High speed measurement of the core diameter of a step-index optical fiber

Abstract

The forward scattering light pattern from a clad optical fiber illuminated perpendicular to its axis is characteristic of the outer diameter, the core diameter, and their respective refractive indices. This pattern is detected by a diode array detector to produce a video signal representation of the scattering pattern. Electronic circuits have been developed to analyze the scattering pattern and detect the angular position of the modulation characteristics of the pattern. This provides a determination of the core to outer diameter ratio of the fiber. Using linearization circuits and the outer diameter measurement signal, linear measurement signal voltages of both core ratio and core diameter are derived. The measurement of core ratio refers to a particular radius vector and means that determinations of circularity and concentricity can also be made.

Research on the measurement method of geometric parameters of microstructure fiber end based on machine vision

“…However, all of these methods need a lot of judgement of people and can not measure in real time, and measurement accuracy can not meet requirement [2,3]. Based on these considerations above, this paper measures the geometric parameters of ellipse twin-core fiber end based on machine vision, image is detected by CMOS camera and is transformed into digital signal, and process signal of image using advanced computer hardware and software technology, obtain all kinds of image eigenvalue, and then proceed pattern recognition and coordinate calculation, sequentially the measurement which is exact, fast, reliable and digitization has come true [4,5], and lays a foundation for further analyzing performance of microstructure fiber.…”