry and Radar Interferometry is advancing rapidly. Whereas with radar polarimetry, the textural fine-structure, target orientation, symmetries and material constituents can be recovered with considerable improvement above that of standard amplitude-only radar; with radar interferometry the spatial (in depth) structure can be explored. In Polarimetric Interferometric Synthetic Aperture Radar (POL-IN-SAR) Imaging, it is possible to recover such co-registered textural and spatial information from POL-IN-SAR digital image data sets simultaneously, including the extraction of Digital Elevation Maps (DEM) from either Polarimetric (scattering matrix) or Interferometric (single platform: dual antenna) SAR systems. Simultaneous Polarimetric-plus-Interferometric SAR offers the additional benefit of obtaining co-registered textural-plus-spatial three-dimensional POL-IN-DEM information, which when applied to Repeat-Pass Image-Overlay Interferometry provides differential background validation, stress assessment and environmental stress-change information with high accuracy. Then, by either designing Multiple Dual-Polarization Antenna POL-IN-SAR systems or by applying advanced POL-IN-SAR image compression techniques, it will result in POL-arimetric TOMO-graphic (Multi-Inter-ferometric) SAR or POL-TOMO-SAR Imaging. This is of direct relevance to local-to-global environmental background validation, stress assessment and stress-change monitoring of the terrestrial and planetary covers.

An airborne X- and L-band synthetic aperture radar system was developed by the Communications Research Laboratory and the National Space Development Agency of Japan in their joint project from 1993 to 1996. It is installed in the airplane, Gulfstream II. In both the azimuth and range directions, the resolution is 1.5 m for the X-band and 3 m for the L-band. Both SARs can make fully polarimetric observations. The X-band SAR has a cross-track interferometric function. In this paper we describe the SAR system, its ground processing system, and its performance. We also discuss motion compensation and interferogram quality.

This paper newly proposes radio-over-fiber systems using cascaded radio-to-optic direct conversion (ROC) scheme. The ROC system can convert a radio signal into an optical signal with the same signal format. The received carrier-to-noise ratio (CNR) performance of the radio-over-fiber systems using the ROC/heterodyne detection (HD) scheme and the ROC/self-heterodyne detection (SHD) scheme are theoretically analyzed. The optimization of an optical modulation index (OMI) in each radio base station (RBS) is also presented. By using the proposed OMI optimization method, the ROC/HD and the ROC/SHD schemes are shown to provide approximately 16 dB and 14 dB improvement over the intensity modulation/direct detection scheme when the number of RBS is 20 and the radio-frequency (RF) signal bandwidth is 150 MHz, respectively. The ROC/SHD scheme enables a receiver structure to become simple while still achieving high received CNR.

The contribution of the paper is two-fold: Firstly, a review of the point set registration literature is given, and secondly, a novel covariance weighted least squares formulation of the multiple view point set registration problem is presented. Point data for surface registration is commonly obtained by non-contact, 3D surface sensors such as scanning laser range finders or structured light systems. Our formulation allows the specification of anisotropic and heteroscedastic (point dependent) 3D noise distributions for each measured point. In contrast, previous algorithms have generally assumed an isotropic sensor noise model, which cannot accurately describe the sensor noise characteristics. For cases where the point measurements are heteroscedastically and anisotropically distributed, registration results obtained with the proposed method show improved accuracy over those produced by an unweighted least squares formulation. Results are presented for both synthetic and real data sets to demonstrate the accuracy and effectiveness of the proposed technique.

Short-circuit photocurrents (ISC) utilizing surface plasmon polariton (SPP) excitation were investigated for the merocyanine (MC) LB film photoelectric device. The device has a prism/MgF2/Al/MC LB film/Ag structure. In the attenuated total reflection (ATR) configuration, SPPs were resonantly excited at the interfaces between MgF2 and Al (MgF2/Al) and between Ag and air (Ag/air). The thickness and the dielectric constants of the layers were evaluated from the ATR measurements. Short-circuit photocurrents, ISCs, as a function of the incident angle of the laser beam were observed simultaneously during the ATR measurements. In the ISC curves, large and small peaks were observed, and the peak angles of the ISC almost corresponded to the dip angles of the ATR curves due to the SPP excitations. Electric fields and optical absorptions in the cell were calculated using the dielectric constants and the film thickness obtained from the ATR measurements. The calculated absorption in the MC layer as a function of the incident angle corresponded to the ISC curve. It was thought that the optical absorption in the MC layer affected directly to the profile of the ISC. Furthermore, the calculated absorption in the cell with the prism and the MgF2 layer exhibited much larger than that of the cell without them. It was estimated that the photocurrents were enhanced by the excitation of SPPs in the ATR configuration.

