Precision Alignment of Optical Fibers Based on Telecentric Stereo Microvision

Optical fiber alignment plays an important role in assembling an optical fiber-based system. Proper alignment can improve optical transmission efficiency of the spliced fiber. As for traditional methods, passive alignment has its drawback of less accuracy, and the active method based on optical power sensing is complex and often cannot find the best solution. In this paper, a novel precision closed-loop method for optical fiber alignment based on telecentric lens is introduced. First, to improve the measurement accuracy of the binocular vision system, a quick and high-precision image-processing algorithm for the glass core of an optical fiber is proposed. Then, a stereo matching problem is solved by combining the epipolar constraint with the geometry constraint especially for telecentric lens, and the 3-D recovery of the optical fibers is achieved. Finally, with the help of a proposed simple eye-to-hand calibration for this microalignment system, a coarse-to-fine strategy is put forward to deal with this five-degree-of-freedom alignment task. The experimental results showed that the proposed method had high performance such as prominent precision and strong robustness in 3-D optical fiber alignment.