Metal roughness profile inspection using a micro-displacement fiber optic bundled sensor

A system and method for roughness or surface profile inspection for a simple polished cylindrical metal using a micro-displacement fiber optic bundled sensor system is demonstrated. The system used a red laser, a probe, a photo-detector, along with an 8 bit ADC and a computerized data acquisition system. The bundled sensor probe consists of both a transmitting and a receiving fiber. This sensor system adopts an intensity modulation technique based on a target of reflecting surface or mirror. The transmitted light of the red laser emits from the transmitting probe impinges the target surface and partially reflected back to the receiving probe. The intensity of the reflected light is measured. The micro-displacement sensor system has high linearity areas in the range of 550 mu m (150-700) mu m and in the range of 900 mu m (1550-2450) mu m. Its sensitivity was 0.15 mu m. The sample has a roughness index of 23%. This method is practically suitable in conjunction with a micro-computed tomography system in order to determine the exact surface profile of the 3D tomography object being inspected prior to the image reconstruction.