Optical Fiber For Rapid Detection Of The Concentration Of Particles In The Micro-sample Study

There are great advantages in detecting concentration of suspending particles in liquid with light. It is convenient to operate by this way and the analytical precision is enhanced with the improvement of photoelectric detection technology, there are some achievements in this aspect home and abroad. Optical fibers show more potential to detect the concentration of micro-sample, with characteristic of flexibility, low transmission loss and small fiber diameter and so on.Based on the theory about light scattering and absorption, the structure with optical fibers for concentration detecting of micro-sample is designed and manufactured, the detecting experiment is partly put out in this paper. The main contents are listed as follows:1. From the phenomenon that incident light is scattered and absorbed by particles in liquid and Mie theory about light scattering, the relation between properties of particles and extinction coefficient is analyzed by MATLAB simulation, and the variation rule of scattering light intensity with angle is explained. Directions for the design of the structure of concentration detecting become available. Based on Lambert-Beer theory, the relation between trasmitted light and the particle contents is analyzed. The scheme of concentration detecting for micro-sample of suspending liquid is ensured, the way is present that both of the light scattered in different angles and light trasmitted is employed to detect concentration.2. Following the simulation of scattering light intensity, a concentration detecting device with optical fibres for micro-sample is designed, in which the angle of reveiving light is changeable continuously. Fibre laster is used to serve as the light source because of the request for properties of incident light and the advantages of optical fiber. According to the comparison of kinds of optical-electrical converters, silicon photoelectric generator is used to serve as the detector for light. Voltage regulated and amplification circuit is design in order to improve the measurement accuracy of measureing.3. The scheme of concentration detecting is put forward and the experiment is carryed out. At last, the experiment datas process is executed, the mehtod of trasmitted light detecting and scattered-trasmitted radio of light is suitable respectively for the different range of concentration. Several problems in the experiment are also listed, along with the improvements.