Anomaly Detection In Optical Fiber Illumination

Nowadays,the technology of semiconductor lighting is closed to mature.Optical fiber-guide lighting system is a new favorite of lighting technology,which is a combination of optical fiber and semiconductor illumination,due to its advantages of photo-electric separation,safety,reliability,long service life,flexible transmission and simple maintenance.Therefore,it is of great significance to study the anomaly detection in laser fiber lighting.In the fiber-guide lighting system,watt-level flux should be coupled into the core of fiber,so the power density is very high.The optical fiber is possible to be deteriorated after undergoing the highly power density beam,and is easy to cause accidents such as combustion when the end face of fiber was polluted.To overcome the above problem,two abnormal detection methods of laser fiber illumination(intra-fiber detection and extra-fiber detection)are proposed in the presented dissertation.In the intra-fiber detection scheme,a free-form lens was designed by using a tailoring method which can couple an LD laser beam at wave length of 450 nm into a multimode fiber with a core diameter of 62.5?m and NA of 0.26.A converging lens of signal rays,which is come from the back-scattering light of fluorescent powder,was designed with a supporting oval method.Near infrared light detection and fluorescence detection methods are respectively employed in the out-of-fiber detection scheme.The research results are as following in detail:1.Inner-fiber inspection scheme.A free-form surface coupling lens was designed,and its coupling efficiency is about 94.4%.Simultaneously,a signal light converging lens was designed and its convergence efficiency theoretical value is about 43%.Coupling lens affects convergence efficiency,without the effect of coupling lens,converging lens convergence efficiency is 32.1%,otherwise,the efficiency is 25%.2.Outer-fiber inspection scheme with the way of “1-7”.The SE method was adopted to design a reverse coupling cover for near-infrared light detection of an 8-core optical fiber cable.The reflective cover is used to couple the detection signal light in a fiber into the other 7 optical fibers respectively.The coupling efficiency of each optical fiber is about 8.5%,which is enough to meet the detection requirements.3.Outer-fiber inspection scheme with the way of “1-1”.One fiber is for blue light while the other one is for detection.The detection light is come from the back scattering of the fluorescent cap.The experimental results show that: the illuminance on the detector is about 20~50 lx when the length of the optical fiber is 100 m and the output power of the illumination optical fiber is about 1.35W~3.13 W,and when the detection optical fiber is 800 m and the output power of the illumination optical fiber is 3.13 W,the detector can also detect the illuminance of 9 lx.