FPGA-based Research On The Key Technology Of Optical Fiber Coating Removal By Laser Ablation

Optical fiber coating protects the fiber core and cladding from outside mechanical and chemical damage and pollution, so that the optical fiber performance and service life are guaranteed. In recent years, with the rapid development of optical fiber sensors industry, it's necessary to do secondary processing of optical fiber, removing coating. The mechanical and chemical methods are widely used in laboratory. Machinery method causes micro-cracks on the surface of the optical fiber cladding, which inevitably deteriorates the performance of fiber and shortens its service life. Chemical methods have the following drawbacks: the process is complex; the length of removed coating is short; thus it's not suitable for optical fiber secondary online processing. The above shortcomings of mechanical and chemical methods can be avoided by utilizing laser ablation to remove coating. This method is easy to control, is suitable for industrial production and causes no additional damage to optical fiber.This dissertation focuses on the application of laser ablation optical fiber coating method and it's research of key technology.First, this dissertation carrys out the structural and functional design for laser ablation optical fiber coating systems, including two dimensional (horizontal and vertical) microscopic imaging, fiber drawing, laser driver and power control, the control of laser position motion,and so on.Second, based on FPGA, it designs microscopic imaging system. The drive of image sensor, image processing and image display are completed on the basis of FPGA. In addition,automatic focusing system is completed, the center coordinates of laser tail fiber end face and fiber side vertical are determined.Third, with the design of the laser ablation of optical fiber coating, the dissertation builds the experiment platform. Using laser ablates the standard single-mode fiber coating. The effect of coating removal are tested in the case that the space between fiber and laser ablation is different. The largest spacing of optical fiber and laser is determined.Finally, using the fiber ablated by the laser and based on electric heating fused method,make a long period fiber grating, construct platform for measuring temperature and measure the temperature sensing properties of the long period fiber grating.