Output Edge Research Articles

Research on Mean Filtering Algorithm in Resonant Micro-Optic Gyro Signal Processing Based on Labview

As one of the new optical sensing devices, Resonant Micro-optic Gyro (RMOG) measures the rotation rate due to the resonance frequency difference based on the optical Sagnac effect. In order to reduce the influence of the light path and circuit noise and the output edge pulse signal, the mean filtering algorithm based on Labview is put forward to improve the gyros performance. The mean filtering algorithm is simulated and realized with Labview, which approves that the algorithm is effective in noise restraining. The test of RMOG demonstrates that the zero bias stability is 1.4 °/s during 1 hour with 10-second smoothing.

Ambrosio-Tortorelli Segmentation of Stochastic Images: Model Extensions, Theoretical Investigations and Numerical Methods

We discuss an extension of the Ambrosio-Tortorelli approximation of the Mumford-Shah functional for the segmentation of images with uncertain gray values resulting from measurement errors and noise. Our approach yields a reliable precision estimate for the segmentation result, and it allows us to quantify the robustness of edges in noisy images and under gray value uncertainty. We develop an ansatz space for such images by identifying gray values with random variables. The use of these stochastic images in the minimization of energies of Ambrosio-Tortorelli type leads to stochastic partial differential equations for a stochastic smoothed version of the original image and a stochastic phase field for the edge set. For the discretization of these equations we utilize the generalized polynomial chaos expansion and the generalized spectral decomposition (GSD) method. In contrast to the simple classical sampling technique, this approach allows for an efficient determination of the stochastic properties of the output image and edge set by computations on an optimally small set of random variables. Also, we use an adaptive grid approach for the spatial dimensions to further improve the performance, and we extend an edge linking method for the classical Ambrosio-Tortorelli model for use with our stochastic model. The performance of the method is demonstrated on artificial data and a data set from a digital camera as well as real medical ultrasound data. A comparison of the intrusive GSD discretization with a stochastic collocation and a Monte Carlo sampling is shown.

A Radiation-Tolerant Superfluorescent Fiber Source in Double-Pass Backward Configuration by Using Reflectivity-Tuning Method

A novel feedback control method by tuning reflectivity was demonstrated for stabilizing mean-wavelength of a double-pass backward (DPB) superfluorescent fiber source (SFS) under 60Co irradiation. The mean-wavelength drift was compensated with increasing dose up to 22 krad, suitable for the applications in the low Earth orbit. The rate of output power loss induced by irradiation could be decreased by 33% when the feedback control was working. The linewidth of the DPB SFS was 16 nm, 1.6 times larger than the reported one by adding an output edge filter. With such a larger linewidth the angle random walk (ARW) of an IFOG can be more reduced.

A New Method for Edge Detection Based on the Criterion of Separability

This paper presents a new edge detection algorithm based on calculating the difference value of two clusters. An edge is defined as a boundary that separates two adjacent regions that are relatively homogenous. For each image pixel, a window is first defined by placing the pixel at the center, and this window is partitioned into two sub- regions respectively in four different directions. An appropriate function is then selected to estimate the difference between each pair of two adjacent regions and to calculate edge information in terms of edge stre ngth and direction by maximizing the difference value. Finally, the non-maxima suppression is adopted to derive the output edge map. Experiments on a variety of noise contaminated images show that the new algorithm is more robust under noisy conditions. In addition, the proposed algorithm can also be applied to color or multi-spectral images.

Interleukin-2-inducible T Cell Kinase (Itk) Network Edge Dependence for the Maturation of iNKT Cell

Invariant natural killer T (iNKT) cells are a unique subset of innate T lymphocytes that are selected by CD1d. They have diverse immune regulatory functions via the rapid production of interferon-γ (IFN-γ) and interleukin-4 (IL-4). In the absence of signaling nodes Itk and Txk, Tec family non-receptor tyrosine kinases, mice exhibit a significant block in iNKT cell development. We now show here that although the Itk node is required for iNKT cell maturation, the kinase domain edge of Itk is not required for continued maturation iNKT cells in the thymus compared with Itk-null mice. This rescue is dependent on the expression of the Txk node. Furthermore, this kinase domain independent edge rescue correlates with the increased expression of the transcription factors T-bet, the IL-2/IL-15 receptor β chain CD122, and suppression of eomesodermin expression. By contrast, α-galactosyl ceramide induced cytokine secretion is dependent on the kinase domain edge of Itk. These findings indicate that the Itk node uses a kinase domain independent edge, a scaffolding function, in the signaling pathway leading to the maturation of iNKT cells. Furthermore, the findings indicate that phosphorylation of substrates by the Itk node is only partially required for maturation of iNKT cells, while functional activation of iNKT cells is dependent on the kinase domain/activity edge of Itk.

