Results 1 - 10 of 12480
Results 1 - 10 of 12480. Search took: 0.035 seconds
|Sort by: date | relevance|
[en] This patent describes an apparatus including a radiation source which emits in a multiplicity of directions for focusing radiation on an object which may receive radiation within a certain solid angle. It comprises a first reflector and a second reflector, the first reflector being elliptical in cross section and having a first focus and a second focus, the second reflector being circular in cross section and having a center, and a radius equal to the distance between the second reflector and the first focus, the first reflector and the second reflector being arranged so that a concave reflecting surface of the first reflector faces a concave reflecting surface of the second reflector, and so arranged that the first focus of the first reflector corresponds to the center of the second reflector, the radiation source being an elongated discharge bulb, the object being a group of two or more optical fibers defining at least one line of optical fibers which are located at the second focus of the first reflector
[en] The characteristics and possible applications of scalpels based on diode and fibre lasers emitting at 0.97, 1.06, 1.56, and 1.9 μm, which are produced and developed by the IRE-Polyus Co., are presented. The advantages of such devices and the possibilities for increasing their output power and extending their spectral range are shown. (laser biology and medicine)
[en] In this work, the relation between 2D- and 3D-strain based piezoresistive gauge factors for carbon fiber filament in plane stress states is developed theoretically. For measuring the gauge factors, carbon fiber filaments are attached to the base specimen surface at different angles. Their resistance response to multidimensional strain field is investigated by four-point bending tests. Piezoresistive models of carbon fiber filament in plane stress states are created using the test results. In the test setup, carbon fiber filaments are placed both on the tension side and the compression side. Both the models show that the piezoresistive response of carbon fiber filament is dominated by the longitudinal strain. Based on the inequality in the sensitivities to tensile strain and compressive strain, the piezoresistive models are modified further. The modified piezoresistive models reveal the following 3D-strain based gauge factors: 1.82 for longitudinal tensile strain, 1.64 for longitudinal compressive strain, 0.10 for transverse tensile strain, and −0.25 for transverse compressive strain. The 2D-strain based gauge factors depend not only on the polarity of the longitudinal strain and transverse strain, but also on the polarity of the strain in the thickness direction. The piezoresistive models are verified experimentally. (paper)
[en] A theoretical method to obtain the propagation and coupling characteristics of channel optical waveguides is presented. The waveguides show graded-index profiles in both transverse directions. Commonly, they are fabricated by metal diffusion on LiNbO3. The method models the waveguide, in the vertical direction, by means a multilayer structure. We combine the effective index method with the WKB method to solve the whole waveguide. Propagation constants for isolated waveguides and results of coupling parameters for directional couplers are presented. (Author) 12 refs
[en] Applications of smart sensors have been extended to safety systems in the aerospace, transportation and civil engineering fields. In particular, structural health monitoring techniques using smart sensors have gradually become necessary and have been developed to prevent dangers to human life and damage to assets. Generally, smart sensors are based on electro-magnets and have several weaknesses, including electro-magnetic interference and distortion. Therefore, fiber optic sensors are an outstanding alternative to overcome the weaknesses of electro-magnetic sensors. However, they require expensive devices and complex systems. This paper proposes a new, affordable and simple sensor system that uses a single fiber to monitor pressures at multiple-points. Moreover, a prototype of the sensor system was manufactured and tested for a feasibility study. Based on the results of this experimental test, a relationship was carefully observed between the bend loss conditions and light-intensity. As a result, it was shown that impacts at multiple-points could be monitored.
[en] At present existence OTDR based techniques have become a standard practice for measuring chromatic dispersion distribution along an optical fiber transmission link. A constructive measurement technique has been offered in this paper, in which a four wavelength bidirectional optical time domain reflectometer (OTDR) has been used to compute the chromatic dispersion allocation beside an optical fiber transmission system. To improve the correction factor a novel formulation has been developed, which leads to an enhanced and defined measurement. The investigational outcomes obtained are in good harmony
[en] We demonstrate the working principle of a one-dimensional intensity-based fiber-optic displacement sensor. The sensor consists of one receiving fiber, which is moved laterally in the optical field emitted by an emitting fiber. It is shown numerically that the sensor response is highly linear (nonlinearity error of 0.1 to 2%) for a wide range of travel (2.24 to 860 μm). The sensor response is also simulated experimentally using a highly precise robot, the results of which correspond very closely to numerical ones. Linearity, travel, and sensitivity are experimentally determined for different gaps between the emitting and the receiving fibers (10 μm to 10 mm). A design chart that includes the nonlinearity error (0.5% to 2%), the travel (2.78 to 860 μm), the sensitivity (0.032 to 0.37 dB/μm), and the gap distance (1 to 10 mm) is finally proposed.
[en] A two-dimensional (2D) tilt sensor based on three optical fiber Bragg gratings (FBGs) is proposed and demonstrated. Experimental results show that a high measurement sensitivity of 192 pm/° and resolution of 0.005° can be achieved and the measurement is insensitive to temperature. Furthermore, the FBGs were subjected to the force directly without any force transmission, which ensures a high measurement accuracy of 0.1°
[en] One of the most important requirements for optical fibres as waveguiding media is uniformity. Polarisation-maintaining anisotropic fibres contain a special type of nonuniformity, which leads to polarisation cross-talk: optical power is transferred from one polarisation mode to the orthogonal mode. In this paper, we report a technique for detecting and locating such nonuniformities in a PANDA anisotropic single-mode fibre using polarised reflectometry. (fiber optics)