This paper describes a highly performance scalable video coder. Wavelet transform is employed to decompose the video frame into different resolutions. Novel features of this coder are 1) a highly efficient multi-resolution motion estimation that requires minimum compuation and overhead motion information is embedded in this scheme; 2) the wavelet coefficients are organized in an extended zero tree (EZT) which is much more efficient than the simple zerotree. We show with experimental results that this video coder achieves good performances both in processing time and compression ratio when applied to typical test video sequences.

The Mobile Agent technology helps in the development of applications in open, distributed and heterogeneous environments such as the Internet and the Web, but it has to answer to the requirements of security and interoperability to achieve wide acceptance. The paper focuses on security and interoperability, and describes a Secure and Open Mobile Agent (SOMA) programming environment where both requirements are main design objectives. On the one hand, SOMA is based on a thorough security model and provides a wide range of mechanisms and tools to build and enforce flexible security policies. On the other hand, the SOMA framework permits to interoperate with different application components designed with different programming styles. SOMA grants interoperability by closely considering compliance with the OMG CORBA and MASIF standards. SOMA has already shown the feasibility and effectiveness of the approach for the development of flexible and adaptive applications in several areas, particularly in network and systems management.

Dislocation properties in InGaN/GaN Quantum Wells and GaN grown on bulk GaN and sapphire substrates by metalorganic chemical vapor deposition (MOCVD) were characterized using cathodoluminescnece (CL), transmission electron microscopy (TEM), atomic force microscopy (AFM) and photoluminescence (PL). It was clearly demonstrated that dislocations act as nonradiative recombination centers in both n-type (undoped and Si-doped) GaN and InGaN layers. Furthermore the very short-minority carrier diffusion length was a key parameter to explain the high light emission efficiency in GaN-based light emitting diodes (LEDs) prepared on sapphire substrates. On the other side band-tail states were detected in the heteroepitaxial InGaN layers only by temperature dependence PL measurement. Additionally InGaN phase separation, which consists of few micron domains, has been produced under growth conditions which favors the spiral growth. These results indicate that the dislocations in the InGaN layers act as triggering centers for the InGaN phase separation which cause both a compositional fluctuation and the formation of few micron phase separated domains. The homoepitaxial InGaN layers showed however quite normal behaviors for all characterizations.

A new manufacturing process for advanced Fiber Bragg Gratings which uses phase plates is described. Its high versatility allows to achieve many type of filters in optical fibers (phase-shifted, apodised, Fabry-Perot).

For measuring high frequency ultrasonic fields which are often spatially distributed and transient, an array probe with small element sensors is highly required. In this paper, we propose a fiber-optic micro-probe array which is based on wavelength-division-multiplexing technique. The element sensor consists of a micro optical cavity of 100 µm long made at the end of optical fiber. Optical path length of the cavity is changed by the applied acoustic field, and the modulation of output light intensity is monitored at another end of the fiber for the information of the acoustic field. Array of sensor elements and a light source as well as a photo detector are connected together by an optical star coupler. The Fabry-Perot resonance wavelength of each sensor element is designed different one another, and the outputs from the sensors are discriminated by sweeping the wavelength of light source with the use of a tunable semiconductor laser. In this paper, the performance of the micro-probe array is discussed experimentally.

This paper reports the performance of an AC-voltage sensor with a LiNbO3 integrated retroreflective structure based on the Y-junction Mach-Zehnder interferometer. This structure is capable of realizing a low-cost sensor chip because of the small chip size and single optical-fiber connection. In the sensitivity and frequency response evaluation, detection sensitivities of 6.3 µ V / Hz have been measured with a frequency response from 6 Hz to 2 GHz. These measurement limitations were also analyzed theoretically and compared with the experimental results. This unique sensor enables precise voltage measurement in an EMI environment, even inside a computer.