LEDs based on InAs/InAsSb heterostructures for CO2 spectroscopy (λ = 4.3 μm)

Light-emitting diodes (LEDs) operating in a 4.1–4.3 μm wavelength range have been created on the basis of InAs/InAsSb heterostructures grown by metalorganic vapor-phase epitaxy. The output radiation power of LEDs is increased using flip-chip design. Investigation of the electrolumuinescent properties of LEDs with smooth and profiled output edge surface showed that the latter LEDs possess a greater efficiency, which is related to an increase in the radiation yield due to multiply repeated reflection from the curved surface. The output power of LED operating in a quasi-continuous wave mode was 30 μW at a current of 200 mA and that in a pulse mode was 0.6 mW at a current pulse amplitude of 2 A.

Boolean Derivatives With Application to Edge Detection for Imaging Systems

This paper introduces a new concept of Boolean derivatives as a fusion of partial derivatives of Boolean functions (PDBFs). Three efficient algorithms for the calculation of PDBFs are presented. It is shown that Boolean function derivatives are useful for the application of identifying the location of edge pixels in binary images. The same concept is extended to the development of a new edge detection algorithm for grayscale images, which yields competitive results, compared with those of traditional methods. Furthermore, a new measure is introduced to automatically determine the parameter values used in the thresholding portion of the binarization procedure. Through computer simulations, demonstrations of Boolean derivatives and the effectiveness of the presented edge detection algorithm, compared with traditional edge detection algorithms, are shown using several synthetic and natural test images. In order to make quantitative comparisons, two quantitative measures are used: one based on the recovery of the original image from the output edge map and the Pratt's figure of merit.

New Measuring Method of Examination of Planar Optical Waveguides

A new method of mode spectrum measurement in planar waveguides is presented. The described end-flre mode spectroscopy technique exploits the difierence of refraction angles of difierent modes skew-incident to the output face of the waveguide. This method provide re- liable measurements of the whole mode spectra in any planar waveguides including step-index waveguides with thick cover layers and deep-buried graded-index waveguide structures. Further- more, the technique allows conducting direct measurements of the maximal refractive index in arbitrary graded-index waveguides as well. Results of the comparative experiments performed by the end-flre mode spectroscopy and other techniques prove a feasibility of the developed method. Parameters of the optical waveguide (WG) deflne the operating performances of the whole photonic device. In order to optimize these parameters, appropriate technology conditions should be chosen. Necessary works include preliminary computer simulation of the process, fabrication of trial samples and their examination. Important part of examination of a planar optical WG is measurement of the WG mode spec- trum. Usually this procedure is performed by well-known m-line spectroscopy technique (e.g., see (1,2)). However, in cases of planar WG structures with thick cover layers or so-called buried graded-index WGs this method does not provide reliable measurements. Thick cover layers or large burying depths do not allow tunneling the modes to the external prism and forming the correspond- ing spatial m-lines. In these cases, some modes (flrst of all, the lower-order modes) may be simply missed in examinations by m-line spectroscopy (3,4). The greater the burying depth the fewer number of modes can be measured by this method. To avoid missing the modes, a layer-by-layer etching of the sample surface could be applied (5,6). However, this procedure have many chances to cut a part of the refractive index proflle occupied by the mode flelds, and that should lead to distortion of the original WG mode spectrum. The use of nonlinear optical efiects like second har- monic generation (4) can be successful only for limited number of optical materials demonstrating high values of the corresponding coe-cients. The paper presents a developed measuring technique named the end-flre mode spectroscopy which provides reliable measurement of the whole mode spectrum (7). This method is suitable for examination of planar WGs having arbitrary refractive index proflles including the case of buried WG structures with any burying depths. Furthermore, here is shown that this technique allows also conducting direct measurements of another important characteristic | the maximal refractive index in graded-index WGs, unlike conventional techniques that involve the set of measured mode indices and employ computing of the maximal value in the refractive index proflle using difierent approximations. 2. METHOD CONTENT The end-flre mode spectroscopy technique of mode index measurement is based on the registration of light beams radiated from the abrupt output edge of a planar WG, with each beam corresponding to the individual mode. Due to the difierent values of mode propagation constants, modes of difierent orders demonstrate difierent refraction angles at the output face of WG if they are directed to this face under the same inclination angle. It is this feature that is exploited by the technique. Both excitation and output of WG modes are performed at WG faces by the end-flre coupling method. This coupling method allows reliable launching and output of the whole mode spectrum in any planar WG. Therefore, the proposed technique can be applied to the analysis of mode spectra of arbitrary planar WGs, including ones with symmetric step-index proflles and deep-buried graded- index WGs.

Decreasing the total divergence of polycapillary X-ray microbeams

The divergence characteristics of intense quasi-parallel X-ray microbeams have been studied at the output of the “microfocus X-ray generator-cylindrical polycapillary structure” system by scanning the beam with a knife edge. It us established that the total microbeam divergence decreases in the region near the output edge of the polycapillary structure (divergence quasi-decrease effect).

Directivity enhancement and deflection of the beam emitted from a photonic crystal waveguide via defect coupling

We experimentally and numerically investigate the spatial distribution of the emission from a photonic crystal waveguide, coupled with defects, that are located at the output edge. Two defects that are located symmetrically enhance the directivity of the beam compared to that of a plain waveguide, as was reported in recently conducted theoretical work. We further demonstrate that a single defect deflects of the beam. By choosing the defect resonance that is close to the edge of the pass band of the waveguide, where the group velocity of the beam within the waveguide is slow, a significant amount of deflection can be achieved.

