Roundness Measurements of Boreholes with Small Diameters Using a Fiber-optic Sensor

摘要

Tactile probing systems are state-of-the-art for roundness measurements. However, the inspection of materials that can easily be deformed or even damaged often prohibits tactile probing. Measurements inside small cavities like sub-millimeter boreholes are often impossible, because of the large diameter of tactile probe tips. Within this work a fiber-optic system for roundness measurements is described. The sensing probe can be miniaturized down to diameters of 800 (mu)m or even below. As the measuring principle is based on low-coherence interferometry, the system provides fast, non-tactile, and highly accurate measurements of the inner roundness and cylindricity of small boreholes.