1.55 μm wavelength region high-stability optical fibre lossvariation measurement using fibre coupler

A 1.55 μm-wavelength high-stability optical fibre loss variation measurement system, using a comparison method with an optical fibre coupler, was developed. Long-term stability within ±0.001 dB over a 120 hour period at a room temperature variation of ±2.2°C has been achieved     

Analysis and measurement of modal noise in an optical fibre

Modal noise in analogue and digital optical fibre systems has been demonstrated to be a significant effect. In this letter, we give some theoretical and experimental results concerning the behaviour of the signal-to-noise ratio in presence of modal noise considering the power from the exit face of a short sample of a graded-index multimode optical fibre.     

Radioluminescent clad optical fibre X-ray sensor

An optical fibre X-ray sensor using cladding to core coupling of radioluminescent emissions from X-ray phosphors is presented. The sensor is tested using a line source normally used in the pre-ionisation of an excimer laser and is calibrated against a pen dosimeter and the emission intensity of a scintillating block.     

OPSEF: an optical sensor for measurement of high electric field intensity

An optical sensor for measurement of high electric field intensity by means of the electro-optic effect in single-crystal bismuth silicon oxide has been successfully developed and the fundamental characteristics measured. By use of this sensor, the electric field intensities between parallel and coaxial electrodes have been measured.     

Vortex shedding fluid flowmeter using optical fibre sensor

An optical fibre flowmeter is described which uses a single fibre mounted transversely to the fluid flow within the pipe. The fibre is vibrated by the natural phenomenon of vortex shedding, causing phase modulation of the optical carrier within. The modulation is detected at the fibre exit by the fibredyne technique, and the flow rate determined from the vibration frequency.     

Simplified optical fibre end-cleave angle measurement device

A modified method of fibre end-cleave angle measurement is described and compared with alternative techniques. The device has no precision parts and has a resolution of better than 0.25 degrees of end angle.     

Photosensitivity measurement in optical fibre with Bragg grating interferometers

A new technique based on two low-finesse fibre Bragg grating Fabry-Perot interferometers to study photosensitivity in optical fibre is presented. Phase evaluation using the Fourier spectra allows precise determination of the evolution of the refractive index with accumulated fluence. Results are given for different germanium/boron codoped fibres and for hydrogen-loaded fibres.     

基于光纤传感器的智能污泥浓度测量系统的研究

介绍了一种基于光纤污泥浓度传感器的实时监测系统。该系统采用了通用单片机作为系统的核心,以LED为光源,利用PWM方式控制发光脉冲,通过光纤传递光信号,以反射结构的光纤探头作为敏感元件,对APD接收到的采样信号进行处理,根据测量结果控制设备来调节污泥浓度。这个装置的特点是体积小、可靠性高、方便和可远程实时检测等。     

光纤电流传感器的实验系统与性能

光纤电流传感器是把光纤缠绕在导线周围,光纤既是信息的传输元件又是信息的敏感元件,因此这种传感器的地面设备以外的部份就只是整根的光纤,这不但解决了绝缘问题,且具有抗电磁干扰、灵敏度高、测量动态范围大的优点,具有广泛的应用前景.二、基本关系式因光纤材料的Faraday效应,在长直导线上绕有N圈光纤时,其偏振光的旋转角度θ为:θ=VNI(1)式中V是Verdet常数.图1为实验系统简图.从波长为632.8nm的He-Ne激光器发出的激光束经     

光纤传感系统评述

光纤传感器对于传感各种物理量有着很大的潜力，其中包括声音、磁场、电流、温度、荧光、加速度、速度和旋转率等等。国外已形成一个新的有前途和研究领域，估计到八十年代后期将会进入实用阶段。本文主要介绍光纤传感器的优点和基本原理。     

An optical fibre sensor for use in a tissue cutting tool

This pre-study investigates a fibre optic alternative to more conventional sensors for measuring force indirectly as bending or deflection in a medical robotic application. The paper discusses problems regarding the integration of fibre optics into a cutting tool for the removal of prostate gland tissue. The aim is to integrate the sensor in a tube rod with an inner diameter of 0.6 mm and use it as a force feedback sensor for the control system of the robot. The paper proposes and evaluates an inexpensive opto-mechatronic device for launching light into and detecting light received from an optical fibre. A simple sensor prototype is constructed to show the feasibility to use a fibre optic sensor for the prostate gland cutting tool.     

Index profile determination in transition region of optical fibre preform

It is shown that the refractive-index profile in the transition region of an optical fibre preform can be obtained by a combination of a measurement of the deflection function and a ray-tracing procedure.     

Novel measurement method for axial residual stress in optical fibre

A novel method for measuring axial residual stress in optical fibre is presented. It is shown that axial residual stress profiles can be reconstructed from optical retardation data measured for several orientations of a fibre. Using this method, the axial stress profile in polarisation-maintaining fibre has been clarified.     

Distributed temperature sensor using Nd3+ -doped optical fibre

We report the measurement of temperature distribution with an Nd3+ -doped multimode optical fibre. By exploiting the temperature-sensitive absorption bands of the doped-glass core, temperature was measured to an accuracy of 2°C over the range ?50°C to 100°C. A spatial resolution of 15 m over a fibre length of 140 m was obtained.     

Hole-assisted optical fibre cord identification technique employing visible light without interrupting communication

A new identification technique for hole-assisted optical fibre cord is proposed, which is realised by launching visible light into the fibre core and observing the leaked light from a bent fibre, without affecting communication.     

Highly sensitive optical hydrogen sensor using circular Pd-coatedsinglemode tapered fibre

A novel optical hydrogen sensor, based on the absorption change of the evanescent fields in a circular Pd-coated singlemode tapered fibre is presented. The proposed sensor is polarisation independent and its sensitivity is adjustable by means of the taper diameter, interaction length, and/or light wavelength. A simple light transmission measurement setup is used to test the sensor. The sensor is suitable for the detection of low hydrogen concentrations with high sensitivity and fast time response. Transmission changes as high as 60% are demonstrated