Robust edge detection

Edge detection is an important issue in computer vision and image understanding systems. Most conventional techniques have assumed Gaussian noise, and their performance could decrease with the departure of noise distribution from normality. In this paper, we present an edge detection approach using robust statistics. The edge structure is first detected by a robust one-way design model, and then localized by a robust contrast test. Finally, hysteresis thresholding is applied to yield the output edge map. To evaluate its performance, experiments were carried out on synthetic and real images corrupted with both Gaussian noise and a mixture of Gaussian and impulsive noise. The results show that the performance of the proposed edge detector is stable and reliable under severe impulsive noise conditions.

Experimental verification of guided modes in 60°-bent defect waveguides in AlGaAs-based air-bridge-type two-dimensional photonic crystal slabs

Sixty-degree-bent defect waveguides (DWGs) in an AlGaAs-based air-bridge-type two-dimensional photonic crystal (2D PC) slab were fabricated, and the resulting optical transmission spectra and the plan-view image of the optical beam propagating along the bent DWG were measured in the wavelength range between 850 and 1100 nm. Using the two output ports of the stripe waveguides, one aligned to and another offset from the output edge of the bent DWG, the guided mode specific to the DWG and the slab mode in the defect-free PC slab were experimentally observed with the same sample. These results were verified using the calculated band structure and transmission spectra.

Augmented APP (A2P2) module for a posteriori probability calculation and channel parameter tracking

The augmented a posteriori probability (APP) module, denoted by A/sup 2/P/sup 2/, comprises two mutually supporting algorithms: (1) a soft-input soft-output (SISO) APP module, adjusted to output edge metric information and (2) a recursive estimator for the channel parameters that benefits from this information at each step of the recursion. The thus-estimated parameters appropriately transform, in turn, the channel output signals that feed the SISO module. When applied to decoding a parallel concatenated convolutional code (PCCC) transmitted by binary phase-shift keying through a channel with frequency offset (0.08/T/sub s/ Hz) and phase jitter (0.23-rad RMS), concentrated at 0.01/T/sub s/ Hz, (T/sub s/-symbol duration), the degradation compared to fully coherent reception is a small fraction of 1 dB, without use of a preamble.

The delay vernier pattern generation technique

The authors describe a new technique for generating an arbitrary digital data stream with very fine timing resolution. Note that this timing resolution specifies the output edge placement precision, not the bit rate. The resolution is determined by the difference between two propagation delays rather than by an absolute delay. Because this difference can be made very small, the circuit, called the delay vernier generator, can achieve unprecedented timing resolution in a particular circuit technology. Also, this very precise timing is obtained without requiring an extremely high speed clock. The generator architecture includes delay-locked loop calibration mechanisms to compensate for process and temperature variations. A prototype chip was fabricated in a 1.2-/spl mu/m CMOS technology, and measurements confirmed that resolutions as fine as 100 ps can be achieved reliably.

Baseband integrated acousto-optic frequency shifter/modulator module for fiber optic at 1.3 mu m

A baseband integrated acoustooptic (AO) frequency shifter/modulator module that consists of a pair of titanium-indiffused proton-exchanged (TIPE) waveguide lenses and a pair of cascaded guided-wave AO Bragg cells has been realized in a Y-cut LiNbO(3) waveguide substrate 0.1 cmx1.0 cmx2.0 cm in size. A device module operating at the optical wavelength of 1.3 mum has provided a -3-dB tunable bandwidth of 120 MHz at baseband. The frequency-shifted or -modulated light propagates in a fixed direction, irrespective of the magnitude of frequency shift or modulation, and is focused into a spot (FWHM) of 6.2-mum size on the output edge of the waveguide. Accordingly, this optical frequency shifter/module can be directly interfaced with single-mode optical fibers to facilitate applications in fiber optic systems.

Fluorescent planar concentrators

Fluorescent planar concentrators have been discussed in the literature for about five years. The advantages of the system are the ability to concentrate both direct and diffuse light, and variability in transparency which offers the possibility of a manifold of hybrid applications. The best total efficiency measured for electrical conversion with a stack of two plates is 4%, the highest energy concentration factor at the output edge was ten. In addition the latest results for thermal conversion are given. The highest stagnation temperatures up to now are in the range of 550°C. Theoretical calculations of the limitations on the concentration factor are presented. The lifetime of the total system could be improved, so the first commercial applications are now being planned.

A wide-angle scanning optical antenna

The design of a modified Rinehart metal dome antenna with a dielectric ring lens at the output edge is discussed. This antenna provides wide-angle scanning of a narrow beam. The dome shape, which provides perfect focus in the plane of scan, is determined by solving an integral equation. The dielectric lens focuses in the plane perpendicular to the plane scan, and results in a much smaller antenna than if an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</tex> -plane horn were fitted to a conventional Rinehart dome. A design procedure for minimizing phase errors and mismatch losses is discussed. The construction of an experimental model which provides a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.7\deg</tex> by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10.7\deg</tex> beam at 40 GHz is described. Pattern and gain data for the 26.5 to 40 GHz band are included and show excellent performance.