Papers by Keyword: Optical Fibre

Abstract: In this paper, we proposed an optical vibration and circulation technique of a microsphere using plural optical flat-top fibres, mounted horizontally on the bottom of a sample chamber, and verify that an optically trapped object can be circulated by controlling laser power emerging from optical fibres without moving the optical fibres. We theoretically analyzed the optical forces exerted on a microsphere, a 10μm diameter polystyrene particle (refractive index 1.59), by laser beams. From these theoretical results, we verify that our proposed optical manipulation technique is useful for the manipulation of biological cells.

Abstract: In this paper, chemically etched axicon fibre was proposed for laser trapping of micro-objects dispersed in liquid. We fabricated axicon microlenses on a single-mode bare optical fibre using a selective chemical etching technique. The laser beam from a fibre axicon microlens was strongly focused and optical forces were sufficient to move microorganisms and biological cells without physical contact. From the experimental results, it was found that our proposed fibre axicon microlens is a promising tool for cell trapping and the apex angle of the chemically etched fibre axicon microlens is a very important parameter for laser trapping.

Abstract: The detection technique of small module gears has a very important research and application value. In this paper, a composite measuring method is presented based on combining traditional mechanical contact measurement with optical image non-contact measurement. First of all, this paper analyzes the basic principle of composite probe composed of optical fiber stylus and CCD imaging system. The tail-end of the stylus is shaped into a micro-sphere, where a small refection mirror is designed. When the laser is transmitted through the fiber, a round facula can be seen from the CCD camera. The micro-sphere is kept contact with the surface of the measured gear at the time of measuring and the error of the measured gear will be reflected by the offset of the facula center. Meanwhile, the sub-pixel extraction algorithm for the center of facula image is presented. Then the calibration principle and method of probe system is analyzed in detail. Finally, the data processing principle of the presented method is discussed for gear measurement.

Abstract: The mechanical strength and failure behavior of two photonic crystal silica optical fibers with different diameters were investigated using tensile test. The effect of polymer coating on the failure behavior was also studied. The results indicated that all fibers failed in a brittle manner and the failure normally initiated from fiber surfaces. The failure loads observed in the coated fibers are higher than that in bare fibers and the reason is explained by the apparent delamination between the fiber and the polymer coating when loaded on the fiber surfaces. The relationship between a characteristic parameter measured on the fracture surfaces and the failure stress was examined.

Abstract: To meet the need of optical fiber photoreactor designed by mechanism of TiO2 photocatalysis, nanometer TiO2 was coated on the surface of optical fiber by dipping nude fibers into an Al(H2PO4)3-contained TiO2 slurry. Effects of slurry conditions, including content of TiO2 and addition of Al(H2PO4)3 adhesive, on coating thickness and quality were determined. Coating process, especially the effect of coating times, was also concerned. Based on the experimental results, fitting slurry conditions and process parameters were suggested for obtaining high-quality TiO2 coating on optical fiber surface.

Abstract: In order to meet a need of application of photocatalyst, a slurry dipping method was adopted for nano-TiO2 coating on optical fiber. Three slurry states were designed and their effects on coating quality were investigated. Experimental results showed that paste state may lead to surface cracks in coating. Both flocculent and dispersive slurry states can form high quality coatings whose coating microstructures are different, the former resulted in a loose and thicker coating and the later resulted in a dense and thinner coating, which supplied a basis for further study on effect of photocatalytic reaction and design of photocatalyst reactor.

Abstract: The state of the wheel surface after dressing is important for processing of a surface to the nano-order level. A laser dresser was developed using ultraviolet (UV) laser light, which imparts no mechanical damage to the resin bond. One feature of this system is that UV laser energy is transmitted by a special optical fiber for UV light, and is transmitted only to the resin bond. Using this newly developed laser dresser, it was possible to ablate the resin bond to a depth of over 2 microns using a fiber with a core diameter of 200 microns.

Abstract: The aim of this study is to develop a new method to measure one-dimensional dose distribution of high-energy electron using a miniature fiber-optic radiation sensor. The measurements are made by a thin plastic optical fiber with an organic scintillating sensor tip. The scintillating light in the visible wavelength range is guided to a silicon photodiode by plastic optical fiber in order to convert light output to electrical signal. The one-dimensional spatial dependence of elctron beam is measured by moving the sensor tip with uniform speed. It is shown that this fiber-optic radiation sensor has better spatial resolution than conventional ion chamber and it needs much less time to measure one-dimensional dose distribution in the high radiation fields.

Abstract: Photonic band gap (PBG) fibers have generated significant interest over the last decade due to the unique set of properties these fibers exhibit. In general, these fibers have been made by drawing a series of glass tubes (which are stacked in an ordered array) into a fiber. These fibers consist of an ordered arrangement of holes or tubes in a glass matrix. In this invited paper we describe a novel type of fiber, called HORHOFs (hybrid ordered random hole optical fibers). In these fibers, the refractive index of the ordered-hole region is controlled by incorporation of very small tubes of glass produced in-situ during the fiber drawing process. The result is a region of controllable glass density inside the “ordered hole”. This allows tailoring of the refractive index of the hole region and of the matrix glass around the holes. Description of the process to produce these new types of fibers, micrographs of some of the fibers produced, some potential applications, and the results of some computer modeling to predict the properties of these fibers, are presented.

Abstract: The objective of this paper is to develop a fiber-optic acoustic emission(AE) sensor applicable to on-line monitoring systems which is suitable for long-distance signal transmission. An AE sensor was developed by use of a fiber-optic cantilever and an extrinsic Fabry-Perot interferometer(EFPI). The efficiency of signal processing was improved by driving the high frequency AE signals into the low frequency ones. In order to verify the developed sensor, the tensile and the pencil lead fracture(PLF) tests were performed including the experiment showing the Kaiser effect. From tests, AE signals were successfully detected in the elastic-plastic deformation range, especially higher signals at the crack propagation. The developed sensor is expected to be used for an on-line monitoring of crack propagation in mechanical systems.