Research On Performance Evaluation And Test Method Of Astronomical Fiber Optic Cable

With the development of astronomical technology,the application of optical fiber in astronomical observation is deepening.Optical fiber as a light medium,it has the advantages of anti-electromagnetic radiation,good toughness,great mechanical strength,strong operability,low cost and so on.In this paper,fiber is mainly used in Integral Field Unit(IFU).IFU obtains three-dimensional spectral information of one-dimensional wavelength in two-dimensional space through single exposure,improving efficiency without losing spatial resolution of spectrum.The performance of optical fiber has the greatest influence on the performance of the whole system,so it is necessary to design a reasonable structure of optical fiber and cable.In this paper,the Fiber Arrayed Solar Optical Telescope(FASOT)is tested and evaluated.In this paper,based on the theory of step-mode multimode optical fiber transmission,several parameters affecting the service life and transmission loss of optical fiber are expounded through the analysis of optical waveguide and focal ratio degradation theory,which provides the theoretical basis for the design of optical fiber and cable,and puts forward the target and requirement of the design of optical fiber and cable.The transmission efficiency and output focal ratio of optical fiber have always been important parameters of optical fiber in astronomical research.The research content of this paper is based on the FASOT-IFU project,and the design of optical fiber structures that can protect optical fiber,stabilize transmission performance and reduce external stress for the more than 8,000 optical fiber required by the FASOT projectIn order to accurately measure the transmission performance of optical fiber and cable,a focal ratio measurement system based on energy method is designed.Compared with the traditional CCD measurement method,this test system has advantages of convenience and rapidity,and is better than the CCD measurement method in terms of measurement accuracy.The system consists of front and rear parts.The front part can control the incident focal ratio of optical fiber,and the latter can measure the transmission efficiency and outgoing focal ratio of optical fiber.First of all,the system is used to test a layer stranded optical cable without reinforcing core.Through analyzing the data structure,it is found that under different laying conditions,the output focal ratio of optical fiber inside the fiber optic cable differs by nearly 20%,indicating that this cable has problems such as uneven distribution of optical fiber stress and excessive influence of external stress on internal optical fiber.Considering the advantages and disadvantages of fiber bundle structure design,it will affect the whole.By optimizing the structure of fiber bundles,a kind of fiber bundle structure with UV curing adhesive and 7 multi-mode fiber bundles arranged in hexagonal structure,and oil paste for filling the gap,is obtained.The minimum bending radius of the fiber bundle of this structure is 5cm,which can withstand the pressure of 70N and the tension below 6N.In addition,in the test,the fiber transmission efficiency within the fiber bundle is stable and the fluctuation is less than 1%,indicating that the internal force of the fiber bundle is uniform.Combined with the optimization of fiber optic cable structure,the fiber optic cable can meet the application requirements.