Metal purity detection using non-target reflectivity plastic optical fiber displacement sensor

A fiber optic displacement sensor (FODS) that uses a fiber probe to detect metal purity based on intensity modulation technique is proposed and demonstrated. A He-Ne laser is used as the light source and three different types of metals which consists of nickel brass, cupronickel, and copper clad-steel are used as the target samples. It is observed that the voltages increase as the metal brightness changes from dark to bright, which consequently depends on the amount of nickel content in the metal. The highest sensitivity of 1.0459 for the front slope is achieved by nickel brass, thus making it useful for close-distance targets. The proposed system is environment friendly and low cost, with additional advantages of high sensitivity and easy installation. Besides its ability to determine the type of metal sample, this FODS can provide a real-time monitoring system suitable for broader applications in sensor field.